From 49ed25b5d2d5dc88f9fa3e268d9bd210acc875de Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <n.nethercote@gmail.com>
Date: Thu, 18 Apr 2024 21:31:17 +1000
Subject: [PATCH 1/4] Remove `NtExpr` and `NtLiteral`.

Notes about tests:
- tests/ui/rfcs/rfc-2294-if-let-guard/feature-gate.rs: some messages are
  now duplicated due to repeated parsing.

- tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.rs: ditto.

- `tests/ui/proc-macro/macro-rules-derive-cfg.rs`: the diff looks large
  but the only difference is the insertion of a single
  invisible-delimited group around a metavar.

- `tests/ui/attributes/nonterminal-expansion.rs`: a slight span
  degradation, somehow related to the recent massive attr parsing
  rewrite (#135726). I couldn't work out exactly what is going wrong,
  but I don't think it's worth holding things up for a single slightly
  suboptimal error message.
---
 compiler/rustc_ast/src/ast_traits.rs          |   2 -
 compiler/rustc_ast/src/mut_visit.rs           |   2 -
 compiler/rustc_ast/src/token.rs               |  71 ++---
 compiler/rustc_ast/src/tokenstream.rs         |   1 -
 compiler/rustc_expand/src/mbe/transcribe.rs   |  35 ++-
 compiler/rustc_parse/messages.ftl             |   2 +-
 compiler/rustc_parse/src/errors.rs            |   4 +-
 compiler/rustc_parse/src/parser/expr.rs       | 220 +++++++++-----
 compiler/rustc_parse/src/parser/item.rs       |  53 +++-
 compiler/rustc_parse/src/parser/mod.rs        |  32 +-
 .../rustc_parse/src/parser/nonterminal.rs     |  16 +-
 compiler/rustc_parse/src/parser/pat.rs        |   2 +-
 tests/ui/attributes/nonterminal-expansion.rs  |   4 +-
 .../attributes/nonterminal-expansion.stderr   |  11 +-
 .../cfg-attr-syntax-validation.rs             |   2 +-
 .../cfg-attr-syntax-validation.stderr         |   2 +-
 tests/ui/macros/nonterminal-matching.rs       |   4 +-
 tests/ui/macros/nonterminal-matching.stderr   |   4 +-
 .../extern-abi-from-mac-literal-frag.rs       |   4 +
 tests/ui/parser/float-field-interpolated.rs   |   8 +-
 .../ui/parser/float-field-interpolated.stderr |   8 +-
 .../ui/parser/macro/trait-non-item-macros.rs  |   2 +-
 .../parser/macro/trait-non-item-macros.stderr |   2 +-
 .../proc-macro/macro-rules-derive-cfg.stdout  | 129 +++++----
 .../rfc-2294-if-let-guard/feature-gate.rs     |   2 +
 .../rfc-2294-if-let-guard/feature-gate.stderr |  26 +-
 .../disallowed-positions.feature.stderr       | 264 +++++++++--------
 .../disallowed-positions.no_feature.stderr    | 274 ++++++++++--------
 .../disallowed-positions.nothing.stderr       | 196 ++++++-------
 .../disallowed-positions.rs                   |   4 +
 30 files changed, 801 insertions(+), 585 deletions(-)

diff --git a/compiler/rustc_ast/src/ast_traits.rs b/compiler/rustc_ast/src/ast_traits.rs
index 849cc650e9d6a..c9e2e9911ef0a 100644
--- a/compiler/rustc_ast/src/ast_traits.rs
+++ b/compiler/rustc_ast/src/ast_traits.rs
@@ -209,13 +209,11 @@ impl HasTokens for Attribute {
 impl HasTokens for Nonterminal {
     fn tokens(&self) -> Option<&LazyAttrTokenStream> {
         match self {
-            Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => expr.tokens(),
             Nonterminal::NtBlock(block) => block.tokens(),
         }
     }
     fn tokens_mut(&mut self) -> Option<&mut Option<LazyAttrTokenStream>> {
         match self {
-            Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => expr.tokens_mut(),
             Nonterminal::NtBlock(block) => block.tokens_mut(),
         }
     }
diff --git a/compiler/rustc_ast/src/mut_visit.rs b/compiler/rustc_ast/src/mut_visit.rs
index 30af6d910bfa2..f7d13acdfc402 100644
--- a/compiler/rustc_ast/src/mut_visit.rs
+++ b/compiler/rustc_ast/src/mut_visit.rs
@@ -899,8 +899,6 @@ pub fn visit_token<T: MutVisitor>(vis: &mut T, t: &mut Token) {
 fn visit_nonterminal<T: MutVisitor>(vis: &mut T, nt: &mut token::Nonterminal) {
     match nt {
         token::NtBlock(block) => vis.visit_block(block),
-        token::NtExpr(expr) => vis.visit_expr(expr),
-        token::NtLiteral(expr) => vis.visit_expr(expr),
     }
 }
 
diff --git a/compiler/rustc_ast/src/token.rs b/compiler/rustc_ast/src/token.rs
index 6e6f0f1b2660e..2081777fff359 100644
--- a/compiler/rustc_ast/src/token.rs
+++ b/compiler/rustc_ast/src/token.rs
@@ -198,16 +198,17 @@ impl Lit {
         }
     }
 
-    /// Keep this in sync with `Token::can_begin_literal_maybe_minus` excluding unary negation.
+    /// Keep this in sync with `Token::can_begin_literal_maybe_minus` and
+    /// `Parser::eat_token_lit` (excluding unary negation).
     pub fn from_token(token: &Token) -> Option<Lit> {
         match token.uninterpolate().kind {
             Ident(name, IdentIsRaw::No) if name.is_bool_lit() => Some(Lit::new(Bool, name, None)),
             Literal(token_lit) => Some(token_lit),
-            Interpolated(ref nt)
-                if let NtExpr(expr) | NtLiteral(expr) = &**nt
-                    && let ast::ExprKind::Lit(token_lit) = expr.kind =>
-            {
-                Some(token_lit)
+            OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
+                MetaVarKind::Literal | MetaVarKind::Expr { .. },
+            ))) => {
+                // Unreachable with the current test suite.
+                panic!("from_token metavar");
             }
             _ => None,
         }
@@ -590,6 +591,9 @@ impl Token {
     /// for which spans affect name resolution and edition checks.
     /// Note that keywords are also identifiers, so they should use this
     /// if they keep spans or perform edition checks.
+    //
+    // Note: `Parser::uninterpolated_token_span` may give better information
+    // than this method does.
     pub fn uninterpolated_span(&self) -> Span {
         match self.kind {
             NtIdent(ident, _) | NtLifetime(ident, _) => ident.span,
@@ -642,12 +646,7 @@ impl Token {
             PathSep                           | // global path
             Lifetime(..)                      | // labeled loop
             Pound                             => true, // expression attributes
-            Interpolated(ref nt) =>
-                matches!(&**nt,
-                    NtBlock(..)   |
-                    NtExpr(..)    |
-                    NtLiteral(..)
-                ),
+            Interpolated(ref nt) => matches!(&**nt, NtBlock(..)),
             OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
                 MetaVarKind::Block |
                 MetaVarKind::Expr { .. } |
@@ -677,11 +676,6 @@ impl Token {
             Lt |                                 // path (UFCS constant)
             Shl => true,                         // path (double UFCS)
             Or => matches!(pat_kind, PatWithOr), // leading vert `|` or-pattern
-            Interpolated(nt) =>
-                matches!(&**nt,
-                    | NtExpr(..)
-                    | NtLiteral(..)
-                ),
             OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
                 MetaVarKind::Expr { .. } |
                 MetaVarKind::Literal |
@@ -724,7 +718,7 @@ impl Token {
         match self.kind {
             OpenDelim(Delimiter::Brace) | Literal(..) | Minus => true,
             Ident(name, IdentIsRaw::No) if name.is_bool_lit() => true,
-            Interpolated(ref nt) => matches!(&**nt, NtExpr(..) | NtBlock(..) | NtLiteral(..)),
+            Interpolated(ref nt) => matches!(&**nt, NtBlock(..)),
             OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
                 MetaVarKind::Expr { .. } | MetaVarKind::Block | MetaVarKind::Literal,
             ))) => true,
@@ -768,22 +762,12 @@ impl Token {
     ///
     /// In other words, would this token be a valid start of `parse_literal_maybe_minus`?
     ///
-    /// Keep this in sync with and `Lit::from_token`, excluding unary negation.
+    /// Keep this in sync with `Lit::from_token` and `Parser::eat_token_lit`
+    /// (excluding unary negation).
     pub fn can_begin_literal_maybe_minus(&self) -> bool {
         match self.uninterpolate().kind {
             Literal(..) | Minus => true,
             Ident(name, IdentIsRaw::No) if name.is_bool_lit() => true,
-            Interpolated(ref nt) => match &**nt {
-                NtLiteral(_) => true,
-                NtExpr(e) => match &e.kind {
-                    ast::ExprKind::Lit(_) => true,
-                    ast::ExprKind::Unary(ast::UnOp::Neg, e) => {
-                        matches!(&e.kind, ast::ExprKind::Lit(_))
-                    }
-                    _ => false,
-                },
-                _ => false,
-            },
             OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(mv_kind))) => match mv_kind {
                 MetaVarKind::Literal => true,
                 MetaVarKind::Expr { can_begin_literal_maybe_minus, .. } => {
@@ -798,14 +782,6 @@ impl Token {
     pub fn can_begin_string_literal(&self) -> bool {
         match self.uninterpolate().kind {
             Literal(..) => true,
-            Interpolated(ref nt) => match &**nt {
-                NtLiteral(_) => true,
-                NtExpr(e) => match &e.kind {
-                    ast::ExprKind::Lit(_) => true,
-                    _ => false,
-                },
-                _ => false,
-            },
             OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(mv_kind))) => match mv_kind {
                 MetaVarKind::Literal => true,
                 MetaVarKind::Expr { can_begin_string_literal, .. } => can_begin_string_literal,
@@ -869,12 +845,17 @@ impl Token {
 
     /// Is this a pre-parsed expression dropped into the token stream
     /// (which happens while parsing the result of macro expansion)?
-    pub fn is_whole_expr(&self) -> bool {
+    pub fn is_metavar_expr(&self) -> bool {
         #[allow(irrefutable_let_patterns)] // FIXME: temporary
         if let Interpolated(nt) = &self.kind
-            && let NtExpr(_) | NtLiteral(_) | NtBlock(_) = &**nt
+            && let NtBlock(_) = &**nt
         {
             true
+        } else if matches!(
+            self.is_metavar_seq(),
+            Some(MetaVarKind::Expr { .. } | MetaVarKind::Literal | MetaVarKind::Path)
+        ) {
+            true
         } else {
             matches!(self.is_metavar_seq(), Some(MetaVarKind::Path))
         }
@@ -882,6 +863,7 @@ impl Token {
 
     /// Is the token an interpolated block (`$b:block`)?
     pub fn is_whole_block(&self) -> bool {
+        #[allow(irrefutable_let_patterns)] // FIXME: temporary
         if let Interpolated(nt) = &self.kind
             && let NtBlock(..) = &**nt
         {
@@ -1100,8 +1082,6 @@ pub enum NtExprKind {
 /// For interpolation during macro expansion.
 pub enum Nonterminal {
     NtBlock(P<ast::Block>),
-    NtExpr(P<ast::Expr>),
-    NtLiteral(P<ast::Expr>),
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Encodable, Decodable, Hash, HashStable_Generic)]
@@ -1191,15 +1171,12 @@ impl Nonterminal {
     pub fn use_span(&self) -> Span {
         match self {
             NtBlock(block) => block.span,
-            NtExpr(expr) | NtLiteral(expr) => expr.span,
         }
     }
 
     pub fn descr(&self) -> &'static str {
         match self {
             NtBlock(..) => "block",
-            NtExpr(..) => "expression",
-            NtLiteral(..) => "literal",
         }
     }
 }
@@ -1218,8 +1195,6 @@ impl fmt::Debug for Nonterminal {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match *self {
             NtBlock(..) => f.pad("NtBlock(..)"),
-            NtExpr(..) => f.pad("NtExpr(..)"),
-            NtLiteral(..) => f.pad("NtLiteral(..)"),
         }
     }
 }
@@ -1242,7 +1217,7 @@ mod size_asserts {
     // tidy-alphabetical-start
     static_assert_size!(Lit, 12);
     static_assert_size!(LitKind, 2);
-    static_assert_size!(Nonterminal, 16);
+    static_assert_size!(Nonterminal, 8);
     static_assert_size!(Token, 24);
     static_assert_size!(TokenKind, 16);
     // tidy-alphabetical-end
diff --git a/compiler/rustc_ast/src/tokenstream.rs b/compiler/rustc_ast/src/tokenstream.rs
index bdd244be6d1cc..161f8e67551fa 100644
--- a/compiler/rustc_ast/src/tokenstream.rs
+++ b/compiler/rustc_ast/src/tokenstream.rs
@@ -462,7 +462,6 @@ impl TokenStream {
     pub fn from_nonterminal_ast(nt: &Nonterminal) -> TokenStream {
         match nt {
             Nonterminal::NtBlock(block) => TokenStream::from_ast(block),
-            Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => TokenStream::from_ast(expr),
         }
     }
 
diff --git a/compiler/rustc_expand/src/mbe/transcribe.rs b/compiler/rustc_expand/src/mbe/transcribe.rs
index cffa4af6ac3d0..6e47ed6eb67c1 100644
--- a/compiler/rustc_expand/src/mbe/transcribe.rs
+++ b/compiler/rustc_expand/src/mbe/transcribe.rs
@@ -3,11 +3,10 @@ use std::sync::Arc;
 
 use rustc_ast::mut_visit::{self, MutVisitor};
 use rustc_ast::token::{
-    self, Delimiter, IdentIsRaw, InvisibleOrigin, Lit, LitKind, MetaVarKind, Nonterminal, Token,
-    TokenKind,
+    self, Delimiter, IdentIsRaw, InvisibleOrigin, Lit, LitKind, MetaVarKind, Token, TokenKind,
 };
 use rustc_ast::tokenstream::{DelimSpacing, DelimSpan, Spacing, TokenStream, TokenTree};
-use rustc_ast::{ExprKind, StmtKind, TyKind};
+use rustc_ast::{ExprKind, StmtKind, TyKind, UnOp};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{Diag, DiagCtxtHandle, PResult, pluralize};
 use rustc_parse::lexer::nfc_normalize;
@@ -340,6 +339,30 @@ pub(super) fn transcribe<'a>(
                             MetaVarKind::Pat(*pat_kind),
                             TokenStream::from_ast(pat),
                         ),
+                        MatchedSingle(ParseNtResult::Expr(expr, kind)) => {
+                            let (can_begin_literal_maybe_minus, can_begin_string_literal) =
+                                match &expr.kind {
+                                    ExprKind::Lit(_) => (true, true),
+                                    ExprKind::Unary(UnOp::Neg, e)
+                                        if matches!(&e.kind, ExprKind::Lit(_)) =>
+                                    {
+                                        (true, false)
+                                    }
+                                    _ => (false, false),
+                                };
+                            mk_delimited(
+                                expr.span,
+                                MetaVarKind::Expr {
+                                    kind: *kind,
+                                    can_begin_literal_maybe_minus,
+                                    can_begin_string_literal,
+                                },
+                                TokenStream::from_ast(expr),
+                            )
+                        }
+                        MatchedSingle(ParseNtResult::Literal(lit)) => {
+                            mk_delimited(lit.span, MetaVarKind::Literal, TokenStream::from_ast(lit))
+                        }
                         MatchedSingle(ParseNtResult::Ty(ty)) => {
                             let is_path = matches!(&ty.kind, TyKind::Path(None, _path));
                             mk_delimited(
@@ -869,10 +892,8 @@ fn extract_symbol_from_pnr<'a>(
             },
             _,
         )) => Ok(*symbol),
-        ParseNtResult::Nt(nt)
-            if let Nonterminal::NtLiteral(expr) = &**nt
-                && let ExprKind::Lit(Lit { kind: LitKind::Str, symbol, suffix: None }) =
-                    &expr.kind =>
+        ParseNtResult::Literal(expr)
+            if let ExprKind::Lit(Lit { kind: LitKind::Str, symbol, suffix: None }) = &expr.kind =>
         {
             Ok(*symbol)
         }
diff --git a/compiler/rustc_parse/messages.ftl b/compiler/rustc_parse/messages.ftl
index 24679692a0b0b..93fa89b68b97a 100644
--- a/compiler/rustc_parse/messages.ftl
+++ b/compiler/rustc_parse/messages.ftl
@@ -858,7 +858,7 @@ parse_unexpected_parentheses_in_match_arm_pattern = unexpected parentheses surro
 parse_unexpected_self_in_generic_parameters = unexpected keyword `Self` in generic parameters
     .note = you cannot use `Self` as a generic parameter because it is reserved for associated items
 
-parse_unexpected_token_after_dot = unexpected token: `{$actual}`
+parse_unexpected_token_after_dot = unexpected token: {$actual}
 
 parse_unexpected_token_after_label = expected `while`, `for`, `loop` or `{"{"}` after a label
     .suggestion_remove_label = consider removing the label
diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs
index 55cb76878238e..dfdef018bc374 100644
--- a/compiler/rustc_parse/src/errors.rs
+++ b/compiler/rustc_parse/src/errors.rs
@@ -1696,10 +1696,10 @@ pub(crate) struct SelfArgumentPointer {
 
 #[derive(Diagnostic)]
 #[diag(parse_unexpected_token_after_dot)]
-pub(crate) struct UnexpectedTokenAfterDot<'a> {
+pub(crate) struct UnexpectedTokenAfterDot {
     #[primary_span]
     pub span: Span,
-    pub actual: Cow<'a, str>,
+    pub actual: String,
 }
 
 #[derive(Diagnostic)]
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 00e75cc2c2fc1..424fee968e1d1 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -4,10 +4,10 @@ use core::mem;
 use core::ops::{Bound, ControlFlow};
 
 use ast::mut_visit::{self, MutVisitor};
-use ast::token::{IdentIsRaw, MetaVarKind};
+use ast::token::IdentIsRaw;
 use ast::{CoroutineKind, ForLoopKind, GenBlockKind, MatchKind, Pat, Path, PathSegment, Recovered};
 use rustc_ast::ptr::P;
-use rustc_ast::token::{self, Delimiter, Token, TokenKind};
+use rustc_ast::token::{self, Delimiter, InvisibleOrigin, MetaVarKind, Token, TokenKind};
 use rustc_ast::tokenstream::TokenTree;
 use rustc_ast::util::case::Case;
 use rustc_ast::util::classify;
@@ -19,7 +19,6 @@ use rustc_ast::{
     MetaItemLit, Movability, Param, RangeLimits, StmtKind, Ty, TyKind, UnOp, UnsafeBinderCastKind,
     YieldKind,
 };
-use rustc_ast_pretty::pprust;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::{Applicability, Diag, PResult, StashKey, Subdiagnostic};
 use rustc_lexer::unescape::unescape_char;
@@ -605,7 +604,7 @@ impl<'a> Parser<'a> {
             // can't continue an expression after an ident
             token::Ident(name, is_raw) => token::ident_can_begin_expr(name, t.span, is_raw),
             token::Literal(..) | token::Pound => true,
-            _ => t.is_whole_expr(),
+            _ => t.is_metavar_expr(),
         };
         self.token.is_ident_named(sym::not) && self.look_ahead(1, token_cannot_continue_expr)
     }
@@ -641,6 +640,13 @@ impl<'a> Parser<'a> {
             TokenKind::NtIdent(..) | TokenKind::NtLifetime(..) | TokenKind::Interpolated(..) => {
                 self.prev_token.span
             }
+            TokenKind::CloseDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(_))) => {
+                // `expr.span` is the interpolated span, because invisible open
+                // and close delims both get marked with the same span, one
+                // that covers the entire thing between them. (See
+                // `rustc_expand::mbe::transcribe::transcribe`.)
+                self.prev_token.span
+            }
             _ => expr.span,
         }
     }
@@ -979,12 +985,30 @@ impl<'a> Parser<'a> {
     }
 
     fn error_unexpected_after_dot(&self) {
-        let actual = pprust::token_to_string(&self.token);
+        let actual = super::token_descr(&self.token);
         let span = self.token.span;
         let sm = self.psess.source_map();
         let (span, actual) = match (&self.token.kind, self.subparser_name) {
-            (token::Eof, Some(_)) if let Ok(actual) = sm.span_to_snippet(sm.next_point(span)) => {
-                (span.shrink_to_hi(), actual.into())
+            (token::Eof, Some(_)) if let Ok(snippet) = sm.span_to_snippet(sm.next_point(span)) => {
+                (span.shrink_to_hi(), format!("`{}`", snippet))
+            }
+            (token::CloseDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(_))), _) => {
+                // No need to report an error. This case will only occur when parsing a pasted
+                // metavariable, and we should have emitted an error when parsing the macro call in
+                // the first place. E.g. in this code:
+                // ```
+                // macro_rules! m { ($e:expr) => { $e }; }
+                //
+                // fn main() {
+                //     let f = 1;
+                //     m!(f.);
+                // }
+                // ```
+                // we'll get an error "unexpected token: `)` when parsing the `m!(f.)`, so we don't
+                // want to issue a second error when parsing the expansion `«f.»` (where `«`/`»`
+                // represent the invisible delimiters).
+                self.dcx().span_delayed_bug(span, "bad dot expr in metavariable");
+                return;
             }
             _ => (span, actual),
         };
@@ -1364,17 +1388,31 @@ impl<'a> Parser<'a> {
         let span = self.token.span;
         if let token::Interpolated(nt) = &self.token.kind {
             match &**nt {
-                token::NtExpr(e) | token::NtLiteral(e) => {
-                    let e = e.clone();
-                    self.bump();
-                    return Ok(e);
-                }
                 token::NtBlock(block) => {
                     let block = block.clone();
                     self.bump();
                     return Ok(self.mk_expr(self.prev_token.span, ExprKind::Block(block, None)));
                 }
             };
+        } else if let Some(expr) = self.eat_metavar_seq_with_matcher(
+            |mv_kind| matches!(mv_kind, MetaVarKind::Expr { .. }),
+            |this| {
+                let expr = this.parse_expr();
+                // FIXME(nnethercote) Sometimes with expressions we get a trailing comma, possibly
+                // related to the FIXME in `collect_tokens_for_expr`. Examples are the multi-line
+                // `assert_eq!` calls involving arguments annotated with `#[rustfmt::skip]` in
+                // `compiler/rustc_index/src/bit_set/tests.rs`.
+                if this.token.kind == token::Comma {
+                    this.bump();
+                }
+                expr
+            },
+        ) {
+            return Ok(expr);
+        } else if let Some(lit) =
+            self.eat_metavar_seq(MetaVarKind::Literal, |this| this.parse_literal_maybe_minus())
+        {
+            return Ok(lit);
         } else if let Some(path) = self.eat_metavar_seq(MetaVarKind::Path, |this| {
             this.collect_tokens_no_attrs(|this| this.parse_path(PathStyle::Type))
         }) {
@@ -2062,87 +2100,107 @@ impl<'a> Parser<'a> {
             .or_else(|()| self.handle_missing_lit(Parser::mk_meta_item_lit_char))
     }
 
-    fn recover_after_dot(&mut self) -> Option<Token> {
-        let mut recovered = None;
+    fn recover_after_dot(&mut self) {
         if self.token == token::Dot {
             // Attempt to recover `.4` as `0.4`. We don't currently have any syntax where
             // dot would follow an optional literal, so we do this unconditionally.
-            recovered = self.look_ahead(1, |next_token| {
+            let recovered = self.look_ahead(1, |next_token| {
+                // If it's an integer that looks like a float, then recover as such.
+                //
+                // We will never encounter the exponent part of a floating
+                // point literal here, since there's no use of the exponent
+                // syntax that also constitutes a valid integer, so we need
+                // not check for that.
                 if let token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) =
                     next_token.kind
+                    && suffix.is_none_or(|s| s == sym::f32 || s == sym::f64)
+                    && symbol.as_str().chars().all(|c| c.is_numeric() || c == '_')
+                    && self.token.span.hi() == next_token.span.lo()
                 {
-                    // If this integer looks like a float, then recover as such.
-                    //
-                    // We will never encounter the exponent part of a floating
-                    // point literal here, since there's no use of the exponent
-                    // syntax that also constitutes a valid integer, so we need
-                    // not check for that.
-                    if suffix.is_none_or(|s| s == sym::f32 || s == sym::f64)
-                        && symbol.as_str().chars().all(|c| c.is_numeric() || c == '_')
-                        && self.token.span.hi() == next_token.span.lo()
-                    {
-                        let s = String::from("0.") + symbol.as_str();
-                        let kind = TokenKind::lit(token::Float, Symbol::intern(&s), suffix);
-                        return Some(Token::new(kind, self.token.span.to(next_token.span)));
-                    }
+                    let s = String::from("0.") + symbol.as_str();
+                    let kind = TokenKind::lit(token::Float, Symbol::intern(&s), suffix);
+                    Some(Token::new(kind, self.token.span.to(next_token.span)))
+                } else {
+                    None
                 }
-                None
             });
-            if let Some(token) = &recovered {
-                self.bump();
+            if let Some(recovered) = recovered {
                 self.dcx().emit_err(errors::FloatLiteralRequiresIntegerPart {
-                    span: token.span,
-                    suggestion: token.span.shrink_to_lo(),
+                    span: recovered.span,
+                    suggestion: recovered.span.shrink_to_lo(),
                 });
+                self.bump();
+                self.token = recovered;
             }
         }
+    }
 
-        recovered
+    /// Keep this in sync with `Token::can_begin_literal_maybe_minus` and
+    /// `Lit::from_token` (excluding unary negation).
+    fn eat_token_lit(&mut self) -> Option<token::Lit> {
+        match self.token.uninterpolate().kind {
+            token::Ident(name, IdentIsRaw::No) if name.is_bool_lit() => {
+                self.bump();
+                Some(token::Lit::new(token::Bool, name, None))
+            }
+            token::Literal(token_lit) => {
+                self.bump();
+                Some(token_lit)
+            }
+            token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
+                MetaVarKind::Literal,
+            ))) => {
+                let lit = self
+                    .eat_metavar_seq(MetaVarKind::Literal, |this| this.parse_literal_maybe_minus())
+                    .expect("metavar seq literal");
+                let ast::ExprKind::Lit(token_lit) = lit.kind else {
+                    panic!("didn't reparse a literal");
+                };
+                Some(token_lit)
+            }
+            token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
+                mv_kind @ MetaVarKind::Expr { can_begin_literal_maybe_minus: true, .. },
+            ))) => {
+                let expr = self
+                    .eat_metavar_seq(mv_kind, |this| this.parse_expr())
+                    .expect("metavar seq expr");
+                let ast::ExprKind::Lit(token_lit) = expr.kind else {
+                    panic!("didn't reparse an expr");
+                };
+                Some(token_lit)
+            }
+            _ => None,
+        }
     }
 
     /// Matches `lit = true | false | token_lit`.
     /// Returns `None` if the next token is not a literal.
-    pub(super) fn parse_opt_token_lit(&mut self) -> Option<(token::Lit, Span)> {
-        let recovered = self.recover_after_dot();
-        let token = recovered.as_ref().unwrap_or(&self.token);
-        let span = token.span;
-
-        token::Lit::from_token(token).map(|token_lit| {
-            self.bump();
-            (token_lit, span)
-        })
+    fn parse_opt_token_lit(&mut self) -> Option<(token::Lit, Span)> {
+        self.recover_after_dot();
+        let span = self.token.span;
+        self.eat_token_lit().map(|token_lit| (token_lit, span))
     }
 
     /// Matches `lit = true | false | token_lit`.
     /// Returns `None` if the next token is not a literal.
-    pub(super) fn parse_opt_meta_item_lit(&mut self) -> Option<MetaItemLit> {
-        let recovered = self.recover_after_dot();
-        let token = recovered.as_ref().unwrap_or(&self.token);
-        match token::Lit::from_token(token) {
-            Some(lit) => {
-                match MetaItemLit::from_token_lit(lit, token.span) {
-                    Ok(lit) => {
-                        self.bump();
-                        Some(lit)
-                    }
-                    Err(err) => {
-                        let span = token.uninterpolated_span();
-                        self.bump();
-                        let guar = report_lit_error(self.psess, err, lit, span);
-                        // Pack possible quotes and prefixes from the original literal into
-                        // the error literal's symbol so they can be pretty-printed faithfully.
-                        let suffixless_lit = token::Lit::new(lit.kind, lit.symbol, None);
-                        let symbol = Symbol::intern(&suffixless_lit.to_string());
-                        let lit = token::Lit::new(token::Err(guar), symbol, lit.suffix);
-                        Some(
-                            MetaItemLit::from_token_lit(lit, span)
-                                .unwrap_or_else(|_| unreachable!()),
-                        )
-                    }
+    fn parse_opt_meta_item_lit(&mut self) -> Option<MetaItemLit> {
+        self.recover_after_dot();
+        let span = self.token.span;
+        let uninterpolated_span = self.uninterpolated_token_span();
+        self.eat_token_lit().map(|token_lit| {
+            match MetaItemLit::from_token_lit(token_lit, span) {
+                Ok(lit) => lit,
+                Err(err) => {
+                    let guar = report_lit_error(&self.psess, err, token_lit, uninterpolated_span);
+                    // Pack possible quotes and prefixes from the original literal into
+                    // the error literal's symbol so they can be pretty-printed faithfully.
+                    let suffixless_lit = token::Lit::new(token_lit.kind, token_lit.symbol, None);
+                    let symbol = Symbol::intern(&suffixless_lit.to_string());
+                    let token_lit = token::Lit::new(token::Err(guar), symbol, token_lit.suffix);
+                    MetaItemLit::from_token_lit(token_lit, uninterpolated_span).unwrap()
                 }
             }
-            None => None,
-        }
+        })
     }
 
     pub(super) fn expect_no_tuple_index_suffix(&self, span: Span, suffix: Symbol) {
@@ -2166,9 +2224,10 @@ impl<'a> Parser<'a> {
     /// Matches `'-' lit | lit` (cf. `ast_validation::AstValidator::check_expr_within_pat`).
     /// Keep this in sync with `Token::can_begin_literal_maybe_minus`.
     pub fn parse_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
-        if let token::Interpolated(nt) = &self.token.kind {
-            match &**nt {
-                // FIXME(nnethercote) The `NtExpr` case should only match if
+        if let Some(expr) = self.eat_metavar_seq_with_matcher(
+            |mv_kind| matches!(mv_kind, MetaVarKind::Expr { .. }),
+            |this| {
+                // FIXME(nnethercote) The `expr` case should only match if
                 // `e` is an `ExprKind::Lit` or an `ExprKind::Unary` containing
                 // an `UnOp::Neg` and an `ExprKind::Lit`, like how
                 // `can_begin_literal_maybe_minus` works. But this method has
@@ -2178,13 +2237,14 @@ impl<'a> Parser<'a> {
                 // `ExprKind::Path` must be accepted when parsing range
                 // patterns. That requires some care. So for now, we continue
                 // being less strict here than we should be.
-                token::NtExpr(e) | token::NtLiteral(e) => {
-                    let e = e.clone();
-                    self.bump();
-                    return Ok(e);
-                }
-                _ => {}
-            };
+                this.parse_expr()
+            },
+        ) {
+            return Ok(expr);
+        } else if let Some(lit) =
+            self.eat_metavar_seq(MetaVarKind::Literal, |this| this.parse_literal_maybe_minus())
+        {
+            return Ok(lit);
         }
 
         let lo = self.token.span;
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index e93fb2473fbfb..20833a0f70f2d 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -1290,12 +1290,24 @@ impl<'a> Parser<'a> {
     }
 
     fn is_unsafe_foreign_mod(&self) -> bool {
-        self.token.is_keyword(kw::Unsafe)
-            && self.is_keyword_ahead(1, &[kw::Extern])
-            && self.look_ahead(
-                2 + self.look_ahead(2, |t| t.can_begin_string_literal() as usize),
-                |t| *t == token::OpenDelim(Delimiter::Brace),
-            )
+        // Look for `unsafe`.
+        if !self.token.is_keyword(kw::Unsafe) {
+            return false;
+        }
+        // Look for `extern`.
+        if !self.is_keyword_ahead(1, &[kw::Extern]) {
+            return false;
+        }
+
+        // Look for the optional ABI string literal.
+        let n = if self.look_ahead(2, |t| t.can_begin_string_literal()) { 3 } else { 2 };
+
+        // Look for the `{`. Use `tree_look_ahead` because the ABI (if present)
+        // might be a metavariable i.e. an invisible-delimited sequence, and
+        // `tree_look_ahead` will consider that a single element when looking
+        // ahead.
+        self.tree_look_ahead(n, |t| matches!(t, TokenTree::Delimited(_, _, Delimiter::Brace, _)))
+            == Some(true)
     }
 
     fn is_static_global(&mut self) -> bool {
@@ -2604,13 +2616,36 @@ impl<'a> Parser<'a> {
                 })
             // `extern ABI fn`
             || self.check_keyword_case(exp!(Extern), case)
+                // Use `tree_look_ahead` because `ABI` might be a metavariable,
+                // i.e. an invisible-delimited sequence, and `tree_look_ahead`
+                // will consider that a single element when looking ahead.
                 && self.look_ahead(1, |t| t.can_begin_string_literal())
-                && (self.look_ahead(2, |t| t.is_keyword_case(kw::Fn, case)) ||
+                && (self.tree_look_ahead(2, |tt| {
+                    match tt {
+                        TokenTree::Token(t, _) => t.is_keyword_case(kw::Fn, case),
+                        TokenTree::Delimited(..) => false,
+                    }
+                }) == Some(true) ||
                     // This branch is only for better diagnostics; `pub`, `unsafe`, etc. are not
                     // allowed here.
                     (self.may_recover()
-                        && self.look_ahead(2, |t| ALL_QUALS.iter().any(|exp| t.is_keyword(exp.kw)))
-                        && self.look_ahead(3, |t| t.is_keyword_case(kw::Fn, case))))
+                        && self.tree_look_ahead(2, |tt| {
+                            match tt {
+                                TokenTree::Token(t, _) =>
+                                    ALL_QUALS.iter().any(|exp| {
+                                        t.is_keyword(exp.kw)
+                                    }),
+                                TokenTree::Delimited(..) => false,
+                            }
+                        }) == Some(true)
+                        && self.tree_look_ahead(3, |tt| {
+                            match tt {
+                                TokenTree::Token(t, _) => t.is_keyword_case(kw::Fn, case),
+                                TokenTree::Delimited(..) => false,
+                            }
+                        }) == Some(true)
+                    )
+                )
     }
 
     /// Parses all the "front matter" (or "qualifiers") for a `fn` declaration,
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index d865fd427641d..a08fbde52a7ce 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -24,8 +24,8 @@ pub use pat::{CommaRecoveryMode, RecoverColon, RecoverComma};
 use path::PathStyle;
 use rustc_ast::ptr::P;
 use rustc_ast::token::{
-    self, Delimiter, IdentIsRaw, InvisibleOrigin, MetaVarKind, Nonterminal, NtPatKind, Token,
-    TokenKind,
+    self, Delimiter, IdentIsRaw, InvisibleOrigin, MetaVarKind, Nonterminal, NtExprKind, NtPatKind,
+    Token, TokenKind,
 };
 use rustc_ast::tokenstream::{AttrsTarget, Spacing, TokenStream, TokenTree};
 use rustc_ast::util::case::Case;
@@ -101,6 +101,7 @@ pub enum ForceCollect {
 #[macro_export]
 macro_rules! maybe_whole {
     ($p:expr, $constructor:ident, |$x:ident| $e:expr) => {
+        #[allow(irrefutable_let_patterns)] // FIXME: temporary
         if let token::Interpolated(nt) = &$p.token.kind
             && let token::$constructor(x) = &**nt
         {
@@ -299,6 +300,10 @@ impl TokenTreeCursor {
         self.stream.get(self.index)
     }
 
+    fn look_ahead(&self, n: usize) -> Option<&TokenTree> {
+        self.stream.get(self.index + n)
+    }
+
     #[inline]
     fn bump(&mut self) {
         self.index += 1;
@@ -1290,6 +1295,17 @@ impl<'a> Parser<'a> {
         looker(&token)
     }
 
+    /// Like `lookahead`, but skips over token trees rather than tokens. Useful
+    /// when looking past possible metavariable pasting sites.
+    pub fn tree_look_ahead<R>(
+        &self,
+        dist: usize,
+        looker: impl FnOnce(&TokenTree) -> R,
+    ) -> Option<R> {
+        assert_ne!(dist, 0);
+        self.token_cursor.curr.look_ahead(dist - 1).map(looker)
+    }
+
     /// Returns whether any of the given keywords are `dist` tokens ahead of the current one.
     pub(crate) fn is_keyword_ahead(&self, dist: usize, kws: &[Symbol]) -> bool {
         self.look_ahead(dist, |t| kws.iter().any(|&kw| t.is_keyword(kw)))
@@ -1706,6 +1722,16 @@ impl<'a> Parser<'a> {
     pub fn approx_token_stream_pos(&self) -> u32 {
         self.num_bump_calls
     }
+
+    pub fn uninterpolated_token_span(&self) -> Span {
+        match &self.token.kind {
+            token::Interpolated(nt) => nt.use_span(),
+            token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(_))) => {
+                self.look_ahead(1, |t| t.span)
+            }
+            _ => self.token.span,
+        }
+    }
 }
 
 pub(crate) fn make_unclosed_delims_error(
@@ -1758,6 +1784,8 @@ pub enum ParseNtResult {
     Item(P<ast::Item>),
     Stmt(P<ast::Stmt>),
     Pat(P<ast::Pat>, NtPatKind),
+    Expr(P<ast::Expr>, NtExprKind),
+    Literal(P<ast::Expr>),
     Ty(P<ast::Ty>),
     Meta(P<ast::AttrItem>),
     Path(P<ast::Path>),
diff --git a/compiler/rustc_parse/src/parser/nonterminal.rs b/compiler/rustc_parse/src/parser/nonterminal.rs
index 1123755ce0037..b4e540d670d16 100644
--- a/compiler/rustc_parse/src/parser/nonterminal.rs
+++ b/compiler/rustc_parse/src/parser/nonterminal.rs
@@ -48,10 +48,6 @@ impl<'a> Parser<'a> {
         /// Old variant of `may_be_ident`. Being phased out.
         fn nt_may_be_ident(nt: &Nonterminal) -> bool {
             match nt {
-                NtExpr(_)
-                | NtLiteral(_) // `true`, `false`
-                => true,
-
                 NtBlock(_) => false,
             }
         }
@@ -95,7 +91,7 @@ impl<'a> Parser<'a> {
                 token::OpenDelim(Delimiter::Brace) => true,
                 token::NtLifetime(..) => true,
                 token::Interpolated(nt) => match &**nt {
-                    NtBlock(_) | NtExpr(_) | NtLiteral(_) => true,
+                    NtBlock(_) => true,
                 },
                 token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(k))) => match k {
                     MetaVarKind::Block
@@ -179,10 +175,14 @@ impl<'a> Parser<'a> {
                     pat_kind,
                 ));
             }
-            NonterminalKind::Expr(_) => NtExpr(self.parse_expr_force_collect()?),
+            NonterminalKind::Expr(expr_kind) => {
+                return Ok(ParseNtResult::Expr(self.parse_expr_force_collect()?, expr_kind));
+            }
             NonterminalKind::Literal => {
-                // The `:literal` matcher does not support attributes
-                NtLiteral(self.collect_tokens_no_attrs(|this| this.parse_literal_maybe_minus())?)
+                // The `:literal` matcher does not support attributes.
+                return Ok(ParseNtResult::Literal(
+                    self.collect_tokens_no_attrs(|this| this.parse_literal_maybe_minus())?,
+                ));
             }
             NonterminalKind::Ty => {
                 return Ok(ParseNtResult::Ty(
diff --git a/compiler/rustc_parse/src/parser/pat.rs b/compiler/rustc_parse/src/parser/pat.rs
index 174cc929fa70d..9612f71b2af93 100644
--- a/compiler/rustc_parse/src/parser/pat.rs
+++ b/compiler/rustc_parse/src/parser/pat.rs
@@ -1252,7 +1252,7 @@ impl<'a> Parser<'a> {
                 || *t == token::Dot // e.g. `.5` for recovery;
                 || matches!(t.kind, token::Literal(..) | token::Minus)
                 || t.is_bool_lit()
-                || t.is_whole_expr()
+                || t.is_metavar_expr()
                 || t.is_lifetime() // recover `'a` instead of `'a'`
                 || (self.may_recover() // recover leading `(`
                     && *t == token::OpenDelim(Delimiter::Parenthesis)
diff --git a/tests/ui/attributes/nonterminal-expansion.rs b/tests/ui/attributes/nonterminal-expansion.rs
index 83c8f00999a72..004a8a23fd61f 100644
--- a/tests/ui/attributes/nonterminal-expansion.rs
+++ b/tests/ui/attributes/nonterminal-expansion.rs
@@ -5,8 +5,7 @@
 macro_rules! pass_nonterminal {
     ($n:expr) => {
         #[repr(align($n))]
-        //~^ ERROR expected unsuffixed literal, found expression `n!()`
-        //~^^ ERROR incorrect `repr(align)` attribute format: `align` expects a literal integer as argument [E0693]
+        //~^ ERROR expected unsuffixed literal, found `expr` metavariable
         struct S;
     };
 }
@@ -16,5 +15,6 @@ macro_rules! n {
 }
 
 pass_nonterminal!(n!());
+//~^ ERROR incorrect `repr(align)` attribute format: `align` expects a literal integer as argument [E0693]
 
 fn main() {}
diff --git a/tests/ui/attributes/nonterminal-expansion.stderr b/tests/ui/attributes/nonterminal-expansion.stderr
index 8a85731bd5a13..9c6cb98f61965 100644
--- a/tests/ui/attributes/nonterminal-expansion.stderr
+++ b/tests/ui/attributes/nonterminal-expansion.stderr
@@ -1,4 +1,4 @@
-error: expected unsuffixed literal, found expression `n!()`
+error: expected unsuffixed literal, found `expr` metavariable
   --> $DIR/nonterminal-expansion.rs:7:22
    |
 LL |         #[repr(align($n))]
@@ -10,15 +10,10 @@ LL | pass_nonterminal!(n!());
    = note: this error originates in the macro `pass_nonterminal` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0693]: incorrect `repr(align)` attribute format: `align` expects a literal integer as argument
-  --> $DIR/nonterminal-expansion.rs:7:22
+  --> $DIR/nonterminal-expansion.rs:17:19
    |
-LL |         #[repr(align($n))]
-   |                      ^^
-...
 LL | pass_nonterminal!(n!());
-   | ----------------------- in this macro invocation
-   |
-   = note: this error originates in the macro `pass_nonterminal` (in Nightly builds, run with -Z macro-backtrace for more info)
+   |                   ^
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/conditional-compilation/cfg-attr-syntax-validation.rs b/tests/ui/conditional-compilation/cfg-attr-syntax-validation.rs
index 416145a0c1560..47418b4e091b2 100644
--- a/tests/ui/conditional-compilation/cfg-attr-syntax-validation.rs
+++ b/tests/ui/conditional-compilation/cfg-attr-syntax-validation.rs
@@ -28,7 +28,7 @@ struct S9;
 macro_rules! generate_s10 {
     ($expr: expr) => {
         #[cfg(feature = $expr)]
-        //~^ ERROR expected unsuffixed literal, found expression `concat!("nonexistent")`
+        //~^ ERROR expected unsuffixed literal, found `expr` metavariable
         struct S10;
     }
 }
diff --git a/tests/ui/conditional-compilation/cfg-attr-syntax-validation.stderr b/tests/ui/conditional-compilation/cfg-attr-syntax-validation.stderr
index d02d0d70a8bcf..66ce2ee98589d 100644
--- a/tests/ui/conditional-compilation/cfg-attr-syntax-validation.stderr
+++ b/tests/ui/conditional-compilation/cfg-attr-syntax-validation.stderr
@@ -54,7 +54,7 @@ LL | #[cfg(a = b"hi")]
    |           |
    |           help: consider removing the prefix
 
-error: expected unsuffixed literal, found expression `concat!("nonexistent")`
+error: expected unsuffixed literal, found `expr` metavariable
   --> $DIR/cfg-attr-syntax-validation.rs:30:25
    |
 LL |         #[cfg(feature = $expr)]
diff --git a/tests/ui/macros/nonterminal-matching.rs b/tests/ui/macros/nonterminal-matching.rs
index b0a7f3e4650fd..a03ede20c5499 100644
--- a/tests/ui/macros/nonterminal-matching.rs
+++ b/tests/ui/macros/nonterminal-matching.rs
@@ -29,8 +29,8 @@ macro_rules! foo {
     (ident $x:ident) => { bar!(ident $x); };
     (lifetime $x:lifetime) => { bar!(lifetime $x); };
     (tt $x:tt) => { bar!(tt $x); };
-    (expr $x:expr) => { bar!(expr $x); }; //~ ERROR: no rules expected expression `3`
-    (literal $x:literal) => { bar!(literal $x); }; //~ ERROR: no rules expected literal `4`
+    (expr $x:expr) => { bar!(expr $x); }; //~ ERROR: no rules expected `expr` metavariable
+    (literal $x:literal) => { bar!(literal $x); }; //~ ERROR: no rules expected `literal` metavariable
     (path $x:path) => { bar!(path $x); }; //~ ERROR: no rules expected `path` metavariable
     (stmt $x:stmt) => { bar!(stmt $x); }; //~ ERROR: no rules expected `stmt` metavariable
 }
diff --git a/tests/ui/macros/nonterminal-matching.stderr b/tests/ui/macros/nonterminal-matching.stderr
index 2d9252fbfc1fa..d01561415664c 100644
--- a/tests/ui/macros/nonterminal-matching.stderr
+++ b/tests/ui/macros/nonterminal-matching.stderr
@@ -23,7 +23,7 @@ LL | complex_nonterminal!(enum E {});
    = help: try using `:tt` instead in the macro definition
    = note: this error originates in the macro `complex_nonterminal` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: no rules expected expression `3`
+error: no rules expected `expr` metavariable
   --> $DIR/nonterminal-matching.rs:32:35
    |
 LL |     (expr $x:expr) => { bar!(expr $x); };
@@ -45,7 +45,7 @@ LL |     (expr 3) => {};
    = help: try using `:tt` instead in the macro definition
    = note: this error originates in the macro `foo` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: no rules expected literal `4`
+error: no rules expected `literal` metavariable
   --> $DIR/nonterminal-matching.rs:33:44
    |
 LL |     (literal $x:literal) => { bar!(literal $x); };
diff --git a/tests/ui/parser/extern-abi-from-mac-literal-frag.rs b/tests/ui/parser/extern-abi-from-mac-literal-frag.rs
index a4e9134218cea..12b6c98705ce6 100644
--- a/tests/ui/parser/extern-abi-from-mac-literal-frag.rs
+++ b/tests/ui/parser/extern-abi-from-mac-literal-frag.rs
@@ -12,6 +12,8 @@ macro_rules! abi_from_lit_frag {
             fn _import();
         }
 
+        unsafe extern $abi {}
+
         extern $abi fn _export() {}
 
         type _PTR = extern $abi fn();
@@ -24,6 +26,8 @@ macro_rules! abi_from_expr_frag {
             fn _import();
         }
 
+        unsafe extern $abi {}
+
         extern $abi fn _export() {}
 
         type _PTR = extern $abi fn();
diff --git a/tests/ui/parser/float-field-interpolated.rs b/tests/ui/parser/float-field-interpolated.rs
index 990f2926dc861..bf7163039c420 100644
--- a/tests/ui/parser/float-field-interpolated.rs
+++ b/tests/ui/parser/float-field-interpolated.rs
@@ -5,10 +5,10 @@ macro_rules! generate_field_accesses {
         let s = S(0, (0, 0));
 
         s.$a; // OK
-        { s.$b; } //~ ERROR unexpected token: `1.1`
-                  //~| ERROR expected one of `.`, `;`, `?`, `}`, or an operator, found literal `1.1`
-        { s.$c; } //~ ERROR unexpected token: `1.1`
-                  //~| ERROR expected one of `.`, `;`, `?`, `}`, or an operator, found expression `1.1`
+        { s.$b; } //~ ERROR unexpected token: `literal` metavariable
+                  //~| ERROR expected one of `.`, `;`, `?`, `}`, or an operator, found `literal` metavariable
+        { s.$c; } //~ ERROR unexpected token: `expr` metavariable
+                  //~| ERROR expected one of `.`, `;`, `?`, `}`, or an operator, found `expr` metavariable
     };
 }
 
diff --git a/tests/ui/parser/float-field-interpolated.stderr b/tests/ui/parser/float-field-interpolated.stderr
index 2a1a4926cb3c6..e2b7e3a7dbe75 100644
--- a/tests/ui/parser/float-field-interpolated.stderr
+++ b/tests/ui/parser/float-field-interpolated.stderr
@@ -1,4 +1,4 @@
-error: unexpected token: `1.1`
+error: unexpected token: `literal` metavariable
   --> $DIR/float-field-interpolated.rs:8:13
    |
 LL |         { s.$b; }
@@ -9,7 +9,7 @@ LL |     generate_field_accesses!(1.1, 1.1, 1.1);
    |
    = note: this error originates in the macro `generate_field_accesses` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: expected one of `.`, `;`, `?`, `}`, or an operator, found literal `1.1`
+error: expected one of `.`, `;`, `?`, `}`, or an operator, found `literal` metavariable
   --> $DIR/float-field-interpolated.rs:8:13
    |
 LL |         { s.$b; }
@@ -20,7 +20,7 @@ LL |     generate_field_accesses!(1.1, 1.1, 1.1);
    |
    = note: this error originates in the macro `generate_field_accesses` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: unexpected token: `1.1`
+error: unexpected token: `expr` metavariable
   --> $DIR/float-field-interpolated.rs:10:13
    |
 LL |         { s.$c; }
@@ -31,7 +31,7 @@ LL |     generate_field_accesses!(1.1, 1.1, 1.1);
    |
    = note: this error originates in the macro `generate_field_accesses` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: expected one of `.`, `;`, `?`, `}`, or an operator, found expression `1.1`
+error: expected one of `.`, `;`, `?`, `}`, or an operator, found `expr` metavariable
   --> $DIR/float-field-interpolated.rs:10:13
    |
 LL |         { s.$c; }
diff --git a/tests/ui/parser/macro/trait-non-item-macros.rs b/tests/ui/parser/macro/trait-non-item-macros.rs
index e93000193b6e3..b4140613cbae7 100644
--- a/tests/ui/parser/macro/trait-non-item-macros.rs
+++ b/tests/ui/parser/macro/trait-non-item-macros.rs
@@ -1,7 +1,7 @@
 macro_rules! bah {
     ($a:expr) => {
         $a
-    }; //~^ ERROR macro expansion ignores expression `2` and any tokens following
+    }; //~^ ERROR macro expansion ignores `expr` metavariable and any tokens following
 }
 
 trait Bar {
diff --git a/tests/ui/parser/macro/trait-non-item-macros.stderr b/tests/ui/parser/macro/trait-non-item-macros.stderr
index 1a82848377895..62b42fa8b8dd7 100644
--- a/tests/ui/parser/macro/trait-non-item-macros.stderr
+++ b/tests/ui/parser/macro/trait-non-item-macros.stderr
@@ -1,4 +1,4 @@
-error: macro expansion ignores expression `2` and any tokens following
+error: macro expansion ignores `expr` metavariable and any tokens following
   --> $DIR/trait-non-item-macros.rs:3:9
    |
 LL |         $a
diff --git a/tests/ui/proc-macro/macro-rules-derive-cfg.stdout b/tests/ui/proc-macro/macro-rules-derive-cfg.stdout
index c1e46b50d40c2..9482b2784d222 100644
--- a/tests/ui/proc-macro/macro-rules-derive-cfg.stdout
+++ b/tests/ui/proc-macro/macro-rules-derive-cfg.stdout
@@ -1,8 +1,9 @@
 PRINT-DERIVE INPUT (DISPLAY): struct
-Foo([bool; #[rustc_dummy(first)] #[rustc_dummy(second)]
-{ #![rustc_dummy(third)] #[rustc_dummy(fourth)] 30 }]);
+Foo([bool; #[rustc_dummy(first)]
+#[rustc_dummy(second)] { #![rustc_dummy(third)] #[rustc_dummy(fourth)] 30 }]);
 PRINT-DERIVE DEEP-RE-COLLECTED (DISPLAY): struct
-Foo([bool; #[rustc_dummy(first)] #[rustc_dummy(second)]
+Foo([bool; #[rustc_dummy(first)]
+#[rustc_dummy(second)]
 { #! [rustc_dummy(third)] #[rustc_dummy(fourth)] 30 }]);
 PRINT-DERIVE INPUT (DEBUG): TokenStream [
     Ident {
@@ -53,97 +54,103 @@ PRINT-DERIVE INPUT (DEBUG): TokenStream [
                         ],
                         span: $DIR/macro-rules-derive-cfg.rs:18:21: 18:63 (#3),
                     },
-                    Punct {
-                        ch: '#',
-                        spacing: Alone,
-                        span: $DIR/macro-rules-derive-cfg.rs:23:13: 23:14 (#0),
-                    },
                     Group {
-                        delimiter: Bracket,
-                        stream: TokenStream [
-                            Ident {
-                                ident: "rustc_dummy",
-                                span: $DIR/macro-rules-derive-cfg.rs:23:36: 23:47 (#0),
-                            },
-                            Group {
-                                delimiter: Parenthesis,
-                                stream: TokenStream [
-                                    Ident {
-                                        ident: "second",
-                                        span: $DIR/macro-rules-derive-cfg.rs:23:48: 23:54 (#0),
-                                    },
-                                ],
-                                span: $DIR/macro-rules-derive-cfg.rs:23:47: 23:55 (#0),
-                            },
-                        ],
-                        span: $DIR/macro-rules-derive-cfg.rs:23:14: 23:57 (#0),
-                    },
-                    Group {
-                        delimiter: Brace,
+                        delimiter: None,
                         stream: TokenStream [
                             Punct {
                                 ch: '#',
-                                spacing: Joint,
-                                span: $DIR/macro-rules-derive-cfg.rs:24:5: 24:6 (#0),
-                            },
-                            Punct {
-                                ch: '!',
                                 spacing: Alone,
-                                span: $DIR/macro-rules-derive-cfg.rs:24:6: 24:7 (#0),
+                                span: $DIR/macro-rules-derive-cfg.rs:23:13: 23:14 (#0),
                             },
                             Group {
                                 delimiter: Bracket,
                                 stream: TokenStream [
                                     Ident {
                                         ident: "rustc_dummy",
-                                        span: $DIR/macro-rules-derive-cfg.rs:24:29: 24:40 (#0),
+                                        span: $DIR/macro-rules-derive-cfg.rs:23:36: 23:47 (#0),
                                     },
                                     Group {
                                         delimiter: Parenthesis,
                                         stream: TokenStream [
                                             Ident {
-                                                ident: "third",
-                                                span: $DIR/macro-rules-derive-cfg.rs:24:41: 24:46 (#0),
+                                                ident: "second",
+                                                span: $DIR/macro-rules-derive-cfg.rs:23:48: 23:54 (#0),
                                             },
                                         ],
-                                        span: $DIR/macro-rules-derive-cfg.rs:24:40: 24:47 (#0),
+                                        span: $DIR/macro-rules-derive-cfg.rs:23:47: 23:55 (#0),
                                     },
                                 ],
-                                span: $DIR/macro-rules-derive-cfg.rs:24:7: 24:49 (#0),
-                            },
-                            Punct {
-                                ch: '#',
-                                spacing: Alone,
-                                span: $DIR/macro-rules-derive-cfg.rs:25:5: 25:6 (#0),
+                                span: $DIR/macro-rules-derive-cfg.rs:23:14: 23:57 (#0),
                             },
                             Group {
-                                delimiter: Bracket,
+                                delimiter: Brace,
                                 stream: TokenStream [
-                                    Ident {
-                                        ident: "rustc_dummy",
-                                        span: $DIR/macro-rules-derive-cfg.rs:25:28: 25:39 (#0),
+                                    Punct {
+                                        ch: '#',
+                                        spacing: Joint,
+                                        span: $DIR/macro-rules-derive-cfg.rs:24:5: 24:6 (#0),
+                                    },
+                                    Punct {
+                                        ch: '!',
+                                        spacing: Alone,
+                                        span: $DIR/macro-rules-derive-cfg.rs:24:6: 24:7 (#0),
                                     },
                                     Group {
-                                        delimiter: Parenthesis,
+                                        delimiter: Bracket,
+                                        stream: TokenStream [
+                                            Ident {
+                                                ident: "rustc_dummy",
+                                                span: $DIR/macro-rules-derive-cfg.rs:24:29: 24:40 (#0),
+                                            },
+                                            Group {
+                                                delimiter: Parenthesis,
+                                                stream: TokenStream [
+                                                    Ident {
+                                                        ident: "third",
+                                                        span: $DIR/macro-rules-derive-cfg.rs:24:41: 24:46 (#0),
+                                                    },
+                                                ],
+                                                span: $DIR/macro-rules-derive-cfg.rs:24:40: 24:47 (#0),
+                                            },
+                                        ],
+                                        span: $DIR/macro-rules-derive-cfg.rs:24:7: 24:49 (#0),
+                                    },
+                                    Punct {
+                                        ch: '#',
+                                        spacing: Alone,
+                                        span: $DIR/macro-rules-derive-cfg.rs:25:5: 25:6 (#0),
+                                    },
+                                    Group {
+                                        delimiter: Bracket,
                                         stream: TokenStream [
                                             Ident {
-                                                ident: "fourth",
-                                                span: $DIR/macro-rules-derive-cfg.rs:25:40: 25:46 (#0),
+                                                ident: "rustc_dummy",
+                                                span: $DIR/macro-rules-derive-cfg.rs:25:28: 25:39 (#0),
+                                            },
+                                            Group {
+                                                delimiter: Parenthesis,
+                                                stream: TokenStream [
+                                                    Ident {
+                                                        ident: "fourth",
+                                                        span: $DIR/macro-rules-derive-cfg.rs:25:40: 25:46 (#0),
+                                                    },
+                                                ],
+                                                span: $DIR/macro-rules-derive-cfg.rs:25:39: 25:47 (#0),
                                             },
                                         ],
-                                        span: $DIR/macro-rules-derive-cfg.rs:25:39: 25:47 (#0),
+                                        span: $DIR/macro-rules-derive-cfg.rs:25:6: 25:49 (#0),
+                                    },
+                                    Literal {
+                                        kind: Integer,
+                                        symbol: "30",
+                                        suffix: None,
+                                        span: $DIR/macro-rules-derive-cfg.rs:26:5: 26:7 (#0),
                                     },
                                 ],
-                                span: $DIR/macro-rules-derive-cfg.rs:25:6: 25:49 (#0),
-                            },
-                            Literal {
-                                kind: Integer,
-                                symbol: "30",
-                                suffix: None,
-                                span: $DIR/macro-rules-derive-cfg.rs:26:5: 26:7 (#0),
+                                span: $DIR/macro-rules-derive-cfg.rs:23:58: 27:2 (#0),
                             },
                         ],
-                        span: $DIR/macro-rules-derive-cfg.rs:23:58: 27:2 (#0),
+                        span: $DIR/macro-rules-derive-cfg.rs:18:64: 18:69 (#3),
                     },
                 ],
                 span: $DIR/macro-rules-derive-cfg.rs:18:13: 18:70 (#3),
diff --git a/tests/ui/rfcs/rfc-2294-if-let-guard/feature-gate.rs b/tests/ui/rfcs/rfc-2294-if-let-guard/feature-gate.rs
index 4b2fc4a03b620..110c03d0e5491 100644
--- a/tests/ui/rfcs/rfc-2294-if-let-guard/feature-gate.rs
+++ b/tests/ui/rfcs/rfc-2294-if-let-guard/feature-gate.rs
@@ -59,8 +59,10 @@ fn _macros() {
     }
     use_expr!((let 0 = 1 && 0 == 0));
     //~^ ERROR expected expression, found `let` statement
+    //~| ERROR expected expression, found `let` statement
     use_expr!((let 0 = 1));
     //~^ ERROR expected expression, found `let` statement
+    //~| ERROR expected expression, found `let` statement
     match () {
         #[cfg(FALSE)]
         () if let 0 = 1 => {}
diff --git a/tests/ui/rfcs/rfc-2294-if-let-guard/feature-gate.stderr b/tests/ui/rfcs/rfc-2294-if-let-guard/feature-gate.stderr
index 1c710b04897cb..0997f0c81a019 100644
--- a/tests/ui/rfcs/rfc-2294-if-let-guard/feature-gate.stderr
+++ b/tests/ui/rfcs/rfc-2294-if-let-guard/feature-gate.stderr
@@ -124,15 +124,33 @@ LL |     use_expr!((let 0 = 1 && 0 == 0));
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/feature-gate.rs:62:16
+  --> $DIR/feature-gate.rs:60:16
+   |
+LL |     use_expr!((let 0 = 1 && 0 == 0));
+   |                ^^^
+   |
+   = note: only supported directly in conditions of `if` and `while` expressions
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: expected expression, found `let` statement
+  --> $DIR/feature-gate.rs:63:16
+   |
+LL |     use_expr!((let 0 = 1));
+   |                ^^^
+   |
+   = note: only supported directly in conditions of `if` and `while` expressions
+
+error: expected expression, found `let` statement
+  --> $DIR/feature-gate.rs:63:16
    |
 LL |     use_expr!((let 0 = 1));
    |                ^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: no rules expected keyword `let`
-  --> $DIR/feature-gate.rs:70:15
+  --> $DIR/feature-gate.rs:72:15
    |
 LL |     macro_rules! use_expr {
    |     --------------------- when calling this macro
@@ -202,7 +220,7 @@ LL |         () if let Range { start: _, end: _ } = (true..true) && false => {}
    = help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`
 
 error[E0658]: `if let` guards are experimental
-  --> $DIR/feature-gate.rs:66:12
+  --> $DIR/feature-gate.rs:68:12
    |
 LL |         () if let 0 = 1 => {}
    |            ^^^^^^^^^^^^
@@ -262,6 +280,6 @@ LL |         () if let Range { start: _, end: _ } = (true..true) && false => {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error: aborting due to 23 previous errors
+error: aborting due to 25 previous errors
 
 For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.feature.stderr b/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.feature.stderr
index db32b8c1de4ff..817e226bc45d5 100644
--- a/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.feature.stderr
+++ b/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.feature.stderr
@@ -233,7 +233,7 @@ LL |     while let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {
    |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:99:9
+  --> $DIR/disallowed-positions.rs:103:9
    |
 LL |     if &let 0 = 0 {}
    |         ^^^^^^^^^
@@ -241,7 +241,7 @@ LL |     if &let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:102:9
+  --> $DIR/disallowed-positions.rs:106:9
    |
 LL |     if !let 0 = 0 {}
    |         ^^^^^^^^^
@@ -249,7 +249,7 @@ LL |     if !let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:104:9
+  --> $DIR/disallowed-positions.rs:108:9
    |
 LL |     if *let 0 = 0 {}
    |         ^^^^^^^^^
@@ -257,7 +257,7 @@ LL |     if *let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:106:9
+  --> $DIR/disallowed-positions.rs:110:9
    |
 LL |     if -let 0 = 0 {}
    |         ^^^^^^^^^
@@ -265,7 +265,7 @@ LL |     if -let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:114:9
+  --> $DIR/disallowed-positions.rs:118:9
    |
 LL |     if (let 0 = 0)? {}
    |         ^^^^^^^^^
@@ -273,20 +273,20 @@ LL |     if (let 0 = 0)? {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:117:16
+  --> $DIR/disallowed-positions.rs:121:16
    |
 LL |     if true || let 0 = 0 {}
    |                ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:117:13
+  --> $DIR/disallowed-positions.rs:121:13
    |
 LL |     if true || let 0 = 0 {}
    |             ^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:119:17
+  --> $DIR/disallowed-positions.rs:123:17
    |
 LL |     if (true || let 0 = 0) {}
    |                 ^^^^^^^^^
@@ -294,7 +294,7 @@ LL |     if (true || let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:121:25
+  --> $DIR/disallowed-positions.rs:125:25
    |
 LL |     if true && (true || let 0 = 0) {}
    |                         ^^^^^^^^^
@@ -302,7 +302,7 @@ LL |     if true && (true || let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:123:25
+  --> $DIR/disallowed-positions.rs:127:25
    |
 LL |     if true || (true && let 0 = 0) {}
    |                         ^^^^^^^^^
@@ -310,7 +310,7 @@ LL |     if true || (true && let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:127:12
+  --> $DIR/disallowed-positions.rs:131:12
    |
 LL |     if x = let 0 = 0 {}
    |            ^^^
@@ -318,7 +318,7 @@ LL |     if x = let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:130:15
+  --> $DIR/disallowed-positions.rs:134:15
    |
 LL |     if true..(let 0 = 0) {}
    |               ^^^^^^^^^
@@ -326,7 +326,7 @@ LL |     if true..(let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:133:11
+  --> $DIR/disallowed-positions.rs:137:11
    |
 LL |     if ..(let 0 = 0) {}
    |           ^^^^^^^^^
@@ -334,7 +334,7 @@ LL |     if ..(let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:135:9
+  --> $DIR/disallowed-positions.rs:139:9
    |
 LL |     if (let 0 = 0).. {}
    |         ^^^^^^^^^
@@ -342,7 +342,7 @@ LL |     if (let 0 = 0).. {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:139:8
+  --> $DIR/disallowed-positions.rs:143:8
    |
 LL |     if let Range { start: _, end: _ } = true..true && false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -350,7 +350,7 @@ LL |     if let Range { start: _, end: _ } = true..true && false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:142:8
+  --> $DIR/disallowed-positions.rs:146:8
    |
 LL |     if let Range { start: _, end: _ } = true..true || false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -358,7 +358,7 @@ LL |     if let Range { start: _, end: _ } = true..true || false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:148:8
+  --> $DIR/disallowed-positions.rs:152:8
    |
 LL |     if let Range { start: F, end } = F..|| true {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -366,7 +366,7 @@ LL |     if let Range { start: F, end } = F..|| true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:154:8
+  --> $DIR/disallowed-positions.rs:158:8
    |
 LL |     if let Range { start: true, end } = t..&&false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -374,7 +374,7 @@ LL |     if let Range { start: true, end } = t..&&false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:158:19
+  --> $DIR/disallowed-positions.rs:162:19
    |
 LL |     if let true = let true = true {}
    |                   ^^^
@@ -382,7 +382,7 @@ LL |     if let true = let true = true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:161:15
+  --> $DIR/disallowed-positions.rs:165:15
    |
 LL |     if return let 0 = 0 {}
    |               ^^^
@@ -390,7 +390,7 @@ LL |     if return let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:164:21
+  --> $DIR/disallowed-positions.rs:168:21
    |
 LL |     loop { if break let 0 = 0 {} }
    |                     ^^^
@@ -398,7 +398,7 @@ LL |     loop { if break let 0 = 0 {} }
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:167:15
+  --> $DIR/disallowed-positions.rs:171:15
    |
 LL |     if (match let 0 = 0 { _ => { false } }) {}
    |               ^^^
@@ -406,7 +406,7 @@ LL |     if (match let 0 = 0 { _ => { false } }) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:170:9
+  --> $DIR/disallowed-positions.rs:174:9
    |
 LL |     if (let 0 = 0, false).1 {}
    |         ^^^^^^^^^
@@ -414,7 +414,7 @@ LL |     if (let 0 = 0, false).1 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:173:9
+  --> $DIR/disallowed-positions.rs:177:9
    |
 LL |     if (let 0 = 0,) {}
    |         ^^^^^^^^^
@@ -422,7 +422,7 @@ LL |     if (let 0 = 0,) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:177:13
+  --> $DIR/disallowed-positions.rs:181:13
    |
 LL |         if (let 0 = 0).await {}
    |             ^^^^^^^^^
@@ -430,7 +430,7 @@ LL |         if (let 0 = 0).await {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:181:12
+  --> $DIR/disallowed-positions.rs:185:12
    |
 LL |     if (|| let 0 = 0) {}
    |            ^^^
@@ -438,7 +438,7 @@ LL |     if (|| let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:184:9
+  --> $DIR/disallowed-positions.rs:188:9
    |
 LL |     if (let 0 = 0)() {}
    |         ^^^^^^^^^
@@ -446,7 +446,7 @@ LL |     if (let 0 = 0)() {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:190:12
+  --> $DIR/disallowed-positions.rs:194:12
    |
 LL |     while &let 0 = 0 {}
    |            ^^^^^^^^^
@@ -454,7 +454,7 @@ LL |     while &let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:193:12
+  --> $DIR/disallowed-positions.rs:197:12
    |
 LL |     while !let 0 = 0 {}
    |            ^^^^^^^^^
@@ -462,7 +462,7 @@ LL |     while !let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:195:12
+  --> $DIR/disallowed-positions.rs:199:12
    |
 LL |     while *let 0 = 0 {}
    |            ^^^^^^^^^
@@ -470,7 +470,7 @@ LL |     while *let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:197:12
+  --> $DIR/disallowed-positions.rs:201:12
    |
 LL |     while -let 0 = 0 {}
    |            ^^^^^^^^^
@@ -478,7 +478,7 @@ LL |     while -let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:205:12
+  --> $DIR/disallowed-positions.rs:209:12
    |
 LL |     while (let 0 = 0)? {}
    |            ^^^^^^^^^
@@ -486,20 +486,20 @@ LL |     while (let 0 = 0)? {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:208:19
+  --> $DIR/disallowed-positions.rs:212:19
    |
 LL |     while true || let 0 = 0 {}
    |                   ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:208:16
+  --> $DIR/disallowed-positions.rs:212:16
    |
 LL |     while true || let 0 = 0 {}
    |                ^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:210:20
+  --> $DIR/disallowed-positions.rs:214:20
    |
 LL |     while (true || let 0 = 0) {}
    |                    ^^^^^^^^^
@@ -507,7 +507,7 @@ LL |     while (true || let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:212:28
+  --> $DIR/disallowed-positions.rs:216:28
    |
 LL |     while true && (true || let 0 = 0) {}
    |                            ^^^^^^^^^
@@ -515,7 +515,7 @@ LL |     while true && (true || let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:214:28
+  --> $DIR/disallowed-positions.rs:218:28
    |
 LL |     while true || (true && let 0 = 0) {}
    |                            ^^^^^^^^^
@@ -523,7 +523,7 @@ LL |     while true || (true && let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:218:15
+  --> $DIR/disallowed-positions.rs:222:15
    |
 LL |     while x = let 0 = 0 {}
    |               ^^^
@@ -531,7 +531,7 @@ LL |     while x = let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:221:18
+  --> $DIR/disallowed-positions.rs:225:18
    |
 LL |     while true..(let 0 = 0) {}
    |                  ^^^^^^^^^
@@ -539,7 +539,7 @@ LL |     while true..(let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:224:14
+  --> $DIR/disallowed-positions.rs:228:14
    |
 LL |     while ..(let 0 = 0) {}
    |              ^^^^^^^^^
@@ -547,7 +547,7 @@ LL |     while ..(let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:226:12
+  --> $DIR/disallowed-positions.rs:230:12
    |
 LL |     while (let 0 = 0).. {}
    |            ^^^^^^^^^
@@ -555,7 +555,7 @@ LL |     while (let 0 = 0).. {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:230:11
+  --> $DIR/disallowed-positions.rs:234:11
    |
 LL |     while let Range { start: _, end: _ } = true..true && false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -563,7 +563,7 @@ LL |     while let Range { start: _, end: _ } = true..true && false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:233:11
+  --> $DIR/disallowed-positions.rs:237:11
    |
 LL |     while let Range { start: _, end: _ } = true..true || false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -571,7 +571,7 @@ LL |     while let Range { start: _, end: _ } = true..true || false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:239:11
+  --> $DIR/disallowed-positions.rs:243:11
    |
 LL |     while let Range { start: F, end } = F..|| true {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -579,7 +579,7 @@ LL |     while let Range { start: F, end } = F..|| true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:245:11
+  --> $DIR/disallowed-positions.rs:249:11
    |
 LL |     while let Range { start: true, end } = t..&&false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -587,7 +587,7 @@ LL |     while let Range { start: true, end } = t..&&false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:249:22
+  --> $DIR/disallowed-positions.rs:253:22
    |
 LL |     while let true = let true = true {}
    |                      ^^^
@@ -595,7 +595,7 @@ LL |     while let true = let true = true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:252:18
+  --> $DIR/disallowed-positions.rs:256:18
    |
 LL |     while return let 0 = 0 {}
    |                  ^^^
@@ -603,7 +603,7 @@ LL |     while return let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:255:39
+  --> $DIR/disallowed-positions.rs:259:39
    |
 LL |     'outer: loop { while break 'outer let 0 = 0 {} }
    |                                       ^^^
@@ -611,7 +611,7 @@ LL |     'outer: loop { while break 'outer let 0 = 0 {} }
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:258:18
+  --> $DIR/disallowed-positions.rs:262:18
    |
 LL |     while (match let 0 = 0 { _ => { false } }) {}
    |                  ^^^
@@ -619,7 +619,7 @@ LL |     while (match let 0 = 0 { _ => { false } }) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:261:12
+  --> $DIR/disallowed-positions.rs:265:12
    |
 LL |     while (let 0 = 0, false).1 {}
    |            ^^^^^^^^^
@@ -627,7 +627,7 @@ LL |     while (let 0 = 0, false).1 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:264:12
+  --> $DIR/disallowed-positions.rs:268:12
    |
 LL |     while (let 0 = 0,) {}
    |            ^^^^^^^^^
@@ -635,7 +635,7 @@ LL |     while (let 0 = 0,) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:268:16
+  --> $DIR/disallowed-positions.rs:272:16
    |
 LL |         while (let 0 = 0).await {}
    |                ^^^^^^^^^
@@ -643,7 +643,7 @@ LL |         while (let 0 = 0).await {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:272:15
+  --> $DIR/disallowed-positions.rs:276:15
    |
 LL |     while (|| let 0 = 0) {}
    |               ^^^
@@ -651,7 +651,7 @@ LL |     while (|| let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:275:12
+  --> $DIR/disallowed-positions.rs:279:12
    |
 LL |     while (let 0 = 0)() {}
    |            ^^^^^^^^^
@@ -659,7 +659,7 @@ LL |     while (let 0 = 0)() {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:292:6
+  --> $DIR/disallowed-positions.rs:296:6
    |
 LL |     &let 0 = 0;
    |      ^^^
@@ -667,7 +667,7 @@ LL |     &let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:295:6
+  --> $DIR/disallowed-positions.rs:299:6
    |
 LL |     !let 0 = 0;
    |      ^^^
@@ -675,7 +675,7 @@ LL |     !let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:297:6
+  --> $DIR/disallowed-positions.rs:301:6
    |
 LL |     *let 0 = 0;
    |      ^^^
@@ -683,7 +683,7 @@ LL |     *let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:299:6
+  --> $DIR/disallowed-positions.rs:303:6
    |
 LL |     -let 0 = 0;
    |      ^^^
@@ -691,7 +691,7 @@ LL |     -let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:301:13
+  --> $DIR/disallowed-positions.rs:305:13
    |
 LL |     let _ = let _ = 3;
    |             ^^^
@@ -699,7 +699,7 @@ LL |     let _ = let _ = 3;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:309:6
+  --> $DIR/disallowed-positions.rs:313:6
    |
 LL |     (let 0 = 0)?;
    |      ^^^
@@ -707,7 +707,7 @@ LL |     (let 0 = 0)?;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:312:13
+  --> $DIR/disallowed-positions.rs:316:13
    |
 LL |     true || let 0 = 0;
    |             ^^^
@@ -715,7 +715,7 @@ LL |     true || let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:314:14
+  --> $DIR/disallowed-positions.rs:318:14
    |
 LL |     (true || let 0 = 0);
    |              ^^^
@@ -723,7 +723,7 @@ LL |     (true || let 0 = 0);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:316:22
+  --> $DIR/disallowed-positions.rs:320:22
    |
 LL |     true && (true || let 0 = 0);
    |                      ^^^
@@ -731,7 +731,7 @@ LL |     true && (true || let 0 = 0);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:320:9
+  --> $DIR/disallowed-positions.rs:324:9
    |
 LL |     x = let 0 = 0;
    |         ^^^
@@ -739,7 +739,7 @@ LL |     x = let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:323:12
+  --> $DIR/disallowed-positions.rs:327:12
    |
 LL |     true..(let 0 = 0);
    |            ^^^
@@ -747,7 +747,7 @@ LL |     true..(let 0 = 0);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:325:8
+  --> $DIR/disallowed-positions.rs:329:8
    |
 LL |     ..(let 0 = 0);
    |        ^^^
@@ -755,7 +755,7 @@ LL |     ..(let 0 = 0);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:327:6
+  --> $DIR/disallowed-positions.rs:331:6
    |
 LL |     (let 0 = 0)..;
    |      ^^^
@@ -763,7 +763,7 @@ LL |     (let 0 = 0)..;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:330:6
+  --> $DIR/disallowed-positions.rs:334:6
    |
 LL |     (let Range { start: _, end: _ } = true..true || false);
    |      ^^^
@@ -771,7 +771,7 @@ LL |     (let Range { start: _, end: _ } = true..true || false);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:334:6
+  --> $DIR/disallowed-positions.rs:338:6
    |
 LL |     (let true = let true = true);
    |      ^^^
@@ -779,7 +779,7 @@ LL |     (let true = let true = true);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:334:17
+  --> $DIR/disallowed-positions.rs:338:17
    |
 LL |     (let true = let true = true);
    |                 ^^^
@@ -787,7 +787,7 @@ LL |     (let true = let true = true);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:340:25
+  --> $DIR/disallowed-positions.rs:344:25
    |
 LL |         let x = true && let y = 1;
    |                         ^^^
@@ -795,7 +795,7 @@ LL |         let x = true && let y = 1;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:346:19
+  --> $DIR/disallowed-positions.rs:350:19
    |
 LL |         [1, 2, 3][let _ = ()]
    |                   ^^^
@@ -803,7 +803,7 @@ LL |         [1, 2, 3][let _ = ()]
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:351:6
+  --> $DIR/disallowed-positions.rs:355:6
    |
 LL |     &let 0 = 0
    |      ^^^
@@ -811,7 +811,7 @@ LL |     &let 0 = 0
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:362:17
+  --> $DIR/disallowed-positions.rs:366:17
    |
 LL |         true && let 1 = 1
    |                 ^^^
@@ -819,7 +819,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:367:17
+  --> $DIR/disallowed-positions.rs:371:17
    |
 LL |         true && let 1 = 1
    |                 ^^^
@@ -827,7 +827,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:372:17
+  --> $DIR/disallowed-positions.rs:376:17
    |
 LL |         true && let 1 = 1
    |                 ^^^
@@ -835,7 +835,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:383:17
+  --> $DIR/disallowed-positions.rs:387:17
    |
 LL |         true && let 1 = 1
    |                 ^^^
@@ -843,7 +843,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expressions must be enclosed in braces to be used as const generic arguments
-  --> $DIR/disallowed-positions.rs:383:9
+  --> $DIR/disallowed-positions.rs:387:9
    |
 LL |         true && let 1 = 1
    |         ^^^^^^^^^^^^^^^^^
@@ -854,124 +854,124 @@ LL |         { true && let 1 = 1 }
    |         +                   +
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:393:9
+  --> $DIR/disallowed-positions.rs:397:9
    |
 LL |     if (let Some(a) = opt && true) {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:393:9
+  --> $DIR/disallowed-positions.rs:397:9
    |
 LL |     if (let Some(a) = opt && true) {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:397:9
+  --> $DIR/disallowed-positions.rs:401:9
    |
 LL |     if (let Some(a) = opt) && true {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:397:9
+  --> $DIR/disallowed-positions.rs:401:9
    |
 LL |     if (let Some(a) = opt) && true {
    |         ^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:400:9
+  --> $DIR/disallowed-positions.rs:404:9
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:400:9
+  --> $DIR/disallowed-positions.rs:404:9
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |         ^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:400:32
+  --> $DIR/disallowed-positions.rs:404:32
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |                                ^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:400:32
+  --> $DIR/disallowed-positions.rs:404:32
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |                                ^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:408:9
+  --> $DIR/disallowed-positions.rs:412:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:408:9
+  --> $DIR/disallowed-positions.rs:412:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:408:31
+  --> $DIR/disallowed-positions.rs:412:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |                               ^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:408:31
+  --> $DIR/disallowed-positions.rs:412:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |                               ^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:412:9
+  --> $DIR/disallowed-positions.rs:416:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:412:9
+  --> $DIR/disallowed-positions.rs:416:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:412:31
+  --> $DIR/disallowed-positions.rs:416:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |                               ^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:412:31
+  --> $DIR/disallowed-positions.rs:416:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |                               ^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:416:9
+  --> $DIR/disallowed-positions.rs:420:9
    |
 LL |     if (let Some(a) = opt && (true)) && true {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:416:9
+  --> $DIR/disallowed-positions.rs:420:9
    |
 LL |     if (let Some(a) = opt && (true)) && true {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:436:22
+  --> $DIR/disallowed-positions.rs:440:22
    |
 LL |     let x = (true && let y = 1);
    |                      ^^^
@@ -979,7 +979,7 @@ LL |     let x = (true && let y = 1);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:441:20
+  --> $DIR/disallowed-positions.rs:445:20
    |
 LL |         ([1, 2, 3][let _ = ()])
    |                    ^^^
@@ -995,15 +995,51 @@ LL |     use_expr!((let 0 = 1 && 0 == 0));
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:93:16
+  --> $DIR/disallowed-positions.rs:91:16
+   |
+LL |     use_expr!((let 0 = 1 && 0 == 0));
+   |                ^^^
+   |
+   = note: only supported directly in conditions of `if` and `while` expressions
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:91:16
+   |
+LL |     use_expr!((let 0 = 1 && 0 == 0));
+   |                ^^^
+   |
+   = note: only supported directly in conditions of `if` and `while` expressions
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:95:16
+   |
+LL |     use_expr!((let 0 = 1));
+   |                ^^^
+   |
+   = note: only supported directly in conditions of `if` and `while` expressions
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:95:16
+   |
+LL |     use_expr!((let 0 = 1));
+   |                ^^^
+   |
+   = note: only supported directly in conditions of `if` and `while` expressions
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:95:16
    |
 LL |     use_expr!((let 0 = 1));
    |                ^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:130:8
+  --> $DIR/disallowed-positions.rs:134:8
    |
 LL |     if true..(let 0 = 0) {}
    |        ^^^^^^^^^^^^^^^^^ expected `bool`, found `Range<bool>`
@@ -1012,7 +1048,7 @@ LL |     if true..(let 0 = 0) {}
             found struct `std::ops::Range<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:139:12
+  --> $DIR/disallowed-positions.rs:143:12
    |
 LL |     if let Range { start: _, end: _ } = true..true && false {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1023,7 +1059,7 @@ LL |     if let Range { start: _, end: _ } = true..true && false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:142:12
+  --> $DIR/disallowed-positions.rs:146:12
    |
 LL |     if let Range { start: _, end: _ } = true..true || false {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1034,7 +1070,7 @@ LL |     if let Range { start: _, end: _ } = true..true || false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:148:12
+  --> $DIR/disallowed-positions.rs:152:12
    |
 LL |     if let Range { start: F, end } = F..|| true {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^   - this expression has type `fn() -> bool`
@@ -1045,7 +1081,7 @@ LL |     if let Range { start: F, end } = F..|| true {}
                   found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:154:12
+  --> $DIR/disallowed-positions.rs:158:12
    |
 LL |     if let Range { start: true, end } = t..&&false {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^   - this expression has type `&&bool`
@@ -1056,7 +1092,7 @@ LL |     if let Range { start: true, end } = t..&&false {}
             found struct `std::ops::Range<_>`
 
 error[E0277]: the `?` operator can only be applied to values that implement `Try`
-  --> $DIR/disallowed-positions.rs:110:20
+  --> $DIR/disallowed-positions.rs:114:20
    |
 LL |         if let 0 = 0? {}
    |                    ^^ the `?` operator cannot be applied to type `{integer}`
@@ -1064,7 +1100,7 @@ LL |         if let 0 = 0? {}
    = help: the trait `Try` is not implemented for `{integer}`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:221:11
+  --> $DIR/disallowed-positions.rs:225:11
    |
 LL |     while true..(let 0 = 0) {}
    |           ^^^^^^^^^^^^^^^^^ expected `bool`, found `Range<bool>`
@@ -1073,7 +1109,7 @@ LL |     while true..(let 0 = 0) {}
             found struct `std::ops::Range<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:230:15
+  --> $DIR/disallowed-positions.rs:234:15
    |
 LL |     while let Range { start: _, end: _ } = true..true && false {}
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1084,7 +1120,7 @@ LL |     while let Range { start: _, end: _ } = true..true && false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:233:15
+  --> $DIR/disallowed-positions.rs:237:15
    |
 LL |     while let Range { start: _, end: _ } = true..true || false {}
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1095,7 +1131,7 @@ LL |     while let Range { start: _, end: _ } = true..true || false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:239:15
+  --> $DIR/disallowed-positions.rs:243:15
    |
 LL |     while let Range { start: F, end } = F..|| true {}
    |               ^^^^^^^^^^^^^^^^^^^^^^^   - this expression has type `fn() -> bool`
@@ -1106,7 +1142,7 @@ LL |     while let Range { start: F, end } = F..|| true {}
                   found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:245:15
+  --> $DIR/disallowed-positions.rs:249:15
    |
 LL |     while let Range { start: true, end } = t..&&false {}
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^   - this expression has type `&&bool`
@@ -1117,7 +1153,7 @@ LL |     while let Range { start: true, end } = t..&&false {}
             found struct `std::ops::Range<_>`
 
 error[E0277]: the `?` operator can only be applied to values that implement `Try`
-  --> $DIR/disallowed-positions.rs:201:23
+  --> $DIR/disallowed-positions.rs:205:23
    |
 LL |         while let 0 = 0? {}
    |                       ^^ the `?` operator cannot be applied to type `{integer}`
@@ -1125,7 +1161,7 @@ LL |         while let 0 = 0? {}
    = help: the trait `Try` is not implemented for `{integer}`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:330:10
+  --> $DIR/disallowed-positions.rs:334:10
    |
 LL |     (let Range { start: _, end: _ } = true..true || false);
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1136,14 +1172,14 @@ LL |     (let Range { start: _, end: _ } = true..true || false);
             found struct `std::ops::Range<_>`
 
 error[E0277]: the `?` operator can only be applied to values that implement `Try`
-  --> $DIR/disallowed-positions.rs:305:17
+  --> $DIR/disallowed-positions.rs:309:17
    |
 LL |         let 0 = 0?;
    |                 ^^ the `?` operator cannot be applied to type `{integer}`
    |
    = help: the trait `Try` is not implemented for `{integer}`
 
-error: aborting due to 121 previous errors
+error: aborting due to 125 previous errors
 
 Some errors have detailed explanations: E0277, E0308.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.no_feature.stderr b/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.no_feature.stderr
index ad16a0f8ed812..bab50c22c0308 100644
--- a/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.no_feature.stderr
+++ b/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.no_feature.stderr
@@ -233,7 +233,7 @@ LL |     while let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {
    |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:99:9
+  --> $DIR/disallowed-positions.rs:103:9
    |
 LL |     if &let 0 = 0 {}
    |         ^^^^^^^^^
@@ -241,7 +241,7 @@ LL |     if &let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:102:9
+  --> $DIR/disallowed-positions.rs:106:9
    |
 LL |     if !let 0 = 0 {}
    |         ^^^^^^^^^
@@ -249,7 +249,7 @@ LL |     if !let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:104:9
+  --> $DIR/disallowed-positions.rs:108:9
    |
 LL |     if *let 0 = 0 {}
    |         ^^^^^^^^^
@@ -257,7 +257,7 @@ LL |     if *let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:106:9
+  --> $DIR/disallowed-positions.rs:110:9
    |
 LL |     if -let 0 = 0 {}
    |         ^^^^^^^^^
@@ -265,7 +265,7 @@ LL |     if -let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:114:9
+  --> $DIR/disallowed-positions.rs:118:9
    |
 LL |     if (let 0 = 0)? {}
    |         ^^^^^^^^^
@@ -273,20 +273,20 @@ LL |     if (let 0 = 0)? {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:117:16
+  --> $DIR/disallowed-positions.rs:121:16
    |
 LL |     if true || let 0 = 0 {}
    |                ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:117:13
+  --> $DIR/disallowed-positions.rs:121:13
    |
 LL |     if true || let 0 = 0 {}
    |             ^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:119:17
+  --> $DIR/disallowed-positions.rs:123:17
    |
 LL |     if (true || let 0 = 0) {}
    |                 ^^^^^^^^^
@@ -294,7 +294,7 @@ LL |     if (true || let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:121:25
+  --> $DIR/disallowed-positions.rs:125:25
    |
 LL |     if true && (true || let 0 = 0) {}
    |                         ^^^^^^^^^
@@ -302,7 +302,7 @@ LL |     if true && (true || let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:123:25
+  --> $DIR/disallowed-positions.rs:127:25
    |
 LL |     if true || (true && let 0 = 0) {}
    |                         ^^^^^^^^^
@@ -310,7 +310,7 @@ LL |     if true || (true && let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:127:12
+  --> $DIR/disallowed-positions.rs:131:12
    |
 LL |     if x = let 0 = 0 {}
    |            ^^^
@@ -318,7 +318,7 @@ LL |     if x = let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:130:15
+  --> $DIR/disallowed-positions.rs:134:15
    |
 LL |     if true..(let 0 = 0) {}
    |               ^^^^^^^^^
@@ -326,7 +326,7 @@ LL |     if true..(let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:133:11
+  --> $DIR/disallowed-positions.rs:137:11
    |
 LL |     if ..(let 0 = 0) {}
    |           ^^^^^^^^^
@@ -334,7 +334,7 @@ LL |     if ..(let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:135:9
+  --> $DIR/disallowed-positions.rs:139:9
    |
 LL |     if (let 0 = 0).. {}
    |         ^^^^^^^^^
@@ -342,7 +342,7 @@ LL |     if (let 0 = 0).. {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:139:8
+  --> $DIR/disallowed-positions.rs:143:8
    |
 LL |     if let Range { start: _, end: _ } = true..true && false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -350,7 +350,7 @@ LL |     if let Range { start: _, end: _ } = true..true && false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:142:8
+  --> $DIR/disallowed-positions.rs:146:8
    |
 LL |     if let Range { start: _, end: _ } = true..true || false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -358,7 +358,7 @@ LL |     if let Range { start: _, end: _ } = true..true || false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:148:8
+  --> $DIR/disallowed-positions.rs:152:8
    |
 LL |     if let Range { start: F, end } = F..|| true {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -366,7 +366,7 @@ LL |     if let Range { start: F, end } = F..|| true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:154:8
+  --> $DIR/disallowed-positions.rs:158:8
    |
 LL |     if let Range { start: true, end } = t..&&false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -374,7 +374,7 @@ LL |     if let Range { start: true, end } = t..&&false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:158:19
+  --> $DIR/disallowed-positions.rs:162:19
    |
 LL |     if let true = let true = true {}
    |                   ^^^
@@ -382,7 +382,7 @@ LL |     if let true = let true = true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:161:15
+  --> $DIR/disallowed-positions.rs:165:15
    |
 LL |     if return let 0 = 0 {}
    |               ^^^
@@ -390,7 +390,7 @@ LL |     if return let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:164:21
+  --> $DIR/disallowed-positions.rs:168:21
    |
 LL |     loop { if break let 0 = 0 {} }
    |                     ^^^
@@ -398,7 +398,7 @@ LL |     loop { if break let 0 = 0 {} }
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:167:15
+  --> $DIR/disallowed-positions.rs:171:15
    |
 LL |     if (match let 0 = 0 { _ => { false } }) {}
    |               ^^^
@@ -406,7 +406,7 @@ LL |     if (match let 0 = 0 { _ => { false } }) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:170:9
+  --> $DIR/disallowed-positions.rs:174:9
    |
 LL |     if (let 0 = 0, false).1 {}
    |         ^^^^^^^^^
@@ -414,7 +414,7 @@ LL |     if (let 0 = 0, false).1 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:173:9
+  --> $DIR/disallowed-positions.rs:177:9
    |
 LL |     if (let 0 = 0,) {}
    |         ^^^^^^^^^
@@ -422,7 +422,7 @@ LL |     if (let 0 = 0,) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:177:13
+  --> $DIR/disallowed-positions.rs:181:13
    |
 LL |         if (let 0 = 0).await {}
    |             ^^^^^^^^^
@@ -430,7 +430,7 @@ LL |         if (let 0 = 0).await {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:181:12
+  --> $DIR/disallowed-positions.rs:185:12
    |
 LL |     if (|| let 0 = 0) {}
    |            ^^^
@@ -438,7 +438,7 @@ LL |     if (|| let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:184:9
+  --> $DIR/disallowed-positions.rs:188:9
    |
 LL |     if (let 0 = 0)() {}
    |         ^^^^^^^^^
@@ -446,7 +446,7 @@ LL |     if (let 0 = 0)() {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:190:12
+  --> $DIR/disallowed-positions.rs:194:12
    |
 LL |     while &let 0 = 0 {}
    |            ^^^^^^^^^
@@ -454,7 +454,7 @@ LL |     while &let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:193:12
+  --> $DIR/disallowed-positions.rs:197:12
    |
 LL |     while !let 0 = 0 {}
    |            ^^^^^^^^^
@@ -462,7 +462,7 @@ LL |     while !let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:195:12
+  --> $DIR/disallowed-positions.rs:199:12
    |
 LL |     while *let 0 = 0 {}
    |            ^^^^^^^^^
@@ -470,7 +470,7 @@ LL |     while *let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:197:12
+  --> $DIR/disallowed-positions.rs:201:12
    |
 LL |     while -let 0 = 0 {}
    |            ^^^^^^^^^
@@ -478,7 +478,7 @@ LL |     while -let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:205:12
+  --> $DIR/disallowed-positions.rs:209:12
    |
 LL |     while (let 0 = 0)? {}
    |            ^^^^^^^^^
@@ -486,20 +486,20 @@ LL |     while (let 0 = 0)? {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:208:19
+  --> $DIR/disallowed-positions.rs:212:19
    |
 LL |     while true || let 0 = 0 {}
    |                   ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:208:16
+  --> $DIR/disallowed-positions.rs:212:16
    |
 LL |     while true || let 0 = 0 {}
    |                ^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:210:20
+  --> $DIR/disallowed-positions.rs:214:20
    |
 LL |     while (true || let 0 = 0) {}
    |                    ^^^^^^^^^
@@ -507,7 +507,7 @@ LL |     while (true || let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:212:28
+  --> $DIR/disallowed-positions.rs:216:28
    |
 LL |     while true && (true || let 0 = 0) {}
    |                            ^^^^^^^^^
@@ -515,7 +515,7 @@ LL |     while true && (true || let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:214:28
+  --> $DIR/disallowed-positions.rs:218:28
    |
 LL |     while true || (true && let 0 = 0) {}
    |                            ^^^^^^^^^
@@ -523,7 +523,7 @@ LL |     while true || (true && let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:218:15
+  --> $DIR/disallowed-positions.rs:222:15
    |
 LL |     while x = let 0 = 0 {}
    |               ^^^
@@ -531,7 +531,7 @@ LL |     while x = let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:221:18
+  --> $DIR/disallowed-positions.rs:225:18
    |
 LL |     while true..(let 0 = 0) {}
    |                  ^^^^^^^^^
@@ -539,7 +539,7 @@ LL |     while true..(let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:224:14
+  --> $DIR/disallowed-positions.rs:228:14
    |
 LL |     while ..(let 0 = 0) {}
    |              ^^^^^^^^^
@@ -547,7 +547,7 @@ LL |     while ..(let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:226:12
+  --> $DIR/disallowed-positions.rs:230:12
    |
 LL |     while (let 0 = 0).. {}
    |            ^^^^^^^^^
@@ -555,7 +555,7 @@ LL |     while (let 0 = 0).. {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:230:11
+  --> $DIR/disallowed-positions.rs:234:11
    |
 LL |     while let Range { start: _, end: _ } = true..true && false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -563,7 +563,7 @@ LL |     while let Range { start: _, end: _ } = true..true && false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:233:11
+  --> $DIR/disallowed-positions.rs:237:11
    |
 LL |     while let Range { start: _, end: _ } = true..true || false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -571,7 +571,7 @@ LL |     while let Range { start: _, end: _ } = true..true || false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:239:11
+  --> $DIR/disallowed-positions.rs:243:11
    |
 LL |     while let Range { start: F, end } = F..|| true {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -579,7 +579,7 @@ LL |     while let Range { start: F, end } = F..|| true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:245:11
+  --> $DIR/disallowed-positions.rs:249:11
    |
 LL |     while let Range { start: true, end } = t..&&false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -587,7 +587,7 @@ LL |     while let Range { start: true, end } = t..&&false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:249:22
+  --> $DIR/disallowed-positions.rs:253:22
    |
 LL |     while let true = let true = true {}
    |                      ^^^
@@ -595,7 +595,7 @@ LL |     while let true = let true = true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:252:18
+  --> $DIR/disallowed-positions.rs:256:18
    |
 LL |     while return let 0 = 0 {}
    |                  ^^^
@@ -603,7 +603,7 @@ LL |     while return let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:255:39
+  --> $DIR/disallowed-positions.rs:259:39
    |
 LL |     'outer: loop { while break 'outer let 0 = 0 {} }
    |                                       ^^^
@@ -611,7 +611,7 @@ LL |     'outer: loop { while break 'outer let 0 = 0 {} }
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:258:18
+  --> $DIR/disallowed-positions.rs:262:18
    |
 LL |     while (match let 0 = 0 { _ => { false } }) {}
    |                  ^^^
@@ -619,7 +619,7 @@ LL |     while (match let 0 = 0 { _ => { false } }) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:261:12
+  --> $DIR/disallowed-positions.rs:265:12
    |
 LL |     while (let 0 = 0, false).1 {}
    |            ^^^^^^^^^
@@ -627,7 +627,7 @@ LL |     while (let 0 = 0, false).1 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:264:12
+  --> $DIR/disallowed-positions.rs:268:12
    |
 LL |     while (let 0 = 0,) {}
    |            ^^^^^^^^^
@@ -635,7 +635,7 @@ LL |     while (let 0 = 0,) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:268:16
+  --> $DIR/disallowed-positions.rs:272:16
    |
 LL |         while (let 0 = 0).await {}
    |                ^^^^^^^^^
@@ -643,7 +643,7 @@ LL |         while (let 0 = 0).await {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:272:15
+  --> $DIR/disallowed-positions.rs:276:15
    |
 LL |     while (|| let 0 = 0) {}
    |               ^^^
@@ -651,7 +651,7 @@ LL |     while (|| let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:275:12
+  --> $DIR/disallowed-positions.rs:279:12
    |
 LL |     while (let 0 = 0)() {}
    |            ^^^^^^^^^
@@ -659,7 +659,7 @@ LL |     while (let 0 = 0)() {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:292:6
+  --> $DIR/disallowed-positions.rs:296:6
    |
 LL |     &let 0 = 0;
    |      ^^^
@@ -667,7 +667,7 @@ LL |     &let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:295:6
+  --> $DIR/disallowed-positions.rs:299:6
    |
 LL |     !let 0 = 0;
    |      ^^^
@@ -675,7 +675,7 @@ LL |     !let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:297:6
+  --> $DIR/disallowed-positions.rs:301:6
    |
 LL |     *let 0 = 0;
    |      ^^^
@@ -683,7 +683,7 @@ LL |     *let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:299:6
+  --> $DIR/disallowed-positions.rs:303:6
    |
 LL |     -let 0 = 0;
    |      ^^^
@@ -691,7 +691,7 @@ LL |     -let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:301:13
+  --> $DIR/disallowed-positions.rs:305:13
    |
 LL |     let _ = let _ = 3;
    |             ^^^
@@ -699,7 +699,7 @@ LL |     let _ = let _ = 3;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:309:6
+  --> $DIR/disallowed-positions.rs:313:6
    |
 LL |     (let 0 = 0)?;
    |      ^^^
@@ -707,7 +707,7 @@ LL |     (let 0 = 0)?;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:312:13
+  --> $DIR/disallowed-positions.rs:316:13
    |
 LL |     true || let 0 = 0;
    |             ^^^
@@ -715,7 +715,7 @@ LL |     true || let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:314:14
+  --> $DIR/disallowed-positions.rs:318:14
    |
 LL |     (true || let 0 = 0);
    |              ^^^
@@ -723,7 +723,7 @@ LL |     (true || let 0 = 0);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:316:22
+  --> $DIR/disallowed-positions.rs:320:22
    |
 LL |     true && (true || let 0 = 0);
    |                      ^^^
@@ -731,7 +731,7 @@ LL |     true && (true || let 0 = 0);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:320:9
+  --> $DIR/disallowed-positions.rs:324:9
    |
 LL |     x = let 0 = 0;
    |         ^^^
@@ -739,7 +739,7 @@ LL |     x = let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:323:12
+  --> $DIR/disallowed-positions.rs:327:12
    |
 LL |     true..(let 0 = 0);
    |            ^^^
@@ -747,7 +747,7 @@ LL |     true..(let 0 = 0);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:325:8
+  --> $DIR/disallowed-positions.rs:329:8
    |
 LL |     ..(let 0 = 0);
    |        ^^^
@@ -755,7 +755,7 @@ LL |     ..(let 0 = 0);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:327:6
+  --> $DIR/disallowed-positions.rs:331:6
    |
 LL |     (let 0 = 0)..;
    |      ^^^
@@ -763,7 +763,7 @@ LL |     (let 0 = 0)..;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:330:6
+  --> $DIR/disallowed-positions.rs:334:6
    |
 LL |     (let Range { start: _, end: _ } = true..true || false);
    |      ^^^
@@ -771,7 +771,7 @@ LL |     (let Range { start: _, end: _ } = true..true || false);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:334:6
+  --> $DIR/disallowed-positions.rs:338:6
    |
 LL |     (let true = let true = true);
    |      ^^^
@@ -779,7 +779,7 @@ LL |     (let true = let true = true);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:334:17
+  --> $DIR/disallowed-positions.rs:338:17
    |
 LL |     (let true = let true = true);
    |                 ^^^
@@ -787,7 +787,7 @@ LL |     (let true = let true = true);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:340:25
+  --> $DIR/disallowed-positions.rs:344:25
    |
 LL |         let x = true && let y = 1;
    |                         ^^^
@@ -795,7 +795,7 @@ LL |         let x = true && let y = 1;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:346:19
+  --> $DIR/disallowed-positions.rs:350:19
    |
 LL |         [1, 2, 3][let _ = ()]
    |                   ^^^
@@ -803,7 +803,7 @@ LL |         [1, 2, 3][let _ = ()]
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:351:6
+  --> $DIR/disallowed-positions.rs:355:6
    |
 LL |     &let 0 = 0
    |      ^^^
@@ -811,7 +811,7 @@ LL |     &let 0 = 0
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:362:17
+  --> $DIR/disallowed-positions.rs:366:17
    |
 LL |         true && let 1 = 1
    |                 ^^^
@@ -819,7 +819,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:367:17
+  --> $DIR/disallowed-positions.rs:371:17
    |
 LL |         true && let 1 = 1
    |                 ^^^
@@ -827,7 +827,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:372:17
+  --> $DIR/disallowed-positions.rs:376:17
    |
 LL |         true && let 1 = 1
    |                 ^^^
@@ -835,7 +835,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:383:17
+  --> $DIR/disallowed-positions.rs:387:17
    |
 LL |         true && let 1 = 1
    |                 ^^^
@@ -843,7 +843,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expressions must be enclosed in braces to be used as const generic arguments
-  --> $DIR/disallowed-positions.rs:383:9
+  --> $DIR/disallowed-positions.rs:387:9
    |
 LL |         true && let 1 = 1
    |         ^^^^^^^^^^^^^^^^^
@@ -854,124 +854,124 @@ LL |         { true && let 1 = 1 }
    |         +                   +
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:393:9
+  --> $DIR/disallowed-positions.rs:397:9
    |
 LL |     if (let Some(a) = opt && true) {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:393:9
+  --> $DIR/disallowed-positions.rs:397:9
    |
 LL |     if (let Some(a) = opt && true) {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:397:9
+  --> $DIR/disallowed-positions.rs:401:9
    |
 LL |     if (let Some(a) = opt) && true {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:397:9
+  --> $DIR/disallowed-positions.rs:401:9
    |
 LL |     if (let Some(a) = opt) && true {
    |         ^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:400:9
+  --> $DIR/disallowed-positions.rs:404:9
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:400:9
+  --> $DIR/disallowed-positions.rs:404:9
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |         ^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:400:32
+  --> $DIR/disallowed-positions.rs:404:32
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |                                ^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:400:32
+  --> $DIR/disallowed-positions.rs:404:32
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |                                ^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:408:9
+  --> $DIR/disallowed-positions.rs:412:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:408:9
+  --> $DIR/disallowed-positions.rs:412:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:408:31
+  --> $DIR/disallowed-positions.rs:412:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |                               ^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:408:31
+  --> $DIR/disallowed-positions.rs:412:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |                               ^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:412:9
+  --> $DIR/disallowed-positions.rs:416:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:412:9
+  --> $DIR/disallowed-positions.rs:416:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:412:31
+  --> $DIR/disallowed-positions.rs:416:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |                               ^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:412:31
+  --> $DIR/disallowed-positions.rs:416:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |                               ^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:416:9
+  --> $DIR/disallowed-positions.rs:420:9
    |
 LL |     if (let Some(a) = opt && (true)) && true {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:416:9
+  --> $DIR/disallowed-positions.rs:420:9
    |
 LL |     if (let Some(a) = opt && (true)) && true {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:436:22
+  --> $DIR/disallowed-positions.rs:440:22
    |
 LL |     let x = (true && let y = 1);
    |                      ^^^
@@ -979,7 +979,7 @@ LL |     let x = (true && let y = 1);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:441:20
+  --> $DIR/disallowed-positions.rs:445:20
    |
 LL |         ([1, 2, 3][let _ = ()])
    |                    ^^^
@@ -995,12 +995,48 @@ LL |     use_expr!((let 0 = 1 && 0 == 0));
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:93:16
+  --> $DIR/disallowed-positions.rs:91:16
+   |
+LL |     use_expr!((let 0 = 1 && 0 == 0));
+   |                ^^^
+   |
+   = note: only supported directly in conditions of `if` and `while` expressions
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:91:16
+   |
+LL |     use_expr!((let 0 = 1 && 0 == 0));
+   |                ^^^
+   |
+   = note: only supported directly in conditions of `if` and `while` expressions
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:95:16
+   |
+LL |     use_expr!((let 0 = 1));
+   |                ^^^
+   |
+   = note: only supported directly in conditions of `if` and `while` expressions
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:95:16
+   |
+LL |     use_expr!((let 0 = 1));
+   |                ^^^
+   |
+   = note: only supported directly in conditions of `if` and `while` expressions
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:95:16
    |
 LL |     use_expr!((let 0 = 1));
    |                ^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0658]: `let` expressions in this position are unstable
   --> $DIR/disallowed-positions.rs:49:8
@@ -1043,7 +1079,7 @@ LL |     while let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/disallowed-positions.rs:404:8
+  --> $DIR/disallowed-positions.rs:408:8
    |
 LL |     if let Some(a) = opt && (true && true) {
    |        ^^^^^^^^^^^^^^^^^
@@ -1053,7 +1089,7 @@ LL |     if let Some(a) = opt && (true && true) {
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/disallowed-positions.rs:420:28
+  --> $DIR/disallowed-positions.rs:424:28
    |
 LL |     if (true && (true)) && let Some(a) = opt {
    |                            ^^^^^^^^^^^^^^^^^
@@ -1063,7 +1099,7 @@ LL |     if (true && (true)) && let Some(a) = opt {
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/disallowed-positions.rs:423:18
+  --> $DIR/disallowed-positions.rs:427:18
    |
 LL |     if (true) && let Some(a) = opt {
    |                  ^^^^^^^^^^^^^^^^^
@@ -1073,7 +1109,7 @@ LL |     if (true) && let Some(a) = opt {
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/disallowed-positions.rs:426:16
+  --> $DIR/disallowed-positions.rs:430:16
    |
 LL |     if true && let Some(a) = opt {
    |                ^^^^^^^^^^^^^^^^^
@@ -1083,7 +1119,7 @@ LL |     if true && let Some(a) = opt {
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/disallowed-positions.rs:431:8
+  --> $DIR/disallowed-positions.rs:435:8
    |
 LL |     if let true = (true && fun()) && (true) {
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -1093,7 +1129,7 @@ LL |     if let true = (true && fun()) && (true) {
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:130:8
+  --> $DIR/disallowed-positions.rs:134:8
    |
 LL |     if true..(let 0 = 0) {}
    |        ^^^^^^^^^^^^^^^^^ expected `bool`, found `Range<bool>`
@@ -1102,7 +1138,7 @@ LL |     if true..(let 0 = 0) {}
             found struct `std::ops::Range<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:139:12
+  --> $DIR/disallowed-positions.rs:143:12
    |
 LL |     if let Range { start: _, end: _ } = true..true && false {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1113,7 +1149,7 @@ LL |     if let Range { start: _, end: _ } = true..true && false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:142:12
+  --> $DIR/disallowed-positions.rs:146:12
    |
 LL |     if let Range { start: _, end: _ } = true..true || false {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1124,7 +1160,7 @@ LL |     if let Range { start: _, end: _ } = true..true || false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:148:12
+  --> $DIR/disallowed-positions.rs:152:12
    |
 LL |     if let Range { start: F, end } = F..|| true {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^   - this expression has type `fn() -> bool`
@@ -1135,7 +1171,7 @@ LL |     if let Range { start: F, end } = F..|| true {}
                   found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:154:12
+  --> $DIR/disallowed-positions.rs:158:12
    |
 LL |     if let Range { start: true, end } = t..&&false {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^   - this expression has type `&&bool`
@@ -1146,7 +1182,7 @@ LL |     if let Range { start: true, end } = t..&&false {}
             found struct `std::ops::Range<_>`
 
 error[E0277]: the `?` operator can only be applied to values that implement `Try`
-  --> $DIR/disallowed-positions.rs:110:20
+  --> $DIR/disallowed-positions.rs:114:20
    |
 LL |         if let 0 = 0? {}
    |                    ^^ the `?` operator cannot be applied to type `{integer}`
@@ -1154,7 +1190,7 @@ LL |         if let 0 = 0? {}
    = help: the trait `Try` is not implemented for `{integer}`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:221:11
+  --> $DIR/disallowed-positions.rs:225:11
    |
 LL |     while true..(let 0 = 0) {}
    |           ^^^^^^^^^^^^^^^^^ expected `bool`, found `Range<bool>`
@@ -1163,7 +1199,7 @@ LL |     while true..(let 0 = 0) {}
             found struct `std::ops::Range<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:230:15
+  --> $DIR/disallowed-positions.rs:234:15
    |
 LL |     while let Range { start: _, end: _ } = true..true && false {}
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1174,7 +1210,7 @@ LL |     while let Range { start: _, end: _ } = true..true && false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:233:15
+  --> $DIR/disallowed-positions.rs:237:15
    |
 LL |     while let Range { start: _, end: _ } = true..true || false {}
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1185,7 +1221,7 @@ LL |     while let Range { start: _, end: _ } = true..true || false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:239:15
+  --> $DIR/disallowed-positions.rs:243:15
    |
 LL |     while let Range { start: F, end } = F..|| true {}
    |               ^^^^^^^^^^^^^^^^^^^^^^^   - this expression has type `fn() -> bool`
@@ -1196,7 +1232,7 @@ LL |     while let Range { start: F, end } = F..|| true {}
                   found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:245:15
+  --> $DIR/disallowed-positions.rs:249:15
    |
 LL |     while let Range { start: true, end } = t..&&false {}
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^   - this expression has type `&&bool`
@@ -1207,7 +1243,7 @@ LL |     while let Range { start: true, end } = t..&&false {}
             found struct `std::ops::Range<_>`
 
 error[E0277]: the `?` operator can only be applied to values that implement `Try`
-  --> $DIR/disallowed-positions.rs:201:23
+  --> $DIR/disallowed-positions.rs:205:23
    |
 LL |         while let 0 = 0? {}
    |                       ^^ the `?` operator cannot be applied to type `{integer}`
@@ -1215,7 +1251,7 @@ LL |         while let 0 = 0? {}
    = help: the trait `Try` is not implemented for `{integer}`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:330:10
+  --> $DIR/disallowed-positions.rs:334:10
    |
 LL |     (let Range { start: _, end: _ } = true..true || false);
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1226,14 +1262,14 @@ LL |     (let Range { start: _, end: _ } = true..true || false);
             found struct `std::ops::Range<_>`
 
 error[E0277]: the `?` operator can only be applied to values that implement `Try`
-  --> $DIR/disallowed-positions.rs:305:17
+  --> $DIR/disallowed-positions.rs:309:17
    |
 LL |         let 0 = 0?;
    |                 ^^ the `?` operator cannot be applied to type `{integer}`
    |
    = help: the trait `Try` is not implemented for `{integer}`
 
-error: aborting due to 130 previous errors
+error: aborting due to 134 previous errors
 
 Some errors have detailed explanations: E0277, E0308, E0658.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.nothing.stderr b/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.nothing.stderr
index 2d5fd1144addd..943956feb4e07 100644
--- a/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.nothing.stderr
+++ b/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.nothing.stderr
@@ -233,7 +233,7 @@ LL |     while let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {
    |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:99:9
+  --> $DIR/disallowed-positions.rs:103:9
    |
 LL |     if &let 0 = 0 {}
    |         ^^^^^^^^^
@@ -241,7 +241,7 @@ LL |     if &let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:102:9
+  --> $DIR/disallowed-positions.rs:106:9
    |
 LL |     if !let 0 = 0 {}
    |         ^^^^^^^^^
@@ -249,7 +249,7 @@ LL |     if !let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:104:9
+  --> $DIR/disallowed-positions.rs:108:9
    |
 LL |     if *let 0 = 0 {}
    |         ^^^^^^^^^
@@ -257,7 +257,7 @@ LL |     if *let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:106:9
+  --> $DIR/disallowed-positions.rs:110:9
    |
 LL |     if -let 0 = 0 {}
    |         ^^^^^^^^^
@@ -265,7 +265,7 @@ LL |     if -let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:114:9
+  --> $DIR/disallowed-positions.rs:118:9
    |
 LL |     if (let 0 = 0)? {}
    |         ^^^^^^^^^
@@ -273,20 +273,20 @@ LL |     if (let 0 = 0)? {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:117:16
+  --> $DIR/disallowed-positions.rs:121:16
    |
 LL |     if true || let 0 = 0 {}
    |                ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:117:13
+  --> $DIR/disallowed-positions.rs:121:13
    |
 LL |     if true || let 0 = 0 {}
    |             ^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:119:17
+  --> $DIR/disallowed-positions.rs:123:17
    |
 LL |     if (true || let 0 = 0) {}
    |                 ^^^^^^^^^
@@ -294,7 +294,7 @@ LL |     if (true || let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:121:25
+  --> $DIR/disallowed-positions.rs:125:25
    |
 LL |     if true && (true || let 0 = 0) {}
    |                         ^^^^^^^^^
@@ -302,7 +302,7 @@ LL |     if true && (true || let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:123:25
+  --> $DIR/disallowed-positions.rs:127:25
    |
 LL |     if true || (true && let 0 = 0) {}
    |                         ^^^^^^^^^
@@ -310,7 +310,7 @@ LL |     if true || (true && let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:127:12
+  --> $DIR/disallowed-positions.rs:131:12
    |
 LL |     if x = let 0 = 0 {}
    |            ^^^
@@ -318,7 +318,7 @@ LL |     if x = let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:130:15
+  --> $DIR/disallowed-positions.rs:134:15
    |
 LL |     if true..(let 0 = 0) {}
    |               ^^^^^^^^^
@@ -326,7 +326,7 @@ LL |     if true..(let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:133:11
+  --> $DIR/disallowed-positions.rs:137:11
    |
 LL |     if ..(let 0 = 0) {}
    |           ^^^^^^^^^
@@ -334,7 +334,7 @@ LL |     if ..(let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:135:9
+  --> $DIR/disallowed-positions.rs:139:9
    |
 LL |     if (let 0 = 0).. {}
    |         ^^^^^^^^^
@@ -342,7 +342,7 @@ LL |     if (let 0 = 0).. {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:139:8
+  --> $DIR/disallowed-positions.rs:143:8
    |
 LL |     if let Range { start: _, end: _ } = true..true && false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -350,7 +350,7 @@ LL |     if let Range { start: _, end: _ } = true..true && false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:142:8
+  --> $DIR/disallowed-positions.rs:146:8
    |
 LL |     if let Range { start: _, end: _ } = true..true || false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -358,7 +358,7 @@ LL |     if let Range { start: _, end: _ } = true..true || false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:148:8
+  --> $DIR/disallowed-positions.rs:152:8
    |
 LL |     if let Range { start: F, end } = F..|| true {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -366,7 +366,7 @@ LL |     if let Range { start: F, end } = F..|| true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:154:8
+  --> $DIR/disallowed-positions.rs:158:8
    |
 LL |     if let Range { start: true, end } = t..&&false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -374,7 +374,7 @@ LL |     if let Range { start: true, end } = t..&&false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:158:19
+  --> $DIR/disallowed-positions.rs:162:19
    |
 LL |     if let true = let true = true {}
    |                   ^^^
@@ -382,7 +382,7 @@ LL |     if let true = let true = true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:161:15
+  --> $DIR/disallowed-positions.rs:165:15
    |
 LL |     if return let 0 = 0 {}
    |               ^^^
@@ -390,7 +390,7 @@ LL |     if return let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:164:21
+  --> $DIR/disallowed-positions.rs:168:21
    |
 LL |     loop { if break let 0 = 0 {} }
    |                     ^^^
@@ -398,7 +398,7 @@ LL |     loop { if break let 0 = 0 {} }
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:167:15
+  --> $DIR/disallowed-positions.rs:171:15
    |
 LL |     if (match let 0 = 0 { _ => { false } }) {}
    |               ^^^
@@ -406,7 +406,7 @@ LL |     if (match let 0 = 0 { _ => { false } }) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:170:9
+  --> $DIR/disallowed-positions.rs:174:9
    |
 LL |     if (let 0 = 0, false).1 {}
    |         ^^^^^^^^^
@@ -414,7 +414,7 @@ LL |     if (let 0 = 0, false).1 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:173:9
+  --> $DIR/disallowed-positions.rs:177:9
    |
 LL |     if (let 0 = 0,) {}
    |         ^^^^^^^^^
@@ -422,7 +422,7 @@ LL |     if (let 0 = 0,) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:177:13
+  --> $DIR/disallowed-positions.rs:181:13
    |
 LL |         if (let 0 = 0).await {}
    |             ^^^^^^^^^
@@ -430,7 +430,7 @@ LL |         if (let 0 = 0).await {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:181:12
+  --> $DIR/disallowed-positions.rs:185:12
    |
 LL |     if (|| let 0 = 0) {}
    |            ^^^
@@ -438,7 +438,7 @@ LL |     if (|| let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:184:9
+  --> $DIR/disallowed-positions.rs:188:9
    |
 LL |     if (let 0 = 0)() {}
    |         ^^^^^^^^^
@@ -446,7 +446,7 @@ LL |     if (let 0 = 0)() {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:190:12
+  --> $DIR/disallowed-positions.rs:194:12
    |
 LL |     while &let 0 = 0 {}
    |            ^^^^^^^^^
@@ -454,7 +454,7 @@ LL |     while &let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:193:12
+  --> $DIR/disallowed-positions.rs:197:12
    |
 LL |     while !let 0 = 0 {}
    |            ^^^^^^^^^
@@ -462,7 +462,7 @@ LL |     while !let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:195:12
+  --> $DIR/disallowed-positions.rs:199:12
    |
 LL |     while *let 0 = 0 {}
    |            ^^^^^^^^^
@@ -470,7 +470,7 @@ LL |     while *let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:197:12
+  --> $DIR/disallowed-positions.rs:201:12
    |
 LL |     while -let 0 = 0 {}
    |            ^^^^^^^^^
@@ -478,7 +478,7 @@ LL |     while -let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:205:12
+  --> $DIR/disallowed-positions.rs:209:12
    |
 LL |     while (let 0 = 0)? {}
    |            ^^^^^^^^^
@@ -486,20 +486,20 @@ LL |     while (let 0 = 0)? {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:208:19
+  --> $DIR/disallowed-positions.rs:212:19
    |
 LL |     while true || let 0 = 0 {}
    |                   ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:208:16
+  --> $DIR/disallowed-positions.rs:212:16
    |
 LL |     while true || let 0 = 0 {}
    |                ^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:210:20
+  --> $DIR/disallowed-positions.rs:214:20
    |
 LL |     while (true || let 0 = 0) {}
    |                    ^^^^^^^^^
@@ -507,7 +507,7 @@ LL |     while (true || let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:212:28
+  --> $DIR/disallowed-positions.rs:216:28
    |
 LL |     while true && (true || let 0 = 0) {}
    |                            ^^^^^^^^^
@@ -515,7 +515,7 @@ LL |     while true && (true || let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:214:28
+  --> $DIR/disallowed-positions.rs:218:28
    |
 LL |     while true || (true && let 0 = 0) {}
    |                            ^^^^^^^^^
@@ -523,7 +523,7 @@ LL |     while true || (true && let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:218:15
+  --> $DIR/disallowed-positions.rs:222:15
    |
 LL |     while x = let 0 = 0 {}
    |               ^^^
@@ -531,7 +531,7 @@ LL |     while x = let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:221:18
+  --> $DIR/disallowed-positions.rs:225:18
    |
 LL |     while true..(let 0 = 0) {}
    |                  ^^^^^^^^^
@@ -539,7 +539,7 @@ LL |     while true..(let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:224:14
+  --> $DIR/disallowed-positions.rs:228:14
    |
 LL |     while ..(let 0 = 0) {}
    |              ^^^^^^^^^
@@ -547,7 +547,7 @@ LL |     while ..(let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:226:12
+  --> $DIR/disallowed-positions.rs:230:12
    |
 LL |     while (let 0 = 0).. {}
    |            ^^^^^^^^^
@@ -555,7 +555,7 @@ LL |     while (let 0 = 0).. {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:230:11
+  --> $DIR/disallowed-positions.rs:234:11
    |
 LL |     while let Range { start: _, end: _ } = true..true && false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -563,7 +563,7 @@ LL |     while let Range { start: _, end: _ } = true..true && false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:233:11
+  --> $DIR/disallowed-positions.rs:237:11
    |
 LL |     while let Range { start: _, end: _ } = true..true || false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -571,7 +571,7 @@ LL |     while let Range { start: _, end: _ } = true..true || false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:239:11
+  --> $DIR/disallowed-positions.rs:243:11
    |
 LL |     while let Range { start: F, end } = F..|| true {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -579,7 +579,7 @@ LL |     while let Range { start: F, end } = F..|| true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:245:11
+  --> $DIR/disallowed-positions.rs:249:11
    |
 LL |     while let Range { start: true, end } = t..&&false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -587,7 +587,7 @@ LL |     while let Range { start: true, end } = t..&&false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:249:22
+  --> $DIR/disallowed-positions.rs:253:22
    |
 LL |     while let true = let true = true {}
    |                      ^^^
@@ -595,7 +595,7 @@ LL |     while let true = let true = true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:252:18
+  --> $DIR/disallowed-positions.rs:256:18
    |
 LL |     while return let 0 = 0 {}
    |                  ^^^
@@ -603,7 +603,7 @@ LL |     while return let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:255:39
+  --> $DIR/disallowed-positions.rs:259:39
    |
 LL |     'outer: loop { while break 'outer let 0 = 0 {} }
    |                                       ^^^
@@ -611,7 +611,7 @@ LL |     'outer: loop { while break 'outer let 0 = 0 {} }
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:258:18
+  --> $DIR/disallowed-positions.rs:262:18
    |
 LL |     while (match let 0 = 0 { _ => { false } }) {}
    |                  ^^^
@@ -619,7 +619,7 @@ LL |     while (match let 0 = 0 { _ => { false } }) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:261:12
+  --> $DIR/disallowed-positions.rs:265:12
    |
 LL |     while (let 0 = 0, false).1 {}
    |            ^^^^^^^^^
@@ -627,7 +627,7 @@ LL |     while (let 0 = 0, false).1 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:264:12
+  --> $DIR/disallowed-positions.rs:268:12
    |
 LL |     while (let 0 = 0,) {}
    |            ^^^^^^^^^
@@ -635,7 +635,7 @@ LL |     while (let 0 = 0,) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:268:16
+  --> $DIR/disallowed-positions.rs:272:16
    |
 LL |         while (let 0 = 0).await {}
    |                ^^^^^^^^^
@@ -643,7 +643,7 @@ LL |         while (let 0 = 0).await {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:272:15
+  --> $DIR/disallowed-positions.rs:276:15
    |
 LL |     while (|| let 0 = 0) {}
    |               ^^^
@@ -651,7 +651,7 @@ LL |     while (|| let 0 = 0) {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:275:12
+  --> $DIR/disallowed-positions.rs:279:12
    |
 LL |     while (let 0 = 0)() {}
    |            ^^^^^^^^^
@@ -659,7 +659,7 @@ LL |     while (let 0 = 0)() {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:292:6
+  --> $DIR/disallowed-positions.rs:296:6
    |
 LL |     &let 0 = 0;
    |      ^^^
@@ -667,7 +667,7 @@ LL |     &let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:295:6
+  --> $DIR/disallowed-positions.rs:299:6
    |
 LL |     !let 0 = 0;
    |      ^^^
@@ -675,7 +675,7 @@ LL |     !let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:297:6
+  --> $DIR/disallowed-positions.rs:301:6
    |
 LL |     *let 0 = 0;
    |      ^^^
@@ -683,7 +683,7 @@ LL |     *let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:299:6
+  --> $DIR/disallowed-positions.rs:303:6
    |
 LL |     -let 0 = 0;
    |      ^^^
@@ -691,7 +691,7 @@ LL |     -let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:301:13
+  --> $DIR/disallowed-positions.rs:305:13
    |
 LL |     let _ = let _ = 3;
    |             ^^^
@@ -699,7 +699,7 @@ LL |     let _ = let _ = 3;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:309:6
+  --> $DIR/disallowed-positions.rs:313:6
    |
 LL |     (let 0 = 0)?;
    |      ^^^
@@ -707,7 +707,7 @@ LL |     (let 0 = 0)?;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:312:13
+  --> $DIR/disallowed-positions.rs:316:13
    |
 LL |     true || let 0 = 0;
    |             ^^^
@@ -715,7 +715,7 @@ LL |     true || let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:314:14
+  --> $DIR/disallowed-positions.rs:318:14
    |
 LL |     (true || let 0 = 0);
    |              ^^^
@@ -723,7 +723,7 @@ LL |     (true || let 0 = 0);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:316:22
+  --> $DIR/disallowed-positions.rs:320:22
    |
 LL |     true && (true || let 0 = 0);
    |                      ^^^
@@ -731,7 +731,7 @@ LL |     true && (true || let 0 = 0);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:320:9
+  --> $DIR/disallowed-positions.rs:324:9
    |
 LL |     x = let 0 = 0;
    |         ^^^
@@ -739,7 +739,7 @@ LL |     x = let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:323:12
+  --> $DIR/disallowed-positions.rs:327:12
    |
 LL |     true..(let 0 = 0);
    |            ^^^
@@ -747,7 +747,7 @@ LL |     true..(let 0 = 0);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:325:8
+  --> $DIR/disallowed-positions.rs:329:8
    |
 LL |     ..(let 0 = 0);
    |        ^^^
@@ -755,7 +755,7 @@ LL |     ..(let 0 = 0);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:327:6
+  --> $DIR/disallowed-positions.rs:331:6
    |
 LL |     (let 0 = 0)..;
    |      ^^^
@@ -763,7 +763,7 @@ LL |     (let 0 = 0)..;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:330:6
+  --> $DIR/disallowed-positions.rs:334:6
    |
 LL |     (let Range { start: _, end: _ } = true..true || false);
    |      ^^^
@@ -771,7 +771,7 @@ LL |     (let Range { start: _, end: _ } = true..true || false);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:334:6
+  --> $DIR/disallowed-positions.rs:338:6
    |
 LL |     (let true = let true = true);
    |      ^^^
@@ -779,7 +779,7 @@ LL |     (let true = let true = true);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:334:17
+  --> $DIR/disallowed-positions.rs:338:17
    |
 LL |     (let true = let true = true);
    |                 ^^^
@@ -787,7 +787,7 @@ LL |     (let true = let true = true);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:340:25
+  --> $DIR/disallowed-positions.rs:344:25
    |
 LL |         let x = true && let y = 1;
    |                         ^^^
@@ -795,7 +795,7 @@ LL |         let x = true && let y = 1;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:346:19
+  --> $DIR/disallowed-positions.rs:350:19
    |
 LL |         [1, 2, 3][let _ = ()]
    |                   ^^^
@@ -803,7 +803,7 @@ LL |         [1, 2, 3][let _ = ()]
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:351:6
+  --> $DIR/disallowed-positions.rs:355:6
    |
 LL |     &let 0 = 0
    |      ^^^
@@ -811,7 +811,7 @@ LL |     &let 0 = 0
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:362:17
+  --> $DIR/disallowed-positions.rs:366:17
    |
 LL |         true && let 1 = 1
    |                 ^^^
@@ -819,7 +819,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:367:17
+  --> $DIR/disallowed-positions.rs:371:17
    |
 LL |         true && let 1 = 1
    |                 ^^^
@@ -827,7 +827,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:372:17
+  --> $DIR/disallowed-positions.rs:376:17
    |
 LL |         true && let 1 = 1
    |                 ^^^
@@ -835,7 +835,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:383:17
+  --> $DIR/disallowed-positions.rs:387:17
    |
 LL |         true && let 1 = 1
    |                 ^^^
@@ -843,7 +843,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expressions must be enclosed in braces to be used as const generic arguments
-  --> $DIR/disallowed-positions.rs:383:9
+  --> $DIR/disallowed-positions.rs:387:9
    |
 LL |         true && let 1 = 1
    |         ^^^^^^^^^^^^^^^^^
@@ -854,124 +854,124 @@ LL |         { true && let 1 = 1 }
    |         +                   +
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:393:9
+  --> $DIR/disallowed-positions.rs:397:9
    |
 LL |     if (let Some(a) = opt && true) {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:393:9
+  --> $DIR/disallowed-positions.rs:397:9
    |
 LL |     if (let Some(a) = opt && true) {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:397:9
+  --> $DIR/disallowed-positions.rs:401:9
    |
 LL |     if (let Some(a) = opt) && true {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:397:9
+  --> $DIR/disallowed-positions.rs:401:9
    |
 LL |     if (let Some(a) = opt) && true {
    |         ^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:400:9
+  --> $DIR/disallowed-positions.rs:404:9
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:400:9
+  --> $DIR/disallowed-positions.rs:404:9
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |         ^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:400:32
+  --> $DIR/disallowed-positions.rs:404:32
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |                                ^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:400:32
+  --> $DIR/disallowed-positions.rs:404:32
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |                                ^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:408:9
+  --> $DIR/disallowed-positions.rs:412:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:408:9
+  --> $DIR/disallowed-positions.rs:412:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:408:31
+  --> $DIR/disallowed-positions.rs:412:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |                               ^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:408:31
+  --> $DIR/disallowed-positions.rs:412:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |                               ^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:412:9
+  --> $DIR/disallowed-positions.rs:416:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:412:9
+  --> $DIR/disallowed-positions.rs:416:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:412:31
+  --> $DIR/disallowed-positions.rs:416:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |                               ^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:412:31
+  --> $DIR/disallowed-positions.rs:416:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |                               ^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:416:9
+  --> $DIR/disallowed-positions.rs:420:9
    |
 LL |     if (let Some(a) = opt && (true)) && true {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:416:9
+  --> $DIR/disallowed-positions.rs:420:9
    |
 LL |     if (let Some(a) = opt && (true)) && true {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:436:22
+  --> $DIR/disallowed-positions.rs:440:22
    |
 LL |     let x = (true && let y = 1);
    |                      ^^^
@@ -979,7 +979,7 @@ LL |     let x = (true && let y = 1);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:441:20
+  --> $DIR/disallowed-positions.rs:445:20
    |
 LL |         ([1, 2, 3][let _ = ()])
    |                    ^^^
diff --git a/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.rs b/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.rs
index 8eb8d617d581c..99f99c2be72de 100644
--- a/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.rs
+++ b/tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.rs
@@ -90,8 +90,12 @@ fn _macros() {
     }
     use_expr!((let 0 = 1 && 0 == 0));
     //[feature,no_feature]~^ ERROR expected expression, found `let` statement
+    //[feature,no_feature]~| ERROR expected expression, found `let` statement
+    //[feature,no_feature]~| ERROR expected expression, found `let` statement
     use_expr!((let 0 = 1));
     //[feature,no_feature]~^ ERROR expected expression, found `let` statement
+    //[feature,no_feature]~| ERROR expected expression, found `let` statement
+    //[feature,no_feature]~| ERROR expected expression, found `let` statement
 }
 
 #[cfg(not(nothing))]

From d59b17c5cdbf345d0088d90fc03faf2501a39757 Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <n.nethercote@gmail.com>
Date: Wed, 26 Mar 2025 15:54:14 +1100
Subject: [PATCH 2/4] Remove `Token::uninterpolated_span`.

In favour of the similar method on `Parser`, which works on things
other than identifiers and lifetimes.
---
 compiler/rustc_ast/src/token.rs         | 27 +++++--------------
 compiler/rustc_parse/src/parser/expr.rs | 14 +++++-----
 compiler/rustc_parse/src/parser/item.rs | 10 +++----
 compiler/rustc_parse/src/parser/mod.rs  | 35 +++++++++++++++++++------
 compiler/rustc_parse/src/parser/ty.rs   |  6 ++---
 5 files changed, 48 insertions(+), 44 deletions(-)

diff --git a/compiler/rustc_ast/src/token.rs b/compiler/rustc_ast/src/token.rs
index 2081777fff359..d57a369eebf2e 100644
--- a/compiler/rustc_ast/src/token.rs
+++ b/compiler/rustc_ast/src/token.rs
@@ -448,8 +448,9 @@ pub enum TokenKind {
 
     /// Identifier token.
     /// Do not forget about `NtIdent` when you want to match on identifiers.
-    /// It's recommended to use `Token::(ident,uninterpolate,uninterpolated_span)` to
-    /// treat regular and interpolated identifiers in the same way.
+    /// It's recommended to use `Token::{ident,uninterpolate}` and
+    /// `Parser::token_uninterpolated_span` to treat regular and interpolated
+    /// identifiers in the same way.
     Ident(Symbol, IdentIsRaw),
     /// This identifier (and its span) is the identifier passed to the
     /// declarative macro. The span in the surrounding `Token` is the span of
@@ -458,8 +459,9 @@ pub enum TokenKind {
 
     /// Lifetime identifier token.
     /// Do not forget about `NtLifetime` when you want to match on lifetime identifiers.
-    /// It's recommended to use `Token::(lifetime,uninterpolate,uninterpolated_span)` to
-    /// treat regular and interpolated lifetime identifiers in the same way.
+    /// It's recommended to use `Token::{ident,uninterpolate}` and
+    /// `Parser::token_uninterpolated_span` to treat regular and interpolated
+    /// identifiers in the same way.
     Lifetime(Symbol, IdentIsRaw),
     /// This identifier (and its span) is the lifetime passed to the
     /// declarative macro. The span in the surrounding `Token` is the span of
@@ -585,23 +587,6 @@ impl Token {
         Token::new(Ident(ident.name, ident.is_raw_guess().into()), ident.span)
     }
 
-    /// For interpolated tokens, returns a span of the fragment to which the interpolated
-    /// token refers. For all other tokens this is just a regular span.
-    /// It is particularly important to use this for identifiers and lifetimes
-    /// for which spans affect name resolution and edition checks.
-    /// Note that keywords are also identifiers, so they should use this
-    /// if they keep spans or perform edition checks.
-    //
-    // Note: `Parser::uninterpolated_token_span` may give better information
-    // than this method does.
-    pub fn uninterpolated_span(&self) -> Span {
-        match self.kind {
-            NtIdent(ident, _) | NtLifetime(ident, _) => ident.span,
-            Interpolated(ref nt) => nt.use_span(),
-            _ => self.span,
-        }
-    }
-
     pub fn is_range_separator(&self) -> bool {
         [DotDot, DotDotDot, DotDotEq].contains(&self.kind)
     }
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 424fee968e1d1..1c2df3ffcd109 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -1318,7 +1318,7 @@ impl<'a> Parser<'a> {
 
     /// Assuming we have just parsed `.`, continue parsing into an expression.
     fn parse_dot_suffix(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
-        if self.token.uninterpolated_span().at_least_rust_2018() && self.eat_keyword(exp!(Await)) {
+        if self.token_uninterpolated_span().at_least_rust_2018() && self.eat_keyword(exp!(Await)) {
             return Ok(self.mk_await_expr(self_arg, lo));
         }
 
@@ -1509,9 +1509,9 @@ impl<'a> Parser<'a> {
                 this.parse_expr_let(restrictions)
             } else if this.eat_keyword(exp!(Underscore)) {
                 Ok(this.mk_expr(this.prev_token.span, ExprKind::Underscore))
-            } else if this.token.uninterpolated_span().at_least_rust_2018() {
+            } else if this.token_uninterpolated_span().at_least_rust_2018() {
                 // `Span::at_least_rust_2018()` is somewhat expensive; don't get it repeatedly.
-                if this.token.uninterpolated_span().at_least_rust_2024()
+                if this.token_uninterpolated_span().at_least_rust_2024()
                     // check for `gen {}` and `gen move {}`
                     // or `async gen {}` and `async gen move {}`
                     && (this.is_gen_block(kw::Gen, 0)
@@ -2186,7 +2186,7 @@ impl<'a> Parser<'a> {
     fn parse_opt_meta_item_lit(&mut self) -> Option<MetaItemLit> {
         self.recover_after_dot();
         let span = self.token.span;
-        let uninterpolated_span = self.uninterpolated_token_span();
+        let uninterpolated_span = self.token_uninterpolated_span();
         self.eat_token_lit().map(|token_lit| {
             match MetaItemLit::from_token_lit(token_lit, span) {
                 Ok(lit) => lit,
@@ -2390,7 +2390,7 @@ impl<'a> Parser<'a> {
         let movability =
             if self.eat_keyword(exp!(Static)) { Movability::Static } else { Movability::Movable };
 
-        let coroutine_kind = if self.token.uninterpolated_span().at_least_rust_2018() {
+        let coroutine_kind = if self.token_uninterpolated_span().at_least_rust_2018() {
             self.parse_coroutine_kind(Case::Sensitive)
         } else {
             None
@@ -2939,7 +2939,7 @@ impl<'a> Parser<'a> {
     /// Parses `for await? <src_pat> in <src_expr> <src_loop_block>` (`for` token already eaten).
     fn parse_expr_for(&mut self, opt_label: Option<Label>, lo: Span) -> PResult<'a, P<Expr>> {
         let is_await =
-            self.token.uninterpolated_span().at_least_rust_2018() && self.eat_keyword(exp!(Await));
+            self.token_uninterpolated_span().at_least_rust_2018() && self.eat_keyword(exp!(Await));
 
         if is_await {
             self.psess.gated_spans.gate(sym::async_for_loop, self.prev_token.span);
@@ -3529,7 +3529,7 @@ impl<'a> Parser<'a> {
         self.token.is_keyword(kw::Try)
             && self
                 .look_ahead(1, |t| *t == token::OpenDelim(Delimiter::Brace) || t.is_whole_block())
-            && self.token.uninterpolated_span().at_least_rust_2018()
+            && self.token_uninterpolated_span().at_least_rust_2018()
     }
 
     /// Parses an `async move? {...}` or `gen move? {...}` expression.
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index 20833a0f70f2d..a8208e4717bdf 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -591,7 +591,7 @@ impl<'a> Parser<'a> {
         }
 
         // Parse stray `impl async Trait`
-        if (self.token.uninterpolated_span().at_least_rust_2018()
+        if (self.token_uninterpolated_span().at_least_rust_2018()
             && self.token.is_keyword(kw::Async))
             || self.is_kw_followed_by_ident(kw::Async)
         {
@@ -877,7 +877,7 @@ impl<'a> Parser<'a> {
             && self.look_ahead(1, |t| t.is_non_raw_ident_where(|i| i.name != kw::As))
         {
             self.bump(); // `default`
-            Defaultness::Default(self.prev_token.uninterpolated_span())
+            Defaultness::Default(self.prev_token_uninterpolated_span())
         } else {
             Defaultness::Final
         }
@@ -1208,7 +1208,7 @@ impl<'a> Parser<'a> {
         attrs: &mut AttrVec,
         mut safety: Safety,
     ) -> PResult<'a, ItemKind> {
-        let extern_span = self.prev_token.uninterpolated_span();
+        let extern_span = self.prev_token_uninterpolated_span();
         let abi = self.parse_abi(); // ABI?
         // FIXME: This recovery should be tested better.
         if safety == Safety::Default
@@ -2781,7 +2781,7 @@ impl<'a> Parser<'a> {
                             .expect("Span extracted directly from keyword should always work");
 
                         err.span_suggestion(
-                            self.token.uninterpolated_span(),
+                            self.token_uninterpolated_span(),
                             format!("`{original_kw}` already used earlier, remove this one"),
                             "",
                             Applicability::MachineApplicable,
@@ -2792,7 +2792,7 @@ impl<'a> Parser<'a> {
                     else if let Some(WrongKw::Misplaced(correct_pos_sp)) = wrong_kw {
                         let correct_pos_sp = correct_pos_sp.to(self.prev_token.span);
                         if let Ok(current_qual) = self.span_to_snippet(correct_pos_sp) {
-                            let misplaced_qual_sp = self.token.uninterpolated_span();
+                            let misplaced_qual_sp = self.token_uninterpolated_span();
                             let misplaced_qual = self.span_to_snippet(misplaced_qual_sp).unwrap();
 
                             err.span_suggestion(
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index a08fbde52a7ce..392a1c1057abb 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -1313,14 +1313,14 @@ impl<'a> Parser<'a> {
 
     /// Parses asyncness: `async` or nothing.
     fn parse_coroutine_kind(&mut self, case: Case) -> Option<CoroutineKind> {
-        let span = self.token.uninterpolated_span();
+        let span = self.token_uninterpolated_span();
         if self.eat_keyword_case(exp!(Async), case) {
             // FIXME(gen_blocks): Do we want to unconditionally parse `gen` and then
             // error if edition <= 2024, like we do with async and edition <= 2018?
-            if self.token.uninterpolated_span().at_least_rust_2024()
+            if self.token_uninterpolated_span().at_least_rust_2024()
                 && self.eat_keyword_case(exp!(Gen), case)
             {
-                let gen_span = self.prev_token.uninterpolated_span();
+                let gen_span = self.prev_token_uninterpolated_span();
                 Some(CoroutineKind::AsyncGen {
                     span: span.to(gen_span),
                     closure_id: DUMMY_NODE_ID,
@@ -1333,7 +1333,7 @@ impl<'a> Parser<'a> {
                     return_impl_trait_id: DUMMY_NODE_ID,
                 })
             }
-        } else if self.token.uninterpolated_span().at_least_rust_2024()
+        } else if self.token_uninterpolated_span().at_least_rust_2024()
             && self.eat_keyword_case(exp!(Gen), case)
         {
             Some(CoroutineKind::Gen {
@@ -1349,9 +1349,9 @@ impl<'a> Parser<'a> {
     /// Parses fn unsafety: `unsafe`, `safe` or nothing.
     fn parse_safety(&mut self, case: Case) -> Safety {
         if self.eat_keyword_case(exp!(Unsafe), case) {
-            Safety::Unsafe(self.prev_token.uninterpolated_span())
+            Safety::Unsafe(self.prev_token_uninterpolated_span())
         } else if self.eat_keyword_case(exp!(Safe), case) {
-            Safety::Safe(self.prev_token.uninterpolated_span())
+            Safety::Safe(self.prev_token_uninterpolated_span())
         } else {
             Safety::Default
         }
@@ -1378,7 +1378,7 @@ impl<'a> Parser<'a> {
                 .look_ahead(1, |t| *t == token::OpenDelim(Delimiter::Brace) || t.is_whole_block())
             && self.eat_keyword_case(exp!(Const), case)
         {
-            Const::Yes(self.prev_token.uninterpolated_span())
+            Const::Yes(self.prev_token_uninterpolated_span())
         } else {
             Const::No
         }
@@ -1723,8 +1723,15 @@ impl<'a> Parser<'a> {
         self.num_bump_calls
     }
 
-    pub fn uninterpolated_token_span(&self) -> Span {
+    /// For interpolated `self.token`, returns a span of the fragment to which
+    /// the interpolated token refers. For all other tokens this is just a
+    /// regular span. It is particularly important to use this for identifiers
+    /// and lifetimes for which spans affect name resolution and edition
+    /// checks. Note that keywords are also identifiers, so they should use
+    /// this if they keep spans or perform edition checks.
+    pub fn token_uninterpolated_span(&self) -> Span {
         match &self.token.kind {
+            token::NtIdent(ident, _) | token::NtLifetime(ident, _) => ident.span,
             token::Interpolated(nt) => nt.use_span(),
             token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(_))) => {
                 self.look_ahead(1, |t| t.span)
@@ -1732,6 +1739,18 @@ impl<'a> Parser<'a> {
             _ => self.token.span,
         }
     }
+
+    /// Like `token_uninterpolated_span`, but works on `self.prev_token`.
+    pub fn prev_token_uninterpolated_span(&self) -> Span {
+        match &self.prev_token.kind {
+            token::NtIdent(ident, _) | token::NtLifetime(ident, _) => ident.span,
+            token::Interpolated(nt) => nt.use_span(),
+            token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(_))) => {
+                self.look_ahead(0, |t| t.span)
+            }
+            _ => self.prev_token.span,
+        }
+    }
 }
 
 pub(crate) fn make_unclosed_delims_error(
diff --git a/compiler/rustc_parse/src/parser/ty.rs b/compiler/rustc_parse/src/parser/ty.rs
index b45ebae079cbc..93705da22c459 100644
--- a/compiler/rustc_parse/src/parser/ty.rs
+++ b/compiler/rustc_parse/src/parser/ty.rs
@@ -775,7 +775,7 @@ impl<'a> Parser<'a> {
     /// Is a `dyn B0 + ... + Bn` type allowed here?
     fn is_explicit_dyn_type(&mut self) -> bool {
         self.check_keyword(exp!(Dyn))
-            && (self.token.uninterpolated_span().at_least_rust_2018()
+            && (self.token_uninterpolated_span().at_least_rust_2018()
                 || self.look_ahead(1, |t| {
                     (can_begin_dyn_bound_in_edition_2015(t) || *t == TokenKind::Star)
                         && !can_continue_type_after_non_fn_ident(t)
@@ -998,13 +998,13 @@ impl<'a> Parser<'a> {
             BoundConstness::Never
         };
 
-        let asyncness = if self.token.uninterpolated_span().at_least_rust_2018()
+        let asyncness = if self.token_uninterpolated_span().at_least_rust_2018()
             && self.eat_keyword(exp!(Async))
         {
             self.psess.gated_spans.gate(sym::async_trait_bounds, self.prev_token.span);
             BoundAsyncness::Async(self.prev_token.span)
         } else if self.may_recover()
-            && self.token.uninterpolated_span().is_rust_2015()
+            && self.token_uninterpolated_span().is_rust_2015()
             && self.is_kw_followed_by_ident(kw::Async)
         {
             self.bump(); // eat `async`

From 81afdbc161300549bb5bbfe0bec5c1a60e11243d Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <n.nethercote@gmail.com>
Date: Mon, 23 Sep 2024 13:04:36 +1000
Subject: [PATCH 3/4] Fix a problem with metavars and inner attributes.

---
 compiler/rustc_ast/src/tokenstream.rs     | 61 +++++++++++++++--------
 tests/ui/attributes/inner-attr-metavar.rs | 14 ++++++
 2 files changed, 53 insertions(+), 22 deletions(-)
 create mode 100644 tests/ui/attributes/inner-attr-metavar.rs

diff --git a/compiler/rustc_ast/src/tokenstream.rs b/compiler/rustc_ast/src/tokenstream.rs
index 161f8e67551fa..fb331e74aeb89 100644
--- a/compiler/rustc_ast/src/tokenstream.rs
+++ b/compiler/rustc_ast/src/tokenstream.rs
@@ -233,35 +233,52 @@ fn attrs_and_tokens_to_token_trees(
 
     // Insert inner attribute tokens.
     if !inner_attrs.is_empty() {
-        let mut found = false;
-        // Check the last two trees (to account for a trailing semi)
-        for tree in res.iter_mut().rev().take(2) {
-            if let TokenTree::Delimited(span, spacing, delim, delim_tokens) = tree {
-                // Inner attributes are only supported on extern blocks, functions,
-                // impls, and modules. All of these have their inner attributes
-                // placed at the beginning of the rightmost outermost braced group:
-                // e.g. fn foo() { #![my_attr] }
-                //
-                // Therefore, we can insert them back into the right location
-                // without needing to do any extra position tracking.
-                //
-                // Note: Outline modules are an exception - they can
-                // have attributes like `#![my_attr]` at the start of a file.
-                // Support for custom attributes in this position is not
-                // properly implemented - we always synthesize fake tokens,
-                // so we never reach this code.
+        let found = insert_inner_attrs(inner_attrs, res);
+        assert!(found, "Failed to find trailing delimited group in: {res:?}");
+    }
+
+    // Inner attributes are only supported on blocks, functions, impls, and
+    // modules. All of these have their inner attributes placed at the
+    // beginning of the rightmost outermost braced group:
+    // e.g. `fn foo() { #![my_attr] }`. (Note: the braces may be within
+    // invisible delimiters.)
+    //
+    // Therefore, we can insert them back into the right location without
+    // needing to do any extra position tracking.
+    //
+    // Note: Outline modules are an exception - they can have attributes like
+    // `#![my_attr]` at the start of a file. Support for custom attributes in
+    // this position is not properly implemented - we always synthesize fake
+    // tokens, so we never reach this code.
+    fn insert_inner_attrs(inner_attrs: &[Attribute], tts: &mut Vec<TokenTree>) -> bool {
+        for tree in tts.iter_mut().rev() {
+            if let TokenTree::Delimited(span, spacing, Delimiter::Brace, stream) = tree {
+                // Found it: the rightmost, outermost braced group.
                 let mut tts = vec![];
                 for inner_attr in inner_attrs {
                     tts.extend(inner_attr.token_trees());
                 }
-                tts.extend(delim_tokens.0.iter().cloned());
+                tts.extend(stream.0.iter().cloned());
                 let stream = TokenStream::new(tts);
-                *tree = TokenTree::Delimited(*span, *spacing, *delim, stream);
-                found = true;
-                break;
+                *tree = TokenTree::Delimited(*span, *spacing, Delimiter::Brace, stream);
+                return true;
+            } else if let TokenTree::Delimited(span, spacing, Delimiter::Invisible(src), stream) =
+                tree
+            {
+                // Recurse inside invisible delimiters.
+                let mut vec: Vec<_> = stream.iter().cloned().collect();
+                if insert_inner_attrs(inner_attrs, &mut vec) {
+                    *tree = TokenTree::Delimited(
+                        *span,
+                        *spacing,
+                        Delimiter::Invisible(*src),
+                        TokenStream::new(vec),
+                    );
+                    return true;
+                }
             }
         }
-        assert!(found, "Failed to find trailing delimited group in: {res:?}");
+        false
     }
 }
 
diff --git a/tests/ui/attributes/inner-attr-metavar.rs b/tests/ui/attributes/inner-attr-metavar.rs
new file mode 100644
index 0000000000000..345121c252e82
--- /dev/null
+++ b/tests/ui/attributes/inner-attr-metavar.rs
@@ -0,0 +1,14 @@
+//@ check-pass
+//
+// During `Nonterminal` removal (#124141) there was at one point a problem with
+// calling from_ast on expressions with inner attributes within metavars -- the
+// inner attributes were being inserted in the wrong place in `from_ast`. This
+// test covers that case.
+
+macro_rules! m3 { ($e:expr) => {} }
+macro_rules! m2 { ($e:expr) => { m3!($e); } }
+macro_rules! m1 { ($e:expr) => { m2!($e); } }
+
+m1!({ #![allow(unused)] 0 });
+
+fn main() {}

From 592d113ff24b91290022d9f1aae271598ff235fa Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <n.nethercote@gmail.com>
Date: Mon, 31 Mar 2025 16:32:55 +1100
Subject: [PATCH 4/4] Fix problem causing `rusqlite` compilation to OOM.

This makes the expression re-parsing more like how it's originally done
in `parse_nonterminal`.
---
 compiler/rustc_parse/src/parser/expr.rs    |   4 +-
 tests/ui/attributes/dont-dup-expr-attrs.rs | 133 +++++++++++++++++++++
 2 files changed, 136 insertions(+), 1 deletion(-)
 create mode 100644 tests/ui/attributes/dont-dup-expr-attrs.rs

diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 1c2df3ffcd109..e1e6b93abf354 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -1397,7 +1397,9 @@ impl<'a> Parser<'a> {
         } else if let Some(expr) = self.eat_metavar_seq_with_matcher(
             |mv_kind| matches!(mv_kind, MetaVarKind::Expr { .. }),
             |this| {
-                let expr = this.parse_expr();
+                // Force collection (as opposed to just `parse_expr`) is required to avoid the
+                // attribute duplication seen in #138478.
+                let expr = this.parse_expr_force_collect();
                 // FIXME(nnethercote) Sometimes with expressions we get a trailing comma, possibly
                 // related to the FIXME in `collect_tokens_for_expr`. Examples are the multi-line
                 // `assert_eq!` calls involving arguments annotated with `#[rustfmt::skip]` in
diff --git a/tests/ui/attributes/dont-dup-expr-attrs.rs b/tests/ui/attributes/dont-dup-expr-attrs.rs
new file mode 100644
index 0000000000000..21da6820a538a
--- /dev/null
+++ b/tests/ui/attributes/dont-dup-expr-attrs.rs
@@ -0,0 +1,133 @@
+//@ check-pass
+//
+// During development of #124141 at one point expression on attributes were
+// being duplicated and `m1` caused an exponential blowup that caused OOM.
+// The number of recursive calls depends on the number of doc comments on the
+// expr block. On each recursive call, the `#[allow(deprecated)]` attribute(s) on
+// the `0` somehow get duplicated, resulting in 1, 2, 4, 8, ... identical
+// attributes.
+//
+// After the fix, the code compiles quickly and normally.
+
+macro_rules! m1 {
+    ($(#[$meta:meta])* { $e:expr }) => {
+        m1! { expr: { $e }, unprocessed: [$(#[$meta])*] }
+    };
+
+    (expr: { $e:expr }, unprocessed: [ #[$meta:meta] $($metas:tt)* ]) => {
+        m1! { expr: { $e }, unprocessed: [ $($metas)* ] }
+    };
+
+    (expr: { $e:expr }, unprocessed: []) => {
+        { $e }
+    }
+}
+
+macro_rules! m2 {
+    ($(#[$meta:meta])* { $e:stmt }) => {
+        m2! { stmt: { $e }, unprocessed: [$(#[$meta])*] }
+    };
+
+    (stmt: { $e:stmt }, unprocessed: [ #[$meta:meta] $($metas:tt)* ]) => {
+        m2! { stmt: { $e }, unprocessed: [ $($metas)* ] }
+    };
+
+    (stmt: { $e:stmt }, unprocessed: []) => {
+        { $e }
+    }
+}
+
+macro_rules! m3 {
+    ($(#[$meta:meta])* { $e:item }) => {
+        m3! { item: { $e }, unprocessed: [$(#[$meta])*] }
+    };
+
+    (item: { $e:item }, unprocessed: [ #[$meta:meta] $($metas:tt)* ]) => {
+        m3! { item: { $e }, unprocessed: [ $($metas)* ] }
+    };
+
+    (item: { $e:item }, unprocessed: []) => {
+        { $e }
+    }
+}
+
+fn main() {
+    // Each additional doc comment line doubles the compile time.
+    m1!(
+        /// a1
+        /// a2
+        /// a3
+        /// a4
+        /// a5
+        /// a6
+        /// a7
+        /// a8
+        /// a9
+        /// a10
+        /// a11
+        /// a12
+        /// a13
+        /// a14
+        /// a15
+        /// a16
+        /// a17
+        /// a18
+        /// a19
+        /// a20
+        {
+            #[allow(deprecated)] 0
+        }
+    );
+
+    m2!(
+        /// a1
+        /// a2
+        /// a3
+        /// a4
+        /// a5
+        /// a6
+        /// a7
+        /// a8
+        /// a9
+        /// a10
+        /// a11
+        /// a12
+        /// a13
+        /// a14
+        /// a15
+        /// a16
+        /// a17
+        /// a18
+        /// a19
+        /// a20
+        {
+            #[allow(deprecated)] let x = 5
+        }
+    );
+
+    m3!(
+        /// a1
+        /// a2
+        /// a3
+        /// a4
+        /// a5
+        /// a6
+        /// a7
+        /// a8
+        /// a9
+        /// a10
+        /// a11
+        /// a12
+        /// a13
+        /// a14
+        /// a15
+        /// a16
+        /// a17
+        /// a18
+        /// a19
+        /// a20
+        {
+            #[allow(deprecated)] struct S;
+        }
+    );
+}