Auto merge of rust-lang#96495 - Dylan-DPC:rollup-9lm4tpp, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - rust-lang#96377 (make `fn() -> _ { .. }` suggestion MachineApplicable)
 - rust-lang#96397 (Make EncodeWide implement FusedIterator)
 - rust-lang#96421 (Less `NoDelim`)
 - rust-lang#96432 (not need `Option` for `dbg_scope`)
 - rust-lang#96466 (Better error messages when collecting into `[T; n]`)
 - rust-lang#96471 (replace let else with `?`)
 - rust-lang#96483 (Add missing `target_feature` to the list of well known cfg names)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

Diff for: compiler/rustc_ast/src/ast.rs

@@ -1542,10 +1542,10 @@ pub enum MacArgs {
 }
 
 impl MacArgs {
-    pub fn delim(&self) -> DelimToken {
+    pub fn delim(&self) -> Option<DelimToken> {
         match self {
-            MacArgs::Delimited(_, delim, _) => delim.to_token(),
-            MacArgs::Empty | MacArgs::Eq(..) => token::NoDelim,
+            MacArgs::Delimited(_, delim, _) => Some(delim.to_token()),
+            MacArgs::Empty | MacArgs::Eq(..) => None,
         }
     }
 

Diff for: compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -464,7 +464,7 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
                 Some(MacHeader::Path(&item.path)),
                 false,
                 None,
-                delim.to_token(),
+                Some(delim.to_token()),
                 tokens,
                 true,
                 span,
@@ -530,7 +530,7 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
                     None,
                     false,
                     None,
-                    *delim,
+                    Some(*delim),
                     tts,
                     convert_dollar_crate,
                     dspan.entire(),
@@ -556,12 +556,12 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
         header: Option<MacHeader<'_>>,
         has_bang: bool,
         ident: Option<Ident>,
-        delim: DelimToken,
+        delim: Option<DelimToken>,
         tts: &TokenStream,
         convert_dollar_crate: bool,
         span: Span,
     ) {
-        if delim == DelimToken::Brace {
+        if delim == Some(DelimToken::Brace) {
             self.cbox(INDENT_UNIT);
         }
         match header {
@@ -577,31 +577,33 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
             self.print_ident(ident);
         }
         match delim {
-            DelimToken::Brace => {
+            Some(DelimToken::Brace) => {
                 if header.is_some() || has_bang || ident.is_some() {
                     self.nbsp();
                 }
                 self.word("{");
                 if !tts.is_empty() {
                     self.space();
                 }
-            }
-            _ => {
-                let token_str = self.token_kind_to_string(&token::OpenDelim(delim));
-                self.word(token_str)
-            }
-        }
-        self.ibox(0);
-        self.print_tts(tts, convert_dollar_crate);
-        self.end();
-        match delim {
-            DelimToken::Brace => {
+                self.ibox(0);
+                self.print_tts(tts, convert_dollar_crate);
+                self.end();
                 let empty = tts.is_empty();
                 self.bclose(span, empty);
             }
-            _ => {
+            Some(delim) => {
+                let token_str = self.token_kind_to_string(&token::OpenDelim(delim));
+                self.word(token_str);
+                self.ibox(0);
+                self.print_tts(tts, convert_dollar_crate);
+                self.end();
                 let token_str = self.token_kind_to_string(&token::CloseDelim(delim));
-                self.word(token_str)
+                self.word(token_str);
+            }
+            None => {
+                self.ibox(0);
+                self.print_tts(tts, convert_dollar_crate);
+                self.end();
             }
         }
     }

Diff for: compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs

@@ -20,7 +20,6 @@ pub fn compute_mir_scopes<'ll, 'tcx>(
     cx: &CodegenCx<'ll, 'tcx>,
     instance: Instance<'tcx>,
     mir: &Body<'tcx>,
-    fn_dbg_scope: &'ll DIScope,
     debug_context: &mut FunctionDebugContext<&'ll DIScope, &'ll DILocation>,
 ) {
     // Find all scopes with variables defined in them.
@@ -38,47 +37,49 @@ pub fn compute_mir_scopes<'ll, 'tcx>(
         // Nothing to emit, of course.
         None
     };
-
+    let mut instantiated = BitSet::new_empty(mir.source_scopes.len());
     // Instantiate all scopes.
     for idx in 0..mir.source_scopes.len() {
         let scope = SourceScope::new(idx);
-        make_mir_scope(cx, instance, mir, fn_dbg_scope, &variables, debug_context, scope);
+        make_mir_scope(cx, instance, mir, &variables, debug_context, &mut instantiated, scope);
     }
+    assert!(instantiated.count() == mir.source_scopes.len());
 }
 
 fn make_mir_scope<'ll, 'tcx>(
     cx: &CodegenCx<'ll, 'tcx>,
     instance: Instance<'tcx>,
     mir: &Body<'tcx>,
-    fn_dbg_scope: &'ll DIScope,
     variables: &Option<BitSet<SourceScope>>,
     debug_context: &mut FunctionDebugContext<&'ll DIScope, &'ll DILocation>,
+    instantiated: &mut BitSet<SourceScope>,
     scope: SourceScope,
 ) {
-    if debug_context.scopes[scope].dbg_scope.is_some() {
+    if instantiated.contains(scope) {
         return;
     }
 
     let scope_data = &mir.source_scopes[scope];
     let parent_scope = if let Some(parent) = scope_data.parent_scope {
-        make_mir_scope(cx, instance, mir, fn_dbg_scope, variables, debug_context, parent);
+        make_mir_scope(cx, instance, mir, variables, debug_context, instantiated, parent);
         debug_context.scopes[parent]
     } else {
         // The root is the function itself.
         let loc = cx.lookup_debug_loc(mir.span.lo());
         debug_context.scopes[scope] = DebugScope {
-            dbg_scope: Some(fn_dbg_scope),
-            inlined_at: None,
             file_start_pos: loc.file.start_pos,
             file_end_pos: loc.file.end_pos,
+            ..debug_context.scopes[scope]
         };
+        instantiated.insert(scope);
         return;
     };
 
     if let Some(vars) = variables && !vars.contains(scope) && scope_data.inlined.is_none() {
         // Do not create a DIScope if there are no variables defined in this
         // MIR `SourceScope`, and it's not `inlined`, to avoid debuginfo bloat.
         debug_context.scopes[scope] = parent_scope;
+        instantiated.insert(scope);
         return;
     }
 
@@ -100,7 +101,7 @@ fn make_mir_scope<'ll, 'tcx>(
         None => unsafe {
             llvm::LLVMRustDIBuilderCreateLexicalBlock(
                 DIB(cx),
-                parent_scope.dbg_scope.unwrap(),
+                parent_scope.dbg_scope,
                 file_metadata,
                 loc.line,
                 loc.col,
@@ -116,9 +117,10 @@ fn make_mir_scope<'ll, 'tcx>(
     });
 
     debug_context.scopes[scope] = DebugScope {
-        dbg_scope: Some(dbg_scope),
+        dbg_scope,
         inlined_at: inlined_at.or(parent_scope.inlined_at),
         file_start_pos: loc.file.start_pos,
         file_end_pos: loc.file.end_pos,
     };
+    instantiated.insert(scope);
 }

Diff for: compiler/rustc_codegen_llvm/src/debuginfo/mod.rs

@@ -286,9 +286,8 @@ impl<'ll, 'tcx> DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         }
 
         // Initialize fn debug context (including scopes).
-        // FIXME(eddyb) figure out a way to not need `Option` for `dbg_scope`.
         let empty_scope = DebugScope {
-            dbg_scope: None,
+            dbg_scope: self.dbg_scope_fn(instance, fn_abi, Some(llfn)),
             inlined_at: None,
             file_start_pos: BytePos(0),
             file_end_pos: BytePos(0),
@@ -297,13 +296,7 @@ impl<'ll, 'tcx> DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
             FunctionDebugContext { scopes: IndexVec::from_elem(empty_scope, &mir.source_scopes) };
 
         // Fill in all the scopes, with the information from the MIR body.
-        compute_mir_scopes(
-            self,
-            instance,
-            mir,
-            self.dbg_scope_fn(instance, fn_abi, Some(llfn)),
-            &mut fn_debug_context,
-        );
+        compute_mir_scopes(self, instance, mir, &mut fn_debug_context);
 
         Some(fn_debug_context)
     }

Diff for: compiler/rustc_codegen_ssa/src/mir/debuginfo.rs

@@ -39,8 +39,7 @@ pub struct PerLocalVarDebugInfo<'tcx, D> {
 
 #[derive(Clone, Copy, Debug)]
 pub struct DebugScope<S, L> {
-    // FIXME(eddyb) this should never be `None`, after initialization.
-    pub dbg_scope: Option<S>,
+    pub dbg_scope: S,
 
     /// Call site location, if this scope was inlined from another function.
     pub inlined_at: Option<L>,
@@ -61,17 +60,12 @@ impl<'tcx, S: Copy, L: Copy> DebugScope<S, L> {
         cx: &Cx,
         span: Span,
     ) -> S {
-        // FIXME(eddyb) this should never be `None`.
-        let dbg_scope = self
-            .dbg_scope
-            .unwrap_or_else(|| bug!("`dbg_scope` is only `None` during initialization"));
-
         let pos = span.lo();
         if pos < self.file_start_pos || pos >= self.file_end_pos {
             let sm = cx.sess().source_map();
-            cx.extend_scope_to_file(dbg_scope, &sm.lookup_char_pos(pos).file)
+            cx.extend_scope_to_file(self.dbg_scope, &sm.lookup_char_pos(pos).file)
         } else {
-            dbg_scope
+            self.dbg_scope
         }
     }
 }

Diff for: compiler/rustc_expand/src/base.rs

@@ -1272,9 +1272,7 @@ pub fn parse_macro_name_and_helper_attrs(
     // Once we've located the `#[proc_macro_derive]` attribute, verify
     // that it's of the form `#[proc_macro_derive(Foo)]` or
     // `#[proc_macro_derive(Foo, attributes(A, ..))]`
-    let Some(list) = attr.meta_item_list() else {
-        return None;
-    };
+    let list = attr.meta_item_list()?;
     if list.len() != 1 && list.len() != 2 {
         diag.span_err(attr.span, "attribute must have either one or two arguments");
         return None;

Diff for: compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -260,16 +260,15 @@ fn generic_extension<'cx, 'tt>(
                 // Merge the gated spans from parsing the matcher with the pre-existing ones.
                 sess.gated_spans.merge(gated_spans_snapshot);
 
-                // Ignore the delimiters on the RHS.
-                let rhs = match &rhses[i] {
-                    mbe::TokenTree::Delimited(_, delimited) => &delimited.tts,
+                let (rhs, rhs_span): (&mbe::Delimited, DelimSpan) = match &rhses[i] {
+                    mbe::TokenTree::Delimited(span, delimited) => (&delimited, *span),
                     _ => cx.span_bug(sp, "malformed macro rhs"),
                 };
                 let arm_span = rhses[i].span();
 
-                let rhs_spans = rhs.iter().map(|t| t.span()).collect::<Vec<_>>();
+                let rhs_spans = rhs.tts.iter().map(|t| t.span()).collect::<Vec<_>>();
                 // rhs has holes ( `$id` and `$(...)` that need filled)
-                let mut tts = match transcribe(cx, &named_matches, &rhs, transparency) {
+                let mut tts = match transcribe(cx, &named_matches, &rhs, rhs_span, transparency) {
                     Ok(tts) => tts,
                     Err(mut err) => {
                         err.emit();

Diff for: compiler/rustc_expand/src/mbe/transcribe.rs

@@ -29,8 +29,8 @@ impl MutVisitor for Marker {
 enum Frame<'a> {
     Delimited {
         tts: &'a [mbe::TokenTree],
-        delim_token: token::DelimToken,
         idx: usize,
+        delim_token: token::DelimToken,
         span: DelimSpan,
     },
     Sequence {
@@ -42,8 +42,8 @@ enum Frame<'a> {
 
 impl<'a> Frame<'a> {
     /// Construct a new frame around the delimited set of tokens.
-    fn new(tts: &'a [mbe::TokenTree]) -> Frame<'a> {
-        Frame::Delimited { tts, delim_token: token::NoDelim, idx: 0, span: DelimSpan::dummy() }
+    fn new(src: &'a mbe::Delimited, span: DelimSpan) -> Frame<'a> {
+        Frame::Delimited { tts: &src.tts, idx: 0, delim_token: src.delim, span }
     }
 }
 
@@ -85,17 +85,18 @@ impl<'a> Iterator for Frame<'a> {
 pub(super) fn transcribe<'a>(
     cx: &ExtCtxt<'a>,
     interp: &FxHashMap<MacroRulesNormalizedIdent, NamedMatch>,
-    src: &[mbe::TokenTree],
+    src: &mbe::Delimited,
+    src_span: DelimSpan,
     transparency: Transparency,
 ) -> PResult<'a, TokenStream> {
     // Nothing for us to transcribe...
-    if src.is_empty() {
+    if src.tts.is_empty() {
         return Ok(TokenStream::default());
     }
 
     // We descend into the RHS (`src`), expanding things as we go. This stack contains the things
     // we have yet to expand/are still expanding. We start the stack off with the whole RHS.
-    let mut stack: SmallVec<[Frame<'_>; 1]> = smallvec![Frame::new(&src)];
+    let mut stack: SmallVec<[Frame<'_>; 1]> = smallvec![Frame::new(&src, src_span)];
 
     // As we descend in the RHS, we will need to be able to match nested sequences of matchers.
     // `repeats` keeps track of where we are in matching at each level, with the last element being

Diff for: compiler/rustc_index/src/bit_set.rs

@@ -1714,7 +1714,7 @@ impl<R: Idx, C: Idx> SparseBitMatrix<R, C> {
     }
 
     pub fn row(&self, row: R) -> Option<&HybridBitSet<C>> {
-        if let Some(Some(row)) = self.rows.get(row) { Some(row) } else { None }
+        self.rows.get(row)?.as_ref()
     }
 
     /// Intersects `row` with `set`. `set` can be either `BitSet` or

Diff for: compiler/rustc_infer/src/infer/error_reporting/nice_region_error/find_anon_type.rs

@@ -25,21 +25,16 @@ pub(crate) fn find_anon_type<'tcx>(
     region: Region<'tcx>,
     br: &ty::BoundRegionKind,
 ) -> Option<(&'tcx hir::Ty<'tcx>, &'tcx hir::FnSig<'tcx>)> {
-    if let Some(anon_reg) = tcx.is_suitable_region(region) {
-        let hir_id = tcx.hir().local_def_id_to_hir_id(anon_reg.def_id);
-        let Some(fn_sig) = tcx.hir().get(hir_id).fn_sig() else {
-            return None
-        };
+    let anon_reg = tcx.is_suitable_region(region)?;
+    let hir_id = tcx.hir().local_def_id_to_hir_id(anon_reg.def_id);
+    let fn_sig = tcx.hir().get(hir_id).fn_sig()?;
 
-        fn_sig
-            .decl
-            .inputs
-            .iter()
-            .find_map(|arg| find_component_for_bound_region(tcx, arg, br))
-            .map(|ty| (ty, fn_sig))
-    } else {
-        None
-    }
+    fn_sig
+        .decl
+        .inputs
+        .iter()
+        .find_map(|arg| find_component_for_bound_region(tcx, arg, br))
+        .map(|ty| (ty, fn_sig))
 }
 
 // This method creates a FindNestedTypeVisitor which returns the type corresponding