Auto merge of #100120 - matthiaskrgr:rollup-g6ycykq, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - #98771 (Add support for link-flavor rust-lld for iOS, tvOS and watchOS)
 - #98835 (relate `closure_substs.parent_substs()` to parent fn in NLL)
 - #99746 (Use `TraitEngine` in more places that don't specifically need `FulfillmentContext::new_in_snapshot`)
 - #99786 (Recover from C++ style `enum struct`)
 - #99795 (Delay a bug when failed to normalize trait ref during specialization)
 - #100029 (Prevent ICE for `doc_alias` on match arm, statement, expression)

Failed merges:

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

Author: bors

Diff for: compiler/rustc_borrowck/src/type_check/mod.rs

@@ -2619,6 +2619,34 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             );
         }
 
+        // Now equate closure substs to regions inherited from `typeck_root_def_id`. Fixes #98589.
+        let typeck_root_def_id = tcx.typeck_root_def_id(self.body.source.def_id());
+        let typeck_root_substs = ty::InternalSubsts::identity_for_item(tcx, typeck_root_def_id);
+
+        let parent_substs = match tcx.def_kind(def_id) {
+            DefKind::Closure => substs.as_closure().parent_substs(),
+            DefKind::Generator => substs.as_generator().parent_substs(),
+            DefKind::InlineConst => substs.as_inline_const().parent_substs(),
+            other => bug!("unexpected item {:?}", other),
+        };
+        let parent_substs = tcx.mk_substs(parent_substs.iter());
+
+        assert_eq!(typeck_root_substs.len(), parent_substs.len());
+        if let Err(_) = self.eq_substs(
+            typeck_root_substs,
+            parent_substs,
+            location.to_locations(),
+            ConstraintCategory::BoringNoLocation,
+        ) {
+            span_mirbug!(
+                self,
+                def_id,
+                "could not relate closure to parent {:?} != {:?}",
+                typeck_root_substs,
+                parent_substs
+            );
+        }
+
         tcx.predicates_of(def_id).instantiate(tcx, substs)
     }
 

Diff for: compiler/rustc_borrowck/src/type_check/relate_tys.rs

@@ -38,6 +38,23 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         .relate(a, b)?;
         Ok(())
     }
+
+    /// Add sufficient constraints to ensure `a == b`. See also [Self::relate_types].
+    pub(super) fn eq_substs(
+        &mut self,
+        a: ty::SubstsRef<'tcx>,
+        b: ty::SubstsRef<'tcx>,
+        locations: Locations,
+        category: ConstraintCategory<'tcx>,
+    ) -> Fallible<()> {
+        TypeRelating::new(
+            self.infcx,
+            NllTypeRelatingDelegate::new(self, locations, category, UniverseInfo::other()),
+            ty::Variance::Invariant,
+        )
+        .relate(a, b)?;
+        Ok(())
+    }
 }
 
 struct NllTypeRelatingDelegate<'me, 'bccx, 'tcx> {

Diff for: compiler/rustc_codegen_ssa/src/back/link.rs

@@ -2675,7 +2675,7 @@ fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
     let llvm_target = &sess.target.llvm_target;
     if sess.target.vendor != "apple"
         || !matches!(os.as_ref(), "ios" | "tvos" | "watchos")
-        || flavor != LinkerFlavor::Gcc
+        || (flavor != LinkerFlavor::Gcc && flavor != LinkerFlavor::Lld(LldFlavor::Ld64))
     {
         return;
     }
@@ -2706,13 +2706,16 @@ fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
             return;
         }
     };
-    if llvm_target.contains("macabi") {
-        cmd.args(&["-target", llvm_target])
-    } else {
-        let arch_name = llvm_target.split('-').next().expect("LLVM target must have a hyphen");
-        cmd.args(&["-arch", arch_name])
+
+    match flavor {
+        LinkerFlavor::Gcc => {
+            cmd.args(&["-isysroot", &sdk_root, "-Wl,-syslibroot", &sdk_root]);
+        }
+        LinkerFlavor::Lld(LldFlavor::Ld64) => {
+            cmd.args(&["-syslibroot", &sdk_root]);
+        }
+        _ => unreachable!(),
     }
-    cmd.args(&["-isysroot", &sdk_root, "-Wl,-syslibroot", &sdk_root]);
 }
 
 fn get_apple_sdk_root(sdk_name: &str) -> Result<String, String> {

Diff for: compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs

@@ -10,7 +10,7 @@ use rustc_middle::mir::*;
 use rustc_middle::ty::{self, subst::SubstsRef, AdtDef, Ty};
 use rustc_span::DUMMY_SP;
 use rustc_trait_selection::traits::{
-    self, FulfillmentContext, ImplSource, Obligation, ObligationCause, SelectionContext,
+    self, ImplSource, Obligation, ObligationCause, SelectionContext, TraitEngineExt,
 };
 
 use super::ConstCx;
@@ -191,7 +191,7 @@ impl Qualif for NeedsNonConstDrop {
 
             // If we successfully found one, then select all of the predicates
             // implied by our const drop impl.
-            let mut fcx = FulfillmentContext::new();
+            let mut fcx = <dyn TraitEngine<'tcx>>::new(cx.tcx);
             for nested in impl_src.nested_obligations() {
                 fcx.register_predicate_obligation(&infcx, nested);
             }

Diff for: compiler/rustc_hir/src/target.rs

@@ -60,51 +60,7 @@ pub enum Target {
 
 impl Display for Target {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(
-            f,
-            "{}",
-            match *self {
-                Target::ExternCrate => "extern crate",
-                Target::Use => "use",
-                Target::Static => "static item",
-                Target::Const => "constant item",
-                Target::Fn => "function",
-                Target::Closure => "closure",
-                Target::Mod => "module",
-                Target::ForeignMod => "foreign module",
-                Target::GlobalAsm => "global asm",
-                Target::TyAlias => "type alias",
-                Target::OpaqueTy => "opaque type",
-                Target::Enum => "enum",
-                Target::Variant => "enum variant",
-                Target::Struct => "struct",
-                Target::Field => "struct field",
-                Target::Union => "union",
-                Target::Trait => "trait",
-                Target::TraitAlias => "trait alias",
-                Target::Impl => "item",
-                Target::Expression => "expression",
-                Target::Statement => "statement",
-                Target::Arm => "match arm",
-                Target::AssocConst => "associated const",
-                Target::Method(kind) => match kind {
-                    MethodKind::Inherent => "inherent method",
-                    MethodKind::Trait { body: false } => "required trait method",
-                    MethodKind::Trait { body: true } => "provided trait method",
-                },
-                Target::AssocTy => "associated type",
-                Target::ForeignFn => "foreign function",
-                Target::ForeignStatic => "foreign static item",
-                Target::ForeignTy => "foreign type",
-                Target::GenericParam(kind) => match kind {
-                    GenericParamKind::Type => "type parameter",
-                    GenericParamKind::Lifetime => "lifetime parameter",
-                    GenericParamKind::Const => "const parameter",
-                },
-                Target::MacroDef => "macro def",
-                Target::Param => "function param",
-            }
-        )
+        write!(f, "{}", Self::name(*self))
     }
 }
 
@@ -185,4 +141,48 @@ impl Target {
             hir::GenericParamKind::Const { .. } => Target::GenericParam(GenericParamKind::Const),
         }
     }
+
+    pub fn name(self) -> &'static str {
+        match self {
+            Target::ExternCrate => "extern crate",
+            Target::Use => "use",
+            Target::Static => "static item",
+            Target::Const => "constant item",
+            Target::Fn => "function",
+            Target::Closure => "closure",
+            Target::Mod => "module",
+            Target::ForeignMod => "foreign module",
+            Target::GlobalAsm => "global asm",
+            Target::TyAlias => "type alias",
+            Target::OpaqueTy => "opaque type",
+            Target::Enum => "enum",
+            Target::Variant => "enum variant",
+            Target::Struct => "struct",
+            Target::Field => "struct field",
+            Target::Union => "union",
+            Target::Trait => "trait",
+            Target::TraitAlias => "trait alias",
+            Target::Impl => "implementation block",
+            Target::Expression => "expression",
+            Target::Statement => "statement",
+            Target::Arm => "match arm",
+            Target::AssocConst => "associated const",
+            Target::Method(kind) => match kind {
+                MethodKind::Inherent => "inherent method",
+                MethodKind::Trait { body: false } => "required trait method",
+                MethodKind::Trait { body: true } => "provided trait method",
+            },
+            Target::AssocTy => "associated type",
+            Target::ForeignFn => "foreign function",
+            Target::ForeignStatic => "foreign static item",
+            Target::ForeignTy => "foreign type",
+            Target::GenericParam(kind) => match kind {
+                GenericParamKind::Type => "type parameter",
+                GenericParamKind::Lifetime => "lifetime parameter",
+                GenericParamKind::Const => "const parameter",
+            },
+            Target::MacroDef => "macro def",
+            Target::Param => "function param",
+        }
+    }
 }

Diff for: compiler/rustc_parse/src/parser/item.rs

@@ -1216,6 +1216,25 @@ impl<'a> Parser<'a> {
 
     /// Parses an enum declaration.
     fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
+        if self.token.is_keyword(kw::Struct) {
+            let mut err = self.struct_span_err(
+                self.prev_token.span.to(self.token.span),
+                "`enum` and `struct` are mutually exclusive",
+            );
+            err.span_suggestion(
+                self.prev_token.span.to(self.token.span),
+                "replace `enum struct` with",
+                "enum",
+                Applicability::MachineApplicable,
+            );
+            if self.look_ahead(1, |t| t.is_ident()) {
+                self.bump();
+                err.emit();
+            } else {
+                return Err(err);
+            }
+        }
+
         let id = self.parse_ident()?;
         let mut generics = self.parse_generics()?;
         generics.where_clause = self.parse_where_clause()?;

Diff for: compiler/rustc_passes/src/check_attr.rs

@@ -596,8 +596,6 @@ impl CheckAttrVisitor<'_> {
 
         let span = meta.span();
         if let Some(location) = match target {
-            Target::Impl => Some("implementation block"),
-            Target::ForeignMod => Some("extern block"),
             Target::AssocTy => {
                 let parent_hir_id = self.tcx.hir().get_parent_item(hir_id);
                 let containing_item = self.tcx.hir().expect_item(parent_hir_id);
@@ -619,7 +617,34 @@ impl CheckAttrVisitor<'_> {
             }
             // we check the validity of params elsewhere
             Target::Param => return false,
-            _ => None,
+            Target::Expression
+            | Target::Statement
+            | Target::Arm
+            | Target::ForeignMod
+            | Target::Closure
+            | Target::Impl => Some(target.name()),
+            Target::ExternCrate
+            | Target::Use
+            | Target::Static
+            | Target::Const
+            | Target::Fn
+            | Target::Mod
+            | Target::GlobalAsm
+            | Target::TyAlias
+            | Target::OpaqueTy
+            | Target::Enum
+            | Target::Variant
+            | Target::Struct
+            | Target::Field
+            | Target::Union
+            | Target::Trait
+            | Target::TraitAlias
+            | Target::Method(..)
+            | Target::ForeignFn
+            | Target::ForeignStatic
+            | Target::ForeignTy
+            | Target::GenericParam(..)
+            | Target::MacroDef => None,
         } {
             tcx.sess.emit_err(errors::DocAliasBadLocation { span, attr_str, location });
             return false;

Diff for: compiler/rustc_target/src/spec/aarch64_apple_ios_macabi.rs

@@ -1,9 +1,14 @@
 use super::apple_sdk_base::{opts, Arch};
-use crate::spec::{FramePointer, Target, TargetOptions};
+use crate::spec::{FramePointer, LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Target {
+    let llvm_target = "arm64-apple-ios14.0-macabi";
+
+    let mut base = opts("ios", Arch::Arm64_macabi);
+    base.add_pre_link_args(LinkerFlavor::Gcc, &["-target", llvm_target]);
+
     Target {
-        llvm_target: "arm64-apple-ios14.0-macabi".into(),
+        llvm_target: llvm_target.into(),
         pointer_width: 64,
         data_layout: "e-m:o-i64:64-i128:128-n32:64-S128".into(),
         arch: "aarch64".into(),
@@ -21,7 +26,7 @@ pub fn target() -> Target {
                 -disable-llvm-passes\0\
                 -Os\0"
                 .into(),
-            ..opts("ios", Arch::Arm64_macabi)
+            ..base
         },
     }
 }

Diff for: compiler/rustc_target/src/spec/apple_base.rs

@@ -109,15 +109,34 @@ pub fn ios_llvm_target(arch: &str) -> String {
     format!("{}-apple-ios{}.{}.0", arch, major, minor)
 }
 
+pub fn ios_lld_platform_version() -> String {
+    let (major, minor) = ios_deployment_target();
+    format!("{}.{}", major, minor)
+}
+
 pub fn ios_sim_llvm_target(arch: &str) -> String {
     let (major, minor) = ios_deployment_target();
     format!("{}-apple-ios{}.{}.0-simulator", arch, major, minor)
 }
 
+fn tvos_deployment_target() -> (u32, u32) {
+    deployment_target("TVOS_DEPLOYMENT_TARGET").unwrap_or((7, 0))
+}
+
+pub fn tvos_lld_platform_version() -> String {
+    let (major, minor) = tvos_deployment_target();
+    format!("{}.{}", major, minor)
+}
+
 fn watchos_deployment_target() -> (u32, u32) {
     deployment_target("WATCHOS_DEPLOYMENT_TARGET").unwrap_or((5, 0))
 }
 
+pub fn watchos_lld_platform_version() -> String {
+    let (major, minor) = watchos_deployment_target();
+    format!("{}.{}", major, minor)
+}
+
 pub fn watchos_sim_llvm_target(arch: &str) -> String {
     let (major, minor) = watchos_deployment_target();
     format!("{}-apple-watchos{}.{}.0-simulator", arch, major, minor)