Auto merge of #143337 - matthiaskrgr:rollup-lqwhe0i, r=matthiaskrgr

Rollup of 9 pull requests

Successful merges:

 - #141847 (Explain `TOCTOU` on the top of `std::fs`, and reference it in functions)
 - #142138 (Add `Vec::into_chunks`)
 - #142321 (Expose elf abi on ppc64 targets)
 - #142886 (ci: aarch64-gnu: Stop skipping `panic_abort_doc_tests`)
 - #143194 (fix bitcast of single-element SIMD vectors)
 - #143231 (Suggest use another lifetime specifier instead of underscore lifetime)
 - #143232 ([COMPILETEST-UNTANGLE 3/N] Use "directives" consistently within compiletest)
 - #143258 (Don't recompute `DisambiguatorState` for every RPITIT in trait definition)
 - #143274 (ci: support optional jobs)

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

Author: bors

compiler/rustc_codegen_ssa/src/mir/rvalue.rs

@@ -1117,7 +1117,7 @@ pub(super) fn transmute_immediate<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     // While optimizations will remove no-op transmutes, they might still be
     // there in debug or things that aren't no-op in MIR because they change
     // the Rust type but not the underlying layout/niche.
-    if from_scalar == to_scalar {
+    if from_scalar == to_scalar && from_backend_ty == to_backend_ty {
         return imm;
     }
 
@@ -1136,13 +1136,7 @@ pub(super) fn transmute_immediate<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     assume_scalar_range(bx, imm, from_scalar, from_backend_ty);
 
     imm = match (from_scalar.primitive(), to_scalar.primitive()) {
-        (Int(..) | Float(_), Int(..) | Float(_)) => {
-            if from_backend_ty == to_backend_ty {
-                imm
-            } else {
-                bx.bitcast(imm, to_backend_ty)
-            }
-        }
+        (Int(..) | Float(_), Int(..) | Float(_)) => bx.bitcast(imm, to_backend_ty),
         (Pointer(..), Pointer(..)) => bx.pointercast(imm, to_backend_ty),
         (Int(..), Pointer(..)) => bx.ptradd(bx.const_null(bx.type_ptr()), imm),
         (Pointer(..), Int(..)) => {

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -2459,13 +2459,15 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 // type a projection.
                 let in_trait = match opaque_ty.origin {
                     hir::OpaqueTyOrigin::FnReturn {
+                        parent,
                         in_trait_or_impl: Some(hir::RpitContext::Trait),
                         ..
                     }
                     | hir::OpaqueTyOrigin::AsyncFn {
+                        parent,
                         in_trait_or_impl: Some(hir::RpitContext::Trait),
                         ..
-                    } => true,
+                    } => Some(parent),
                     hir::OpaqueTyOrigin::FnReturn {
                         in_trait_or_impl: None | Some(hir::RpitContext::TraitImpl),
                         ..
@@ -2474,7 +2476,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                         in_trait_or_impl: None | Some(hir::RpitContext::TraitImpl),
                         ..
                     }
-                    | hir::OpaqueTyOrigin::TyAlias { .. } => false,
+                    | hir::OpaqueTyOrigin::TyAlias { .. } => None,
                 };
 
                 self.lower_opaque_ty(opaque_ty.def_id, in_trait)
@@ -2594,17 +2596,25 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
     /// Lower an opaque type (i.e., an existential impl-Trait type) from the HIR.
     #[instrument(level = "debug", skip(self), ret)]
-    fn lower_opaque_ty(&self, def_id: LocalDefId, in_trait: bool) -> Ty<'tcx> {
+    fn lower_opaque_ty(&self, def_id: LocalDefId, in_trait: Option<LocalDefId>) -> Ty<'tcx> {
         let tcx = self.tcx();
 
         let lifetimes = tcx.opaque_captured_lifetimes(def_id);
         debug!(?lifetimes);
 
-        // If this is an RPITIT and we are using the new RPITIT lowering scheme, we
-        // generate the def_id of an associated type for the trait and return as
-        // type a projection.
-        let def_id = if in_trait {
-            tcx.associated_type_for_impl_trait_in_trait(def_id).to_def_id()
+        // If this is an RPITIT and we are using the new RPITIT lowering scheme,
+        // do a linear search to map this to the synthetic associated type that
+        // it will be lowered to.
+        let def_id = if let Some(parent_def_id) = in_trait {
+            *tcx.associated_types_for_impl_traits_in_associated_fn(parent_def_id)
+                .iter()
+                .find(|rpitit| match tcx.opt_rpitit_info(**rpitit) {
+                    Some(ty::ImplTraitInTraitData::Trait { opaque_def_id, .. }) => {
+                        opaque_def_id.expect_local() == def_id
+                    }
+                    _ => unreachable!(),
+                })
+                .unwrap()
         } else {
             def_id.to_def_id()
         };
@@ -2627,7 +2637,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         });
         debug!(?args);
 
-        if in_trait {
+        if in_trait.is_some() {
             Ty::new_projection_from_args(tcx, def_id, args)
         } else {
             Ty::new_opaque(tcx, def_id, args)

compiler/rustc_middle/src/query/mod.rs

@@ -1093,13 +1093,6 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    /// Given an impl trait in trait `opaque_ty_def_id`, create and return the corresponding
-    /// associated item.
-    query associated_type_for_impl_trait_in_trait(opaque_ty_def_id: LocalDefId) -> LocalDefId {
-        desc { |tcx| "creating the associated item corresponding to the opaque type `{}`", tcx.def_path_str(opaque_ty_def_id.to_def_id()) }
-        cache_on_disk_if { true }
-    }
-
     /// Given an `impl_id`, return the trait it implements along with some header information.
     /// Return `None` if this is an inherent impl.
     query impl_trait_header(impl_id: DefId) -> Option<ty::ImplTraitHeader<'tcx>> {

compiler/rustc_resolve/messages.ftl

@@ -432,6 +432,7 @@ resolve_undeclared_label =
 
 resolve_underscore_lifetime_is_reserved = `'_` cannot be used here
     .label = `'_` is a reserved lifetime name
+    .help = use another lifetime specifier
 
 resolve_unexpected_res_change_ty_to_const_param_sugg =
     you might have meant to write a const parameter here

compiler/rustc_resolve/src/errors.rs

@@ -934,6 +934,7 @@ pub(crate) struct ImplicitElidedLifetimeNotAllowedHere {
 
 #[derive(Diagnostic)]
 #[diag(resolve_underscore_lifetime_is_reserved, code = E0637)]
+#[help]
 pub(crate) struct UnderscoreLifetimeIsReserved {
     #[primary_span]
     #[label]

compiler/rustc_target/src/spec/targets/powerpc64_unknown_freebsd.rs

@@ -10,6 +10,7 @@ pub(crate) fn target() -> Target {
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m64"]);
     base.max_atomic_width = Some(64);
     base.stack_probes = StackProbeType::Inline;
+    base.abi = "elfv2".into();
     base.llvm_abiname = "elfv2".into();
 
     Target {

compiler/rustc_target/src/spec/targets/powerpc64_unknown_linux_gnu.rs

@@ -10,6 +10,7 @@ pub(crate) fn target() -> Target {
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m64"]);
     base.max_atomic_width = Some(64);
     base.stack_probes = StackProbeType::Inline;
+    base.abi = "elfv1".into();
     base.llvm_abiname = "elfv1".into();
 
     Target {

compiler/rustc_target/src/spec/targets/powerpc64_unknown_linux_musl.rs

@@ -12,6 +12,7 @@ pub(crate) fn target() -> Target {
     base.stack_probes = StackProbeType::Inline;
     // FIXME(compiler-team#422): musl targets should be dynamically linked by default.
     base.crt_static_default = true;
+    base.abi = "elfv2".into();
     base.llvm_abiname = "elfv2".into();
 
     Target {

compiler/rustc_target/src/spec/targets/powerpc64_unknown_openbsd.rs

@@ -10,6 +10,7 @@ pub(crate) fn target() -> Target {
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m64"]);
     base.max_atomic_width = Some(64);
     base.stack_probes = StackProbeType::Inline;
+    base.abi = "elfv2".into();
     base.llvm_abiname = "elfv2".into();
 
     Target {

compiler/rustc_target/src/spec/targets/powerpc64_wrs_vxworks.rs

@@ -10,6 +10,7 @@ pub(crate) fn target() -> Target {
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m64"]);
     base.max_atomic_width = Some(64);
     base.stack_probes = StackProbeType::Inline;
+    base.abi = "elfv1".into();
     base.llvm_abiname = "elfv1".into();
 
     Target {

compiler/rustc_target/src/spec/targets/powerpc64le_unknown_freebsd.rs

@@ -8,6 +8,7 @@ pub(crate) fn target() -> Target {
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m64"]);
     base.max_atomic_width = Some(64);
     base.stack_probes = StackProbeType::Inline;
+    base.abi = "elfv2".into();
     base.llvm_abiname = "elfv2".into();
 
     Target {

compiler/rustc_target/src/spec/targets/powerpc64le_unknown_linux_gnu.rs

@@ -8,6 +8,7 @@ pub(crate) fn target() -> Target {
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m64"]);
     base.max_atomic_width = Some(64);
     base.stack_probes = StackProbeType::Inline;
+    base.abi = "elfv2".into();
     base.llvm_abiname = "elfv2".into();
 
     Target {

compiler/rustc_target/src/spec/targets/powerpc64le_unknown_linux_musl.rs

@@ -10,6 +10,7 @@ pub(crate) fn target() -> Target {
     base.stack_probes = StackProbeType::Inline;
     // FIXME(compiler-team#422): musl targets should be dynamically linked by default.
     base.crt_static_default = true;
+    base.abi = "elfv2".into();
     base.llvm_abiname = "elfv2".into();
 
     Target {

compiler/rustc_ty_utils/src/assoc.rs

@@ -1,9 +1,8 @@
-use rustc_data_structures::fx::FxIndexSet;
+use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, DefIdMap, LocalDefId};
 use rustc_hir::definitions::{DefPathData, DisambiguatorState};
 use rustc_hir::intravisit::{self, Visitor};
-use rustc_hir::{self as hir, AmbigArg};
 use rustc_middle::query::Providers;
 use rustc_middle::ty::{self, ImplTraitInTraitData, TyCtxt};
 use rustc_middle::{bug, span_bug};
@@ -14,7 +13,6 @@ pub(crate) fn provide(providers: &mut Providers) {
         associated_item_def_ids,
         associated_items,
         associated_types_for_impl_traits_in_associated_fn,
-        associated_type_for_impl_trait_in_trait,
         impl_item_implementor_ids,
         ..*providers
     };
@@ -160,20 +158,22 @@ fn associated_item_from_impl_item_ref(impl_item_ref: &hir::ImplItemRef) -> ty::A
         container: ty::AssocItemContainer::Impl,
     }
 }
-struct RPITVisitor {
-    rpits: FxIndexSet<LocalDefId>,
+struct RPITVisitor<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    synthetics: Vec<LocalDefId>,
+    data: DefPathData,
+    disambiguator: DisambiguatorState,
 }
 
-impl<'tcx> Visitor<'tcx> for RPITVisitor {
-    fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx, AmbigArg>) {
-        if let hir::TyKind::OpaqueDef(opaq) = ty.kind
-            && self.rpits.insert(opaq.def_id)
-        {
-            for bound in opaq.bounds {
-                intravisit::walk_param_bound(self, bound);
-            }
-        }
-        intravisit::walk_ty(self, ty)
+impl<'tcx> Visitor<'tcx> for RPITVisitor<'tcx> {
+    fn visit_opaque_ty(&mut self, opaque: &'tcx hir::OpaqueTy<'tcx>) -> Self::Result {
+        self.synthetics.push(associated_type_for_impl_trait_in_trait(
+            self.tcx,
+            opaque.def_id,
+            self.data,
+            &mut self.disambiguator,
+        ));
+        intravisit::walk_opaque_ty(self, opaque)
     }
 }
 
@@ -194,14 +194,18 @@ fn associated_types_for_impl_traits_in_associated_fn(
 
     match tcx.def_kind(parent_def_id) {
         DefKind::Trait => {
-            let mut visitor = RPITVisitor { rpits: FxIndexSet::default() };
-
             if let Some(output) = tcx.hir_get_fn_output(fn_def_id) {
+                let data = DefPathData::AnonAssocTy(tcx.item_name(fn_def_id.to_def_id()));
+                let mut visitor = RPITVisitor {
+                    tcx,
+                    synthetics: vec![],
+                    data,
+                    disambiguator: DisambiguatorState::with(parent_def_id, data, 0),
+                };
                 visitor.visit_fn_ret_ty(output);
-
-                tcx.arena.alloc_from_iter(visitor.rpits.iter().map(|opaque_ty_def_id| {
-                    tcx.associated_type_for_impl_trait_in_trait(opaque_ty_def_id).to_def_id()
-                }))
+                tcx.arena.alloc_from_iter(
+                    visitor.synthetics.into_iter().map(|def_id| def_id.to_def_id()),
+                )
             } else {
                 &[]
             }
@@ -211,7 +215,6 @@ fn associated_types_for_impl_traits_in_associated_fn(
             let Some(trait_fn_def_id) = tcx.associated_item(fn_def_id).trait_item_def_id else {
                 return &[];
             };
-
             tcx.arena.alloc_from_iter(
                 tcx.associated_types_for_impl_traits_in_associated_fn(trait_fn_def_id).iter().map(
                     move |&trait_assoc_def_id| {
@@ -236,6 +239,8 @@ fn associated_types_for_impl_traits_in_associated_fn(
 fn associated_type_for_impl_trait_in_trait(
     tcx: TyCtxt<'_>,
     opaque_ty_def_id: LocalDefId,
+    data: DefPathData,
+    disambiguator: &mut DisambiguatorState,
 ) -> LocalDefId {
     let (hir::OpaqueTyOrigin::FnReturn { parent: fn_def_id, .. }
     | hir::OpaqueTyOrigin::AsyncFn { parent: fn_def_id, .. }) =
@@ -246,22 +251,15 @@ fn associated_type_for_impl_trait_in_trait(
     let trait_def_id = tcx.local_parent(fn_def_id);
     assert_eq!(tcx.def_kind(trait_def_id), DefKind::Trait);
 
-    // Collect all opaque types in return position for the method and use
-    // the index as the disambiguator to make an unique def path.
-    let mut visitor = RPITVisitor { rpits: FxIndexSet::default() };
-    visitor.visit_fn_ret_ty(tcx.hir_get_fn_output(fn_def_id).unwrap());
-    let disambiguator = visitor.rpits.get_index_of(&opaque_ty_def_id).unwrap().try_into().unwrap();
-
     let span = tcx.def_span(opaque_ty_def_id);
     // Also use the method name to create an unique def path.
-    let data = DefPathData::AnonAssocTy(tcx.item_name(fn_def_id.to_def_id()));
     let trait_assoc_ty = tcx.at(span).create_def(
         trait_def_id,
         // No name because this is an anonymous associated type.
         None,
         DefKind::AssocTy,
         Some(data),
-        &mut DisambiguatorState::with(trait_def_id, data, disambiguator),
+        disambiguator,
     );
 
     let local_def_id = trait_assoc_ty.def_id();

library/alloc/src/vec/mod.rs

@@ -3031,6 +3031,61 @@ impl<T, A: Allocator> Vec<T, A> {
             (initialized, spare, &mut self.len)
         }
     }
+
+    /// Groups every `N` elements in the `Vec<T>` into chunks to produce a `Vec<[T; N]>`, dropping
+    /// elements in the remainder. `N` must be greater than zero.
+    ///
+    /// If the capacity is not a multiple of the chunk size, the buffer will shrink down to the
+    /// nearest multiple with a reallocation or deallocation.
+    ///
+    /// This function can be used to reverse [`Vec::into_flattened`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(vec_into_chunks)]
+    ///
+    /// let vec = vec![0, 1, 2, 3, 4, 5, 6, 7];
+    /// assert_eq!(vec.into_chunks::<3>(), [[0, 1, 2], [3, 4, 5]]);
+    ///
+    /// let vec = vec![0, 1, 2, 3];
+    /// let chunks: Vec<[u8; 10]> = vec.into_chunks();
+    /// assert!(chunks.is_empty());
+    ///
+    /// let flat = vec![0; 8 * 8 * 8];
+    /// let reshaped: Vec<[[[u8; 8]; 8]; 8]> = flat.into_chunks().into_chunks().into_chunks();
+    /// assert_eq!(reshaped.len(), 1);
+    /// ```
+    #[cfg(not(no_global_oom_handling))]
+    #[unstable(feature = "vec_into_chunks", issue = "142137")]
+    pub fn into_chunks<const N: usize>(mut self) -> Vec<[T; N], A> {
+        const {
+            assert!(N != 0, "chunk size must be greater than zero");
+        }
+
+        let (len, cap) = (self.len(), self.capacity());
+
+        let len_remainder = len % N;
+        if len_remainder != 0 {
+            self.truncate(len - len_remainder);
+        }
+
+        let cap_remainder = cap % N;
+        if !T::IS_ZST && cap_remainder != 0 {
+            self.buf.shrink_to_fit(cap - cap_remainder);
+        }
+
+        let (ptr, _, _, alloc) = self.into_raw_parts_with_alloc();
+
+        // SAFETY:
+        // - `ptr` and `alloc` were just returned from `self.into_raw_parts_with_alloc()`
+        // - `[T; N]` has the same alignment as `T`
+        // - `size_of::<[T; N]>() * cap / N == size_of::<T>() * cap`
+        // - `len / N <= cap / N` because `len <= cap`
+        // - the allocated memory consists of `len / N` valid values of type `[T; N]`
+        // - `cap / N` fits the size of the allocated memory after shrinking
+        unsafe { Vec::from_raw_parts_in(ptr.cast(), len / N, cap / N, alloc) }
+    }
 }
 
 impl<T: Clone, A: Allocator> Vec<T, A> {