Auto merge of #143322 - matthiaskrgr:rollup-h6xw7i5, r=matthiaskrgr

Rollup of 10 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)
 - #143260 (Use the correct export kind for __rust_alloc_error_handler_should_panic)
 - #143274 (ci: support optional jobs)

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

Author: bors

compiler/rustc_codegen_ssa/src/back/symbol_export.rs

@@ -219,13 +219,18 @@ fn exported_non_generic_symbols_provider_local<'tcx>(
 
     // Mark allocator shim symbols as exported only if they were generated.
     if allocator_kind_for_codegen(tcx).is_some() {
-        for symbol_name in ALLOCATOR_METHODS
+        for (symbol_name, export_kind) in ALLOCATOR_METHODS
             .iter()
-            .map(|method| mangle_internal_symbol(tcx, global_fn_name(method.name).as_str()))
+            .map(|method| {
+                (
+                    mangle_internal_symbol(tcx, global_fn_name(method.name).as_str()),
+                    SymbolExportKind::Text,
+                )
+            })
             .chain([
-                mangle_internal_symbol(tcx, "__rust_alloc_error_handler"),
-                mangle_internal_symbol(tcx, OomStrategy::SYMBOL),
-                mangle_internal_symbol(tcx, NO_ALLOC_SHIM_IS_UNSTABLE),
+                (mangle_internal_symbol(tcx, "__rust_alloc_error_handler"), SymbolExportKind::Text),
+                (mangle_internal_symbol(tcx, OomStrategy::SYMBOL), SymbolExportKind::Data),
+                (mangle_internal_symbol(tcx, NO_ALLOC_SHIM_IS_UNSTABLE), SymbolExportKind::Text),
             ])
         {
             let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(tcx, &symbol_name));
@@ -234,7 +239,7 @@ fn exported_non_generic_symbols_provider_local<'tcx>(
                 exported_symbol,
                 SymbolExportInfo {
                     level: SymbolExportLevel::Rust,
-                    kind: SymbolExportKind::Text,
+                    kind: export_kind,
                     used: false,
                     rustc_std_internal_symbol: true,
                 },

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 {