Auto merge of #147838 - matthiaskrgr:rollup-r8r148d, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - #140153 (Implement `Debug` for `EncodeWide`)
 - #145724 (the `#[track_caller]` shim should not inherit `#[no_mangle]`)
 - #147258 (iter repeat: panic on last)
 - #147454 (Fix backtraces with `-C panic=abort` on qnx; emit unwind tables by default)
 - #147468 (Implement fs api set_times and set_times_nofollow)
 - #147764 (Undo CopyForDeref assertion in const qualif)
 - #147805 (use module_child index as disambiguator for external items)
 - #147824 (docs: update Motor OS target docs)

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

Author: bors

compiler/rustc_codegen_cranelift/src/abi/mod.rs

@@ -467,7 +467,7 @@ pub(crate) fn codegen_terminator_call<'tcx>(
         true
     } else {
         instance.is_some_and(|inst| {
-            fx.tcx.codegen_fn_attrs(inst.def_id()).flags.contains(CodegenFnAttrFlags::COLD)
+            fx.tcx.codegen_instance_attrs(inst.def).flags.contains(CodegenFnAttrFlags::COLD)
         })
     };
     if is_cold {

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -200,10 +200,11 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
         let fn_ty = bx.fn_decl_backend_type(fn_abi);
 
         let fn_attrs = if bx.tcx().def_kind(fx.instance.def_id()).has_codegen_attrs() {
-            Some(bx.tcx().codegen_fn_attrs(fx.instance.def_id()))
+            Some(bx.tcx().codegen_instance_attrs(fx.instance.def))
         } else {
             None
         };
+        let fn_attrs = fn_attrs.as_deref();
 
         if !fn_abi.can_unwind {
             unwind = mir::UnwindAction::Unreachable;

compiler/rustc_const_eval/src/check_consts/qualifs.rs

@@ -234,7 +234,7 @@ where
 
         Rvalue::Discriminant(place) => in_place::<Q, _>(cx, in_local, place.as_ref()),
 
-        Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in runtime MIR"),
+        Rvalue::CopyForDeref(place) => in_place::<Q, _>(cx, in_local, place.as_ref()),
 
         Rvalue::Use(operand)
         | Rvalue::Repeat(operand, _)

compiler/rustc_middle/src/middle/codegen_fn_attrs.rs

@@ -13,6 +13,8 @@ impl<'tcx> TyCtxt<'tcx> {
         self,
         instance_kind: InstanceKind<'_>,
     ) -> Cow<'tcx, CodegenFnAttrs> {
+        // NOTE: we try to not clone the `CodegenFnAttrs` when that is not needed.
+        // The `to_mut` method used below clones the inner value.
         let mut attrs = Cow::Borrowed(self.codegen_fn_attrs(instance_kind.def_id()));
 
         // Drop the `#[naked]` attribute on non-item `InstanceKind`s, like the shims that
@@ -23,6 +25,28 @@ impl<'tcx> TyCtxt<'tcx> {
             }
         }
 
+        // A shim created by `#[track_caller]` should not inherit any attributes
+        // that modify the symbol name. Failing to remove these attributes from
+        // the shim leads to errors like `symbol `foo` is already defined`.
+        //
+        // A `ClosureOnceShim` with the track_caller attribute does not have a symbol,
+        // and therefore can be skipped here.
+        if let InstanceKind::ReifyShim(_, _) = instance_kind
+            && attrs.flags.contains(CodegenFnAttrFlags::TRACK_CALLER)
+        {
+            if attrs.flags.contains(CodegenFnAttrFlags::NO_MANGLE) {
+                attrs.to_mut().flags.remove(CodegenFnAttrFlags::NO_MANGLE);
+            }
+
+            if attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
+                attrs.to_mut().flags.remove(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL);
+            }
+
+            if attrs.symbol_name.is_some() {
+                attrs.to_mut().symbol_name = None;
+            }
+        }
+
         attrs
     }
 }

compiler/rustc_mir_transform/src/inline.rs

@@ -245,7 +245,7 @@ impl<'tcx> Inliner<'tcx> for ForceInliner<'tcx> {
     fn on_inline_failure(&self, callsite: &CallSite<'tcx>, reason: &'static str) {
         let tcx = self.tcx();
         let InlineAttr::Force { attr_span, reason: justification } =
-            tcx.codegen_fn_attrs(callsite.callee.def_id()).inline
+            tcx.codegen_instance_attrs(callsite.callee.def).inline
         else {
             bug!("called on item without required inlining");
         };
@@ -603,7 +603,8 @@ fn try_inlining<'tcx, I: Inliner<'tcx>>(
     let tcx = inliner.tcx();
     check_mir_is_available(inliner, caller_body, callsite.callee)?;
 
-    let callee_attrs = tcx.codegen_fn_attrs(callsite.callee.def_id());
+    let callee_attrs = tcx.codegen_instance_attrs(callsite.callee.def);
+    let callee_attrs = callee_attrs.as_ref();
     check_inline::is_inline_valid_on_fn(tcx, callsite.callee.def_id())?;
     check_codegen_attributes(inliner, callsite, callee_attrs)?;
     inliner.check_codegen_attributes_extra(callee_attrs)?;

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -77,6 +77,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         parent: Module<'ra>,
         ident: Ident,
         ns: Namespace,
+        child_index: usize,
         res: Res,
         vis: Visibility<DefId>,
         span: Span,
@@ -86,10 +87,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         // Even if underscore names cannot be looked up, we still need to add them to modules,
         // because they can be fetched by glob imports from those modules, and bring traits
         // into scope both directly and through glob imports.
-        let key = BindingKey::new_disambiguated(ident, ns, || {
-            parent.underscore_disambiguator.update_unchecked(|d| d + 1);
-            parent.underscore_disambiguator.get()
-        });
+        let key =
+            BindingKey::new_disambiguated(ident, ns, || (child_index + 1).try_into().unwrap()); // 0 indicates no underscore
         if self
             .resolution_or_default(parent, key)
             .borrow_mut_unchecked()
@@ -233,9 +232,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     }
 
     pub(crate) fn build_reduced_graph_external(&self, module: Module<'ra>) {
-        for child in self.tcx.module_children(module.def_id()) {
+        for (i, child) in self.tcx.module_children(module.def_id()).into_iter().enumerate() {
             let parent_scope = ParentScope::module(module, self.arenas);
-            self.build_reduced_graph_for_external_crate_res(child, parent_scope)
+            self.build_reduced_graph_for_external_crate_res(child, parent_scope, i)
         }
     }
 
@@ -244,6 +243,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         &self,
         child: &ModChild,
         parent_scope: ParentScope<'ra>,
+        child_index: usize,
     ) {
         let parent = parent_scope.module;
         let ModChild { ident, res, vis, ref reexport_chain } = *child;
@@ -272,7 +272,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 _,
             )
             | Res::PrimTy(..)
-            | Res::ToolMod => self.define_extern(parent, ident, TypeNS, res, vis, span, expansion),
+            | Res::ToolMod => {
+                self.define_extern(parent, ident, TypeNS, child_index, res, vis, span, expansion)
+            }
             Res::Def(
                 DefKind::Fn
                 | DefKind::AssocFn
@@ -281,9 +283,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 | DefKind::AssocConst
                 | DefKind::Ctor(..),
                 _,
-            ) => self.define_extern(parent, ident, ValueNS, res, vis, span, expansion),
+            ) => self.define_extern(parent, ident, ValueNS, child_index, res, vis, span, expansion),
             Res::Def(DefKind::Macro(..), _) | Res::NonMacroAttr(..) => {
-                self.define_extern(parent, ident, MacroNS, res, vis, span, expansion)
+                self.define_extern(parent, ident, MacroNS, child_index, res, vis, span, expansion)
             }
             Res::Def(
                 DefKind::TyParam

compiler/rustc_target/src/spec/base/nto_qnx.rs

@@ -12,6 +12,9 @@ pub(crate) fn opts() -> TargetOptions {
         has_thread_local: false,
         linker: Some("qcc".into()),
         os: "nto".into(),
+        // We want backtraces to work by default and they rely on unwind tables
+        // (regardless of `-C panic` strategy).
+        default_uwtable: true,
         position_independent_executables: true,
         static_position_independent_executables: true,
         relro_level: RelroLevel::Full,

library/alloc/src/wtf8/tests.rs

@@ -579,6 +579,17 @@ fn wtf8_encode_wide_size_hint() {
     assert!(iter.next().is_none());
 }
 
+#[test]
+fn wtf8_encode_wide_debug() {
+    let mut string = Wtf8Buf::from_str("aé ");
+    string.push(CodePoint::from_u32(0xD83D).unwrap());
+    string.push_char('💩');
+    assert_eq!(
+        format!("{:?}", string.encode_wide()),
+        r#"EncodeWide(['a', 'é', ' ', 0xD83D, 0xD83D, 0xDCA9])"#
+    );
+}
+
 #[test]
 fn wtf8_clone_into() {
     let mut string = Wtf8Buf::new();

library/core/src/iter/sources/repeat.rs

@@ -101,8 +101,9 @@ impl<A: Clone> Iterator for Repeat<A> {
         Some(self.element.clone())
     }
 
+    #[track_caller]
     fn last(self) -> Option<A> {
-        Some(self.element)
+        panic!("iterator is infinite");
     }
 
     #[track_caller]

library/core/src/wtf8.rs

@@ -562,15 +562,36 @@ impl Iterator for EncodeWide<'_> {
     }
 }
 
+#[stable(feature = "encode_wide_fused_iterator", since = "1.62.0")]
+impl FusedIterator for EncodeWide<'_> {}
+
+#[stable(feature = "encode_wide_debug", since = "CURRENT_RUSTC_VERSION")]
 impl fmt::Debug for EncodeWide<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("EncodeWide").finish_non_exhaustive()
+        struct CodeUnit(u16);
+        impl fmt::Debug for CodeUnit {
+            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                // This output attempts to balance readability with precision.
+                // Render characters which take only one WTF-16 code unit using
+                // `char` syntax and everything else as code units with hex
+                // integer syntax (including paired and unpaired surrogate
+                // halves). Since Rust has no `char`-like type for WTF-16, this
+                // isn't perfect, so if this output isn't suitable, it is open
+                // to being changed (see #140153).
+                match char::from_u32(self.0 as u32) {
+                    Some(c) => write!(f, "{c:?}"),
+                    None => write!(f, "0x{:04X}", self.0),
+                }
+            }
+        }
+
+        write!(f, "EncodeWide(")?;
+        f.debug_list().entries(self.clone().map(CodeUnit)).finish()?;
+        write!(f, ")")?;
+        Ok(())
     }
 }
 
-#[stable(feature = "encode_wide_fused_iterator", since = "1.62.0")]
-impl FusedIterator for EncodeWide<'_> {}
-
 impl Hash for CodePoint {
     #[inline]
     fn hash<H: Hasher>(&self, state: &mut H) {