Auto merge of rust-lang#139881 - matthiaskrgr:rollup-7x6zcrc, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#138455 (`librustdoc`: more `impl fmt::Display`)
 - rust-lang#139818 (Normalize ADT field in `find_tails_for_unsizing`)
 - rust-lang#139819 (Use `rust-cache` to speed-up `citool` compilation)
 - rust-lang#139824 (Remove safe remove)
 - rust-lang#139848 ( Reduce kw::Empty usage, part 5)
 - rust-lang#139859 (CI: rename MacOS runner)
 - rust-lang#139877 (Add warning comment to `Take::get_ref` and `Chain::get_ref`)

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

Author: bors

Diff for: .github/workflows/ci.yml

@@ -53,6 +53,13 @@ jobs:
     steps:
       - name: Checkout the source code
         uses: actions/checkout@v4
+      # Cache citool to make its build faster, as it's in the critical path.
+      # The rust-cache doesn't bleed into the main `job`, so it should not affect any other
+      # Rust compilation.
+      - name: Cache citool
+        uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+        with:
+          workspaces: src/ci/citool
       - name: Calculate the CI job matrix
         env:
           COMMIT_MESSAGE: ${{ github.event.head_commit.message }}

Diff for: compiler/rustc_ast_lowering/src/lib.rs

@@ -1765,7 +1765,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         ident: Ident,
         is_anon_in_path: IsAnonInPath,
     ) -> &'hir hir::Lifetime {
-        debug_assert_ne!(ident.name, kw::Empty);
         let res = self.resolver.get_lifetime_res(id).unwrap_or(LifetimeRes::Error);
         let res = match res {
             LifetimeRes::Param { param, .. } => hir::LifetimeName::Param(param),

Diff for: compiler/rustc_hir_typeck/src/expr.rs

@@ -1600,11 +1600,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 Ok(method)
             }
             Err(error) => {
-                if segment.ident.name == kw::Empty {
-                    span_bug!(rcvr.span, "empty method name")
-                } else {
-                    Err(self.report_method_error(expr.hir_id, rcvr_t, error, expected, false))
-                }
+                Err(self.report_method_error(expr.hir_id, rcvr_t, error, expected, false))
             }
         };
 
@@ -2941,9 +2937,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             return Ty::new_error(self.tcx(), guar);
         }
 
-        let guar = if field.name == kw::Empty {
-            self.dcx().span_bug(field.span, "field name with no name")
-        } else if self.method_exists_for_diagnostic(
+        let guar = if self.method_exists_for_diagnostic(
             field,
             base_ty,
             expr.hir_id,

Diff for: compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -27,9 +27,9 @@ use rustc_middle::ty::{
 };
 use rustc_middle::{bug, span_bug};
 use rustc_session::lint;
+use rustc_span::Span;
 use rustc_span::def_id::LocalDefId;
 use rustc_span::hygiene::DesugaringKind;
-use rustc_span::{Span, kw};
 use rustc_trait_selection::error_reporting::infer::need_type_info::TypeAnnotationNeeded;
 use rustc_trait_selection::traits::{
     self, NormalizeExt, ObligationCauseCode, StructurallyNormalizeExt,
@@ -833,7 +833,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
                 let trait_missing_method =
                     matches!(error, method::MethodError::NoMatch(_)) && ty.normalized.is_trait();
-                assert_ne!(item_name.name, kw::Empty);
                 self.report_method_error(
                     hir_id,
                     ty.normalized,

Diff for: compiler/rustc_incremental/src/persist/fs.rs

@@ -290,7 +290,7 @@ pub(crate) fn prepare_session_directory(sess: &Session, crate_name: Symbol) {
 
             // Try to remove the session directory we just allocated. We don't
             // know if there's any garbage in it from the failed copy action.
-            if let Err(err) = safe_remove_dir_all(&session_dir) {
+            if let Err(err) = std_fs::remove_dir_all(&session_dir) {
                 sess.dcx().emit_warn(errors::DeletePartial { path: &session_dir, err });
             }
 
@@ -324,7 +324,7 @@ pub fn finalize_session_directory(sess: &Session, svh: Option<Svh>) {
             incr_comp_session_dir.display()
         );
 
-        if let Err(err) = safe_remove_dir_all(&*incr_comp_session_dir) {
+        if let Err(err) = std_fs::remove_dir_all(&*incr_comp_session_dir) {
             sess.dcx().emit_warn(errors::DeleteFull { path: &incr_comp_session_dir, err });
         }
 
@@ -715,7 +715,7 @@ pub(crate) fn garbage_collect_session_directories(sess: &Session) -> io::Result<
     for directory_name in session_directories {
         if !lock_file_to_session_dir.items().any(|(_, dir)| *dir == directory_name) {
             let path = crate_directory.join(directory_name);
-            if let Err(err) = safe_remove_dir_all(&path) {
+            if let Err(err) = std_fs::remove_dir_all(&path) {
                 sess.dcx().emit_warn(errors::InvalidGcFailed { path: &path, err });
             }
         }
@@ -821,7 +821,7 @@ pub(crate) fn garbage_collect_session_directories(sess: &Session) -> io::Result<
     all_except_most_recent(deletion_candidates).into_items().all(|(path, lock)| {
         debug!("garbage_collect_session_directories() - deleting `{}`", path.display());
 
-        if let Err(err) = safe_remove_dir_all(&path) {
+        if let Err(err) = std_fs::remove_dir_all(&path) {
             sess.dcx().emit_warn(errors::FinalizedGcFailed { path: &path, err });
         } else {
             delete_session_dir_lock_file(sess, &lock_file_path(&path));
@@ -839,7 +839,7 @@ pub(crate) fn garbage_collect_session_directories(sess: &Session) -> io::Result<
 fn delete_old(sess: &Session, path: &Path) {
     debug!("garbage_collect_session_directories() - deleting `{}`", path.display());
 
-    if let Err(err) = safe_remove_dir_all(path) {
+    if let Err(err) = std_fs::remove_dir_all(path) {
         sess.dcx().emit_warn(errors::SessionGcFailed { path, err });
     } else {
         delete_session_dir_lock_file(sess, &lock_file_path(path));
@@ -862,30 +862,8 @@ fn all_except_most_recent(
     }
 }
 
-/// Since paths of artifacts within session directories can get quite long, we
-/// need to support deleting files with very long paths. The regular
-/// WinApi functions only support paths up to 260 characters, however. In order
-/// to circumvent this limitation, we canonicalize the path of the directory
-/// before passing it to std::fs::remove_dir_all(). This will convert the path
-/// into the '\\?\' format, which supports much longer paths.
-fn safe_remove_dir_all(p: &Path) -> io::Result<()> {
-    let canonicalized = match try_canonicalize(p) {
-        Ok(canonicalized) => canonicalized,
-        Err(err) if err.kind() == io::ErrorKind::NotFound => return Ok(()),
-        Err(err) => return Err(err),
-    };
-
-    std_fs::remove_dir_all(canonicalized)
-}
-
 fn safe_remove_file(p: &Path) -> io::Result<()> {
-    let canonicalized = match try_canonicalize(p) {
-        Ok(canonicalized) => canonicalized,
-        Err(err) if err.kind() == io::ErrorKind::NotFound => return Ok(()),
-        Err(err) => return Err(err),
-    };
-
-    match std_fs::remove_file(canonicalized) {
+    match std_fs::remove_file(p) {
         Err(err) if err.kind() == io::ErrorKind::NotFound => Ok(()),
         result => result,
     }

Diff for: compiler/rustc_monomorphize/src/collector.rs

@@ -688,7 +688,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
                 let target_ty = self.monomorphize(target_ty);
                 let source_ty = self.monomorphize(source_ty);
                 let (source_ty, target_ty) =
-                    find_vtable_types_for_unsizing(self.tcx.at(span), source_ty, target_ty);
+                    find_tails_for_unsizing(self.tcx.at(span), source_ty, target_ty);
                 // This could also be a different Unsize instruction, like
                 // from a fixed sized array to a slice. But we are only
                 // interested in things that produce a vtable.
@@ -1037,36 +1037,35 @@ fn should_codegen_locally<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) ->
 ///
 /// Finally, there is also the case of custom unsizing coercions, e.g., for
 /// smart pointers such as `Rc` and `Arc`.
-fn find_vtable_types_for_unsizing<'tcx>(
+fn find_tails_for_unsizing<'tcx>(
     tcx: TyCtxtAt<'tcx>,
     source_ty: Ty<'tcx>,
     target_ty: Ty<'tcx>,
 ) -> (Ty<'tcx>, Ty<'tcx>) {
-    let ptr_vtable = |inner_source: Ty<'tcx>, inner_target: Ty<'tcx>| {
-        let typing_env = ty::TypingEnv::fully_monomorphized();
-        if tcx.type_has_metadata(inner_source, typing_env) {
-            (inner_source, inner_target)
-        } else {
-            tcx.struct_lockstep_tails_for_codegen(inner_source, inner_target, typing_env)
-        }
-    };
+    let typing_env = ty::TypingEnv::fully_monomorphized();
+    debug_assert!(!source_ty.has_param(), "{source_ty} should be fully monomorphic");
+    debug_assert!(!target_ty.has_param(), "{target_ty} should be fully monomorphic");
 
     match (source_ty.kind(), target_ty.kind()) {
-        (&ty::Ref(_, a, _), &ty::Ref(_, b, _) | &ty::RawPtr(b, _))
-        | (&ty::RawPtr(a, _), &ty::RawPtr(b, _)) => ptr_vtable(a, b),
+        (
+            &ty::Ref(_, source_pointee, _),
+            &ty::Ref(_, target_pointee, _) | &ty::RawPtr(target_pointee, _),
+        )
+        | (&ty::RawPtr(source_pointee, _), &ty::RawPtr(target_pointee, _)) => {
+            tcx.struct_lockstep_tails_for_codegen(source_pointee, target_pointee, typing_env)
+        }
+
+        // `Box<T>` could go through the ADT code below, b/c it'll unpeel to `Unique<T>`,
+        // and eventually bottom out in a raw ref, but we can micro-optimize it here.
         (_, _)
             if let Some(source_boxed) = source_ty.boxed_ty()
                 && let Some(target_boxed) = target_ty.boxed_ty() =>
         {
-            ptr_vtable(source_boxed, target_boxed)
+            tcx.struct_lockstep_tails_for_codegen(source_boxed, target_boxed, typing_env)
         }
 
-        // T as dyn* Trait
-        (_, &ty::Dynamic(_, _, ty::DynStar)) => ptr_vtable(source_ty, target_ty),
-
         (&ty::Adt(source_adt_def, source_args), &ty::Adt(target_adt_def, target_args)) => {
             assert_eq!(source_adt_def, target_adt_def);
-
             let CustomCoerceUnsized::Struct(coerce_index) =
                 match crate::custom_coerce_unsize_info(tcx, source_ty, target_ty) {
                     Ok(ccu) => ccu,
@@ -1075,21 +1074,23 @@ fn find_vtable_types_for_unsizing<'tcx>(
                         return (e, e);
                     }
                 };
+            let coerce_field = &source_adt_def.non_enum_variant().fields[coerce_index];
+            // We're getting a possibly unnormalized type, so normalize it.
+            let source_field =
+                tcx.normalize_erasing_regions(typing_env, coerce_field.ty(*tcx, source_args));
+            let target_field =
+                tcx.normalize_erasing_regions(typing_env, coerce_field.ty(*tcx, target_args));
+            find_tails_for_unsizing(tcx, source_field, target_field)
+        }
 
-            let source_fields = &source_adt_def.non_enum_variant().fields;
-            let target_fields = &target_adt_def.non_enum_variant().fields;
-
-            assert!(
-                coerce_index.index() < source_fields.len()
-                    && source_fields.len() == target_fields.len()
-            );
+        // `T` as `dyn* Trait` unsizes *directly*.
+        //
+        // FIXME(dyn_star): This case is a bit awkward, b/c we're not really computing
+        // a tail here. We probably should handle this separately in the *caller* of
+        // this function, rather than returning something that is semantically different
+        // than what we return above.
+        (_, &ty::Dynamic(_, _, ty::DynStar)) => (source_ty, target_ty),
 
-            find_vtable_types_for_unsizing(
-                tcx,
-                source_fields[coerce_index].ty(*tcx, source_args),
-                target_fields[coerce_index].ty(*tcx, target_args),
-            )
-        }
         _ => bug!(
             "find_vtable_types_for_unsizing: invalid coercion {:?} -> {:?}",
             source_ty,
@@ -1308,7 +1309,7 @@ fn visit_mentioned_item<'tcx>(
         }
         MentionedItem::UnsizeCast { source_ty, target_ty } => {
             let (source_ty, target_ty) =
-                find_vtable_types_for_unsizing(tcx.at(span), source_ty, target_ty);
+                find_tails_for_unsizing(tcx.at(span), source_ty, target_ty);
             // This could also be a different Unsize instruction, like
             // from a fixed sized array to a slice. But we are only
             // interested in things that produce a vtable.

Diff for: compiler/rustc_resolve/src/imports.rs

@@ -1012,7 +1012,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
                         // 2 segments, so the `resolve_path` above won't trigger it.
                         let mut full_path = import.module_path.clone();
-                        full_path.push(Segment::from_ident(Ident::empty()));
+                        full_path.push(Segment::from_ident(Ident::dummy()));
                         self.lint_if_path_starts_with_module(Some(finalize), &full_path, None);
                     }
 

Diff for: compiler/rustc_symbol_mangling/src/v0.rs

@@ -776,7 +776,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
                                     self.push_disambiguator(
                                         disambiguated_field.disambiguator as u64,
                                     );
-                                    self.push_ident(field_name.unwrap_or(kw::Empty).as_str());
+                                    self.push_ident(field_name.unwrap().as_str());
 
                                     field.print(self)?;
                                 }

Diff for: library/std/src/io/mod.rs

@@ -2658,6 +2658,10 @@ impl<T, U> Chain<T, U> {
 
     /// Gets references to the underlying readers in this `Chain`.
     ///
+    /// Care should be taken to avoid modifying the internal I/O state of the
+    /// underlying readers as doing so may corrupt the internal state of this
+    /// `Chain`.
+    ///
     /// # Examples
     ///
     /// ```no_run
@@ -2915,6 +2919,10 @@ impl<T> Take<T> {
 
     /// Gets a reference to the underlying reader.
     ///
+    /// Care should be taken to avoid modifying the internal I/O state of the
+    /// underlying reader as doing so may corrupt the internal limit of this
+    /// `Take`.
+    ///
     /// # Examples
     ///
     /// ```no_run

Diff for: src/ci/github-actions/jobs.yml

@@ -23,8 +23,8 @@ runners:
     os: ubuntu-24.04-16core-64gb
     <<: *base-job
 
-  - &job-macos-xl
-    os: macos-13 # We use the standard runner for now
+  - &job-macos
+    os: macos-13
     <<: *base-job
 
   - &job-macos-m1
@@ -380,7 +380,7 @@ auto:
       NO_OVERFLOW_CHECKS: 1
       DIST_REQUIRE_ALL_TOOLS: 1
       CODEGEN_BACKENDS: llvm,cranelift
-    <<: *job-macos-xl
+    <<: *job-macos
 
   - name: dist-apple-various
     env:
@@ -397,18 +397,18 @@ auto:
       NO_LLVM_ASSERTIONS: 1
       NO_DEBUG_ASSERTIONS: 1
       NO_OVERFLOW_CHECKS: 1
-    <<: *job-macos-xl
+    <<: *job-macos
 
   - name: x86_64-apple-1
     env:
       <<: *env-x86_64-apple-tests
-    <<: *job-macos-xl
+    <<: *job-macos
 
   - name: x86_64-apple-2
     env:
       SCRIPT: ./x.py --stage 2 test tests/ui tests/rustdoc
       <<: *env-x86_64-apple-tests
-    <<: *job-macos-xl
+    <<: *job-macos
 
   - name: dist-aarch64-apple
     env:

Diff for: src/librustdoc/clean/types.rs

@@ -517,7 +517,7 @@ impl Item {
                     Some(RenderedLink {
                         original_text: s.clone(),
                         new_text: link_text.clone(),
-                        tooltip: link_tooltip(*id, fragment, cx),
+                        tooltip: link_tooltip(*id, fragment, cx).to_string(),
                         href,
                     })
                 } else {