Auto merge of rust-lang#133423 - jieyouxu:rollup-m3gyoz6, r=jieyouxu

Rollup of 6 pull requests

Successful merges:

 - rust-lang#132730 (std: allow after-main use of synchronization primitives)
 - rust-lang#133105 (only store valid proc macro item for doc link)
 - rust-lang#133260 (Constify the `Deref`/`DerefMut` traits, too)
 - rust-lang#133297 (Remove legacy bitcode for iOS)
 - rust-lang#133298 (Mention that std::fs::remove_dir_all fails on files)
 - rust-lang#133384 (add a test for target-feature-ABI warnings in closures and when calling extern fn)

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

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -955,24 +955,7 @@ pub(crate) fn bitcode_section_name(cgcx: &CodegenContext<LlvmCodegenBackend>) ->
     }
 }
 
-/// Embed the bitcode of an LLVM module in the LLVM module itself.
-///
-/// This is done primarily for iOS where it appears to be standard to compile C
-/// code at least with `-fembed-bitcode` which creates two sections in the
-/// executable:
-///
-/// * __LLVM,__bitcode
-/// * __LLVM,__cmdline
-///
-/// It appears *both* of these sections are necessary to get the linker to
-/// recognize what's going on. A suitable cmdline value is taken from the
-/// target spec.
-///
-/// Furthermore debug/O1 builds don't actually embed bitcode but rather just
-/// embed an empty section.
-///
-/// Basically all of this is us attempting to follow in the footsteps of clang
-/// on iOS. See #35968 for lots more info.
+/// Embed the bitcode of an LLVM module for LTO in the LLVM module itself.
 unsafe fn embed_bitcode(
     cgcx: &CodegenContext<LlvmCodegenBackend>,
     llcx: &llvm::Context,

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -432,11 +432,9 @@ struct CompiledModules {
 
 fn need_bitcode_in_object(tcx: TyCtxt<'_>) -> bool {
     let sess = tcx.sess;
-    let requested_for_rlib = sess.opts.cg.embed_bitcode
+    sess.opts.cg.embed_bitcode
         && tcx.crate_types().contains(&CrateType::Rlib)
-        && sess.opts.output_types.contains_key(&OutputType::Exe);
-    let forced_by_target = sess.target.forces_embed_bitcode;
-    requested_for_rlib || forced_by_target
+        && sess.opts.output_types.contains_key(&OutputType::Exe)
 }
 
 fn need_pre_lto_bitcode_for_incr_comp(sess: &Session) -> bool {

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -576,9 +576,9 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
     // If this closure is marked `#[inline(always)]`, simply skip adding `#[target_feature]`.
     //
     // At this point, `unsafe` has already been checked and `#[target_feature]` only affects codegen.
-    // Emitting both `#[inline(always)]` and `#[target_feature]` can potentially result in an
-    // ICE, because LLVM errors when the function fails to be inlined due to a target feature
-    // mismatch.
+    // Due to LLVM limitations, emitting both `#[inline(always)]` and `#[target_feature]` is *unsound*:
+    // the function may be inlined into a caller with fewer target features. Also see
+    // <https://github.com/rust-lang/rust/issues/116573>.
     //
     // Using `#[inline(always)]` implies that this closure will most likely be inlined into
     // its parent function, which effectively inherits the features anyway. Boxing this closure

compiler/rustc_resolve/src/late.rs

@@ -4794,14 +4794,10 @@ impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                 let res = self.r.resolve_rustdoc_path(path.as_str(), *ns, self.parent_scope);
                 if let Some(res) = res
                     && let Some(def_id) = res.opt_def_id()
-                    && !def_id.is_local()
-                    && self.r.tcx.crate_types().contains(&CrateType::ProcMacro)
-                    && matches!(
-                        self.r.tcx.sess.opts.resolve_doc_links,
-                        ResolveDocLinks::ExportedMetadata
-                    )
+                    && self.is_invalid_proc_macro_item_for_doc(def_id)
                 {
-                    // Encoding foreign def ids in proc macro crate metadata will ICE.
+                    // Encoding def ids in proc macro crate metadata will ICE,
+                    // because it will only store proc macros for it.
                     return None;
                 }
                 res
@@ -4810,6 +4806,17 @@ impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
         res
     }
 
+    fn is_invalid_proc_macro_item_for_doc(&self, did: DefId) -> bool {
+        if !matches!(self.r.tcx.sess.opts.resolve_doc_links, ResolveDocLinks::ExportedMetadata)
+            || !self.r.tcx.crate_types().contains(&CrateType::ProcMacro)
+        {
+            return false;
+        }
+        let Some(local_did) = did.as_local() else { return true };
+        let Some(node_id) = self.r.def_id_to_node_id.get(local_did) else { return true };
+        !self.r.proc_macros.contains(node_id)
+    }
+
     fn resolve_doc_links(&mut self, attrs: &[Attribute], maybe_exported: MaybeExported<'_>) {
         match self.r.tcx.sess.opts.resolve_doc_links {
             ResolveDocLinks::None => return,
@@ -4872,14 +4879,9 @@ impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                         .traits_in_scope(None, &self.parent_scope, SyntaxContext::root(), None)
                         .into_iter()
                         .filter_map(|tr| {
-                            if !tr.def_id.is_local()
-                                && self.r.tcx.crate_types().contains(&CrateType::ProcMacro)
-                                && matches!(
-                                    self.r.tcx.sess.opts.resolve_doc_links,
-                                    ResolveDocLinks::ExportedMetadata
-                                )
-                            {
-                                // Encoding foreign def ids in proc macro crate metadata will ICE.
+                            if self.is_invalid_proc_macro_item_for_doc(tr.def_id) {
+                                // Encoding def ids in proc macro crate metadata will ICE.
+                                // because it will only store proc macros for it.
                                 return None;
                             }
                             Some(tr.def_id)

compiler/rustc_target/src/spec/mod.rs

@@ -2327,8 +2327,6 @@ pub struct TargetOptions {
     /// If we give emcc .o files that are actually .bc files it
     /// will 'just work'.
     pub obj_is_bitcode: bool,
-    /// Whether the target requires that emitted object code includes bitcode.
-    pub forces_embed_bitcode: bool,
     /// Content of the LLVM cmdline section associated with embedded bitcode.
     pub bitcode_llvm_cmdline: StaticCow<str>,
 
@@ -2671,7 +2669,6 @@ impl Default for TargetOptions {
             allow_asm: true,
             has_thread_local: false,
             obj_is_bitcode: false,
-            forces_embed_bitcode: false,
             bitcode_llvm_cmdline: "".into(),
             min_atomic_width: None,
             max_atomic_width: None,
@@ -3412,7 +3409,6 @@ impl Target {
         key!(main_needs_argc_argv, bool);
         key!(has_thread_local, bool);
         key!(obj_is_bitcode, bool);
-        key!(forces_embed_bitcode, bool);
         key!(bitcode_llvm_cmdline);
         key!(max_atomic_width, Option<u64>);
         key!(min_atomic_width, Option<u64>);
@@ -3687,7 +3683,6 @@ impl ToJson for Target {
         target_option_val!(main_needs_argc_argv);
         target_option_val!(has_thread_local);
         target_option_val!(obj_is_bitcode);
-        target_option_val!(forces_embed_bitcode);
         target_option_val!(bitcode_llvm_cmdline);
         target_option_val!(min_atomic_width);
         target_option_val!(max_atomic_width);

library/core/src/ops/deref.rs

@@ -133,6 +133,7 @@
 #[doc(alias = "&*")]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_diagnostic_item = "Deref"]
+#[cfg_attr(not(bootstrap), const_trait)]
 pub trait Deref {
     /// The resulting type after dereferencing.
     #[stable(feature = "rust1", since = "1.0.0")]
@@ -147,6 +148,7 @@ pub trait Deref {
     fn deref(&self) -> &Self::Target;
 }
 
+#[cfg(bootstrap)]
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> Deref for &T {
     type Target = T;
@@ -157,9 +159,21 @@ impl<T: ?Sized> Deref for &T {
     }
 }
 
+#[cfg(not(bootstrap))]
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: ?Sized> const Deref for &T {
+    type Target = T;
+
+    #[rustc_diagnostic_item = "noop_method_deref"]
+    fn deref(&self) -> &T {
+        *self
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> !DerefMut for &T {}
 
+#[cfg(bootstrap)]
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> Deref for &mut T {
     type Target = T;
@@ -169,6 +183,16 @@ impl<T: ?Sized> Deref for &mut T {
     }
 }
 
+#[cfg(not(bootstrap))]
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: ?Sized> const Deref for &mut T {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        *self
+    }
+}
+
 /// Used for mutable dereferencing operations, like in `*v = 1;`.
 ///
 /// In addition to being used for explicit dereferencing operations with the
@@ -258,23 +282,46 @@ impl<T: ?Sized> Deref for &mut T {
 /// *x = 'b';
 /// assert_eq!('b', x.value);
 /// ```
+#[cfg(not(bootstrap))]
+#[lang = "deref_mut"]
+#[doc(alias = "*")]
+#[stable(feature = "rust1", since = "1.0.0")]
+#[const_trait]
+pub trait DerefMut: ~const Deref {
+    /// Mutably dereferences the value.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_diagnostic_item = "deref_mut_method"]
+    fn deref_mut(&mut self) -> &mut Self::Target;
+}
+
+/// Bootstrap
 #[lang = "deref_mut"]
 #[doc(alias = "*")]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[cfg(bootstrap)]
 pub trait DerefMut: Deref {
     /// Mutably dereferences the value.
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_diagnostic_item = "deref_mut_method"]
     fn deref_mut(&mut self) -> &mut Self::Target;
 }
 
+#[cfg(bootstrap)]
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> DerefMut for &mut T {
     fn deref_mut(&mut self) -> &mut T {
         *self
     }
 }
 
+#[cfg(not(bootstrap))]
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: ?Sized> const DerefMut for &mut T {
+    fn deref_mut(&mut self) -> &mut T {
+        *self
+    }
+}
+
 /// Perma-unstable marker trait. Indicates that the type has a well-behaved [`Deref`]
 /// (and, if applicable, [`DerefMut`]) implementation. This is relied on for soundness
 /// of deref patterns.

library/std/src/fs.rs

@@ -2804,8 +2804,9 @@ pub fn remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
 ///
 /// See [`fs::remove_file`] and [`fs::remove_dir`].
 ///
-/// `remove_dir_all` will fail if `remove_dir` or `remove_file` fail on any constituent paths, including the root path.
+/// `remove_dir_all` will fail if `remove_dir` or `remove_file` fail on any constituent paths, including the root `path`.
 /// As a result, the directory you are deleting must exist, meaning that this function is not idempotent.
+/// Additionally, `remove_dir_all` will also fail if the `path` is not a directory.
 ///
 /// Consider ignoring the error if validating the removal is not required for your use case.
 ///

library/std/src/lib.rs

@@ -174,9 +174,6 @@
 //!
 //! - after-main use of thread-locals, which also affects additional features:
 //!   - [`thread::current()`]
-//!   - [`thread::scope()`]
-//!   - [`sync::mpmc`]
-//!   - [`sync::mpsc`]
 //! - before-main stdio file descriptors are not guaranteed to be open on unix platforms
 //!
 //!

library/std/src/sync/mpmc/array.rs

@@ -346,7 +346,8 @@ impl<T> Channel<T> {
                 }
 
                 // Block the current thread.
-                let sel = cx.wait_until(deadline);
+                // SAFETY: the context belongs to the current thread.
+                let sel = unsafe { cx.wait_until(deadline) };
 
                 match sel {
                     Selected::Waiting => unreachable!(),
@@ -397,7 +398,8 @@ impl<T> Channel<T> {
                 }
 
                 // Block the current thread.
-                let sel = cx.wait_until(deadline);
+                // SAFETY: the context belongs to the current thread.
+                let sel = unsafe { cx.wait_until(deadline) };
 
                 match sel {
                     Selected::Waiting => unreachable!(),

library/std/src/sync/mpmc/context.rs

@@ -69,7 +69,7 @@ impl Context {
             inner: Arc::new(Inner {
                 select: AtomicUsize::new(Selected::Waiting.into()),
                 packet: AtomicPtr::new(ptr::null_mut()),
-                thread: thread::current(),
+                thread: thread::current_or_unnamed(),
                 thread_id: current_thread_id(),
             }),
         }
@@ -112,8 +112,11 @@ impl Context {
     /// Waits until an operation is selected and returns it.
     ///
     /// If the deadline is reached, `Selected::Aborted` will be selected.
+    ///
+    /// # Safety
+    /// This may only be called from the thread this `Context` belongs to.
     #[inline]
-    pub fn wait_until(&self, deadline: Option<Instant>) -> Selected {
+    pub unsafe fn wait_until(&self, deadline: Option<Instant>) -> Selected {
         loop {
             // Check whether an operation has been selected.
             let sel = Selected::from(self.inner.select.load(Ordering::Acquire));
@@ -126,7 +129,8 @@ impl Context {
                 let now = Instant::now();
 
                 if now < end {
-                    thread::park_timeout(end - now);
+                    // SAFETY: guaranteed by caller.
+                    unsafe { self.inner.thread.park_timeout(end - now) };
                 } else {
                     // The deadline has been reached. Try aborting select.
                     return match self.try_select(Selected::Aborted) {
@@ -135,7 +139,8 @@ impl Context {
                     };
                 }
             } else {
-                thread::park();
+                // SAFETY: guaranteed by caller.
+                unsafe { self.inner.thread.park() };
             }
         }
     }

library/std/src/sync/mpmc/list.rs

@@ -444,7 +444,8 @@ impl<T> Channel<T> {
                 }
 
                 // Block the current thread.
-                let sel = cx.wait_until(deadline);
+                // SAFETY: the context belongs to the current thread.
+                let sel = unsafe { cx.wait_until(deadline) };
 
                 match sel {
                     Selected::Waiting => unreachable!(),

library/std/src/sync/mpmc/zero.rs

@@ -190,7 +190,8 @@ impl<T> Channel<T> {
             drop(inner);
 
             // Block the current thread.
-            let sel = cx.wait_until(deadline);
+            // SAFETY: the context belongs to the current thread.
+            let sel = unsafe { cx.wait_until(deadline) };
 
             match sel {
                 Selected::Waiting => unreachable!(),
@@ -257,7 +258,8 @@ impl<T> Channel<T> {
             drop(inner);
 
             // Block the current thread.
-            let sel = cx.wait_until(deadline);
+            // SAFETY: the context belongs to the current thread.
+            let sel = unsafe { cx.wait_until(deadline) };
 
             match sel {
                 Selected::Waiting => unreachable!(),

library/std/src/sys/sync/once/queue.rs

@@ -93,7 +93,7 @@ const QUEUE_MASK: usize = !STATE_MASK;
 // use interior mutability.
 #[repr(align(4))] // Ensure the two lower bits are free to use as state bits.
 struct Waiter {
-    thread: Cell<Option<Thread>>,
+    thread: Thread,
     signaled: AtomicBool,
     next: Cell<*const Waiter>,
 }
@@ -238,7 +238,7 @@ fn wait(
     return_on_poisoned: bool,
 ) -> StateAndQueue {
     let node = &Waiter {
-        thread: Cell::new(Some(thread::current())),
+        thread: thread::current_or_unnamed(),
         signaled: AtomicBool::new(false),
         next: Cell::new(ptr::null()),
     };
@@ -277,7 +277,8 @@ fn wait(
             // can park ourselves, the result could be this thread never gets
             // unparked. Luckily `park` comes with the guarantee that if it got
             // an `unpark` just before on an unparked thread it does not park.
-            thread::park();
+            // SAFETY: we retrieved this handle on the current thread above.
+            unsafe { node.thread.park() }
         }
 
         return state_and_queue.load(Acquire);
@@ -309,7 +310,7 @@ impl Drop for WaiterQueue<'_> {
             let mut queue = to_queue(current);
             while !queue.is_null() {
                 let next = (*queue).next.get();
-                let thread = (*queue).thread.take().unwrap();
+                let thread = (*queue).thread.clone();
                 (*queue).signaled.store(true, Release);
                 thread.unpark();
                 queue = next;