Rollup of 7 pull requests

RELEASES.md

@@ -503,7 +503,7 @@ Compatibility Notes
 * We have renamed `std::panic::PanicInfo` to `std::panic::PanicHookInfo`. The old name will continue to work as an alias, but will result in a deprecation warning starting in Rust 1.82.0.
 
   `core::panic::PanicInfo` will remain unchanged, however, as this is now a *different type*.
- 
+
   The reason is that these types have different roles: `std::panic::PanicHookInfo` is the argument to the [panic hook](https://doc.rust-lang.org/stable/std/panic/fn.set_hook.html) in std context (where panics can have an arbitrary payload), while `core::panic::PanicInfo` is the argument to the [`#[panic_handler]`](https://doc.rust-lang.org/nomicon/panic-handler.html) in no_std context (where panics always carry a formatted *message*). Separating these types allows us to add more useful methods to these types, such as `std::panic::PanicHookInfo::payload_as_str()` and `core::panic::PanicInfo::message()`.
 
 * The new sort implementations may panic if a type's implementation of [`Ord`](https://doc.rust-lang.org/std/cmp/trait.Ord.html) (or the given comparison function) does not implement a [total order](https://en.wikipedia.org/wiki/Total_order) as the trait requires. `Ord`'s supertraits (`PartialOrd`, `Eq`, and `PartialEq`) must also be consistent. The previous implementations would not "notice" any problem, but the new implementations have a good chance of detecting inconsistencies, throwing a panic rather than returning knowingly unsorted data.
@@ -584,7 +584,7 @@ Stabilized APIs
 - [`impl Default for Arc<CStr>`](https://doc.rust-lang.org/beta/alloc/sync/struct.Arc.html#impl-Default-for-Arc%3CCStr%3E)
 - [`impl Default for Arc<[T]>`](https://doc.rust-lang.org/beta/alloc/sync/struct.Arc.html#impl-Default-for-Arc%3C%5BT%5D%3E)
 - [`impl IntoIterator for Box<[T]>`](https://doc.rust-lang.org/beta/alloc/boxed/struct.Box.html#impl-IntoIterator-for-Box%3C%5BI%5D,+A%3E)
-- [`impl FromIterator<String> for Box<str>`](https://doc.rust-lang.org/beta/alloc/boxed/struct.Box.html#impl-FromIterator%3CString%3E-for-Box%3Cstr%3E) 
+- [`impl FromIterator<String> for Box<str>`](https://doc.rust-lang.org/beta/alloc/boxed/struct.Box.html#impl-FromIterator%3CString%3E-for-Box%3Cstr%3E)
 - [`impl FromIterator<char> for Box<str>`](https://doc.rust-lang.org/beta/alloc/boxed/struct.Box.html#impl-FromIterator%3Cchar%3E-for-Box%3Cstr%3E)
 - [`LazyCell`](https://doc.rust-lang.org/beta/core/cell/struct.LazyCell.html)
 - [`LazyLock`](https://doc.rust-lang.org/beta/std/sync/struct.LazyLock.html)
@@ -1816,7 +1816,7 @@ Compiler
 - [Detect uninhabited types early in const eval](https://github.com/rust-lang/rust/pull/109435/)
 - [Switch to LLD as default linker for {arm,thumb}v4t-none-eabi](https://github.com/rust-lang/rust/pull/109721/)
 - [Add tier 3 target `loongarch64-unknown-linux-gnu`](https://github.com/rust-lang/rust/pull/96971)
-- [Add tier 3 target for `i586-pc-nto-qnx700` (QNX Neutrino RTOS, version 7.0)](https://github.com/rust-lang/rust/pull/109173/), 
+- [Add tier 3 target for `i586-pc-nto-qnx700` (QNX Neutrino RTOS, version 7.0)](https://github.com/rust-lang/rust/pull/109173/),
 - [Insert alignment checks for pointer dereferences as debug assertions](https://github.com/rust-lang/rust/pull/98112)
   This catches undefined behavior at runtime, and may cause existing code to fail.
 
@@ -2023,7 +2023,7 @@ Compatibility Notes
   If `tools = [...]` is set in config.toml, we will respect a missing rustdoc in that list. By
   default rustdoc remains included. To retain the prior behavior explicitly add `"rustdoc"` to the
   list.
-  
+
 <a id="1.69.0-Internal-Changes"></a>
 
 Internal Changes

compiler/rustc_const_eval/src/interpret/place.rs

@@ -1018,29 +1018,48 @@ where
         self.allocate_dyn(layout, kind, MemPlaceMeta::None)
     }
 
-    /// Returns a wide MPlace of type `str` to a new 1-aligned allocation.
-    /// Immutable strings are deduplicated and stored in global memory.
-    pub fn allocate_str(
+    /// Allocates a sequence of bytes in the interpreter's memory.
+    /// For immutable allocations, uses deduplication to reuse existing memory.
+    /// For mutable allocations, creates a new unique allocation.
+    pub fn allocate_bytes(
         &mut self,
-        str: &str,
+        bytes: &[u8],
+        align: Align,
         kind: MemoryKind<M::MemoryKind>,
         mutbl: Mutability,
-    ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> {
-        let tcx = self.tcx.tcx;
-
+    ) -> InterpResult<'tcx, Pointer<M::Provenance>> {
         // Use cache for immutable strings.
-        let ptr = if mutbl.is_not() {
+        if mutbl.is_not() {
             // Use dedup'd allocation function.
             let salt = M::get_global_alloc_salt(self, None);
-            let id = tcx.allocate_bytes_dedup(str.as_bytes(), salt);
+            let id = self.tcx.allocate_bytes_dedup(bytes, salt);
 
             // Turn untagged "global" pointers (obtained via `tcx`) into the machine pointer to the allocation.
-            M::adjust_alloc_root_pointer(&self, Pointer::from(id), Some(kind))?
+            M::adjust_alloc_root_pointer(&self, Pointer::from(id), Some(kind))
         } else {
-            self.allocate_bytes_ptr(str.as_bytes(), Align::ONE, kind, mutbl)?
-        };
-        let meta = Scalar::from_target_usize(u64::try_from(str.len()).unwrap(), self);
+            // Allocate new memory for mutable data.
+            self.allocate_bytes_ptr(bytes, align, kind, mutbl)
+        }
+    }
+
+    /// Allocates a string in the interpreter's memory with metadata for length.
+    /// Uses `allocate_bytes` internally but adds string-specific metadata handling.
+    pub fn allocate_str(
+        &mut self,
+        str: &str,
+        kind: MemoryKind<M::MemoryKind>,
+        mutbl: Mutability,
+    ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> {
+        let bytes = str.as_bytes();
+        let ptr = self.allocate_bytes(bytes, Align::ONE, kind, mutbl)?;
+
+        // Create length metadata for the string.
+        let meta = Scalar::from_target_usize(u64::try_from(bytes.len()).unwrap(), self);
+
+        // Get layout for Rust's str type.
         let layout = self.layout_of(self.tcx.types.str_).unwrap();
+
+        // Combine pointer and metadata into a wide pointer.
         interp_ok(self.ptr_with_meta_to_mplace(
             ptr.into(),
             MemPlaceMeta::Meta(meta),

compiler/rustc_lint/messages.ftl

@@ -359,7 +359,6 @@ lint_improper_ctypes_128bit = 128-bit integers don't currently have a known stab
 lint_improper_ctypes_array_help = consider passing a pointer to the array
 
 lint_improper_ctypes_array_reason = passing raw arrays by value is not FFI-safe
-lint_improper_ctypes_box = box cannot be represented as a single pointer
 
 lint_improper_ctypes_char_help = consider using `u32` or `libc::wchar_t` instead
 
@@ -377,7 +376,9 @@ lint_improper_ctypes_enum_repr_help =
 lint_improper_ctypes_enum_repr_reason = enum has no representation hint
 lint_improper_ctypes_fnptr_help = consider using an `extern fn(...) -> ...` function pointer instead
 
+lint_improper_ctypes_fnptr_indirect_reason = the function pointer to `{$ty}` is FFI-unsafe due to `{$inner_ty}`
 lint_improper_ctypes_fnptr_reason = this function pointer has Rust-specific calling convention
+
 lint_improper_ctypes_non_exhaustive = this enum is non-exhaustive
 lint_improper_ctypes_non_exhaustive_variant = this enum has non-exhaustive variants
 
@@ -388,7 +389,11 @@ lint_improper_ctypes_opaque = opaque types have no C equivalent
 lint_improper_ctypes_pat_help = consider using the base type instead
 
 lint_improper_ctypes_pat_reason = pattern types have no C equivalent
-lint_improper_ctypes_slice_help = consider using a raw pointer instead
+
+lint_improper_ctypes_sized_ptr_to_unsafe_type =
+    this reference (`{$ty}`) is ABI-compatible with a C pointer, but `{$inner_ty}` itself does not have a C layout
+
+lint_improper_ctypes_slice_help = consider using a raw pointer to the slice's first element (and a length) instead
 
 lint_improper_ctypes_slice_reason = slices have no C equivalent
 lint_improper_ctypes_str_help = consider using `*const u8` and a length instead
@@ -414,6 +419,10 @@ lint_improper_ctypes_union_layout_help = consider adding a `#[repr(C)]` or `#[re
 lint_improper_ctypes_union_layout_reason = this union has unspecified layout
 lint_improper_ctypes_union_non_exhaustive = this union is non-exhaustive
 
+lint_improper_ctypes_unsized_box = this box for an unsized type contains metadata, which makes it incompatible with a C pointer
+lint_improper_ctypes_unsized_ptr = this pointer to an unsized type contains metadata, which makes it incompatible with a C pointer
+lint_improper_ctypes_unsized_ref = this reference to an unsized type contains metadata, which makes it incompatible with a C pointer
+
 lint_incomplete_include =
     include macro expected single expression in source
 

compiler/rustc_lint/src/early.rs

@@ -245,6 +245,7 @@ impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T>
 
     fn visit_lifetime(&mut self, lt: &'a ast::Lifetime, _: ast_visit::LifetimeCtxt) {
         self.check_id(lt.id);
+        ast_visit::walk_lifetime(self, lt);
     }
 
     fn visit_path(&mut self, p: &'a ast::Path, id: ast::NodeId) {
@@ -259,6 +260,7 @@ impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T>
 
     fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
         lint_callback!(self, check_attribute, attr);
+        ast_visit::walk_attribute(self, attr);
     }
 
     fn visit_mac_def(&mut self, mac: &'a ast::MacroDef, id: ast::NodeId) {

compiler/rustc_lint/src/hidden_unicode_codepoints.rs

@@ -9,6 +9,7 @@ use crate::lints::{
 use crate::{EarlyContext, EarlyLintPass, LintContext};
 
 declare_lint! {
+    #[allow(text_direction_codepoint_in_literal)]
     /// The `text_direction_codepoint_in_literal` lint detects Unicode codepoints that change the
     /// visual representation of text on screen in a way that does not correspond to their on
     /// memory representation.

compiler/rustc_lint/src/lints.rs

@@ -1851,13 +1851,44 @@ pub(crate) struct UnpredictableFunctionPointerComparisonsSuggestion<'a> {
     pub right: Span,
 }
 
+pub(crate) struct ImproperCTypesLayer<'a> {
+    pub ty: Ty<'a>,
+    pub inner_ty: Option<Ty<'a>>,
+    pub note: DiagMessage,
+    pub span_note: Option<Span>,
+    pub help: Option<DiagMessage>,
+}
+
+impl<'a> Subdiagnostic for ImproperCTypesLayer<'a> {
+    fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
+        self,
+        diag: &mut Diag<'_, G>,
+        f: &F,
+    ) {
+        diag.arg("ty", self.ty);
+        if let Some(ty) = self.inner_ty {
+            diag.arg("inner_ty", ty);
+        }
+
+        if let Some(help) = self.help {
+            let msg = f(diag, help.into());
+            diag.help(msg);
+        }
+
+        let msg = f(diag, self.note.into());
+        diag.note(msg);
+        if let Some(note) = self.span_note {
+            let msg = f(diag, fluent::lint_note.into());
+            diag.span_note(note, msg);
+        };
+    }
+}
+
 pub(crate) struct ImproperCTypes<'a> {
     pub ty: Ty<'a>,
     pub desc: &'a str,
     pub label: Span,
-    pub help: Option<DiagMessage>,
-    pub note: DiagMessage,
-    pub span_note: Option<Span>,
+    pub reasons: Vec<ImproperCTypesLayer<'a>>,
 }
 
 // Used because of the complexity of Option<DiagMessage>, DiagMessage, and Option<Span>
@@ -1867,12 +1898,8 @@ impl<'a> LintDiagnostic<'a, ()> for ImproperCTypes<'_> {
         diag.arg("ty", self.ty);
         diag.arg("desc", self.desc);
         diag.span_label(self.label, fluent::lint_label);
-        if let Some(help) = self.help {
-            diag.help(help);
-        }
-        diag.note(self.note);
-        if let Some(note) = self.span_note {
-            diag.span_note(note, fluent::lint_note);
+        for reason in self.reasons.into_iter() {
+            diag.subdiagnostic(reason);
         }
     }
 }