rust-lang · Zalathar · Aug 9, 2025 · Aug 9, 2025 · Aug 10, 2025 · Aug 10, 2025
diff --git a/.editorconfig b/.editorconfig
@@ -8,20 +8,23 @@ root = true
 end_of_line = lf
 charset = utf-8
 insert_final_newline = true
+trim_trailing_whitespace = true
+indent_style = space
+indent_size = 4
 
 # some tests need trailing whitespace in output snapshots
-[!tests/]
-trim_trailing_whitespace = true
+[tests/**]
+trim_trailing_whitespace = false
 # for actual source code files of test, we still don't want trailing whitespace
 [tests/**.{rs,js}]
 trim_trailing_whitespace = true
 # these specific source files need to have trailing whitespace.
 [tests/ui/{frontmatter/frontmatter-whitespace-3.rs,parser/shebang/shebang-space.rs}]
 trim_trailing_whitespace = false
 
-[!src/llvm-project]
-indent_style = space
-indent_size = 4
+[src/llvm-project]
+indent_style = unset
+indent_size = unset
 
 [*.rs]
 max_line_length = 100

diff --git a/compiler/rustc_attr_parsing/messages.ftl b/compiler/rustc_attr_parsing/messages.ftl
@@ -151,7 +151,7 @@ attr_parsing_unrecognized_repr_hint =
 attr_parsing_unstable_cfg_target_compact =
     compact `cfg(target(..))` is experimental and subject to change
 
-attr_parsing_unstable_feature_bound_incompatible_stability = Item annotated with `#[unstable_feature_bound]` should not be stable
+attr_parsing_unstable_feature_bound_incompatible_stability = item annotated with `#[unstable_feature_bound]` should not be stable
     .help = If this item is meant to be stable, do not use any functions annotated with `#[unstable_feature_bound]`. Otherwise, mark this item as unstable with `#[unstable]`
 
 attr_parsing_unsupported_literal_cfg_boolean =

diff --git a/compiler/rustc_codegen_ssa/messages.ftl b/compiler/rustc_codegen_ssa/messages.ftl
@@ -40,15 +40,15 @@ codegen_ssa_dynamic_linking_with_lto =
     .note = only 'staticlib', 'bin', and 'cdylib' outputs are supported with LTO
 
 codegen_ssa_error_calling_dlltool =
-    Error calling dlltool '{$dlltool_path}': {$error}
+    error calling dlltool '{$dlltool_path}': {$error}
 
 codegen_ssa_error_creating_import_library =
-    Error creating import library for {$lib_name}: {$error}
+    error creating import library for {$lib_name}: {$error}
 
 codegen_ssa_error_creating_remark_dir = failed to create remark directory: {$error}
 
 codegen_ssa_error_writing_def_file =
-    Error writing .DEF file: {$error}
+    error writing .DEF file: {$error}
 
 codegen_ssa_expected_name_value_pair = expected name value pair
 
@@ -264,9 +264,9 @@ codegen_ssa_shuffle_indices_evaluation = could not evaluate shuffle_indices at c
 
 codegen_ssa_specify_libraries_to_link = use the `-l` flag to specify native libraries to link
 
-codegen_ssa_static_library_native_artifacts = Link against the following native artifacts when linking against this static library. The order and any duplication can be significant on some platforms.
+codegen_ssa_static_library_native_artifacts = link against the following native artifacts when linking against this static library. The order and any duplication can be significant on some platforms.
 
-codegen_ssa_static_library_native_artifacts_to_file = Native artifacts to link against have been written to {$path}. The order and any duplication can be significant on some platforms.
+codegen_ssa_static_library_native_artifacts_to_file = native artifacts to link against have been written to {$path}. The order and any duplication can be significant on some platforms.
 
 codegen_ssa_stripping_debug_info_failed = stripping debug info with `{$util}` failed: {$status}
     .note = {$output}
@@ -364,13 +364,13 @@ codegen_ssa_unable_to_run = unable to run `{$util}`: {$error}
 
 codegen_ssa_unable_to_run_dsymutil = unable to run `dsymutil`: {$error}
 
-codegen_ssa_unable_to_write_debugger_visualizer = Unable to write debugger visualizer file `{$path}`: {$error}
+codegen_ssa_unable_to_write_debugger_visualizer = unable to write debugger visualizer file `{$path}`: {$error}
 
 codegen_ssa_unexpected_parameter_name = unexpected parameter name
     .label = expected `{$prefix_nops}` or `{$entry_nops}`
 
 codegen_ssa_unknown_archive_kind =
-    Don't know how to build archive of type: {$kind}
+    don't know how to build archive of type: {$kind}
 
 codegen_ssa_unknown_ctarget_feature =
     unknown and unstable feature specified for `-Ctarget-feature`: `{$feature}`

diff --git a/compiler/rustc_const_eval/messages.ftl b/compiler/rustc_const_eval/messages.ftl
@@ -457,7 +457,7 @@ const_eval_validation_failure =
     it is undefined behavior to use this value
 
 const_eval_validation_failure_note =
-    The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
+    the rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
 
 const_eval_validation_front_matter_invalid_value = constructing invalid value
 const_eval_validation_front_matter_invalid_value_with_path = constructing invalid value at {$path}

diff --git a/compiler/rustc_driver_impl/messages.ftl b/compiler/rustc_driver_impl/messages.ftl
@@ -14,7 +14,7 @@ driver_impl_ice_version = rustc {$version} running on {$triple}
 
 driver_impl_rlink_corrupt_file = corrupt metadata encountered in `{$file}`
 
-driver_impl_rlink_empty_version_number = The input does not contain version number
+driver_impl_rlink_empty_version_number = the input does not contain version number
 
 driver_impl_rlink_encoding_version_mismatch = .rlink file was produced with encoding version `{$version_array}`, but the current version is `{$rlink_version}`
 
@@ -24,6 +24,6 @@ driver_impl_rlink_rustc_version_mismatch = .rlink file was produced by rustc ver
 
 driver_impl_rlink_unable_to_read = failed to read rlink file: `{$err}`
 
-driver_impl_rlink_wrong_file_type = The input does not look like a .rlink file
+driver_impl_rlink_wrong_file_type = the input does not look like a .rlink file
 
 driver_impl_unstable_feature_usage = cannot dump feature usage metrics: {$error}
diff --git a/compiler/rustc_lexer/src/lib.rs b/compiler/rustc_lexer/src/lib.rs
@@ -331,24 +331,37 @@ pub fn is_whitespace(c: char) -> bool {
 
     matches!(
         c,
-        // Usual ASCII suspects
-        '\u{0009}'   // \t
-        | '\u{000A}' // \n
+        // End-of-line characters
+        | '\u{000A}' // line feed (\n)
         | '\u{000B}' // vertical tab
         | '\u{000C}' // form feed
-        | '\u{000D}' // \r
-        | '\u{0020}' // space
-
-        // NEXT LINE from latin1
-        | '\u{0085}'
+        | '\u{000D}' // carriage return (\r)
+        | '\u{0085}' // next line (from latin1)
+        | '\u{2028}' // LINE SEPARATOR
+        | '\u{2029}' // PARAGRAPH SEPARATOR
 
-        // Bidi markers
+        // `Default_Ignorable_Code_Point` characters
         | '\u{200E}' // LEFT-TO-RIGHT MARK
         | '\u{200F}' // RIGHT-TO-LEFT MARK
 
-        // Dedicated whitespace characters from Unicode
-        | '\u{2028}' // LINE SEPARATOR
-        | '\u{2029}' // PARAGRAPH SEPARATOR
+        // Horizontal space characters
+        | '\u{0009}'   // tab (\t)
+        | '\u{0020}' // space
+    )
+}
+
+/// True if `c` is considered horizontal whitespace according to Rust language definition.
+pub fn is_horizontal_whitespace(c: char) -> bool {
+    // This is Pattern_White_Space.
+    //
+    // Note that this set is stable (ie, it doesn't change with different
+    // Unicode versions), so it's ok to just hard-code the values.
+
+    matches!(
+        c,
+        // Horizontal space characters
+        '\u{0009}'   // tab (\t)
+        | '\u{0020}' // space
     )
 }
 
@@ -538,7 +551,7 @@ impl Cursor<'_> {
         debug_assert!(length_opening >= 3);
 
         // whitespace between the opening and the infostring.
-        self.eat_while(|ch| ch != '\n' && is_whitespace(ch));
+        self.eat_while(|ch| ch != '\n' && is_horizontal_whitespace(ch));
 
         // copied from `eat_identifier`, but allows `-` and `.` in infostring to allow something like
         // `---Cargo.toml` as a valid opener
@@ -547,7 +560,7 @@ impl Cursor<'_> {
             self.eat_while(|c| is_id_continue(c) || c == '-' || c == '.');
         }
 
-        self.eat_while(|ch| ch != '\n' && is_whitespace(ch));
+        self.eat_while(|ch| ch != '\n' && is_horizontal_whitespace(ch));
         let invalid_infostring = self.first() != '\n';
 
         let mut found = false;
@@ -588,7 +601,7 @@ impl Cursor<'_> {
                 // on a standalone line. Might be wrong.
                 while let Some(closing) = rest.find("---") {
                     let preceding_chars_start = rest[..closing].rfind("\n").map_or(0, |i| i + 1);
-                    if rest[preceding_chars_start..closing].chars().all(is_whitespace) {
+                    if rest[preceding_chars_start..closing].chars().all(is_horizontal_whitespace) {
                         // candidate found
                         potential_closing = Some(closing);
                         break;

diff --git a/compiler/rustc_parse/messages.ftl b/compiler/rustc_parse/messages.ftl
@@ -58,7 +58,7 @@ parse_async_use_order_incorrect = the order of `use` and `async` is incorrect
 parse_at_dot_dot_in_struct_pattern = `@ ..` is not supported in struct patterns
     .suggestion = bind to each field separately or, if you don't need them, just remove `{$ident} @`
 
-parse_at_in_struct_pattern = Unexpected `@` in struct pattern
+parse_at_in_struct_pattern = unexpected `@` in struct pattern
     .note = struct patterns use `field: pattern` syntax to bind to fields
     .help = consider replacing `new_name @ field_name` with `field_name: new_name` if that is what you intended
 

diff --git a/compiler/rustc_parse/src/lexer/mod.rs b/compiler/rustc_parse/src/lexer/mod.rs
@@ -6,7 +6,7 @@ use rustc_ast::util::unicode::{TEXT_FLOW_CONTROL_CHARS, contains_text_flow_contr
 use rustc_errors::codes::*;
 use rustc_errors::{Applicability, Diag, DiagCtxtHandle, StashKey};
 use rustc_lexer::{
-    Base, Cursor, DocStyle, FrontmatterAllowed, LiteralKind, RawStrError, is_whitespace,
+    Base, Cursor, DocStyle, FrontmatterAllowed, LiteralKind, RawStrError, is_horizontal_whitespace,
 };
 use rustc_literal_escaper::{EscapeError, Mode, check_for_errors};
 use rustc_session::lint::BuiltinLintDiag;
@@ -597,7 +597,7 @@ impl<'psess, 'src> Lexer<'psess, 'src> {
 
         let last_line_start = within.rfind('\n').map_or(0, |i| i + 1);
         let last_line = &within[last_line_start..];
-        let last_line_trimmed = last_line.trim_start_matches(is_whitespace);
+        let last_line_trimmed = last_line.trim_start_matches(is_horizontal_whitespace);
         let last_line_start_pos = frontmatter_opening_end_pos + BytePos(last_line_start as u32);
 
         let frontmatter_span = self.mk_sp(frontmatter_opening_pos, self.pos);
@@ -640,7 +640,7 @@ impl<'psess, 'src> Lexer<'psess, 'src> {
             });
         }
 
-        if !rest.trim_matches(is_whitespace).is_empty() {
+        if !rest.trim_matches(is_horizontal_whitespace).is_empty() {
             let span = self.mk_sp(last_line_start_pos, self.pos);
             self.dcx().emit_err(errors::FrontmatterExtraCharactersAfterClose { span });
         }

diff --git a/compiler/rustc_query_system/messages.ftl b/compiler/rustc_query_system/messages.ftl
@@ -18,8 +18,8 @@ query_system_cycle_usage = cycle used when {$usage}
 query_system_increment_compilation = internal compiler error: encountered incremental compilation error with {$dep_node}
     .help = This is a known issue with the compiler. Run {$run_cmd} to allow your project to compile
 
-query_system_increment_compilation_note1 = Please follow the instructions below to create a bug report with the provided information
-query_system_increment_compilation_note2 = See <https://github.com/rust-lang/rust/issues/84970> for more information
+query_system_increment_compilation_note1 = please follow the instructions below to create a bug report with the provided information
+query_system_increment_compilation_note2 = see <https://github.com/rust-lang/rust/issues/84970> for more information
 
 query_system_overflow_note = query depth increased by {$depth} when {$desc}
 

diff --git a/compiler/rustc_resolve/src/ident.rs b/compiler/rustc_resolve/src/ident.rs
@@ -422,6 +422,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         // to detect potential ambiguities.
         let mut innermost_result: Option<(NameBinding<'_>, Flags)> = None;
         let mut determinacy = Determinacy::Determined;
+        let mut extern_prelude_item_binding = None;
+        let mut extern_prelude_flag_binding = None;
         // Shadowed bindings don't need to be marked as used or non-speculatively loaded.
         macro finalize_scope() {
             if innermost_result.is_none() { finalize } else { None }
@@ -558,15 +560,21 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     Scope::ExternPreludeItems => {
                         // FIXME: use `finalize_scope` here.
                         match this.reborrow().extern_prelude_get_item(ident, finalize.is_some()) {
-                            Some(binding) => Ok((binding, Flags::empty())),
+                            Some(binding) => {
+                                extern_prelude_item_binding = Some(binding);
+                                Ok((binding, Flags::empty()))
+                            }
                             None => Err(Determinacy::determined(
                                 this.graph_root.unexpanded_invocations.borrow().is_empty(),
                             )),
                         }
                     }
                     Scope::ExternPreludeFlags => {
                         match this.extern_prelude_get_flag(ident, finalize_scope!().is_some()) {
-                            Some(binding) => Ok((binding, Flags::empty())),
+                            Some(binding) => {
+                                extern_prelude_flag_binding = Some(binding);
+                                Ok((binding, Flags::empty()))
+                            }
                             None => Err(Determinacy::Determined),
                         }
                     }
@@ -686,7 +694,16 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                                 } else {
                                     None
                                 };
-                                if let Some(kind) = ambiguity_error_kind {
+                                // Skip ambiguity errors for extern flag bindings "overridden"
+                                // by extern item bindings.
+                                // FIXME: Remove with lang team approval.
+                                let issue_145575_hack = Some(binding)
+                                    == extern_prelude_flag_binding
+                                    && extern_prelude_item_binding.is_some()
+                                    && extern_prelude_item_binding != Some(innermost_binding);
+                                if let Some(kind) = ambiguity_error_kind
+                                    && !issue_145575_hack
+                                {
                                     let misc = |f: Flags| {
                                         if f.contains(Flags::MISC_SUGGEST_CRATE) {
                                             AmbiguityErrorMisc::SuggestCrate

diff --git a/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none.rs b/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none.rs
@@ -17,7 +17,7 @@ pub(crate) fn target() -> Target {
         arch: "loongarch64".into(),
         options: TargetOptions {
             cpu: "generic".into(),
-            features: "+f,+d".into(),
+            features: "+f,+d,-lsx".into(),
             linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
             linker: Some("rust-lld".into()),
             llvm_abiname: "lp64d".into(),

diff --git a/library/Cargo.lock b/library/Cargo.lock
@@ -327,7 +327,8 @@ dependencies = [
  "rustc-demangle",
  "std_detect",
  "unwind",
- "wasi",
+ "wasi 0.11.1+wasi-snapshot-preview1",
+ "wasi 0.14.3+wasi-0.2.4",
  "windows-targets 0.0.0",
 ]
 
@@ -399,6 +400,17 @@ dependencies = [
  "rustc-std-workspace-core",
 ]
 
+[[package]]
+name = "wasi"
+version = "0.14.3+wasi-0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6a51ae83037bdd272a9e28ce236db8c07016dd0d50c27038b3f407533c030c95"
+dependencies = [
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+ "wit-bindgen",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.59.0"
@@ -475,3 +487,13 @@ name = "windows_x86_64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
+
+[[package]]
+name = "wit-bindgen"
+version = "0.45.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "052283831dbae3d879dc7f51f3d92703a316ca49f91540417d38591826127814"
+dependencies = [
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
diff --git a/library/alloc/src/borrow.rs b/library/alloc/src/borrow.rs
@@ -17,9 +17,11 @@ use crate::fmt;
 use crate::string::String;
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, B: ?Sized> Borrow<B> for Cow<'a, B>
+#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
+impl<'a, B: ?Sized> const Borrow<B> for Cow<'a, B>
 where
     B: ToOwned,
+    B::Owned: [const] Borrow<B>,
 {
     fn borrow(&self) -> &B {
         &**self
@@ -326,9 +328,10 @@ impl<B: ?Sized + ToOwned> Cow<'_, B> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<B: ?Sized + ToOwned> Deref for Cow<'_, B>
+#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
+impl<B: ?Sized + ToOwned> const Deref for Cow<'_, B>
 where
-    B::Owned: Borrow<B>,
+    B::Owned: [const] Borrow<B>,
 {
     type Target = B;
 
@@ -439,7 +442,11 @@ where
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized + ToOwned> AsRef<T> for Cow<'_, T> {
+#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
+impl<T: ?Sized + ToOwned> const AsRef<T> for Cow<'_, T>
+where
+    T::Owned: [const] Borrow<T>,
+{
     fn as_ref(&self) -> &T {
         self
     }

diff --git a/library/alloc/src/collections/mod.rs b/library/alloc/src/collections/mod.rs
@@ -128,17 +128,19 @@ pub use realalloc::collections::TryReserveErrorKind;
     reason = "Uncertain how much info should be exposed",
     issue = "48043"
 )]
+#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 #[cfg(not(test))]
-impl From<TryReserveErrorKind> for TryReserveError {
+impl const From<TryReserveErrorKind> for TryReserveError {
     #[inline]
     fn from(kind: TryReserveErrorKind) -> Self {
         Self { kind }
     }
 }
 
 #[unstable(feature = "try_reserve_kind", reason = "new API", issue = "48043")]
+#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 #[cfg(not(test))]
-impl From<LayoutError> for TryReserveErrorKind {
+impl const From<LayoutError> for TryReserveErrorKind {
     /// Always evaluates to [`TryReserveErrorKind::CapacityOverflow`].
     #[inline]
     fn from(_: LayoutError) -> Self {