Rollup of 6 pull requests

Cargo.lock

@@ -5999,7 +5999,6 @@ dependencies = [
 name = "unwind"
 version = "0.0.0"
 dependencies = [
- "cfg-if",
  "compiler_builtins",
  "core",
  "libc",

compiler/rustc_codegen_cranelift/example/mini_core_hello_world.rs

@@ -112,8 +112,8 @@ fn start<T: Termination + 'static>(
 
 static mut NUM: u8 = 6 * 7;
 
-// FIXME: Use `SyncUnsafeCell` instead of allowing `static_mut_ref` lint
-#[allow(static_mut_ref)]
+// FIXME: Use `SyncUnsafeCell` instead of allowing `static_mut_refs` lint
+#[allow(static_mut_refs)]
 static NUM_REF: &'static u8 = unsafe { &NUM };
 
 unsafe fn zeroed<T>() -> T {

compiler/rustc_codegen_gcc/example/mini_core_hello_world.rs

@@ -99,8 +99,8 @@ fn start<T: Termination + 'static>(
 
 static mut NUM: u8 = 6 * 7;
 
-// FIXME: Use `SyncUnsafeCell` instead of allowing `static_mut_ref` lint
-#[allow(static_mut_ref)]
+// FIXME: Use `SyncUnsafeCell` instead of allowing `static_mut_refs` lint
+#[allow(static_mut_refs)]
 static NUM_REF: &'static u8 = unsafe { &NUM };
 
 macro_rules! assert {

compiler/rustc_error_codes/src/error_codes/E0796.md

@@ -1,22 +1,26 @@
-Reference of mutable static.
+You have created a reference to a mutable static.
 
 Erroneous code example:
 
 ```compile_fail,edition2024,E0796
 static mut X: i32 = 23;
-static mut Y: i32 = 24;
 
-unsafe {
-  let y = &X;
-  let ref x = X;
-  let (x, y) = (&X, &Y);
-  foo(&X);
+fn work() {
+  let _val = unsafe { X };
 }
 
-fn foo<'a>(_x: &'a i32) {}
+let x_ref = unsafe { &mut X };
+work();
+// The next line has Undefined Behavior!
+// `x_ref` is a mutable reference and allows no aliases,
+// but `work` has been reading the reference between
+// the moment `x_ref` was created and when it was used.
+// This violates the uniqueness of `x_ref`.
+*x_ref = 42;
 ```
 
-Mutable statics can be written to by multiple threads: aliasing violations or
-data races will cause undefined behavior.
+A reference to a mutable static has lifetime `'static`. This is very dangerous
+as it is easy to accidentally overlap the lifetime of that reference with
+other, conflicting accesses to the same static.
 
-Reference of mutable static is a hard error from 2024 edition.
+References to mutable statics are a hard error in the 2024 edition.

compiler/rustc_expand/messages.ftl

@@ -61,6 +61,11 @@ expand_invalid_cfg_multiple_predicates = multiple `cfg` predicates are specified
 expand_invalid_cfg_no_parens = `cfg` is not followed by parentheses
 expand_invalid_cfg_no_predicate = `cfg` predicate is not specified
 expand_invalid_cfg_predicate_literal = `cfg` predicate key cannot be a literal
+
+expand_invalid_fragment_specifier =
+    invalid fragment specifier `{$fragment}`
+    .help = {$help}
+
 expand_macro_body_stability =
     macros cannot have body stability attributes
     .label = invalid body stability attribute

compiler/rustc_expand/src/errors.rs

@@ -408,3 +408,13 @@ pub struct DuplicateMatcherBinding {
     #[label(expand_label2)]
     pub prev: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag(expand_invalid_fragment_specifier)]
+#[help]
+pub struct InvalidFragmentSpecifier {
+    #[primary_span]
+    pub span: Span,
+    pub fragment: Ident,
+    pub help: String,
+}

compiler/rustc_expand/src/mbe/quoted.rs

@@ -1,3 +1,4 @@
+use crate::errors;
 use crate::mbe::macro_parser::count_metavar_decls;
 use crate::mbe::{Delimited, KleeneOp, KleeneToken, MetaVarExpr, SequenceRepetition, TokenTree};
 
@@ -60,11 +61,11 @@ pub(super) fn parse(
                     Some(&tokenstream::TokenTree::Token(Token { kind: token::Colon, span }, _)) => {
                         match trees.next() {
                             Some(tokenstream::TokenTree::Token(token, _)) => match token.ident() {
-                                Some((frag, _)) => {
+                                Some((fragment, _)) => {
                                     let span = token.span.with_lo(start_sp.lo());
 
                                     let kind =
-                                        token::NonterminalKind::from_symbol(frag.name, || {
+                                        token::NonterminalKind::from_symbol(fragment.name, || {
                                             // FIXME(#85708) - once we properly decode a foreign
                                             // crate's `SyntaxContext::root`, then we can replace
                                             // this with just `span.edition()`. A
@@ -81,14 +82,13 @@ pub(super) fn parse(
                                         })
                                         .unwrap_or_else(
                                             || {
-                                                let msg = format!(
-                                                    "invalid fragment specifier `{}`",
-                                                    frag.name
+                                                sess.dcx().emit_err(
+                                                    errors::InvalidFragmentSpecifier {
+                                                        span,
+                                                        fragment,
+                                                        help: VALID_FRAGMENT_NAMES_MSG.into(),
+                                                    },
                                                 );
-                                                sess.dcx()
-                                                    .struct_span_err(span, msg)
-                                                    .with_help(VALID_FRAGMENT_NAMES_MSG)
-                                                    .emit();
                                                 token::NonterminalKind::Ident
                                             },
                                         );

compiler/rustc_hir_analysis/messages.ftl

@@ -373,19 +373,24 @@ hir_analysis_start_not_target_feature = `#[start]` function is not allowed to ha
 hir_analysis_start_not_track_caller = `#[start]` function is not allowed to be `#[track_caller]`
     .label = `#[start]` function is not allowed to be `#[track_caller]`
 
-hir_analysis_static_mut_ref = reference of mutable static is disallowed
-    .label = reference of mutable static
-    .note = mutable statics can be written to by multiple threads: aliasing violations or data races will cause undefined behavior
-    .suggestion = shared references are dangerous since if there's any kind of mutation of that static while the reference lives, that's UB; use `addr_of!` instead to create a raw pointer
-    .suggestion_mut = mutable references are dangerous since if there's any other pointer or reference used for that static while the reference lives, that's UB; use `addr_of_mut!` instead to create a raw pointer
-
-hir_analysis_static_mut_ref_lint = {$shared}reference of mutable static is discouraged
-    .label = shared reference of mutable static
-    .label_mut = mutable reference of mutable static
-    .suggestion = shared references are dangerous since if there's any kind of mutation of that static while the reference lives, that's UB; use `addr_of!` instead to create a raw pointer
-    .suggestion_mut = mutable references are dangerous since if there's any other pointer or reference used for that static while the reference lives, that's UB; use `addr_of_mut!` instead to create a raw pointer
-    .note = reference of mutable static is a hard error from 2024 edition
-    .why_note = mutable statics can be written to by multiple threads: aliasing violations or data races will cause undefined behavior
+hir_analysis_static_mut_ref = creating a {$shared} reference to a mutable static
+    .label = {$shared} reference to mutable static
+    .note = {$shared ->
+        [shared] this shared reference has lifetime `'static`, but if the static ever gets mutated, or a mutable reference is created, then any further use of this shared reference is Undefined Behavior
+        *[mutable] this mutable reference has lifetime `'static`, but if the static gets accessed (read or written) by any other means, or any other reference is created, then any further use of this mutable reference is Undefined Behavior
+    }
+    .suggestion = use `addr_of!` instead to create a raw pointer
+    .suggestion_mut = use `addr_of_mut!` instead to create a raw pointer
+
+hir_analysis_static_mut_refs_lint = creating a {$shared} reference to mutable static is discouraged
+    .label = {$shared} reference to mutable static
+    .suggestion = use `addr_of!` instead to create a raw pointer
+    .suggestion_mut = use `addr_of_mut!` instead to create a raw pointer
+    .note = this will be a hard error in the 2024 edition
+    .why_note = {$shared ->
+        [shared] this shared reference has lifetime `'static`, but if the static ever gets mutated, or a mutable reference is created, then any further use of this shared reference is Undefined Behavior
+        *[mutable] this mutable reference has lifetime `'static`, but if the static gets accessed (read or written) by any other means, or any other reference is created, then any further use of this mutable reference is Undefined Behavior
+    }
 
 hir_analysis_static_specialize = cannot specialize on `'static` lifetime
 

compiler/rustc_hir_analysis/src/check/errs.rs

@@ -1,6 +1,6 @@
 use rustc_hir as hir;
 use rustc_hir_pretty::qpath_to_string;
-use rustc_lint_defs::builtin::STATIC_MUT_REF;
+use rustc_lint_defs::builtin::STATIC_MUT_REFS;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::Span;
 use rustc_type_ir::Mutability;
@@ -66,32 +66,24 @@ fn handle_static_mut_ref(
     hir_id: hir::HirId,
 ) {
     if e2024 {
-        let sugg = if mutable {
-            errors::StaticMutRefSugg::Mut { span, var }
+        let (sugg, shared) = if mutable {
+            (errors::StaticMutRefSugg::Mut { span, var }, "mutable")
         } else {
-            errors::StaticMutRefSugg::Shared { span, var }
+            (errors::StaticMutRefSugg::Shared { span, var }, "shared")
         };
-        tcx.sess.parse_sess.dcx.emit_err(errors::StaticMutRef { span, sugg });
+        tcx.sess.parse_sess.dcx.emit_err(errors::StaticMutRef { span, sugg, shared });
         return;
     }
 
-    let (label, sugg, shared) = if mutable {
-        (
-            errors::RefOfMutStaticLabel::Mut { span },
-            errors::RefOfMutStaticSugg::Mut { span, var },
-            "mutable ",
-        )
+    let (sugg, shared) = if mutable {
+        (errors::RefOfMutStaticSugg::Mut { span, var }, "mutable")
     } else {
-        (
-            errors::RefOfMutStaticLabel::Shared { span },
-            errors::RefOfMutStaticSugg::Shared { span, var },
-            "shared ",
-        )
+        (errors::RefOfMutStaticSugg::Shared { span, var }, "shared")
     };
     tcx.emit_node_span_lint(
-        STATIC_MUT_REF,
+        STATIC_MUT_REFS,
         hir_id,
         span,
-        errors::RefOfMutStatic { shared, why_note: (), label, sugg },
+        errors::RefOfMutStatic { span, sugg, shared },
     );
 }

compiler/rustc_hir_analysis/src/errors.rs

@@ -1455,12 +1455,13 @@ pub struct OnlyCurrentTraitsPointerSugg<'a> {
 #[derive(Diagnostic)]
 #[diag(hir_analysis_static_mut_ref, code = E0796)]
 #[note]
-pub struct StaticMutRef {
+pub struct StaticMutRef<'a> {
     #[primary_span]
     #[label]
     pub span: Span,
     #[subdiagnostic]
     pub sugg: StaticMutRefSugg,
+    pub shared: &'a str,
 }
 
 #[derive(Subdiagnostic)]
@@ -1491,30 +1492,15 @@ pub enum StaticMutRefSugg {
 
 // STATIC_MUT_REF lint
 #[derive(LintDiagnostic)]
-#[diag(hir_analysis_static_mut_ref_lint)]
+#[diag(hir_analysis_static_mut_refs_lint)]
 #[note]
+#[note(hir_analysis_why_note)]
 pub struct RefOfMutStatic<'a> {
-    pub shared: &'a str,
-    #[note(hir_analysis_why_note)]
-    pub why_note: (),
-    #[subdiagnostic]
-    pub label: RefOfMutStaticLabel,
+    #[label]
+    pub span: Span,
     #[subdiagnostic]
     pub sugg: RefOfMutStaticSugg,
-}
-
-#[derive(Subdiagnostic)]
-pub enum RefOfMutStaticLabel {
-    #[label(hir_analysis_label)]
-    Shared {
-        #[primary_span]
-        span: Span,
-    },
-    #[label(hir_analysis_label_mut)]
-    Mut {
-        #[primary_span]
-        span: Span,
-    },
+    pub shared: &'a str,
 }
 
 #[derive(Subdiagnostic)]

compiler/rustc_lint/src/lib.rs

@@ -325,6 +325,7 @@ fn register_builtins(store: &mut LintStore) {
     store.register_renamed("or_patterns_back_compat", "rust_2021_incompatible_or_patterns");
     store.register_renamed("non_fmt_panic", "non_fmt_panics");
     store.register_renamed("unused_tuple_struct_fields", "dead_code");
+    store.register_renamed("static_mut_ref", "static_mut_refs");
 
     // These were moved to tool lints, but rustc still sees them when compiling normally, before
     // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use

compiler/rustc_lint_defs/src/builtin.rs

@@ -89,7 +89,7 @@ declare_lint_pass! {
         SINGLE_USE_LIFETIMES,
         SOFT_UNSTABLE,
         STABLE_FEATURES,
-        STATIC_MUT_REF,
+        STATIC_MUT_REFS,
         SUSPICIOUS_AUTO_TRAIT_IMPLS,
         TEST_UNSTABLE_LINT,
         TEXT_DIRECTION_CODEPOINT_IN_COMMENT,
@@ -1769,7 +1769,7 @@ declare_lint! {
 }
 
 declare_lint! {
-    /// The `static_mut_ref` lint checks for shared or mutable references
+    /// The `static_mut_refs` lint checks for shared or mutable references
     /// of mutable static inside `unsafe` blocks and `unsafe` functions.
     ///
     /// ### Example
@@ -1807,9 +1807,9 @@ declare_lint! {
     /// Shared or mutable references of mutable static are almost always a mistake and
     /// can lead to undefined behavior and various other problems in your code.
     ///
-    /// This lint is "warn" by default on editions up to 2021, from 2024 there is
+    /// This lint is "warn" by default on editions up to 2021, in 2024 there is
     /// a hard error instead.
-    pub STATIC_MUT_REF,
+    pub STATIC_MUT_REFS,
     Warn,
     "shared references or mutable references of mutable static is discouraged",
     @future_incompatible = FutureIncompatibleInfo {

compiler/rustc_target/src/spec/targets/x86_64_pc_windows_gnu.rs

@@ -3,14 +3,15 @@ use crate::spec::{base, Cc, LinkerFlavor, Lld, Target};
 pub fn target() -> Target {
     let mut base = base::windows_gnu::opts();
     base.cpu = "x86-64".into();
+    base.features = "+cx16,+sse3,+sahf".into();
     base.plt_by_default = false;
     // Use high-entropy 64 bit address space for ASLR
     base.add_pre_link_args(
         LinkerFlavor::Gnu(Cc::No, Lld::No),
         &["-m", "i386pep", "--high-entropy-va"],
     );
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m64", "-Wl,--high-entropy-va"]);
-    base.max_atomic_width = Some(64);
+    base.max_atomic_width = Some(128);
     base.linker = Some("x86_64-w64-mingw32-gcc".into());
 
     Target {

compiler/rustc_target/src/spec/targets/x86_64_pc_windows_gnullvm.rs

@@ -3,9 +3,10 @@ use crate::spec::{base, Cc, LinkerFlavor, Lld, Target};
 pub fn target() -> Target {
     let mut base = base::windows_gnullvm::opts();
     base.cpu = "x86-64".into();
+    base.features = "+cx16,+sse3,+sahf".into();
     base.plt_by_default = false;
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m64"]);
-    base.max_atomic_width = Some(64);
+    base.max_atomic_width = Some(128);
     base.linker = Some("x86_64-w64-mingw32-clang".into());
 
     Target {

compiler/rustc_target/src/spec/targets/x86_64_pc_windows_msvc.rs

@@ -3,8 +3,9 @@ use crate::spec::{base, SanitizerSet, Target};
 pub fn target() -> Target {
     let mut base = base::windows_msvc::opts();
     base.cpu = "x86-64".into();
+    base.features = "+cx16,+sse3,+sahf".into();
     base.plt_by_default = false;
-    base.max_atomic_width = Some(64);
+    base.max_atomic_width = Some(128);
     base.supported_sanitizers = SanitizerSet::ADDRESS;
 
     Target {

compiler/rustc_target/src/spec/targets/x86_64_uwp_windows_gnu.rs

@@ -3,14 +3,15 @@ use crate::spec::{base, Cc, LinkerFlavor, Lld, Target};
 pub fn target() -> Target {
     let mut base = base::windows_uwp_gnu::opts();
     base.cpu = "x86-64".into();
+    base.features = "+cx16,+sse3,+sahf".into();
     base.plt_by_default = false;
     // Use high-entropy 64 bit address space for ASLR
     base.add_pre_link_args(
         LinkerFlavor::Gnu(Cc::No, Lld::No),
         &["-m", "i386pep", "--high-entropy-va"],
     );
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m64", "-Wl,--high-entropy-va"]);
-    base.max_atomic_width = Some(64);
+    base.max_atomic_width = Some(128);
 
     Target {
         llvm_target: "x86_64-pc-windows-gnu".into(),

compiler/rustc_target/src/spec/targets/x86_64_uwp_windows_msvc.rs

@@ -3,8 +3,9 @@ use crate::spec::{base, Target};
 pub fn target() -> Target {
     let mut base = base::windows_uwp_msvc::opts();
     base.cpu = "x86-64".into();
+    base.features = "+cx16,+sse3,+sahf".into();
     base.plt_by_default = false;
-    base.max_atomic_width = Some(64);
+    base.max_atomic_width = Some(128);
 
     Target {
         llvm_target: "x86_64-pc-windows-msvc".into(),