Rollup merge of #142491 - jdonszelmann:cold, r=oli-obk

tgross35 · web-flow · commit f0374dced537 · 2025-06-20T13:35:59.000-04:00
Rework #[cold] attribute parser

r? `@oli-obk`
diff --git a/compiler/rustc_attr_data_structures/src/attributes.rs b/compiler/rustc_attr_data_structures/src/attributes.rs
@@ -202,6 +202,9 @@ pub enum AttributeKind {
         span: Span,
     },
 
+    /// Represents `#[cold]`.
+    Cold(Span),
+
     /// Represents `#[rustc_confusables]`.
     Confusables {
         symbols: ThinVec<Symbol>,
diff --git a/compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs b/compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs
@@ -38,3 +38,21 @@ impl<S: Stage> SingleAttributeParser<S> for OptimizeParser {
         Some(AttributeKind::Optimize(res, cx.attr_span))
     }
 }
+
+pub(crate) struct ColdParser;
+
+impl<S: Stage> SingleAttributeParser<S> for ColdParser {
+    const PATH: &[rustc_span::Symbol] = &[sym::cold];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepLast;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const TEMPLATE: AttributeTemplate = template!(Word);
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        if !args.no_args() {
+            cx.expected_no_args(args.span().unwrap_or(cx.attr_span));
+            return None;
+        };
+
+        Some(AttributeKind::Cold(cx.attr_span))
+    }
+}
diff --git a/compiler/rustc_attr_parsing/src/context.rs b/compiler/rustc_attr_parsing/src/context.rs
@@ -15,7 +15,7 @@ use rustc_session::Session;
 use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span, Symbol, sym};
 
 use crate::attributes::allow_unstable::{AllowConstFnUnstableParser, AllowInternalUnstableParser};
-use crate::attributes::codegen_attrs::OptimizeParser;
+use crate::attributes::codegen_attrs::{ColdParser, OptimizeParser};
 use crate::attributes::confusables::ConfusablesParser;
 use crate::attributes::deprecation::DeprecationParser;
 use crate::attributes::inline::{InlineParser, RustcForceInlineParser};
@@ -106,6 +106,7 @@ attribute_parsers!(
 
         // tidy-alphabetical-start
         Single<AsPtrParser>,
+        Single<ColdParser>,
         Single<ConstStabilityIndirectParser>,
         Single<DeprecationParser>,
         Single<InlineParser>,
@@ -234,6 +235,16 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
         })
     }
 
+    pub(crate) fn expected_no_args(&self, args_span: Span) -> ErrorGuaranteed {
+        self.emit_err(AttributeParseError {
+            span: args_span,
+            attr_span: self.attr_span,
+            template: self.template.clone(),
+            attribute: self.attr_path.clone(),
+            reason: AttributeParseErrorReason::ExpectedNoArgs,
+        })
+    }
+
     /// emit an error that a `name = value` pair was expected at this span. The symbol can be given for
     /// a nicer error message talking about the specific name that was found lacking a value.
     pub(crate) fn expected_name_value(&self, span: Span, name: Option<Symbol>) -> ErrorGuaranteed {
diff --git a/compiler/rustc_attr_parsing/src/session_diagnostics.rs b/compiler/rustc_attr_parsing/src/session_diagnostics.rs
@@ -474,6 +474,7 @@ pub(crate) struct UnrecognizedReprHint {
 }
 
 pub(crate) enum AttributeParseErrorReason {
+    ExpectedNoArgs,
     ExpectedStringLiteral { byte_string: Option<Span> },
     ExpectedSingleArgument,
     ExpectedList,
@@ -529,6 +530,10 @@ impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for AttributeParseError {
                 diag.span_label(self.span, format!("didn't expect a literal here"));
                 diag.code(E0565);
             }
+            AttributeParseErrorReason::ExpectedNoArgs => {
+                diag.span_label(self.span, format!("didn't expect any arguments here"));
+                diag.code(E0565);
+            }
             AttributeParseErrorReason::ExpectedNameValue(None) => {
                 diag.span_label(
                     self.span,
diff --git a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
@@ -4,7 +4,7 @@ use rustc_abi::ExternAbi;
 use rustc_ast::expand::autodiff_attrs::{AutoDiffAttrs, DiffActivity, DiffMode};
 use rustc_ast::{LitKind, MetaItem, MetaItemInner, attr};
 use rustc_attr_data_structures::{
-    AttributeKind, InlineAttr, InstructionSetAttr, OptimizeAttr, find_attr,
+    AttributeKind, InlineAttr, InstructionSetAttr, OptimizeAttr, ReprAttr, find_attr,
 };
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE, LocalDefId};
@@ -110,16 +110,27 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
             }
         };
 
-        if let hir::Attribute::Parsed(AttributeKind::Align { align, .. }) = attr {
-            codegen_fn_attrs.alignment = Some(*align);
+        if let hir::Attribute::Parsed(p) = attr {
+            match p {
+                AttributeKind::Repr(reprs) => {
+                    codegen_fn_attrs.alignment = reprs
+                        .iter()
+                        .filter_map(
+                            |(r, _)| if let ReprAttr::ReprAlign(x) = r { Some(*x) } else { None },
+                        )
+                        .max();
+                }
+                AttributeKind::Cold(_) => codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD,
+                AttributeKind::Align { align, .. } => codegen_fn_attrs.alignment = Some(*align),
+                _ => {}
+            }
         }
 
         let Some(Ident { name, .. }) = attr.ident() else {
             continue;
         };
 
         match name {
-            sym::cold => codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD,
             sym::rustc_allocator => codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR,
             sym::ffi_pure => codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE,
             sym::ffi_const => codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST,
diff --git a/compiler/rustc_parse/src/validate_attr.rs b/compiler/rustc_parse/src/validate_attr.rs
@@ -292,6 +292,7 @@ fn emit_malformed_attribute(
             | sym::align
             | sym::deprecated
             | sym::optimize
+            | sym::cold
     ) {
         return;
     }
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
@@ -149,10 +149,12 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 }
                 Attribute::Parsed(AttributeKind::Repr(_)) => { /* handled below this loop and elsewhere */
                 }
+                Attribute::Parsed(AttributeKind::Cold(attr_span)) => {
+                    self.check_cold(hir_id, *attr_span, span, target)
+                }
                 Attribute::Parsed(AttributeKind::Align { align, span: repr_span }) => {
                     self.check_align(span, target, *align, *repr_span)
                 }
-
                 Attribute::Parsed(
                     AttributeKind::BodyStability { .. }
                     | AttributeKind::ConstStabilityIndirect
@@ -245,7 +247,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         [sym::ffi_pure, ..] => self.check_ffi_pure(attr.span(), attrs, target),
                         [sym::ffi_const, ..] => self.check_ffi_const(attr.span(), target),
                         [sym::link_ordinal, ..] => self.check_link_ordinal(attr, span, target),
-                        [sym::cold, ..] => self.check_cold(hir_id, attr, span, target),
                         [sym::link, ..] => self.check_link(hir_id, attr, span, target),
                         [sym::link_name, ..] => self.check_link_name(hir_id, attr, span, target),
                         [sym::link_section, ..] => self.check_link_section(hir_id, attr, span, target),
@@ -651,8 +652,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             sym::repr,
             sym::align,
             sym::rustc_std_internal_symbol,
-            // code generation
-            sym::cold,
             // documentation
             sym::doc,
         ];
@@ -688,7 +687,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         Attribute::Parsed(
                             AttributeKind::Deprecation { .. }
                             | AttributeKind::Repr { .. }
-                            | AttributeKind::Align { .. },
+                            | AttributeKind::Align { .. }
+                            | AttributeKind::Cold(..),
                         ) => {
                             continue;
                         }
@@ -1637,23 +1637,23 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
     }
 
     /// Checks if `#[cold]` is applied to a non-function.
-    fn check_cold(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
+    fn check_cold(&self, hir_id: HirId, attr_span: Span, span: Span, target: Target) {
         match target {
             Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => {}
             // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
             // `#[cold]` attribute with just a lint, because we previously
             // erroneously allowed it and some crates used it accidentally, to be compatible
             // with crates depending on them, we can't throw an error here.
             Target::Field | Target::Arm | Target::MacroDef => {
-                self.inline_attr_str_error_with_macro_def(hir_id, attr.span(), "cold");
+                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "cold");
             }
             _ => {
                 // FIXME: #[cold] was previously allowed on non-functions and some crates used
                 // this, so only emit a warning.
                 self.tcx.emit_node_span_lint(
                     UNUSED_ATTRIBUTES,
                     hir_id,
-                    attr.span(),
+                    attr_span,
                     errors::Cold { span, on_crate: hir_id == CRATE_HIR_ID },
                 );
             }
diff --git a/src/rustdoc-json-types/lib.rs b/src/rustdoc-json-types/lib.rs
@@ -37,8 +37,8 @@ pub type FxHashMap<K, V> = HashMap<K, V>; // re-export for use in src/librustdoc
 // will instead cause conflicts. See #94591 for more. (This paragraph and the "Latest feature" line
 // are deliberately not in a doc comment, because they need not be in public docs.)
 //
-// Latest feature: Pretty printing of optimize attributes changed
-pub const FORMAT_VERSION: u32 = 49;
+// Latest feature: Pretty printing of cold attributes changed
+pub const FORMAT_VERSION: u32 = 50;
 
 /// The root of the emitted JSON blob.
 ///
diff --git a/tests/ui/attributes/expected-word.rs b/tests/ui/attributes/expected-word.rs
@@ -0,0 +1,3 @@
+#[cold = true]
+//~^ ERROR malformed `cold` attribute input [E0565]
+fn main() {}
diff --git a/tests/ui/attributes/expected-word.stderr b/tests/ui/attributes/expected-word.stderr
@@ -0,0 +1,12 @@
+error[E0565]: malformed `cold` attribute input
+  --> $DIR/expected-word.rs:1:1
+   |
+LL | #[cold = true]
+   | ^^^^^^^------^
+   | |      |
+   | |      didn't expect any arguments here
+   | help: must be of the form: `#[cold]`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0565`.
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs.stderr b/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs.stderr
@@ -379,14 +379,6 @@ warning: `#[proc_macro_derive]` only has an effect on functions
 LL | #![proc_macro_derive()]
    | ^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: attribute should be applied to a function definition
-  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:62:1
-   |
-LL | #![cold]
-   | ^^^^^^^^ cannot be applied to crates
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-
 warning: attribute should be applied to an `extern` block with non-Rust ABI
   --> $DIR/issue-43106-gating-of-builtin-attrs.rs:64:1
    |
@@ -417,6 +409,14 @@ warning: `#[must_use]` has no effect when applied to a module
 LL | #![must_use]
    | ^^^^^^^^^^^^
 
+warning: attribute should be applied to a function definition
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:62:1
+   |
+LL | #![cold]
+   | ^^^^^^^^ cannot be applied to crates
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
 warning: `#[macro_use]` only has an effect on `extern crate` and modules
   --> $DIR/issue-43106-gating-of-builtin-attrs.rs:176:5
    |
diff --git a/tests/ui/lint/unused/unused-attr-duplicate.stderr b/tests/ui/lint/unused/unused-attr-duplicate.stderr
@@ -102,18 +102,6 @@ note: attribute also specified here
 LL | #[automatically_derived]
    | ^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: unused attribute
-  --> $DIR/unused-attr-duplicate.rs:77:1
-   |
-LL | #[cold]
-   | ^^^^^^^ help: remove this attribute
-   |
-note: attribute also specified here
-  --> $DIR/unused-attr-duplicate.rs:76:1
-   |
-LL | #[cold]
-   | ^^^^^^^
-
 error: unused attribute
   --> $DIR/unused-attr-duplicate.rs:79:1
    |
@@ -289,5 +277,17 @@ LL | #[inline(always)]
    | ^^^^^^^^^^^^^^^^^
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 
+error: unused attribute
+  --> $DIR/unused-attr-duplicate.rs:77:1
+   |
+LL | #[cold]
+   | ^^^^^^^ help: remove this attribute
+   |
+note: attribute also specified here
+  --> $DIR/unused-attr-duplicate.rs:76:1
+   |
+LL | #[cold]
+   | ^^^^^^^
+
 error: aborting due to 23 previous errors
 

Original file line number	Diff line number	Diff line change
`@@ -292,6 +292,7 @@ fn emit_malformed_attribute(`
`292`	`292`	`\| sym::align`
`293`	`293`	`\| sym::deprecated`
`294`	`294`	`\| sym::optimize`
	`295`	`+ \| sym::cold`
`295`	`296`	`) {`
`296`	`297`	`return;`
`297`	`298`	`}`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+#[cold = true]`
	`2`	+//~^ ERROR malformed `cold` attribute input [E0565]
	`3`	`+fn main() {}`