Port #[export_name] to the new attribute parsing infrastructure

JonathanBrouwer · JonathanBrouwer · commit 287d9afce729 · 2025-06-26T08:50:42.000+02:00
Signed-off-by: Jonathan Brouwer &lt;jonathantbrouwer@gmail.com&gt;
diff --git a/compiler/rustc_attr_data_structures/src/attributes.rs b/compiler/rustc_attr_data_structures/src/attributes.rs
@@ -231,6 +231,14 @@ pub enum AttributeKind {
     /// Represents [`#[doc]`](https://doc.rust-lang.org/stable/rustdoc/write-documentation/the-doc-attribute.html).
     DocComment { style: AttrStyle, kind: CommentKind, span: Span, comment: Symbol },
 
+    /// Represents [`#[export_name]`](https://doc.rust-lang.org/reference/abi.html#the-export_name-attribute).
+    ExportName {
+        /// The name to export this item with.
+        /// It may not contain \0 bytes as it will be converted to a null-terminated string.
+        name: Symbol,
+        span: Span,
+    },
+
     /// Represents `#[inline]` and `#[rustc_force_inline]`.
     Inline(InlineAttr, Span),
 
diff --git a/compiler/rustc_attr_data_structures/src/encode_cross_crate.rs b/compiler/rustc_attr_data_structures/src/encode_cross_crate.rs
@@ -22,6 +22,7 @@ impl AttributeKind {
             ConstStabilityIndirect => No,
             Deprecation { .. } => Yes,
             DocComment { .. } => Yes,
+            ExportName { .. } => Yes,
             Inline(..) => No,
             MacroTransparency(..) => Yes,
             Repr(..) => No,
diff --git a/compiler/rustc_attr_parsing/messages.ftl b/compiler/rustc_attr_parsing/messages.ftl
@@ -93,9 +93,12 @@ attr_parsing_naked_functions_incompatible_attribute =
     attribute incompatible with `#[unsafe(naked)]`
     .label = the `{$attr}` attribute is incompatible with `#[unsafe(naked)]`
     .naked_attribute = function marked with `#[unsafe(naked)]` here
+
 attr_parsing_non_ident_feature =
     'feature' is not an identifier
 
+attr_parsing_null_on_export = `export_name` may not contain null characters
+
 attr_parsing_repr_ident =
     meta item in `repr` must be an identifier
 
diff --git a/compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs b/compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs
@@ -6,7 +6,7 @@ use rustc_span::{Span, Symbol, sym};
 use super::{AcceptMapping, AttributeOrder, AttributeParser, OnDuplicate, SingleAttributeParser};
 use crate::context::{AcceptContext, FinalizeContext, Stage};
 use crate::parser::ArgParser;
-use crate::session_diagnostics::NakedFunctionIncompatibleAttribute;
+use crate::session_diagnostics::{NakedFunctionIncompatibleAttribute, NullOnExport};
 
 pub(crate) struct OptimizeParser;
 
@@ -59,6 +59,33 @@ impl<S: Stage> SingleAttributeParser<S> for ColdParser {
     }
 }
 
+pub(crate) struct ExportNameParser;
+
+impl<S: Stage> SingleAttributeParser<S> for ExportNameParser {
+    const PATH: &[rustc_span::Symbol] = &[sym::export_name];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepFirst;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
+    const TEMPLATE: AttributeTemplate = template!(NameValueStr: "name");
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let Some(nv) = args.name_value() else {
+            cx.expected_name_value(cx.attr_span, None);
+            return None;
+        };
+        let Some(name) = nv.value_as_str() else {
+            cx.expected_string_literal(nv.value_span, Some(nv.value_as_lit()));
+            return None;
+        };
+        if name.as_str().contains('\0') {
+            // `#[export_name = ...]` will be converted to a null-terminated string,
+            // so it may not contain any null characters.
+            cx.emit_err(NullOnExport { span: cx.attr_span });
+            return None;
+        }
+        Some(AttributeKind::ExportName { name, span: cx.attr_span })
+    }
+}
+
 #[derive(Default)]
 pub(crate) struct NakedParser {
     span: Option<Span>,
diff --git a/compiler/rustc_attr_parsing/src/context.rs b/compiler/rustc_attr_parsing/src/context.rs
@@ -16,7 +16,7 @@ use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span, Symbol, sym};
 
 use crate::attributes::allow_unstable::{AllowConstFnUnstableParser, AllowInternalUnstableParser};
 use crate::attributes::codegen_attrs::{
-    ColdParser, NakedParser, NoMangleParser, OptimizeParser, TrackCallerParser,
+    ColdParser, ExportNameParser, NakedParser, NoMangleParser, OptimizeParser, TrackCallerParser,
 };
 use crate::attributes::confusables::ConfusablesParser;
 use crate::attributes::deprecation::DeprecationParser;
@@ -117,6 +117,7 @@ attribute_parsers!(
         Single<ConstContinueParser>,
         Single<ConstStabilityIndirectParser>,
         Single<DeprecationParser>,
+        Single<ExportNameParser>,
         Single<InlineParser>,
         Single<LoopMatchParser>,
         Single<MayDangleParser>,
diff --git a/compiler/rustc_attr_parsing/src/session_diagnostics.rs b/compiler/rustc_attr_parsing/src/session_diagnostics.rs
@@ -445,6 +445,13 @@ pub(crate) struct MustUseIllFormedAttributeInput {
     pub suggestions: DiagArgValue,
 }
 
+#[derive(Diagnostic)]
+#[diag(attr_parsing_null_on_export, code = E0648)]
+pub(crate) struct NullOnExport {
+    #[primary_span]
+    pub span: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(attr_parsing_stability_outside_std, code = E0734)]
 pub(crate) struct StabilityOutsideStd {
diff --git a/compiler/rustc_codegen_ssa/messages.ftl b/compiler/rustc_codegen_ssa/messages.ftl
@@ -230,8 +230,6 @@ codegen_ssa_no_natvis_directory = error enumerating natvis directory: {$error}
 
 codegen_ssa_no_saved_object_file = cached cgu {$cgu_name} should have an object file, but doesn't
 
-codegen_ssa_null_on_export = `export_name` may not contain null characters
-
 codegen_ssa_out_of_range_integer = integer value out of range
     .label = value must be between `0` and `255`
 
diff --git a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
@@ -119,6 +119,10 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                         .max();
                 }
                 AttributeKind::Cold(_) => codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD,
+                AttributeKind::ExportName { name, span: attr_span } => {
+                    codegen_fn_attrs.export_name = Some(*name);
+                    mixed_export_name_no_mangle_lint_state.track_export_name(*attr_span);
+                }
                 AttributeKind::Naked(_) => codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED,
                 AttributeKind::Align { align, .. } => codegen_fn_attrs.alignment = Some(*align),
                 AttributeKind::NoMangle(attr_span) => {
@@ -223,17 +227,6 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                 }
             }
             sym::thread_local => codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL,
-            sym::export_name => {
-                if let Some(s) = attr.value_str() {
-                    if s.as_str().contains('\0') {
-                        // `#[export_name = ...]` will be converted to a null-terminated string,
-                        // so it may not contain any null characters.
-                        tcx.dcx().emit_err(errors::NullOnExport { span: attr.span() });
-                    }
-                    codegen_fn_attrs.export_name = Some(s);
-                    mixed_export_name_no_mangle_lint_state.track_export_name(attr.span());
-                }
-            }
             sym::target_feature => {
                 let Some(sig) = tcx.hir_node_by_def_id(did).fn_sig() else {
                     tcx.dcx().span_delayed_bug(attr.span(), "target_feature applied to non-fn");
diff --git a/compiler/rustc_codegen_ssa/src/errors.rs b/compiler/rustc_codegen_ssa/src/errors.rs
@@ -140,13 +140,6 @@ pub(crate) struct RequiresRustAbi {
     pub span: Span,
 }
 
-#[derive(Diagnostic)]
-#[diag(codegen_ssa_null_on_export, code = E0648)]
-pub(crate) struct NullOnExport {
-    #[primary_span]
-    pub span: Span,
-}
-
 #[derive(Diagnostic)]
 #[diag(codegen_ssa_unsupported_instruction_set, code = E0779)]
 pub(crate) struct UnsupportedInstructionSet {
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
@@ -977,9 +977,9 @@ impl<'tcx> LateLintPass<'tcx> for InvalidNoMangleItems {
         };
         match it.kind {
             hir::ItemKind::Fn { generics, .. } => {
-                if let Some(attr_span) = attr::find_by_name(attrs, sym::export_name)
-                    .map(|at| at.span())
-                    .or_else(|| find_attr!(attrs, AttributeKind::NoMangle(span) => *span))
+                if let Some(attr_span) =
+                    find_attr!(attrs, AttributeKind::ExportName {span, ..} => *span)
+                        .or_else(|| find_attr!(attrs, AttributeKind::NoMangle(span) => *span))
                 {
                     check_no_mangle_on_generic_fn(attr_span, None, generics, it.span);
                 }
@@ -1010,9 +1010,11 @@ impl<'tcx> LateLintPass<'tcx> for InvalidNoMangleItems {
                 for it in *items {
                     if let hir::AssocItemKind::Fn { .. } = it.kind {
                         let attrs = cx.tcx.hir_attrs(it.id.hir_id());
-                        if let Some(attr_span) = attr::find_by_name(attrs, sym::export_name)
-                            .map(|at| at.span())
-                            .or_else(|| find_attr!(attrs, AttributeKind::NoMangle(span) => *span))
+                        if let Some(attr_span) =
+                            find_attr!(attrs, AttributeKind::ExportName {span, ..} => *span)
+                                .or_else(
+                                    || find_attr!(attrs, AttributeKind::NoMangle(span) => *span),
+                                )
                         {
                             check_no_mangle_on_generic_fn(
                                 attr_span,
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
@@ -169,6 +169,9 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 Attribute::Parsed(AttributeKind::Cold(attr_span)) => {
                     self.check_cold(hir_id, *attr_span, span, target)
                 }
+                Attribute::Parsed(AttributeKind::ExportName { span: attr_span, .. }) => {
+                    self.check_export_name(hir_id, *attr_span, span, target)
+                }
                 Attribute::Parsed(AttributeKind::Align { align, span: repr_span }) => {
                     self.check_align(span, target, *align, *repr_span)
                 }
@@ -223,7 +226,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                             &mut doc_aliases,
                         ),
                         [sym::no_link, ..] => self.check_no_link(hir_id, attr, span, target),
-                        [sym::export_name, ..] => self.check_export_name(hir_id, attr, span, target),
                         [sym::rustc_layout_scalar_valid_range_start, ..]
                         | [sym::rustc_layout_scalar_valid_range_end, ..] => {
                             self.check_rustc_layout_scalar_valid_range(attr, span, target)
@@ -1653,7 +1655,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
     }
 
     /// Checks if `#[export_name]` is applied to a function or static.
-    fn check_export_name(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
+    fn check_export_name(&self, hir_id: HirId, attr_span: Span, span: Span, target: Target) {
         match target {
             Target::Static | Target::Fn => {}
             Target::Method(..) if self.is_impl_item(hir_id) => {}
@@ -1662,10 +1664,10 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             // 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(), "export_name");
+                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "export_name");
             }
             _ => {
-                self.dcx().emit_err(errors::ExportName { attr_span: attr.span(), span });
+                self.dcx().emit_err(errors::ExportName { attr_span, span });
             }
         }
     }
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
@@ -755,8 +755,11 @@ impl Item {
             .filter_map(|attr| {
                 // NoMangle is special cased, as it appears in HTML output, and we want to show it in source form, not HIR printing.
                 // It is also used by cargo-semver-checks.
-                if matches!(attr, hir::Attribute::Parsed(AttributeKind::NoMangle(..))) {
+                if let hir::Attribute::Parsed(AttributeKind::NoMangle(..)) = attr {
                     Some("#[no_mangle]".to_string())
+                } else if let hir::Attribute::Parsed(AttributeKind::ExportName { name, .. }) = attr
+                {
+                    Some(format!("#[export_name = \"{name}\"]"))
                 } else if is_json {
                     match attr {
                         // rustdoc-json stores this in `Item::deprecation`, so we
diff --git a/tests/ui/lint/unused/unused-attr-duplicate.stderr b/tests/ui/lint/unused/unused-attr-duplicate.stderr
@@ -89,19 +89,6 @@ note: attribute also specified here
 LL | #[automatically_derived]
    | ^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: unused attribute
-  --> $DIR/unused-attr-duplicate.rs:92:1
-   |
-LL | #[export_name = "exported_symbol_name"]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove this attribute
-   |
-note: attribute also specified here
-  --> $DIR/unused-attr-duplicate.rs:94:1
-   |
-LL | #[export_name = "exported_symbol_name2"]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = 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:102:1
    |
@@ -277,6 +264,19 @@ note: attribute also specified here
 LL | #[track_caller]
    | ^^^^^^^^^^^^^^^
 
+error: unused attribute
+  --> $DIR/unused-attr-duplicate.rs:92:1
+   |
+LL | #[export_name = "exported_symbol_name"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove this attribute
+   |
+note: attribute also specified here
+  --> $DIR/unused-attr-duplicate.rs:94:1
+   |
+LL | #[export_name = "exported_symbol_name2"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = 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:98:1
    |
