rust-lang · tgross35 · Apr 24, 2025 · Apr 26, 2025 · Feb 27, 2025 · May 22, 2025
diff --git a/compiler/rustc_attr_parsing/messages.ftl b/compiler/rustc_attr_parsing/messages.ftl
@@ -32,6 +32,11 @@ attr_parsing_ill_formed_attribute_input = {$num_suggestions ->
         *[other] valid forms for the attribute are {$suggestions}
     }
 
+attr_parsing_invalid_macro_export_arguments = {$num_suggestions ->
+        [1] attribute must be of the form {$suggestions}
+        *[other] valid forms for the attribute are {$suggestions}
+    }
+
 attr_parsing_incorrect_repr_format_align_one_arg =
     incorrect `repr(align)` attribute format: `align` takes exactly one argument in parentheses
 

diff --git a/compiler/rustc_attr_parsing/src/attributes/macro_attrs.rs b/compiler/rustc_attr_parsing/src/attributes/macro_attrs.rs
@@ -1,10 +1,14 @@
 use rustc_errors::DiagArgValue;
 use rustc_feature::{AttributeTemplate, template};
 use rustc_hir::attrs::{AttributeKind, MacroUseArgs};
+use rustc_hir::lints::AttributeLintKind;
 use rustc_span::{Span, Symbol, sym};
 use thin_vec::ThinVec;
 
-use crate::attributes::{AcceptMapping, AttributeParser, NoArgsAttributeParser, OnDuplicate};
+use crate::attributes::{
+    AcceptMapping, AttributeOrder, AttributeParser, NoArgsAttributeParser, OnDuplicate,
+    SingleAttributeParser,
+};
 use crate::context::{AcceptContext, FinalizeContext, Stage};
 use crate::parser::ArgParser;
 use crate::session_diagnostics;
@@ -113,3 +117,58 @@ impl<S: Stage> AttributeParser<S> for MacroUseParser {
         Some(AttributeKind::MacroUse { span: self.first_span?, arguments: self.state })
     }
 }
+
+pub(crate) struct MacroExportParser;
+
+impl<S: Stage> SingleAttributeParser<S> for crate::attributes::macro_attrs::MacroExportParser {
+    const PATH: &[Symbol] = &[sym::macro_export];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const TEMPLATE: AttributeTemplate = template!(Word, List: "local_inner_macros");
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let suggestions =
+            || <Self as SingleAttributeParser<S>>::TEMPLATE.suggestions(false, "macro_export");
+        let local_inner_macros = match args {
+            ArgParser::NoArgs => false,
+            ArgParser::List(list) => {
+                let Some(l) = list.single() else {
+                    let span = cx.attr_span;
+                    cx.emit_lint(
+                        AttributeLintKind::InvalidMacroExportArguments {
+                            suggestions: suggestions(),
+                        },
+                        span,
+                    );
+                    return None;
+                };
+                match l.meta_item().and_then(|i| i.path().word_sym()) {
+                    Some(sym::local_inner_macros) => true,
+                    _ => {
+                        let span = cx.attr_span;
+                        cx.emit_lint(
+                            AttributeLintKind::InvalidMacroExportArguments {
+                                suggestions: suggestions(),
+                            },
+                            span,
+                        );
+                        return None;
+                    }
+                }
+            }
+            ArgParser::NameValue(_) => {
+                let span = cx.attr_span;
+                let suggestions = suggestions();
+                cx.emit_err(session_diagnostics::IllFormedAttributeInputLint {
+                    num_suggestions: suggestions.len(),
+                    suggestions: DiagArgValue::StrListSepByAnd(
+                        suggestions.into_iter().map(|s| format!("`{s}`").into()).collect(),
+                    ),
+                    span,
+                });
+                return None;
+            }
+        };
+        Some(AttributeKind::MacroExport { span: cx.attr_span, local_inner_macros })
+    }
+}
diff --git a/compiler/rustc_attr_parsing/src/context.rs b/compiler/rustc_attr_parsing/src/context.rs
@@ -32,7 +32,7 @@ use crate::attributes::lint_helpers::{
     AsPtrParser, AutomaticallyDerivedParser, PassByValueParser, PubTransparentParser,
 };
 use crate::attributes::loop_match::{ConstContinueParser, LoopMatchParser};
-use crate::attributes::macro_attrs::{MacroEscapeParser, MacroUseParser};
+use crate::attributes::macro_attrs::{MacroEscapeParser, MacroExportParser, MacroUseParser};
 use crate::attributes::must_use::MustUseParser;
 use crate::attributes::no_implicit_prelude::NoImplicitPreludeParser;
 use crate::attributes::non_exhaustive::NonExhaustiveParser;
@@ -164,6 +164,7 @@ attribute_parsers!(
         Single<LinkNameParser>,
         Single<LinkOrdinalParser>,
         Single<LinkSectionParser>,
+        Single<MacroExportParser>,
         Single<MustUseParser>,
         Single<OptimizeParser>,
         Single<PathAttributeParser>,

diff --git a/compiler/rustc_attr_parsing/src/lints.rs b/compiler/rustc_attr_parsing/src/lints.rs
@@ -34,5 +34,17 @@ pub fn emit_attribute_lint<L: LintEmitter>(lint: &AttributeLint<HirId>, lint_emi
             *first_span,
             session_diagnostics::EmptyAttributeList { attr_span: *first_span },
         ),
+        AttributeLintKind::InvalidMacroExportArguments { suggestions } => lint_emitter
+            .emit_node_span_lint(
+                rustc_session::lint::builtin::INVALID_MACRO_EXPORT_ARGUMENTS,
+                *id,
+                *span,
+                session_diagnostics::IllFormedAttributeInput {
+                    num_suggestions: suggestions.len(),
+                    suggestions: DiagArgValue::StrListSepByAnd(
+                        suggestions.into_iter().map(|s| format!("`{s}`").into()).collect(),
+                    ),
+                },
+            ),
     }
 }
diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
@@ -910,9 +910,9 @@ impl SyntaxExtension {
         let allow_internal_unsafe =
             ast::attr::find_by_name(attrs, sym::allow_internal_unsafe).is_some();
 
-        let local_inner_macros = ast::attr::find_by_name(attrs, sym::macro_export)
-            .and_then(|macro_export| macro_export.meta_item_list())
-            .is_some_and(|l| ast::attr::list_contains_name(&l, sym::local_inner_macros));
+        let local_inner_macros =
+            *find_attr!(attrs, AttributeKind::MacroExport {local_inner_macros: l, ..} => l)
+                .unwrap_or(&false);
         let collapse_debuginfo = Self::get_collapse_debuginfo(sess, attrs, !is_local);
         tracing::debug!(?name, ?local_inner_macros, ?collapse_debuginfo, ?allow_internal_unsafe);
 

diff --git a/compiler/rustc_hir/src/attrs/data_structures.rs b/compiler/rustc_hir/src/attrs/data_structures.rs
@@ -360,6 +360,9 @@ pub enum AttributeKind {
     /// Represents `#[macro_escape]`.
     MacroEscape(Span),
 
+    /// Represents [`#[macro_export]`](https://doc.rust-lang.org/reference/macros-by-example.html#r-macro.decl.scope.path).
+    MacroExport { span: Span, local_inner_macros: bool },
+
     /// Represents `#[rustc_macro_transparency]`.
     MacroTransparency(Transparency),
 

diff --git a/compiler/rustc_hir/src/attrs/encode_cross_crate.rs b/compiler/rustc_hir/src/attrs/encode_cross_crate.rs
@@ -46,6 +46,7 @@ impl AttributeKind {
             LinkSection { .. } => Yes, // Needed for rustdoc
             LoopMatch(..) => No,
             MacroEscape(..) => No,
+            MacroExport { .. } => Yes,
             MacroTransparency(..) => Yes,
             MacroUse { .. } => No,
             Marker(..) => No,

diff --git a/compiler/rustc_hir/src/lints.rs b/compiler/rustc_hir/src/lints.rs
@@ -31,7 +31,22 @@ pub struct AttributeLint<Id> {
 
 #[derive(Clone, Debug, HashStable_Generic)]
 pub enum AttributeLintKind {
-    UnusedDuplicate { this: Span, other: Span, warning: bool },
-    IllFormedAttributeInput { suggestions: Vec<String> },
-    EmptyAttribute { first_span: Span },
+    UnusedDuplicate {
+        this: Span,
+        other: Span,
+        warning: bool,
+    },
+    IllFormedAttributeInput {
+        suggestions: Vec<String>,
+    },
+    EmptyAttribute {
+        first_span: Span,
+    },
+
+    /// Copy of `IllFormedAttributeInput`
+    /// specifically for the `invalid_macro_export_arguments` lint until that is removed,
+    /// see <https://github.com/rust-lang/rust/pull/143857#issuecomment-3079175663>
+    InvalidMacroExportArguments {
+        suggestions: Vec<String>,
+    },
 }
diff --git a/compiler/rustc_lint/src/non_local_def.rs b/compiler/rustc_lint/src/non_local_def.rs
@@ -1,11 +1,12 @@
 use rustc_errors::MultiSpan;
+use rustc_hir::attrs::AttributeKind;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::intravisit::{self, Visitor, VisitorExt};
-use rustc_hir::{Body, HirId, Item, ItemKind, Node, Path, TyKind};
+use rustc_hir::{Body, HirId, Item, ItemKind, Node, Path, TyKind, find_attr};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::{declare_lint, impl_lint_pass};
 use rustc_span::def_id::{DefId, LOCAL_CRATE};
-use rustc_span::{ExpnKind, MacroKind, Span, kw, sym};
+use rustc_span::{ExpnKind, MacroKind, Span, kw};
 
 use crate::lints::{NonLocalDefinitionsCargoUpdateNote, NonLocalDefinitionsDiag};
 use crate::{LateContext, LateLintPass, LintContext, fluent_generated as fluent};
@@ -241,7 +242,10 @@ impl<'tcx> LateLintPass<'tcx> for NonLocalDefinitions {
                 )
             }
             ItemKind::Macro(_, _macro, MacroKind::Bang)
-                if cx.tcx.has_attr(item.owner_id.def_id, sym::macro_export) =>
+                if find_attr!(
+                    cx.tcx.get_all_attrs(item.owner_id.def_id),
+                    AttributeKind::MacroExport { .. }
+                ) =>
             {
                 cx.emit_span_lint(
                     NON_LOCAL_DEFINITIONS,

diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
@@ -4188,8 +4188,13 @@ declare_lint! {
     /// You can't have multiple arguments in a `#[macro_export(..)]`, or mention arguments other than `local_inner_macros`.
     ///
     pub INVALID_MACRO_EXPORT_ARGUMENTS,
-    Warn,
+    Deny,
     "\"invalid_parameter\" isn't a valid argument for `#[macro_export]`",
+    @future_incompatible = FutureIncompatibleInfo {
+        reason: FutureIncompatibilityReason::FutureReleaseError,
+        reference: "issue #57571 <https://github.com/rust-lang/rust/issues/57571>",
+        report_in_deps: true,
+    };
 }
 
 declare_lint! {

diff --git a/compiler/rustc_passes/messages.ftl b/compiler/rustc_passes/messages.ftl
@@ -399,10 +399,6 @@ passes_invalid_attr_at_crate_level =
 passes_invalid_attr_at_crate_level_item =
     the inner attribute doesn't annotate this {$kind}
 
-passes_invalid_macro_export_arguments = invalid `#[macro_export]` argument
-
-passes_invalid_macro_export_arguments_too_many_items = `#[macro_export]` can only take 1 or 0 arguments
-
 passes_lang_item_fn = {$name ->
     [panic_impl] `#[panic_handler]`
     *[other] `{$name}` lang item

diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
@@ -38,9 +38,8 @@ use rustc_middle::{bug, span_bug};
 use rustc_session::config::CrateType;
 use rustc_session::lint;
 use rustc_session::lint::builtin::{
-    CONFLICTING_REPR_HINTS, INVALID_DOC_ATTRIBUTES, INVALID_MACRO_EXPORT_ARGUMENTS,
-    MALFORMED_DIAGNOSTIC_ATTRIBUTES, MISPLACED_DIAGNOSTIC_ATTRIBUTES, UNUSED_ATTRIBUTES,
-    USELESS_DEPRECATED,
+    CONFLICTING_REPR_HINTS, INVALID_DOC_ATTRIBUTES, MALFORMED_DIAGNOSTIC_ATTRIBUTES,
+    MISPLACED_DIAGNOSTIC_ATTRIBUTES, UNUSED_ATTRIBUTES, USELESS_DEPRECATED,
 };
 use rustc_session::parse::feature_err;
 use rustc_span::edition::Edition;
@@ -291,6 +290,9 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     | AttributeKind::Dummy
                     | AttributeKind::RustcBuiltinMacro { .. },
                 ) => { /* do nothing  */ }
+                Attribute::Parsed(AttributeKind::MacroExport { span, .. }) => {
+                    self.check_macro_export(hir_id, *span, target)
+                }
                 Attribute::Parsed(AttributeKind::AsPtr(attr_span)) => {
                     self.check_applied_to_fn_or_method(hir_id, *attr_span, span, target)
                 }
@@ -383,7 +385,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         [sym::ffi_const, ..] => self.check_ffi_const(attr.span(), target),
                         [sym::link, ..] => self.check_link(hir_id, attr, span, target),
                         [sym::path, ..] => self.check_generic_attr_unparsed(hir_id, attr, target, Target::Mod),
-                        [sym::macro_export, ..] => self.check_macro_export(hir_id, attr, target),
                         [sym::should_panic, ..] => {
                             self.check_generic_attr_unparsed(hir_id, attr, target, Target::Fn)
                         }
@@ -2432,32 +2433,14 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    fn check_macro_export(&self, hir_id: HirId, attr: &Attribute, target: Target) {
+    fn check_macro_export(&self, hir_id: HirId, attr_span: Span, target: Target) {
         if target != Target::MacroDef {
             self.tcx.emit_node_span_lint(
                 UNUSED_ATTRIBUTES,
                 hir_id,
-                attr.span(),
+                attr_span,
                 errors::MacroExport::Normal,
             );
-        } else if let Some(meta_item_list) = attr.meta_item_list()
-            && !meta_item_list.is_empty()
-        {
-            if meta_item_list.len() > 1 {
-                self.tcx.emit_node_span_lint(
-                    INVALID_MACRO_EXPORT_ARGUMENTS,
-                    hir_id,
-                    attr.span(),
-                    errors::MacroExport::TooManyItems,
-                );
-            } else if !meta_item_list[0].has_name(sym::local_inner_macros) {
-                self.tcx.emit_node_span_lint(
-                    INVALID_MACRO_EXPORT_ARGUMENTS,
-                    hir_id,
-                    meta_item_list[0].span(),
-                    errors::MacroExport::InvalidArgument,
-                );
-            }
         } else {
             // special case when `#[macro_export]` is applied to a macro 2.0
             let (_, macro_definition, _) = self.tcx.hir_node(hir_id).expect_item().expect_macro();
@@ -2467,7 +2450,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 self.tcx.emit_node_span_lint(
                     UNUSED_ATTRIBUTES,
                     hir_id,
-                    attr.span(),
+                    attr_span,
                     errors::MacroExport::OnDeclMacro,
                 );
             }
@@ -2820,7 +2803,9 @@ impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
         // In the long run, the checks should be harmonized.
         if let ItemKind::Macro(_, macro_def, _) = item.kind {
             let def_id = item.owner_id.to_def_id();
-            if macro_def.macro_rules && !self.tcx.has_attr(def_id, sym::macro_export) {
+            if macro_def.macro_rules
+                && !find_attr!(self.tcx.get_all_attrs(def_id), AttributeKind::MacroExport { .. })
+            {
                 check_non_exported_macro_for_invalid_attrs(self.tcx, item);
             }
         }
@@ -2950,7 +2935,6 @@ fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
     // which were unsuccessfully resolved due to cannot determine
     // resolution for the attribute macro error.
     const ATTRS_TO_CHECK: &[Symbol] = &[
-        sym::macro_export,
         sym::rustc_main,
         sym::derive,
         sym::test,
@@ -2975,6 +2959,8 @@ fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
             (*span, sym::path)
         } else if let Attribute::Parsed(AttributeKind::AutomaticallyDerived(span)) = attr {
             (*span, sym::automatically_derived)
+        } else if let Attribute::Parsed(AttributeKind::MacroExport { span, .. }) = attr {
+            (*span, sym::macro_export)
         } else {
             continue;
         };

diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs
@@ -786,12 +786,6 @@ pub(crate) enum MacroExport {
     #[diag(passes_macro_export_on_decl_macro)]
     #[note]
     OnDeclMacro,
-
-    #[diag(passes_invalid_macro_export_arguments)]
-    InvalidArgument,
-
-    #[diag(passes_invalid_macro_export_arguments_too_many_items)]
-    TooManyItems,
 }
 
 #[derive(Subdiagnostic)]

diff --git a/src/librustdoc/html/render/search_index.rs b/src/librustdoc/html/render/search_index.rs
@@ -6,6 +6,8 @@ use std::collections::{BTreeMap, VecDeque};
 use encode::{bitmap_to_string, write_vlqhex_to_string};
 use rustc_ast::join_path_syms;
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
+use rustc_hir::attrs::AttributeKind;
+use rustc_hir::find_attr;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::def_id::DefId;
 use rustc_span::sym;
@@ -421,16 +423,17 @@ pub(crate) fn build_index(
                     if fqp.last() != Some(&item.name) {
                         return None;
                     }
-                    let path =
-                        if item.ty == ItemType::Macro && tcx.has_attr(defid, sym::macro_export) {
-                            // `#[macro_export]` always exports to the crate root.
-                            tcx.crate_name(defid.krate).to_string()
-                        } else {
-                            if fqp.len() < 2 {
-                                return None;
-                            }
-                            join_path_syms(&fqp[..fqp.len() - 1])
-                        };
+                    let path = if item.ty == ItemType::Macro
+                        && find_attr!(tcx.get_all_attrs(defid), AttributeKind::MacroExport { .. })
+                    {
+                        // `#[macro_export]` always exports to the crate root.
+                        tcx.crate_name(defid.krate).to_string()
+                    } else {
+                        if fqp.len() < 2 {
+                            return None;
+                        }
+                        join_path_syms(&fqp[..fqp.len() - 1])
+                    };
                     if path == item.path {
                         return None;
                     }