Rollup merge of #143138 - JonathanBrouwer:link_name_parser, r=jdonszelmann

Port `#[link_name]` to the new attribute parsing infrastructure

Ports `link_name` to the new attribute parsing infrastructure for https://github.com/rust-lang/rust/issues/131229#issuecomment-2971353197

r? `@jdonszelmann`

compiler/rustc_attr_data_structures/src/attributes.rs

@@ -253,6 +253,9 @@ pub enum AttributeKind {
     /// Represents `#[inline]` and `#[rustc_force_inline]`.
     Inline(InlineAttr, Span),
 
+    /// Represents `#[link_name]`.
+    LinkName { name: Symbol, span: Span },
+
     /// Represents `#[loop_match]`.
     LoopMatch(Span),
 

compiler/rustc_attr_data_structures/src/encode_cross_crate.rs

@@ -29,6 +29,7 @@ impl AttributeKind {
             Stability { .. } => Yes,
             Cold(..) => No,
             ConstContinue(..) => No,
+            LinkName { .. } => Yes,
             LoopMatch(..) => No,
             MayDangle(..) => No,
             MustUse { .. } => Yes,

compiler/rustc_attr_parsing/src/attributes/link_attrs.rs

@@ -0,0 +1,30 @@
+use rustc_attr_data_structures::AttributeKind;
+use rustc_attr_data_structures::AttributeKind::LinkName;
+use rustc_feature::{AttributeTemplate, template};
+use rustc_span::{Symbol, sym};
+
+use crate::attributes::{AttributeOrder, OnDuplicate, SingleAttributeParser};
+use crate::context::{AcceptContext, Stage};
+use crate::parser::ArgParser;
+
+pub(crate) struct LinkNameParser;
+
+impl<S: Stage> SingleAttributeParser<S> for LinkNameParser {
+    const PATH: &[Symbol] = &[sym::link_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;
+        };
+
+        Some(LinkName { name, span: cx.attr_span })
+    }
+}

compiler/rustc_attr_parsing/src/attributes/mod.rs

@@ -31,6 +31,7 @@ pub(crate) mod codegen_attrs;
 pub(crate) mod confusables;
 pub(crate) mod deprecation;
 pub(crate) mod inline;
+pub(crate) mod link_attrs;
 pub(crate) mod lint_helpers;
 pub(crate) mod loop_match;
 pub(crate) mod must_use;

compiler/rustc_attr_parsing/src/context.rs

@@ -22,6 +22,7 @@ use crate::attributes::codegen_attrs::{
 use crate::attributes::confusables::ConfusablesParser;
 use crate::attributes::deprecation::DeprecationParser;
 use crate::attributes::inline::{InlineParser, RustcForceInlineParser};
+use crate::attributes::link_attrs::LinkNameParser;
 use crate::attributes::lint_helpers::{AsPtrParser, PubTransparentParser};
 use crate::attributes::loop_match::{ConstContinueParser, LoopMatchParser};
 use crate::attributes::must_use::MustUseParser;
@@ -121,6 +122,7 @@ attribute_parsers!(
         Single<DeprecationParser>,
         Single<ExportNameParser>,
         Single<InlineParser>,
+        Single<LinkNameParser>,
         Single<LoopMatchParser>,
         Single<MayDangleParser>,
         Single<MustUseParser>,

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -123,6 +123,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                 }
                 AttributeKind::Naked(_) => codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED,
                 AttributeKind::Align { align, .. } => codegen_fn_attrs.alignment = Some(*align),
+                AttributeKind::LinkName { name, .. } => codegen_fn_attrs.link_name = Some(*name),
                 AttributeKind::NoMangle(attr_span) => {
                     if tcx.opt_item_name(did.to_def_id()).is_some() {
                         codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
@@ -262,7 +263,6 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                     }
                 }
             }
-            sym::link_name => codegen_fn_attrs.link_name = attr.value_str(),
             sym::link_ordinal => {
                 link_ordinal_span = Some(attr.span());
                 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {

compiler/rustc_lint/src/foreign_modules.rs

@@ -1,4 +1,5 @@
 use rustc_abi::FIRST_VARIANT;
+use rustc_attr_data_structures::{AttributeKind, find_attr};
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_data_structures::unord::{UnordMap, UnordSet};
 use rustc_hir as hir;
@@ -6,7 +7,7 @@ use rustc_hir::def::DefKind;
 use rustc_middle::query::Providers;
 use rustc_middle::ty::{self, AdtDef, Instance, Ty, TyCtxt};
 use rustc_session::declare_lint;
-use rustc_span::{Span, Symbol, sym};
+use rustc_span::{Span, Symbol};
 use tracing::{debug, instrument};
 
 use crate::lints::{BuiltinClashingExtern, BuiltinClashingExternSub};
@@ -182,7 +183,11 @@ fn name_of_extern_decl(tcx: TyCtxt<'_>, fi: hir::OwnerId) -> SymbolName {
             // information, we could have codegen_fn_attrs also give span information back for
             // where the attribute was defined. However, until this is found to be a
             // bottleneck, this does just fine.
-            (overridden_link_name, tcx.get_attr(fi, sym::link_name).unwrap().span())
+            (
+                overridden_link_name,
+                find_attr!(tcx.get_all_attrs(fi), AttributeKind::LinkName {span, ..} => *span)
+                    .unwrap(),
+            )
         })
     {
         SymbolName::Link(overridden_link_name, overridden_link_name_span)

compiler/rustc_parse/src/validate_attr.rs

@@ -302,6 +302,7 @@ fn emit_malformed_attribute(
             | sym::no_mangle
             | sym::must_use
             | sym::track_caller
+            | sym::link_name
     ) {
         return;
     }

compiler/rustc_passes/src/check_attr.rs

@@ -191,6 +191,9 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 Attribute::Parsed(AttributeKind::AsPtr(attr_span)) => {
                     self.check_applied_to_fn_or_method(hir_id, *attr_span, span, target)
                 }
+                Attribute::Parsed(AttributeKind::LinkName { span: attr_span, name }) => {
+                    self.check_link_name(hir_id, *attr_span, *name, span, target)
+                }
                 Attribute::Parsed(AttributeKind::MayDangle(attr_span)) => {
                     self.check_may_dangle(hir_id, *attr_span)
                 }
@@ -283,7 +286,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         [sym::ffi_const, ..] => self.check_ffi_const(attr.span(), target),
                         [sym::link_ordinal, ..] => self.check_link_ordinal(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),
                         [sym::macro_use, ..] | [sym::macro_escape, ..] => {
                             self.check_macro_use(hir_id, attr, target)
@@ -1604,7 +1606,14 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
     }
 
     /// Checks if `#[link_name]` is applied to an item other than a foreign function or static.
-    fn check_link_name(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
+    fn check_link_name(
+        &self,
+        hir_id: HirId,
+        attr_span: Span,
+        name: Symbol,
+        span: Span,
+        target: Target,
+    ) {
         match target {
             Target::ForeignFn | Target::ForeignStatic => {}
             // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
@@ -1612,27 +1621,18 @@ 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(), "link_name");
+                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "link_name");
             }
             _ => {
-                // FIXME: #[cold] was previously allowed on non-functions/statics and some crates
+                // FIXME: #[link_name] was previously allowed on non-functions/statics and some crates
                 // used this, so only emit a warning.
-                let attr_span = matches!(target, Target::ForeignMod).then_some(attr.span());
-                if let Some(s) = attr.value_str() {
+                let help_span = matches!(target, Target::ForeignMod).then_some(attr_span);
                 self.tcx.emit_node_span_lint(
                     UNUSED_ATTRIBUTES,
                     hir_id,
-                        attr.span(),
-                        errors::LinkName { span, attr_span, value: s.as_str() },
+                    attr_span,
+                    errors::LinkName { span, help_span, value: name.as_str() },
                 );
-                } else {
-                    self.tcx.emit_node_span_lint(
-                        UNUSED_ATTRIBUTES,
-                        hir_id,
-                        attr.span(),
-                        errors::LinkName { span, attr_span, value: "..." },
-                    );
-                };
             }
         }
     }

compiler/rustc_passes/src/errors.rs

@@ -502,7 +502,7 @@ pub(crate) struct Link {
 #[warning]
 pub(crate) struct LinkName<'a> {
     #[help]
-    pub attr_span: Option<Span>,
+    pub help_span: Option<Span>,
     #[label]
     pub span: Span,
     pub value: &'a str,

tests/ui/extern/issue-47725.rs

@@ -17,12 +17,9 @@ extern "C" {
 #[link_name]
 //~^ ERROR malformed `link_name` attribute input
 //~| HELP must be of the form
-//~| WARN attribute should be applied to a foreign function or static [unused_attributes]
-//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-//~| HELP try `#[link(name = "...")]` instead
+//~| NOTE expected this to be of the form `link_name = "..."
 extern "C" {
     fn bar() -> u32;
 }
-//~^^^ NOTE not a foreign function or static
 
 fn main() {}

tests/ui/extern/issue-47725.stderr

@@ -1,8 +1,11 @@
-error: malformed `link_name` attribute input
+error[E0539]: malformed `link_name` attribute input
   --> $DIR/issue-47725.rs:17:1
    |
 LL | #[link_name]
-   | ^^^^^^^^^^^^ help: must be of the form: `#[link_name = "name"]`
+   | ^^^^^^^^^^^^
+   | |
+   | expected this to be of the form `link_name = "..."`
+   | help: must be of the form: `#[link_name = "name"]`
 
 warning: attribute should be applied to a foreign function or static
   --> $DIR/issue-47725.rs:3:1
@@ -38,23 +41,6 @@ help: try `#[link(name = "foobar")]` instead
 LL | #[link_name = "foobar"]
    | ^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: attribute should be applied to a foreign function or static
-  --> $DIR/issue-47725.rs:17:1
-   |
-LL |   #[link_name]
-   |   ^^^^^^^^^^^^
-...
-LL | / extern "C" {
-LL | |     fn bar() -> u32;
-LL | | }
-   | |_- not a foreign function or static
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-help: try `#[link(name = "...")]` instead
-  --> $DIR/issue-47725.rs:17:1
-   |
-LL | #[link_name]
-   | ^^^^^^^^^^^^
-
-error: aborting due to 1 previous error; 3 warnings emitted
+error: aborting due to 1 previous error; 2 warnings emitted
 
+For more information about this error, try `rustc --explain E0539`.

tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs.stderr

@@ -387,14 +387,6 @@ LL | #![link()]
    |
    = 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 a foreign function or static
-  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:66:1
-   |
-LL | #![link_name = "1900"]
-   | ^^^^^^^^^^^^^^^^^^^^^^ not a foreign function or static
-   |
-   = 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 a function or static
   --> $DIR/issue-43106-gating-of-builtin-attrs.rs:69:1
    |
@@ -411,6 +403,14 @@ LL | #![cold]
    |
    = 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 a foreign function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:66:1
+   |
+LL | #![link_name = "1900"]
+   | ^^^^^^^^^^^^^^^^^^^^^^ not a foreign function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
 warning: `#[must_use]` has no effect when applied to a module
   --> $DIR/issue-43106-gating-of-builtin-attrs.rs:72:1
    |

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:86:5
-   |
-LL |     #[link_name = "this_does_not_exist"]
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove this attribute
-   |
-note: attribute also specified here
-  --> $DIR/unused-attr-duplicate.rs:88:5
-   |
-LL |     #[link_name = "rust_dbg_extern_identity_u32"]
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = 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:14:1
    |
@@ -252,6 +239,19 @@ note: attribute also specified here
 LL | #[track_caller]
    | ^^^^^^^^^^^^^^^
 
+error: unused attribute
+  --> $DIR/unused-attr-duplicate.rs:86:5
+   |
+LL |     #[link_name = "this_does_not_exist"]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove this attribute
+   |
+note: attribute also specified here
+  --> $DIR/unused-attr-duplicate.rs:88:5
+   |
+LL |     #[link_name = "rust_dbg_extern_identity_u32"]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = 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:92:1
    |