Warn on macro calls for attributes that had this behaviour previously

Author: JonathanBrouwer

compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs

@@ -127,6 +127,7 @@ impl<S: Stage> SingleAttributeParser<S> for ExportNameParser {
         Warn(Target::Field),
         Warn(Target::Arm),
         Warn(Target::MacroDef),
+        Warn(Target::MacroCall),
     ]);
     const TEMPLATE: AttributeTemplate = template!(NameValueStr: "name");
 
@@ -174,6 +175,7 @@ impl<S: Stage> AttributeParser<S> for NakedParser {
         Allow(Target::Method(MethodKind::Inherent)),
         Allow(Target::Method(MethodKind::Trait { body: true })),
         Allow(Target::Method(MethodKind::TraitImpl)),
+        Warn(Target::MacroCall),
     ]);
 
     fn finalize(self, cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
@@ -278,6 +280,7 @@ impl<S: Stage> NoArgsAttributeParser<S> for TrackCallerParser {
         Warn(Target::MacroDef),
         Warn(Target::Arm),
         Warn(Target::Field),
+        Warn(Target::MacroCall),
     ]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::TrackCaller;
 }
@@ -365,7 +368,8 @@ impl<S: Stage> AttributeParser<S> for UsedParser {
             }
         },
     )];
-    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Static)]);
+    const ALLOWED_TARGETS: AllowedTargets =
+        AllowedTargets::AllowList(&[Allow(Target::Static), Warn(Target::MacroCall)]);
 
     fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         // Ratcheting behaviour, if both `linker` and `compiler` are specified, use `linker`
@@ -450,6 +454,7 @@ impl<S: Stage> CombineAttributeParser<S> for TargetFeatureParser {
         Warn(Target::Field),
         Warn(Target::Arm),
         Warn(Target::MacroDef),
+        Warn(Target::MacroCall),
     ]);
 }
 

compiler/rustc_attr_parsing/src/attributes/deprecation.rs

@@ -60,6 +60,7 @@ impl<S: Stage> SingleAttributeParser<S> for DeprecationParser {
         Allow(Target::Variant),
         Allow(Target::Impl { of_trait: false }), //FIXME This does not make sense
         Allow(Target::Crate),
+        Warn(Target::MacroCall),
         Error(Target::WherePredicate),
     ]);
     const TEMPLATE: AttributeTemplate = template!(

compiler/rustc_attr_parsing/src/attributes/inline.rs

@@ -25,6 +25,7 @@ impl<S: Stage> SingleAttributeParser<S> for InlineParser {
         Warn(Target::MacroDef),
         Warn(Target::Arm),
         Warn(Target::AssocConst),
+        Warn(Target::MacroCall),
     ]);
     const TEMPLATE: AttributeTemplate = template!(
         Word,

compiler/rustc_attr_parsing/src/attributes/link_attrs.rs

@@ -110,8 +110,11 @@ impl<S: Stage> SingleAttributeParser<S> for LinkOrdinalParser {
     const PATH: &[Symbol] = &[sym::link_ordinal];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
-    const ALLOWED_TARGETS: AllowedTargets =
-        AllowedTargets::AllowList(&[Allow(Target::ForeignFn), Allow(Target::ForeignStatic)]);
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::ForeignFn),
+        Allow(Target::ForeignStatic),
+        Warn(Target::MacroCall),
+    ]);
     const TEMPLATE: AttributeTemplate = template!(
         List: &["ordinal"],
         "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_ordinal-attribute"

compiler/rustc_attr_parsing/src/attributes/non_exhaustive.rs

@@ -19,6 +19,7 @@ impl<S: Stage> NoArgsAttributeParser<S> for NonExhaustiveParser {
         Warn(Target::Field),
         Warn(Target::Arm),
         Warn(Target::MacroDef),
+        Warn(Target::MacroCall),
     ]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::NonExhaustive;
 }

compiler/rustc_attr_parsing/src/attributes/proc_macro_attrs.rs

@@ -1,20 +1,21 @@
 use super::prelude::*;
 
+const PROC_MACRO_ALLOWED_TARGETS: AllowedTargets =
+    AllowedTargets::AllowList(&[Allow(Target::Fn), Warn(Target::Crate), Warn(Target::MacroCall)]);
+
 pub(crate) struct ProcMacroParser;
 impl<S: Stage> NoArgsAttributeParser<S> for ProcMacroParser {
     const PATH: &[Symbol] = &[sym::proc_macro];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
-    const ALLOWED_TARGETS: AllowedTargets =
-        AllowedTargets::AllowList(&[Allow(Target::Fn), Warn(Target::Crate)]);
+    const ALLOWED_TARGETS: AllowedTargets = PROC_MACRO_ALLOWED_TARGETS;
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::ProcMacro;
 }
 
 pub(crate) struct ProcMacroAttributeParser;
 impl<S: Stage> NoArgsAttributeParser<S> for ProcMacroAttributeParser {
     const PATH: &[Symbol] = &[sym::proc_macro_attribute];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
-    const ALLOWED_TARGETS: AllowedTargets =
-        AllowedTargets::AllowList(&[Allow(Target::Fn), Warn(Target::Crate)]);
+    const ALLOWED_TARGETS: AllowedTargets = PROC_MACRO_ALLOWED_TARGETS;
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::ProcMacroAttribute;
 }
 
@@ -23,8 +24,7 @@ impl<S: Stage> SingleAttributeParser<S> for ProcMacroDeriveParser {
     const PATH: &[Symbol] = &[sym::proc_macro_derive];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
-    const ALLOWED_TARGETS: AllowedTargets =
-        AllowedTargets::AllowList(&[Allow(Target::Fn), Warn(Target::Crate)]);
+    const ALLOWED_TARGETS: AllowedTargets = PROC_MACRO_ALLOWED_TARGETS;
     const TEMPLATE: AttributeTemplate = template!(
         List: &["TraitName", "TraitName, attributes(name1, name2, ...)"],
         "https://doc.rust-lang.org/reference/procedural-macros.html#derive-macros"

compiler/rustc_expand/src/expand.rs

@@ -2185,6 +2185,11 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                     BuiltinLintDiag::UnusedDocComment(attr.span),
                 );
             } else if rustc_attr_parsing::is_builtin_attr(attr) {
+                // FIXME: We currently cannot emit lints here from the early stage, which is needed to emit warnings for
+                // emitting the unused warning on macro calls. As a temporary warning the unused lint is still emitted here,
+                // even for parsed attributes.
+                // We should add an exception for parsed attributes here (and remove this check entirely, eventually).
+
                 let attr_name = attr.ident().unwrap().name;
                 // `#[cfg]` and `#[cfg_attr]` are special - they are
                 // eagerly evaluated.