Fix deprecation attributes on foreign statics

compiler/rustc_attr_parsing/src/attributes/deprecation.rs

@@ -54,6 +54,8 @@ impl<S: Stage> SingleAttributeParser<S> for DeprecationParser {
         Allow(Target::TyAlias),
         Allow(Target::Use),
         Allow(Target::ForeignFn),
+        Allow(Target::ForeignStatic),
+        Allow(Target::ForeignTy),
         Allow(Target::Field),
         Allow(Target::Trait),
         Allow(Target::AssocTy),

compiler/rustc_attr_parsing/src/context.rs

@@ -1060,6 +1060,9 @@ pub(crate) fn allowed_targets_applied(
         if !features.stmt_expr_attributes() {
             allowed_targets.retain(|t| !matches!(t, Target::Expression | Target::Statement));
         }
+        if !features.extern_types() {
+            allowed_targets.retain(|t| !matches!(t, Target::ForeignTy));
+        }
     }
 
     // We define groups of "similar" targets.

tests/ui/deprecation/deprecation-sanity.rs

@@ -42,4 +42,9 @@ impl Default for X {
     }
 }
 
+unsafe extern "C" {
+    #[deprecated]
+    static FOO: std::ffi::c_int;
+}
+
 fn main() { }

tests/ui/deprecation/deprecation-sanity.stderr

@@ -177,7 +177,7 @@ LL | #[deprecated = "hello"]
    | ^^^^^^^^^^^^^^^^^^^^^^^
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = help: `#[deprecated]` can be applied to functions, data types, modules, unions, constants, statics, macro defs, type aliases, use statements, struct fields, traits, associated types, associated consts, enum variants, inherent impl blocks, crates
+   = help: `#[deprecated]` can be applied to functions, data types, modules, unions, constants, statics, macro defs, type aliases, use statements, foreign statics, struct fields, traits, associated types, associated consts, enum variants, inherent impl blocks, crates
    = note: `#[deny(useless_deprecated)]` on by default
 
 error: aborting due to 10 previous errors

tests/ui/where-clauses/unsupported_attribute.stderr

@@ -64,15 +64,15 @@ error: `#[deprecated]` attribute cannot be used on where predicates
 LL |     #[deprecated] T: Trait,
    |     ^^^^^^^^^^^^^
    |
-   = help: `#[deprecated]` can be applied to functions, data types, modules, unions, constants, statics, macro defs, type aliases, use statements, struct fields, traits, associated types, associated consts, enum variants, inherent impl blocks, crates
+   = help: `#[deprecated]` can be applied to functions, data types, modules, unions, constants, statics, macro defs, type aliases, use statements, foreign statics, struct fields, traits, associated types, associated consts, enum variants, inherent impl blocks, crates
 
 error: `#[deprecated]` attribute cannot be used on where predicates
   --> $DIR/unsupported_attribute.rs:25:5
    |
 LL |     #[deprecated] 'a: 'static,
    |     ^^^^^^^^^^^^^
    |
-   = help: `#[deprecated]` can be applied to functions, data types, modules, unions, constants, statics, macro defs, type aliases, use statements, struct fields, traits, associated types, associated consts, enum variants, inherent impl blocks, crates
+   = help: `#[deprecated]` can be applied to functions, data types, modules, unions, constants, statics, macro defs, type aliases, use statements, foreign statics, struct fields, traits, associated types, associated consts, enum variants, inherent impl blocks, crates
 
 error: `#[automatically_derived]` attribute cannot be used on where predicates
   --> $DIR/unsupported_attribute.rs:26:5