Rewrite target checking of rustc_dummy

compiler/rustc_attr_parsing/src/attributes/dummy.rs

@@ -5,20 +5,21 @@ use rustc_span::{Symbol, sym};
 use crate::attributes::{OnDuplicate, SingleAttributeParser};
 use crate::context::AcceptContext;
 use crate::parser::ArgParser;
-use crate::target_checking::{ALL_TARGETS, AllowedTargets};
+use crate::target_checking::AllowedTargets;
 use crate::unstable;
 
 pub(crate) struct RustcDummyParser;
 impl SingleAttributeParser for RustcDummyParser {
     const PATH: &[Symbol] = &[sym::rustc_dummy];
     const ON_DUPLICATE: OnDuplicate = OnDuplicate::Ignore;
-    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS);
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::ManuallyChecked;
     const TEMPLATE: AttributeTemplate = template!(Word); // Anything, really
     const STABILITY: AttributeStability =
         unstable!(rustc_attrs, "the `#[rustc_dummy]` attribute is used for rustc unit tests");
 
-    fn convert(_: &mut AcceptContext<'_, '_>, args: &ArgParser) -> Option<AttributeKind> {
+    fn convert(cx: &mut AcceptContext<'_, '_>, args: &ArgParser) -> Option<AttributeKind> {
         args.ignore_args();
+        cx.ignore_target_checks();
         Some(AttributeKind::RustcDummy)
     }
 }

compiler/rustc_attr_parsing/src/target_checking.rs

@@ -422,11 +422,15 @@ impl<'f, 'sess> AcceptContext<'f, 'sess> {
         attribute_args: &'static str,
         allowed_targets: &AllowedTargets,
     ) {
+        self.ignore_target_checks();
+        AttributeParser::check_target(allowed_targets, attribute_args, self);
+    }
+
+    pub(crate) fn ignore_target_checks(&mut self) {
         #[cfg(debug_assertions)]
         {
             self.has_target_been_checked = true;
         }
-        AttributeParser::check_target(allowed_targets, attribute_args, self);
     }
 }