Address review comments

compiler/rustc_feature/src/builtin_attrs.rs

@@ -251,7 +251,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     // Modules, prelude, and resolution:
     ungated!(path, Normal, template!(NameValueStr: "file")),
     ungated!(no_std, CrateLevel, template!(Word)),
-    ungated!(no_implicit_prelude, CrateLevel, template!(Word)),
+    ungated!(no_implicit_prelude, Normal, template!(Word)),
     ungated!(non_exhaustive, Normal, template!(Word)),
 
     // Runtime

compiler/rustc_passes/src/check_attr.rs

@@ -130,6 +130,12 @@ impl CheckAttrVisitor<'tcx> {
                 sym::ignore | sym::should_panic | sym::proc_macro_derive => {
                     self.check_generic_attr(hir_id, attr, target, &[Target::Fn])
                 }
+                sym::automatically_derived => {
+                    self.check_generic_attr(hir_id, attr, target, &[Target::Impl])
+                }
+                sym::no_implicit_prelude => {
+                    self.check_generic_attr(hir_id, attr, target, &[Target::Mod])
+                }
                 _ => {}
             }
 
@@ -290,7 +296,6 @@ impl CheckAttrVisitor<'tcx> {
                 b.push_str(&(allowed_target.to_string() + "s"));
                 b
             });
-            //let supported_names = allowed_targets.iter().fold(String::new(), |msg, t| msg + ", " + &t.to_string());
             self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
                 lint.build(&format!("`#[{name}]` only has an effect on {}", supported_names))
                     .emit();

src/test/ui/feature-gates/issue-43106-gating-of-builtin-attrs.rs

@@ -275,18 +275,20 @@ mod path {
     //~^ WARN `#[path]` only has an effect
 }
 
-// Don't warn on `automatically_derived` - a custom derive
-// could reasonally annotate anything that it emits with
-// this attribute
 #[automatically_derived]
+//~^ WARN `#[automatically_derived]` only has an effect
 mod automatically_derived {
     mod inner { #![automatically_derived] }
+    //~^ WARN `#[automatically_derived]
 
     #[automatically_derived] fn f() { }
+    //~^ WARN `#[automatically_derived]
 
     #[automatically_derived] struct S;
+    //~^ WARN `#[automatically_derived]
 
     #[automatically_derived] type T = S;
+    //~^ WARN `#[automatically_derived]
 
     #[automatically_derived] impl S { }
 }
@@ -368,22 +370,20 @@ mod ignore {
 }
 
 #[no_implicit_prelude]
-//~^ WARN crate-level attribute
 mod no_implicit_prelude {
     mod inner { #![no_implicit_prelude] }
-    //~^ WARN crate-level attribute
 
     #[no_implicit_prelude] fn f() { }
-    //~^ WARN crate-level attribute
+    //~^ WARN `#[no_implicit_prelude]` only has an effect
 
     #[no_implicit_prelude] struct S;
-    //~^ WARN crate-level attribute
+    //~^ WARN `#[no_implicit_prelude]` only has an effect
 
     #[no_implicit_prelude] type T = S;
-    //~^ WARN crate-level attribute
+    //~^ WARN `#[no_implicit_prelude]` only has an effect
 
     #[no_implicit_prelude] impl S { }
-    //~^ WARN crate-level attribute
+    //~^ WARN `#[no_implicit_prelude]` only has an effect
 }
 
 #[reexport_test_harness_main = "2900"]