Make rustc_deny_explicit_impl only local as well

Author: compiler-errors

compiler/rustc_feature/src/builtin_attrs.rs

@@ -705,7 +705,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         "#[rustc_allow_incoherent_impl] has to be added to all impl items of an incoherent inherent impl."
     ),
     rustc_attr!(
-        rustc_deny_explicit_impl, AttributeType::Normal, template!(Word), ErrorFollowing, @only_local: false,
+        rustc_deny_explicit_impl, AttributeType::Normal, template!(Word), ErrorFollowing, @only_local: true,
         "#[rustc_deny_explicit_impl] enforces that a trait can have no user-provided impls"
     ),
     rustc_attr!(

compiler/rustc_hir_analysis/src/coherence/mod.rs

@@ -10,7 +10,6 @@ use rustc_errors::{error_code, struct_span_err};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::query::Providers;
 use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt};
-use rustc_span::sym;
 use rustc_trait_selection::traits;
 
 mod builtin;
@@ -44,7 +43,7 @@ fn enforce_trait_manually_implementable(
     let impl_header_span = tcx.def_span(impl_def_id);
 
     // Disallow *all* explicit impls of traits marked `#[rustc_deny_explicit_impl]`
-    if tcx.has_attr(trait_def_id, sym::rustc_deny_explicit_impl) {
+    if tcx.trait_def(trait_def_id).deny_explicit_impl {
         let trait_name = tcx.item_name(trait_def_id);
         let mut err = struct_span_err!(
             tcx.sess,

compiler/rustc_hir_analysis/src/collect.rs

@@ -986,6 +986,7 @@ fn trait_def(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::TraitDef {
             no_dups.then_some(list)
         });
     let do_not_implement_via_object = tcx.has_attr(def_id, sym::rustc_do_not_implement_via_object);
+    let deny_explicit_impl = tcx.has_attr(def_id, sym::rustc_deny_explicit_impl);
 
     ty::TraitDef {
         def_id: def_id.to_def_id(),
@@ -997,7 +998,8 @@ fn trait_def(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::TraitDef {
         skip_array_during_method_dispatch,
         specialization_kind,
         must_implement_one_of,
-        do_not_implement_via_object,
+        implement_via_object,
+        deny_explicit_impl,
     }
 }
 

compiler/rustc_middle/src/ty/trait_def.rs

@@ -57,6 +57,9 @@ pub struct TraitDef {
     /// denied. This only applies to built-in trait, and is marked via
     /// `#[rustc_do_not_implement_via_object]`.
     pub do_not_implement_via_object: bool,
+
+    /// Whether a trait is fully built-in, and any implementation is disallowed.
+    pub deny_explicit_impl: bool,
 }
 
 /// Whether this trait is treated specially by the standard library