fix: Error on illegal `[const]`s inside blocks within legal positions

3 files changed, 55 insertions, 16 deletions

diff --git a/compiler/rustc_ast_passes/messages.ftl b/compiler/rustc_ast_passes/messages.ftl
index af93d55c898..42f3569f0f1 100644
--- a/compiler/rustc_ast_passes/messages.ftl
+++ b/compiler/rustc_ast_passes/messages.ftl
@@ -241,6 +241,10 @@ ast_passes_tilde_const_disallowed = `[const]` is not allowed here
     .trait_assoc_ty = associated types in non-`const` traits cannot have `[const]` trait bounds
     .trait_impl_assoc_ty = associated types in non-const impls cannot have `[const]` trait bounds
     .inherent_assoc_ty = inherent associated types cannot have `[const]` trait bounds
+    .struct = structs cannot have `[const]` trait bounds
+    .enum = enums cannot have `[const]` trait bounds
+    .union = unions cannot have `[const]` trait bounds
+    .anon_const = anonymous constants cannot have `[const]` trait bounds
     .object = trait objects cannot have `[const]` trait bounds
     .item = this item cannot have `[const]` trait bounds
 
diff --git a/compiler/rustc_ast_passes/src/ast_validation.rs b/compiler/rustc_ast_passes/src/ast_validation.rs
index 895a457ec1d..ae482ceb9b7 100644
--- a/compiler/rustc_ast_passes/src/ast_validation.rs
+++ b/compiler/rustc_ast_passes/src/ast_validation.rs
@@ -1124,7 +1124,9 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                         );
                     }
                 }
-                visit::walk_item(self, item)
+                self.with_tilde_const(Some(TildeConstReason::Enum { span: item.span }), |this| {
+                    visit::walk_item(this, item)
+                });
             }
             ItemKind::Trait(box Trait {
                 constness,
@@ -1175,26 +1177,32 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                 }
                 visit::walk_item(self, item)
             }
-            ItemKind::Struct(ident, generics, vdata) => match vdata {
-                VariantData::Struct { fields, .. } => {
-                    self.visit_attrs_vis_ident(&item.attrs, &item.vis, ident);
-                    self.visit_generics(generics);
-                    walk_list!(self, visit_field_def, fields);
-                }
-                _ => visit::walk_item(self, item),
-            },
+            ItemKind::Struct(ident, generics, vdata) => {
+                self.with_tilde_const(Some(TildeConstReason::Struct { span: item.span }), |this| {
+                    match vdata {
+                        VariantData::Struct { fields, .. } => {
+                            this.visit_attrs_vis_ident(&item.attrs, &item.vis, ident);
+                            this.visit_generics(generics);
+                            walk_list!(this, visit_field_def, fields);
+                        }
+                        _ => visit::walk_item(this, item),
+                    }
+                })
+            }
             ItemKind::Union(ident, generics, vdata) => {
                 if vdata.fields().is_empty() {
                     self.dcx().emit_err(errors::FieldlessUnion { span: item.span });
                 }
-                match vdata {
-                    VariantData::Struct { fields, .. } => {
-                        self.visit_attrs_vis_ident(&item.attrs, &item.vis, ident);
-                        self.visit_generics(generics);
-                        walk_list!(self, visit_field_def, fields);
+                self.with_tilde_const(Some(TildeConstReason::Union { span: item.span }), |this| {
+                    match vdata {
+                        VariantData::Struct { fields, .. } => {
+                            this.visit_attrs_vis_ident(&item.attrs, &item.vis, ident);
+                            this.visit_generics(generics);
+                            walk_list!(this, visit_field_def, fields);
+                        }
+                        _ => visit::walk_item(this, item),
                     }
-                    _ => visit::walk_item(self, item),
-                }
+                });
             }
             ItemKind::Const(box ConstItem { defaultness, expr, .. }) => {
                 self.check_defaultness(item.span, *defaultness);
@@ -1623,6 +1631,13 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
             _ => self.with_in_trait_impl(None, |this| visit::walk_assoc_item(this, item, ctxt)),
         }
     }
+
+    fn visit_anon_const(&mut self, anon_const: &'a AnonConst) {
+        self.with_tilde_const(
+            Some(TildeConstReason::AnonConst { span: anon_const.value.span }),
+            |this| visit::walk_anon_const(this, anon_const),
+        )
+    }
 }
 
 /// When encountering an equality constraint in a `where` clause, emit an error. If the code seems
diff --git a/compiler/rustc_ast_passes/src/errors.rs b/compiler/rustc_ast_passes/src/errors.rs
index fd4b2528541..8b5873a3ef3 100644
--- a/compiler/rustc_ast_passes/src/errors.rs
+++ b/compiler/rustc_ast_passes/src/errors.rs
@@ -623,6 +623,26 @@ pub(crate) enum TildeConstReason {
         #[primary_span]
         span: Span,
     },
+    #[note(ast_passes_struct)]
+    Struct {
+        #[primary_span]
+        span: Span,
+    },
+    #[note(ast_passes_enum)]
+    Enum {
+        #[primary_span]
+        span: Span,
+    },
+    #[note(ast_passes_union)]
+    Union {
+        #[primary_span]
+        span: Span,
+    },
+    #[note(ast_passes_anon_const)]
+    AnonConst {
+        #[primary_span]
+        span: Span,
+    },
     #[note(ast_passes_object)]
     TraitObject,
     #[note(ast_passes_item)]