Rollup merge of #123841 - Kohei316:remove_qualifier_sugg, r=wesleywiser

Improve diagnostic by suggesting to remove visibility qualifier

Resolves #123529
This PR improve diagnostic by suggesting to remove visibility qualifier.

Author: matthiaskrgr

compiler/rustc_ast_passes/messages.ftl

@@ -273,6 +273,7 @@ ast_passes_visibility_not_permitted =
     .trait_impl = trait items always share the visibility of their trait
     .individual_impl_items = place qualifiers on individual impl items instead
     .individual_foreign_items = place qualifiers on individual foreign items instead
+    .remove_qualifier_sugg = remove the qualifier
 
 ast_passes_where_clause_after_type_alias = where clauses are not allowed after the type for type aliases
     .note = see issue #112792 <https://github.com/rust-lang/rust/issues/112792> for more information

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -266,7 +266,11 @@ impl<'a> AstValidator<'a> {
             return;
         }
 
-        self.dcx().emit_err(errors::VisibilityNotPermitted { span: vis.span, note });
+        self.dcx().emit_err(errors::VisibilityNotPermitted {
+            span: vis.span,
+            note,
+            remove_qualifier_sugg: vis.span,
+        });
     }
 
     fn check_decl_no_pat(decl: &FnDecl, mut report_err: impl FnMut(Span, Option<Ident>, bool)) {

compiler/rustc_ast_passes/src/errors.rs

@@ -31,6 +31,12 @@ pub struct VisibilityNotPermitted {
     pub span: Span,
     #[subdiagnostic]
     pub note: VisibilityNotPermittedNote,
+    #[suggestion(
+        ast_passes_remove_qualifier_sugg,
+        code = "",
+        applicability = "machine-applicable"
+    )]
+    pub remove_qualifier_sugg: Span,
 }
 
 #[derive(Subdiagnostic)]

tests/ui/error-codes/E0449.fixed

@@ -0,0 +1,18 @@
+//@ run-rustfix
+
+#![allow(warnings)]
+
+struct Bar;
+
+trait Foo {
+    fn foo();
+}
+
+ impl Bar {} //~ ERROR E0449
+
+ impl Foo for Bar { //~ ERROR E0449
+     fn foo() {} //~ ERROR E0449
+}
+
+fn main() {
+}

tests/ui/error-codes/E0449.rs

@@ -1,3 +1,7 @@
+//@ run-rustfix
+
+#![allow(warnings)]
+
 struct Bar;
 
 trait Foo {

tests/ui/error-codes/E0449.stderr

@@ -1,24 +1,24 @@
 error[E0449]: visibility qualifiers are not permitted here
-  --> $DIR/E0449.rs:7:1
+  --> $DIR/E0449.rs:11:1
    |
 LL | pub impl Bar {}
-   | ^^^
+   | ^^^ help: remove the qualifier
    |
    = note: place qualifiers on individual impl items instead
 
 error[E0449]: visibility qualifiers are not permitted here
-  --> $DIR/E0449.rs:9:1
+  --> $DIR/E0449.rs:13:1
    |
 LL | pub impl Foo for Bar {
-   | ^^^
+   | ^^^ help: remove the qualifier
    |
    = note: trait items always share the visibility of their trait
 
 error[E0449]: visibility qualifiers are not permitted here
-  --> $DIR/E0449.rs:10:5
+  --> $DIR/E0449.rs:14:5
    |
 LL |     pub fn foo() {}
-   |     ^^^
+   |     ^^^ help: remove the qualifier
    |
    = note: trait items always share the visibility of their trait
 

tests/ui/issues/issue-28433.stderr

@@ -2,15 +2,15 @@ error[E0449]: visibility qualifiers are not permitted here
   --> $DIR/issue-28433.rs:2:5
    |
 LL |     pub Duck,
-   |     ^^^
+   |     ^^^ help: remove the qualifier
    |
    = note: enum variants and their fields always share the visibility of the enum they are in
 
 error[E0449]: visibility qualifiers are not permitted here
   --> $DIR/issue-28433.rs:5:5
    |
 LL |     pub(crate) Dove
-   |     ^^^^^^^^^^
+   |     ^^^^^^^^^^ help: remove the qualifier
    |
    = note: enum variants and their fields always share the visibility of the enum they are in
 

tests/ui/parser/assoc/assoc-static-semantic-fail.stderr

@@ -138,7 +138,7 @@ error[E0449]: visibility qualifiers are not permitted here
   --> $DIR/assoc-static-semantic-fail.rs:32:5
    |
 LL |     pub(crate) default static TD: u8;
-   |     ^^^^^^^^^^
+   |     ^^^^^^^^^^ help: remove the qualifier
    |
    = note: trait items always share the visibility of their trait
 
@@ -162,7 +162,7 @@ error[E0449]: visibility qualifiers are not permitted here
   --> $DIR/assoc-static-semantic-fail.rs:47:5
    |
 LL |     pub default static TD: u8;
-   |     ^^^
+   |     ^^^ help: remove the qualifier
    |
    = note: trait items always share the visibility of their trait
 

tests/ui/parser/default.stderr

@@ -21,7 +21,7 @@ error[E0449]: visibility qualifiers are not permitted here
   --> $DIR/default.rs:17:5
    |
 LL |     pub default fn foo<T: Default>() -> T {
-   |     ^^^
+   |     ^^^ help: remove the qualifier
    |
    = note: trait items always share the visibility of their trait
 

tests/ui/parser/trait-pub-assoc-const.stderr

@@ -2,7 +2,7 @@ error[E0449]: visibility qualifiers are not permitted here
   --> $DIR/trait-pub-assoc-const.rs:2:5
    |
 LL |     pub const Foo: u32;
-   |     ^^^
+   |     ^^^ help: remove the qualifier
    |
    = note: trait items always share the visibility of their trait