Tweak wording of missing angle backets in qualified path

compiler/rustc_parse/messages.ftl

@@ -509,7 +509,7 @@ parse_maybe_fn_typo_with_impl = you might have meant to write `impl` instead of
 
 parse_maybe_recover_from_bad_qpath_stage_2 =
     missing angle brackets in associated item path
-    .suggestion = try: `{$ty}`
+    .suggestion = types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
 
 parse_maybe_recover_from_bad_type_plus =
     expected a path on the left-hand side of `+`, not `{$ty}`

compiler/rustc_parse/src/errors.rs

@@ -59,9 +59,18 @@ pub(crate) enum BadTypePlusSub {
 #[diag(parse_maybe_recover_from_bad_qpath_stage_2)]
 pub(crate) struct BadQPathStage2 {
     #[primary_span]
-    #[suggestion(code = "", applicability = "maybe-incorrect")]
     pub span: Span,
-    pub ty: String,
+    #[subdiagnostic]
+    pub wrap: WrapType,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(parse_suggestion, applicability = "machine-applicable")]
+pub(crate) struct WrapType {
+    #[suggestion_part(code = "<")]
+    pub lo: Span,
+    #[suggestion_part(code = ">")]
+    pub hi: Span,
 }
 
 #[derive(Diagnostic)]

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -16,7 +16,7 @@ use crate::errors::{
     StructLiteralBodyWithoutPath, StructLiteralBodyWithoutPathSugg, StructLiteralNeedingParens,
     StructLiteralNeedingParensSugg, SuggAddMissingLetStmt, SuggEscapeIdentifier, SuggRemoveComma,
     TernaryOperator, UnexpectedConstInGenericParam, UnexpectedConstParamDeclaration,
-    UnexpectedConstParamDeclarationSugg, UnmatchedAngleBrackets, UseEqInstead,
+    UnexpectedConstParamDeclarationSugg, UnmatchedAngleBrackets, UseEqInstead, WrapType,
 };
 
 use crate::fluent_generated as fluent;
@@ -1589,10 +1589,9 @@ impl<'a> Parser<'a> {
         self.parse_path_segments(&mut path.segments, T::PATH_STYLE, None)?;
         path.span = ty_span.to(self.prev_token.span);
 
-        let ty_str = self.span_to_snippet(ty_span).unwrap_or_else(|_| pprust::ty_to_string(&ty));
         self.sess.emit_err(BadQPathStage2 {
-            span: path.span,
+            span: ty_span,
-            ty: format!("<{}>::{}", ty_str, pprust::path_to_string(&path)),
+            wrap: WrapType { lo: ty_span.shrink_to_lo(), hi: ty_span.shrink_to_hi() },
         });
 
         let path_span = ty_span.shrink_to_hi(); // Use an empty path since `position == 0`.

tests/ui/did_you_mean/bad-assoc-expr.stderr

@@ -2,60 +2,104 @@ error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-expr.rs:3:5
    |
 LL |     [i32; 4]::clone(&a);
-   |     ^^^^^^^^^^^^^^^ help: try: `<[i32; 4]>::clone`
+   |     ^^^^^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |     <[i32; 4]>::clone(&a);
+   |     +        +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-expr.rs:6:5
    |
 LL |     [i32]::as_ref(&a);
-   |     ^^^^^^^^^^^^^ help: try: `<[i32]>::as_ref`
+   |     ^^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |     <[i32]>::as_ref(&a);
+   |     +     +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-expr.rs:9:5
    |
 LL |     (u8)::clone(&0);
-   |     ^^^^^^^^^^^ help: try: `<(u8)>::clone`
+   |     ^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |     <(u8)>::clone(&0);
+   |     +    +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-expr.rs:12:5
    |
 LL |     (u8, u8)::clone(&(0, 0));
-   |     ^^^^^^^^^^^^^^^ help: try: `<(u8, u8)>::clone`
+   |     ^^^^^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |     <(u8, u8)>::clone(&(0, 0));
+   |     +        +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-expr.rs:15:6
    |
 LL |     &(u8)::clone(&0);
-   |      ^^^^^^^^^^^ help: try: `<(u8)>::clone`
+   |      ^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |     &<(u8)>::clone(&0);
+   |      +    +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-expr.rs:18:10
    |
 LL |     10 + (u8)::clone(&0);
-   |          ^^^^^^^^^^^ help: try: `<(u8)>::clone`
+   |          ^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |     10 + <(u8)>::clone(&0);
+   |          +    +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-expr.rs:32:13
    |
 LL |     let _ = ty!()::clone(&0);
-   |             ^^^^^^^^^^^^ help: try: `<ty!()>::clone`
+   |             ^^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |     let _ = <ty!()>::clone(&0);
+   |             +     +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-expr.rs:34:5
    |
 LL |     ty!()::clone(&0);
-   |     ^^^^^^^^^^^^ help: try: `<ty!()>::clone`
+   |     ^^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |     <ty!()>::clone(&0);
+   |     +     +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-expr.rs:23:19
    |
 LL |     ($ty: ty) => ($ty::clone(&0))
-   |                   ^^^^^^^^^^ help: try: `<$ty>::clone`
+   |                   ^^^
 ...
 LL |     expr!(u8);
    |     --------- in this macro invocation
    |
    = note: this error originates in the macro `expr` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |     ($ty: ty) => (<$ty>::clone(&0))
+   |                   +   +
 
 error: aborting due to 9 previous errors
 

tests/ui/did_you_mean/bad-assoc-pat.stderr

@@ -2,42 +2,71 @@ error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-pat.rs:3:9
    |
 LL |         [u8]::AssocItem => {}
-   |         ^^^^^^^^^^^^^^^ help: try: `<[u8]>::AssocItem`
+   |         ^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |         <[u8]>::AssocItem => {}
+   |         +    +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-pat.rs:6:9
    |
 LL |         (u8, u8)::AssocItem => {}
-   |         ^^^^^^^^^^^^^^^^^^^ help: try: `<(u8, u8)>::AssocItem`
+   |         ^^^^^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |         <(u8, u8)>::AssocItem => {}
+   |         +        +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-pat.rs:9:9
    |
 LL |         _::AssocItem => {}
-   |         ^^^^^^^^^^^^ help: try: `<_>::AssocItem`
+   |         ^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |         <_>::AssocItem => {}
+   |         + +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-pat.rs:14:10
    |
 LL |         &(u8,)::AssocItem => {}
-   |          ^^^^^^^^^^^^^^^^ help: try: `<(u8,)>::AssocItem`
+   |          ^^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |         &<(u8,)>::AssocItem => {}
+   |          +     +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-pat.rs:32:9
    |
 LL |         ty!()::AssocItem => {}
-   |         ^^^^^^^^^^^^^^^^ help: try: `<ty!()>::AssocItem`
+   |         ^^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |         <ty!()>::AssocItem => {}
+   |         +     +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-pat.rs:21:19
    |
 LL |     ($ty: ty) => ($ty::AssocItem)
-   |                   ^^^^^^^^^^^^^^ help: try: `<$ty>::AssocItem`
+   |                   ^^^
 ...
 LL |         pat!(u8) => {}
    |         -------- in this macro invocation
    |
    = note: this error originates in the macro `pat` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |     ($ty: ty) => (<$ty>::AssocItem)
+   |                   +   +
 
 error[E0599]: no associated item named `AssocItem` found for slice `[u8]` in the current scope
   --> $DIR/bad-assoc-pat.rs:3:15

tests/ui/did_you_mean/bad-assoc-ty.stderr

@@ -2,60 +2,104 @@ error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-ty.rs:1:10
    |
 LL | type A = [u8; 4]::AssocTy;
-   |          ^^^^^^^^^^^^^^^^ help: try: `<[u8; 4]>::AssocTy`
+   |          ^^^^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL | type A = <[u8; 4]>::AssocTy;
+   |          +       +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-ty.rs:5:10
    |
 LL | type B = [u8]::AssocTy;
-   |          ^^^^^^^^^^^^^ help: try: `<[u8]>::AssocTy`
+   |          ^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL | type B = <[u8]>::AssocTy;
+   |          +    +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-ty.rs:9:10
    |
 LL | type C = (u8)::AssocTy;
-   |          ^^^^^^^^^^^^^ help: try: `<(u8)>::AssocTy`
+   |          ^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL | type C = <(u8)>::AssocTy;
+   |          +    +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-ty.rs:13:10
    |
 LL | type D = (u8, u8)::AssocTy;
-   |          ^^^^^^^^^^^^^^^^^ help: try: `<(u8, u8)>::AssocTy`
+   |          ^^^^^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL | type D = <(u8, u8)>::AssocTy;
+   |          +        +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-ty.rs:17:10
    |
 LL | type E = _::AssocTy;
-   |          ^^^^^^^^^^ help: try: `<_>::AssocTy`
+   |          ^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL | type E = <_>::AssocTy;
+   |          + +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-ty.rs:21:19
    |
 LL | type F = &'static (u8)::AssocTy;
-   |                   ^^^^^^^^^^^^^ help: try: `<(u8)>::AssocTy`
+   |                   ^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL | type F = &'static <(u8)>::AssocTy;
+   |                   +    +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-ty.rs:27:10
    |
 LL | type G = dyn 'static + (Send)::AssocTy;
-   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `<dyn 'static + (Send)>::AssocTy`
+   |          ^^^^^^^^^^^^^^^^^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL | type G = <dyn 'static + (Send)>::AssocTy;
+   |          +                    +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-ty.rs:46:10
    |
 LL | type I = ty!()::AssocTy;
-   |          ^^^^^^^^^^^^^^ help: try: `<ty!()>::AssocTy`
+   |          ^^^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL | type I = <ty!()>::AssocTy;
+   |          +     +
 
 error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-ty.rs:39:19
    |
 LL |     ($ty: ty) => ($ty::AssocTy);
-   |                   ^^^^^^^^^^^^ help: try: `<$ty>::AssocTy`
+   |                   ^^^
 ...
 LL | type J = ty!(u8);
    |          ------- in this macro invocation
    |
    = note: this error originates in the macro `ty` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |     ($ty: ty) => (<$ty>::AssocTy);
+   |                   +   +
 
 error[E0223]: ambiguous associated type
   --> $DIR/bad-assoc-ty.rs:1:10

tests/ui/parser/issues/issue-89388.stderr

@@ -2,7 +2,12 @@ error: missing angle brackets in associated item path
   --> $DIR/issue-89388.rs:5:24
    |
 LL |     let _ = option.map([_]::to_vec);
-   |                        ^^^^^^^^^^^ help: try: `<[_]>::to_vec`
+   |                        ^^^
+   |
+help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
+   |
+LL |     let _ = option.map(<[_]>::to_vec);
+   |                        +   +
 
 error: aborting due to previous error