migrate maybe_recover_from_bad_qpath_stage_2 diagnostic

compiler/rustc_error_messages/locales/en-US/parser.ftl

@@ -14,3 +14,7 @@ parser-add-paren = try adding parentheses
 parser-forgot-paren = perhaps you forgot parentheses?
 
 parser-expect-path = expected a path
+
+parser-maybe-recover-from-bad-qpath-stage-2 =
+    missing angle brackets in associated item path
+    .suggestion = try: `{$ty}`

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -286,6 +286,15 @@ pub enum BadTypePlusSub {
     },
 }
 
+#[derive(SessionDiagnostic)]
+#[error(slug = "parser-maybe-recover-from-bad-qpath-stage-2")]
+struct BadQPathStage2 {
+    #[primary_span]
+    #[suggestion(applicability = "maybe-incorrect")]
+    span: Span,
+    ty: String,
+}
+
 // SnapshotParser is used to create a snapshot of the parser
 // without causing duplicate errors being emitted when the `Parser`
 // is dropped.
@@ -1469,15 +1478,10 @@ impl<'a> Parser<'a> {
         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.struct_span_err(path.span, "missing angle brackets in associated item path")
+        self.sess.emit_err(BadQPathStage2 {
-            .span_suggestion(
+            span: path.span,
-                // This is a best-effort recovery.
+            ty: format!("<{}>::{}", ty_str, pprust::path_to_string(&path)),
-                path.span,
+        });
-                "try",
-                format!("<{}>::{}", ty_str, pprust::path_to_string(&path)),
-                Applicability::MaybeIncorrect,
-            )
-            .emit();
 
         let path_span = ty_span.shrink_to_hi(); // Use an empty path since `position == 0`.
         Ok(P(T::recovered(Some(QSelf { ty, path_span, position: 0 }), path)))