Structured suggestion for missing mut/const in pointer

compiler/rustc_parse/src/parser/ty.rs

@@ -397,10 +397,13 @@ impl<'a> Parser<'a> {
     fn parse_ty_ptr(&mut self) -> PResult<'a, TyKind> {
         let mutbl = self.parse_const_or_mut().unwrap_or_else(|| {
             let span = self.prev_token.span;
-            let msg = "expected mut or const in raw pointer type";
-            self.struct_span_err(span, msg)
-                .span_label(span, msg)
-                .help("use `*mut T` or `*const T` as appropriate")
+            self.struct_span_err(span, "expected `mut` or `const` keyword in raw pointer type")
+                .span_suggestions(
+                    span.shrink_to_hi(),
+                    "add `mut` or `const` here",
+                    ["mut ".to_string(), "const ".to_string()].into_iter(),
+                    Applicability::HasPlaceholders,
+                )
                 .emit();
             Mutability::Not
         });