Smaller span for unnessary mut suggestion

Author: estebank

compiler/rustc_parse/src/errors.rs

@@ -2278,9 +2278,8 @@ pub(crate) enum InvalidMutInPattern {
     #[note(parse_note_mut_pattern_usage)]
     NonIdent {
         #[primary_span]
-        #[suggestion(code = "{pat}", applicability = "machine-applicable")]
+        #[suggestion(code = "", applicability = "machine-applicable")]
         span: Span,
-        pat: String,
     },
 }
 

compiler/rustc_parse/src/parser/pat.rs

@@ -638,13 +638,13 @@ impl<'a> Parser<'a> {
 
     /// Error on `mut $pat` where `$pat` is not an ident.
     fn ban_mut_general_pat(&self, lo: Span, pat: &Pat, changed_any_binding: bool) {
-        let span = lo.to(pat.span);
-        let pat = pprust::pat_to_string(&pat);
-
         self.sess.emit_err(if changed_any_binding {
-            InvalidMutInPattern::NestedIdent { span, pat }
+            InvalidMutInPattern::NestedIdent {
+                span: lo.to(pat.span),
+                pat: pprust::pat_to_string(&pat),
+            }
         } else {
-            InvalidMutInPattern::NonIdent { span, pat }
+            InvalidMutInPattern::NonIdent { span: lo.until(pat.span) }
         });
     }
 

tests/ui/parser/issues/issue-32501.stderr

@@ -2,7 +2,7 @@ error: `mut` must be followed by a named binding
   --> $DIR/issue-32501.rs:7:9
    |
 LL |     let mut _ = 0;
-   |         ^^^^^ help: remove the `mut` prefix: `_`
+   |         ^^^^ help: remove the `mut` prefix
    |
    = note: `mut` may be followed by `variable` and `variable @ pattern`
 

tests/ui/parser/issues/issue-65122-mac-invoc-in-mut-patterns.stderr

@@ -2,7 +2,7 @@ error: `mut` must be followed by a named binding
   --> $DIR/issue-65122-mac-invoc-in-mut-patterns.rs:6:13
    |
 LL |         let mut $eval = ();
-   |             ^^^^^^^^^ help: remove the `mut` prefix: `does_not_exist!()`
+   |             ^^^^ help: remove the `mut` prefix
 ...
 LL |     mac1! { does_not_exist!() }
    |     --------------------------- in this macro invocation
@@ -25,7 +25,7 @@ error: `mut` must be followed by a named binding
   --> $DIR/issue-65122-mac-invoc-in-mut-patterns.rs:13:13
    |
 LL |         let mut $eval = ();
-   |             ^^^ help: remove the `mut` prefix: `does_not_exist!()`
+   |             ^^^ help: remove the `mut` prefix
 ...
 LL |     mac2! { does_not_exist!() }
    |     --------------------------- in this macro invocation

tests/ui/parser/mut-patterns.stderr

@@ -2,15 +2,15 @@ error: `mut` must be followed by a named binding
   --> $DIR/mut-patterns.rs:9:9
    |
 LL |     let mut _ = 0;
-   |         ^^^^^ help: remove the `mut` prefix: `_`
+   |         ^^^^ help: remove the `mut` prefix
    |
    = note: `mut` may be followed by `variable` and `variable @ pattern`
 
 error: `mut` must be followed by a named binding
   --> $DIR/mut-patterns.rs:10:9
    |
 LL |     let mut (_, _) = (0, 0);
-   |         ^^^^^^^^^^ help: remove the `mut` prefix: `(_, _)`
+   |         ^^^^ help: remove the `mut` prefix
    |
    = note: `mut` may be followed by `variable` and `variable @ pattern`
 

tests/ui/self/self_type_keyword.stderr

@@ -14,7 +14,7 @@ error: `mut` must be followed by a named binding
   --> $DIR/self_type_keyword.rs:16:9
    |
 LL |         mut Self => (),
-   |         ^^^^^^^^ help: remove the `mut` prefix: `Self`
+   |         ^^^^ help: remove the `mut` prefix
    |
    = note: `mut` may be followed by `variable` and `variable @ pattern`