tweak var/auto/mut recovery

Author: Centril

src/librustc_parse/parser/stmt.rs

@@ -42,16 +42,16 @@ impl<'a> Parser<'a> {
             return self.parse_local_mk(lo, attrs.into()).map(Some)
         }
         if self.is_kw_followed_by_ident(kw::Mut) {
-            return self.recover_stmt_local(lo, attrs.into(), "missing `let`", "let mut");
+            return self.recover_stmt_local(lo, attrs.into(), "missing keyword", "let mut");
         }
         if self.is_kw_followed_by_ident(kw::Auto) {
             self.bump(); // `auto`
-            let msg = "to introduce a variable, write `let` instead of `auto`";
+            let msg = "write `let` instead of `auto` to introduce a new variable";
             return self.recover_stmt_local(lo, attrs.into(), msg, "let");
         }
         if self.is_kw_followed_by_ident(sym::var) {
             self.bump(); // `var`
-            let msg = "to introduce a variable, write `let` instead of `var`";
+            let msg = "write `let` instead of `var` to introduce a new variable";
             return self.recover_stmt_local(lo, attrs.into(), msg, "let");
         }
 
@@ -208,14 +208,14 @@ impl<'a> Parser<'a> {
 
     fn recover_stmt_local(
         &mut self,
-        span: Span,
+        lo: Span,
         attrs: AttrVec,
         msg: &str,
         sugg: &str,
     ) -> PResult<'a, Option<Stmt>> {
-        let stmt = self.parse_local_mk(span, attrs)?;
-        self.struct_span_err(stmt.span, "invalid variable declaration")
-            .span_suggestion_short(span, msg, sugg.to_string(), Applicability::MachineApplicable)
+        let stmt = self.parse_local_mk(lo, attrs)?;
+        self.struct_span_err(lo, "invalid variable declaration")
+            .span_suggestion(lo, msg, sugg.to_string(), Applicability::MachineApplicable)
             .emit();
         Ok(Some(stmt))
     }

src/test/ui/parser/issue-65257-invalid-var-decl-recovery.rs

@@ -1,20 +1,20 @@
 fn main() {
     auto n = 0;//~ ERROR invalid variable declaration
-    //~^ HELP to introduce a variable, write `let` instead of `auto`
+    //~^ HELP write `let` instead of `auto` to introduce a new variable
     auto m;//~ ERROR invalid variable declaration
-    //~^ HELP to introduce a variable, write `let` instead of `auto`
+    //~^ HELP write `let` instead of `auto` to introduce a new variable
     m = 0;
 
     var n = 0;//~ ERROR invalid variable declaration
-    //~^ HELP to introduce a variable, write `let` instead of `var`
+    //~^ HELP write `let` instead of `var` to introduce a new variable
     var m;//~ ERROR invalid variable declaration
-    //~^ HELP to introduce a variable, write `let` instead of `var`
+    //~^ HELP write `let` instead of `var` to introduce a new variable
     m = 0;
 
     mut n = 0;//~ ERROR invalid variable declaration
-    //~^ HELP missing `let`
+    //~^ HELP missing keyword
     mut var;//~ ERROR invalid variable declaration
-    //~^ HELP missing `let`
+    //~^ HELP missing keyword
     var = 0;
 
     let _recovery_witness: () = 0; //~ ERROR mismatched types

src/test/ui/parser/issue-65257-invalid-var-decl-recovery.stderr

@@ -2,49 +2,57 @@ error: invalid variable declaration
   --> $DIR/issue-65257-invalid-var-decl-recovery.rs:2:5
    |
 LL |     auto n = 0;
-   |     ----^^^^^^
-   |     |
-   |     help: to introduce a variable, write `let` instead of `auto`
+   |     ^^^^
+   |
+help: write `let` instead of `auto` to introduce a new variable
+   |
+LL |     let n = 0;
+   |     ^^^
 
 error: invalid variable declaration
   --> $DIR/issue-65257-invalid-var-decl-recovery.rs:4:5
    |
 LL |     auto m;
-   |     ----^^
-   |     |
-   |     help: to introduce a variable, write `let` instead of `auto`
+   |     ^^^^
+   |
+help: write `let` instead of `auto` to introduce a new variable
+   |
+LL |     let m;
+   |     ^^^
 
 error: invalid variable declaration
   --> $DIR/issue-65257-invalid-var-decl-recovery.rs:8:5
    |
 LL |     var n = 0;
-   |     ---^^^^^^
-   |     |
-   |     help: to introduce a variable, write `let` instead of `var`
+   |     ^^^
+   |
+help: write `let` instead of `var` to introduce a new variable
+   |
+LL |     let n = 0;
+   |     ^^^
 
 error: invalid variable declaration
   --> $DIR/issue-65257-invalid-var-decl-recovery.rs:10:5
    |
 LL |     var m;
-   |     ---^^
-   |     |
-   |     help: to introduce a variable, write `let` instead of `var`
+   |     ^^^
+   |
+help: write `let` instead of `var` to introduce a new variable
+   |
+LL |     let m;
+   |     ^^^
 
 error: invalid variable declaration
   --> $DIR/issue-65257-invalid-var-decl-recovery.rs:14:5
    |
 LL |     mut n = 0;
-   |     ---^^^^^^
-   |     |
-   |     help: missing `let`
+   |     ^^^ help: missing keyword: `let mut`
 
 error: invalid variable declaration
   --> $DIR/issue-65257-invalid-var-decl-recovery.rs:16:5
    |
 LL |     mut var;
-   |     ---^^^^
-   |     |
-   |     help: missing `let`
+   |     ^^^ help: missing keyword: `let mut`
 
 error[E0308]: mismatched types
   --> $DIR/issue-65257-invalid-var-decl-recovery.rs:20:33