Rollup merge of #127835 - estebank:issue-127823, r=compiler-errors

Fix ICE in suggestion caused by `⩵` being recovered as `==`

The second suggestion shown here would previously incorrectly assume that the span corresponding to `⩵` was 2 bytes wide composed by 2 1 byte wide chars, so a span pointing at `==` could point only at one of the `=` to remove it. Instead, we now replace the whole thing (as we should have the whole time):

```
error: unknown start of token: \u{2a75}
  --> $DIR/unicode-double-equals-recovery.rs:1:16
   |
LL | const A: usize ⩵ 2;
   |                ^
   |
help: Unicode character '⩵' (Two Consecutive Equals Signs) looks like '==' (Double Equals Sign), but it is not
   |
LL | const A: usize == 2;
   |                ~~

error: unexpected `==`
  --> $DIR/unicode-double-equals-recovery.rs:1:16
   |
LL | const A: usize ⩵ 2;
   |                ^
   |
help: try using `=` instead
   |
LL | const A: usize = 2;
   |                ~
```

Fix #127823.

compiler/rustc_parse/src/errors.rs

@@ -660,9 +660,8 @@ pub(crate) struct RemoveLet {
 #[diag(parse_use_eq_instead)]
 pub(crate) struct UseEqInstead {
  #[primary_span]
+ #[suggestion(style = "verbose", applicability = "machine-applicable", code = "=")]
  pub span: Span,
- #[suggestion(style = "verbose", applicability = "machine-applicable", code = "")]
- pub suggestion: Span,
 }
 
 #[derive(Diagnostic)]

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -566,10 +566,7 @@ impl<'a> Parser<'a> {
  && expected.iter().any(|tok| matches!(tok, TokenType::Token(TokenKind::Eq)))
  {
  // Likely typo: `=` → `==` in let expr or enum item
- return Err(self.dcx().create_err(UseEqInstead {
- span: self.token.span,
- suggestion: self.token.span.with_lo(self.token.span.lo() + BytePos(1)),
- }));
+ return Err(self.dcx().create_err(UseEqInstead { span: self.token.span }));
  }
 
  if self.token.is_keyword(kw::Move) && self.prev_token.is_keyword(kw::Async) {

tests/ui/parser/issues/issue-101477-enum.stderr

@@ -7,9 +7,8 @@ LL | B == 2
  = help: enum variants can be `Variant`, `Variant = <integer>`, `Variant(Type, ..., TypeN)` or `Variant { fields: Types }`
 help: try using `=` instead
  |
-LL - B == 2
-LL + B = 2
- |
+LL | B = 2
+ | ~
 
 error: expected item, found `==`
  --> $DIR/issue-101477-enum.rs:6:7

tests/ui/parser/issues/issue-101477-let.stderr

@@ -6,9 +6,8 @@ LL | let x == 2;
  |
 help: try using `=` instead
  |
-LL - let x == 2;
-LL + let x = 2;
- |
+LL | let x = 2;
+ | ~
 
 error: aborting due to 1 previous error
 

tests/ui/parser/recover/unicode-double-equals-recovery.rs

@@ -0,0 +1,3 @@
+const A: usize ⩵ 2;
+//~^ ERROR unknown start of token: \u{2a75}
+//~| ERROR unexpected `==`

tests/ui/parser/recover/unicode-double-equals-recovery.stderr

@@ -0,0 +1,24 @@
+error: unknown start of token: \u{2a75}
+ --> $DIR/unicode-double-equals-recovery.rs:1:16
+ |
+LL | const A: usize ⩵ 2;
+ | ^
+ |
+help: Unicode character '⩵' (Two Consecutive Equals Signs) looks like '==' (Double Equals Sign), but it is not
+ |
+LL | const A: usize == 2;
+ | ~~
+
+error: unexpected `==`
+ --> $DIR/unicode-double-equals-recovery.rs:1:16
+ |
+LL | const A: usize ⩵ 2;
+ | ^
+ |
+help: try using `=` instead
+ |
+LL | const A: usize = 2;
+ | ~
+
+error: aborting due to 2 previous errors
+