Detect more cases of `=` to `:` typo

When a `Local` is fully parsed, but not followed by a `;`, keep the `:` span
arround and mention it. If the type could continue being parsed as an
expression, suggest replacing the `:` with a `=`.

```
error: expected one of `!`, `+`, `->`, `::`, `;`, or `=`, found `.`
 --> file.rs:2:32
  |
2 |     let _: std::env::temp_dir().join("foo");
  |          -                     ^ expected one of `!`, `+`, `->`, `::`, `;`, or `=`
  |          |
  |          while parsing the type for `_`
  |          help: use `=` if you meant to assign
```

Fix #119665.

1 files changed, 2 insertions, 2 deletions

diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index f5a7bfd42ff..dad43181586 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -430,7 +430,7 @@ impl<'a> Parser<'a> {
     /// The method does not advance the current token.
     ///
     /// Also performs recovery for `and` / `or` which are mistaken for `&&` and `||` respectively.
-    fn check_assoc_op(&self) -> Option<Spanned<AssocOp>> {
+    pub fn check_assoc_op(&self) -> Option<Spanned<AssocOp>> {
         let (op, span) = match (AssocOp::from_token(&self.token), self.token.ident()) {
             // When parsing const expressions, stop parsing when encountering `>`.
             (
@@ -994,7 +994,7 @@ impl<'a> Parser<'a> {
         }
     }
 
-    fn parse_dot_suffix_expr(&mut self, lo: Span, base: P<Expr>) -> PResult<'a, P<Expr>> {
+    pub fn parse_dot_suffix_expr(&mut self, lo: Span, base: P<Expr>) -> PResult<'a, P<Expr>> {
         match self.token.uninterpolate().kind {
             token::Ident(..) => self.parse_dot_suffix(base, lo),
             token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) => {