Auto merge of #84024 - estebank:unclosed-brace-use, r=jackh726

Avoid `;` -> `,` recovery and unclosed `}` recovery from being too verbose

Those two recovery attempts have a very bad interaction that causes too
unnecessary output. Add a simple gate to avoid interpreting a `;` as a
`,` when there are unclosed braces.

Fix #83498.

Author: bors

compiler/rustc_parse/src/parser/mod.rs

@@ -703,6 +703,8 @@ impl<'a> Parser<'a> {
         let mut recovered = false;
         let mut trailing = false;
         let mut v = vec![];
+        let unclosed_delims = !self.unclosed_delims.is_empty();
+
         while !self.expect_any_with_type(kets, expect) {
             if let token::CloseDelim(..) | token::Eof = self.token.kind {
                 break;
@@ -723,7 +725,7 @@ impl<'a> Parser<'a> {
 
                             // Attempt to keep parsing if it was a similar separator.
                             if let Some(ref tokens) = t.similar_tokens() {
-                                if tokens.contains(&self.token.kind) {
+                                if tokens.contains(&self.token.kind) && !unclosed_delims {
                                     self.bump();
                                 }
                             }

src/test/ui/parser/issue-63116.stderr

@@ -12,11 +12,11 @@ error: expected one of `!`, `(`, `)`, `+`, `,`, `::`, or `<`, found `;`
 LL | impl W <s(f;Y(;]
    |            ^ expected one of 7 possible tokens
 
-error: expected one of `!`, `&&`, `&`, `(`, `)`, `*`, `+`, `,`, `->`, `...`, `::`, `:`, `<`, `=`, `>`, `?`, `[`, `_`, `async`, `const`, `dyn`, `extern`, `fn`, `for`, `impl`, `unsafe`, lifetime, or path, found `;`
-  --> $DIR/issue-63116.rs:3:15
+error: mismatched closing delimiter: `]`
+  --> $DIR/issue-63116.rs:3:16
    |
 LL | impl W <s(f;Y(;]
-   |              -^ help: `)` may belong here
+   |              - ^ mismatched closing delimiter
    |              |
    |              unclosed delimiter
 

src/test/ui/parser/use-unclosed-brace.rs

@@ -0,0 +1,12 @@
+// error-pattern: expected one of `,`, `::`, `as`, or `}`, found `;`
+// error-pattern: this file contains an unclosed delimiter
+// error-pattern: expected item, found `}`
+use foo::{bar, baz;
+
+use std::fmt::Display;
+
+mod bar { }
+
+mod baz { }
+
+fn main() {}

src/test/ui/parser/use-unclosed-brace.stderr

@@ -0,0 +1,27 @@
+error: this file contains an unclosed delimiter
+  --> $DIR/use-unclosed-brace.rs:12:14
+   |
+LL | use foo::{bar, baz;
+   |          - unclosed delimiter
+...
+LL | fn main() {}
+   |              ^
+
+error: expected one of `,`, `::`, `as`, or `}`, found `;`
+  --> $DIR/use-unclosed-brace.rs:4:19
+   |
+LL | use foo::{bar, baz;
+   |          -        ^
+   |          |        |
+   |          |        expected one of `,`, `::`, `as`, or `}`
+   |          |        help: `}` may belong here
+   |          unclosed delimiter
+
+error: expected item, found `}`
+  --> $DIR/use-unclosed-brace.rs:12:14
+   |
+LL | fn main() {}
+   |              ^ expected item
+
+error: aborting due to 3 previous errors
+