use nearest open delimiter

Signed-off-by: xizheyin <xizheyin@smail.nju.edu.cn>

Author: xizheyin

compiler/rustc_parse/src/lexer/diagnostics.rs

@@ -50,7 +50,7 @@ pub(super) fn report_missing_open_delim(
             };
 
             if let Some(unclosed_span) = unmatch_brace.unclosed_span {
-                err.span_label(unclosed_span, "unclosed delimiter before unmatched delimiter");
+                err.span_label(unclosed_span, "the nearest open delimiter");
             }
             err.span_label(
                 unmatch_brace.found_span.shrink_to_lo(),

tests/ui/parser/deli-ident-issue-2.stderr

@@ -2,7 +2,7 @@ error: unexpected closing delimiter: `}`
   --> $DIR/deli-ident-issue-2.rs:5:1
    |
 LL |     if 1 < 2 {
-   |              - unclosed delimiter before unmatched delimiter
+   |              - the nearest open delimiter
 LL |         let _a = vec!];
    |                      - missing open `[` for this delimiter
 LL |     }

tests/ui/parser/issues/issue-68987-unmatch-issue-2.stderr

@@ -2,7 +2,7 @@ error: unexpected closing delimiter: `}`
   --> $DIR/issue-68987-unmatch-issue-2.rs:14:1
    |
 LL | async fn obstest() -> Result<> {
-   |                                - unclosed delimiter before unmatched delimiter
+   |                                - the nearest open delimiter
 LL |     let obs_connect = || -> Result<(), MyError) {
    |                                               - missing open `(` for this delimiter
 ...

tests/ui/parser/issues/issue-68987-unmatch-issue-3.stderr

@@ -2,7 +2,7 @@ error: unexpected closing delimiter: `}`
   --> $DIR/issue-68987-unmatch-issue-3.rs:8:1
    |
 LL |     while cnt < j {
-   |                   - unclosed delimiter before unmatched delimiter
+   |                   - the nearest open delimiter
 LL |         write!&mut res, " ");
    |                            - missing open `(` for this delimiter
 LL |     }

tests/ui/parser/issues/unnessary-error-issue-138401.stderr

@@ -2,7 +2,7 @@ error: unexpected closing delimiter: `}`
   --> $DIR/unnessary-error-issue-138401.rs:3:1
    |
 LL | pub fn foo(x: i64) -> i64 {
-   |                           - unclosed delimiter before unmatched delimiter
+   |                           - the nearest open delimiter
 LL |     x.abs)
    |          - missing open `(` for this delimiter
 LL | }