Rollup merge of #147546 - chenyukang:yukang-fix-break-label-147542, r=jackh726

Suppress unused_parens for labeled break
Fixes#147542

Author: Zalathar

compiler/rustc_lint/src/unused.rs

@@ -914,7 +914,16 @@ trait UnusedDelimLint {
 (value,UnusedDelimsCtx::ReturnValue,false,Some(left),None,true)
 }
 
-Break(_,Some(ref value)) => {
+Break(label,Some(ref value)) => {
+// Don't lint on `break 'label ({...})` - the parens are necessary
+// to disambiguate from `break 'label {...}` which would be a syntax error.
+// This avoids conflicts with the `break_with_label_and_loop` lint.
+if label.is_some()
+ && matches!(value.kind, ast::ExprKind::Paren(ref inner)
+if matches!(inner.kind, ast::ExprKind::Block(..)))
+{
+return;
+}
 (value,UnusedDelimsCtx::BreakValue,false,None,None,true)
 }
 

tests/ui/lint/unused/break-label-with-parens-147542.rs

@@ -0,0 +1,22 @@
+//@ check-pass
+
+// Regression test for #147542
+// Ensures that we don't suggest removing parens in a break with label and loop
+// when the parens are necessary for correct parsing.
+
+#![warn(unused_parens)]
+#![warn(break_with_label_and_loop)]
+
+fnxyz() -> usize{
+'foo:{
+// parens bellow are necessary break of break with label and loop
+break'foo ({
+println!("Hello!");
+123
+});
+}
+}
+
+fnmain(){
+xyz();
+}