Avoid deleting labeled blocks

Author: sanxiyn

clippy_lints/src/no_effect.rs

@@ -357,7 +357,7 @@ fn reduce_expression<'a>(cx: &LateContext<'_>, expr: &'a Expr<'a>) -> Option<Vec
             }
         },
         ExprKind::Block(block, _) => {
-            if block.stmts.is_empty() {
+            if block.stmts.is_empty() && !block.targeted_by_break {
                 block.expr.as_ref().and_then(|e| {
                     match block.rules {
                         BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided) => None,

tests/ui/unnecessary_operation.fixed

@@ -106,4 +106,11 @@ fn main() {
 
     // Issue #11885
     Cout << 16;
+
+    // Issue #11575
+    // Bad formatting is required to trigger the bug
+    #[rustfmt::skip]
+    'label: {
+        break 'label
+    };
 }

tests/ui/unnecessary_operation.rs

@@ -110,4 +110,11 @@ fn main() {
 
     // Issue #11885
     Cout << 16;
+
+    // Issue #11575
+    // Bad formatting is required to trigger the bug
+    #[rustfmt::skip]
+    'label: {
+        break 'label
+    };
 }