[clang] [clang][bytecode] Handle missing target label in break statement (PR #180532)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr created https://github.com/llvm/llvm-project/pull/180532

Happens in error cases.

>From 14524c4d3bfebb8b9bc1693c609371be10e8e5db Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Mon, 9 Feb 2026 15:35:36 +0100
Subject: [PATCH] [clang][bytecode] Handle missing target label in break
 statement

---
 clang/lib/AST/ByteCode/Compiler.cpp |  4 +++-
 clang/test/AST/ByteCode/invalid.cpp | 13 +++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/clang/lib/AST/ByteCode/Compiler.cpp b/clang/lib/AST/ByteCode/Compiler.cpp
index a0138c402e143..58871fe79b36d 100644
--- a/clang/lib/AST/ByteCode/Compiler.cpp
+++ b/clang/lib/AST/ByteCode/Compiler.cpp
@@ -6036,7 +6036,9 @@ bool Compiler<Emitter>::visitBreakStmt(const BreakStmt *S) {
     }
   }
 
-  assert(TargetLabel);
+  // Faulty break statement (e.g. label redefined or named loops disabled).
+  if (!TargetLabel)
+    return false;
 
   for (VariableScope<Emitter> *C = this->VarScope; C != BreakScope;
        C = C->getParent()) {
diff --git a/clang/test/AST/ByteCode/invalid.cpp b/clang/test/AST/ByteCode/invalid.cpp
index c8298fa2c2b9b..f7d11a9be3f8e 100644
--- a/clang/test/AST/ByteCode/invalid.cpp
+++ b/clang/test/AST/ByteCode/invalid.cpp
@@ -151,3 +151,16 @@ namespace NullRecord {
   };
   S2 s = S2();
 }
+
+namespace NamedLoops {
+  constexpr int foo() {
+  bar: // both-note {{previous definition is here}} \
+       // both-warning {{use of this statement in a constexpr function is a C++23 extension}}
+    return 0;
+
+  bar: // both-error {{redefinition of label 'bar'}}
+    do {
+      break bar; // both-error {{named 'break' is only supported in C2y}}
+    } while (0);
+  }
+}