[clang] [clang][bytecode] Reject CK_BitCast nodes with errors early (PR #179087)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr created https://github.com/llvm/llvm-project/pull/179087

Fixes https://github.com/llvm/llvm-project/issues/179020

>From 2d725d567892b38c27adffac18aa592ed67e7c4c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Sun, 1 Feb 2026 06:52:53 +0100
Subject: [PATCH] [clang][bytecode] Reject CK_BitCast nodes with errors early

Fixes https://github.com/llvm/llvm-project/issues/179020
---
 clang/lib/AST/ByteCode/Compiler.cpp | 2 ++
 clang/test/AST/ByteCode/invalid.cpp | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/clang/lib/AST/ByteCode/Compiler.cpp b/clang/lib/AST/ByteCode/Compiler.cpp
index da1db48c55a07..af076f90733df 100644
--- a/clang/lib/AST/ByteCode/Compiler.cpp
+++ b/clang/lib/AST/ByteCode/Compiler.cpp
@@ -477,6 +477,8 @@ bool Compiler<Emitter>::VisitCastExpr(const CastExpr *CE) {
     return this->delegate(SubExpr);
 
   case CK_BitCast: {
+    if (CE->containsErrors())
+      return false;
     QualType CETy = CE->getType();
     // Reject bitcasts to atomic types.
     if (CETy->isAtomicType()) {
diff --git a/clang/test/AST/ByteCode/invalid.cpp b/clang/test/AST/ByteCode/invalid.cpp
index f7f2da2769d65..bfb33d0cc6dce 100644
--- a/clang/test/AST/ByteCode/invalid.cpp
+++ b/clang/test/AST/ByteCode/invalid.cpp
@@ -132,3 +132,8 @@ namespace RetVoidInInvalidFunc {
   };
   X<foo()> x; // both-error {{non-type template argument is not a constant expression}}
 }
+
+namespace BitCastWithErrors {
+  template<class T> int f(); // both-note {{candidate template ignored}}
+  static union { char *x = f(); }; // both-error {{no matching function for call to 'f'}}
+}