From cae23fd0988e48cb16d27fade251ce6b43ff9fa9 Mon Sep 17 00:00:00 2001
From: Gabor Horvath <gaborh@apple.com>
Date: Mon, 8 Sep 2025 11:46:24 +0100
Subject: [PATCH] [cxx-interop] Make the size of anonymous types metadata is
 unchanged

Add a null pointer to the value witness table instead of completely
skipping emitting the pointer.
---
 lib/IRGen/GenMeta.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/IRGen/GenMeta.cpp b/lib/IRGen/GenMeta.cpp
index c5fc0b6f837fa..1d6b23d4ee9d6 100644
--- a/lib/IRGen/GenMeta.cpp
+++ b/lib/IRGen/GenMeta.cpp
@@ -6940,11 +6940,13 @@ namespace {
     }
 
     void addValueWitnessTable() {
+      llvm::Constant* vwtPointer = nullptr;
       if (auto cd = Target->getClangDecl())
         if (auto rd = dyn_cast<clang::RecordDecl>(cd))
           if (rd->isAnonymousStructOrUnion())
-            return;
-      auto vwtPointer = emitValueWitnessTable(/*relative*/ false).getValue();
+            vwtPointer = llvm::Constant::getNullValue(IGM.WitnessTablePtrTy);
+      if (!vwtPointer)
+        vwtPointer = emitValueWitnessTable(/*relative*/ false).getValue();
       B.addSignedPointer(vwtPointer,
                          IGM.getOptions().PointerAuth.ValueWitnessTable,
                          PointerAuthEntity());