[clang][DebugInfo] Fix iterator invalidation during EmitGlobalVariable

[Michael137]

This patch fixes an issue introduced in #71780 where, if EmitGlobalVariable triggered a call to CreateRecordStaticField it would invalidate the StaticDataMemberDefinitionsToEmit iterator that
is currently in-use.

This fixes a crash reported in #71780 (comment)

[llvmbot]

@llvm/pr-subscribers-clang-codegen
@llvm/pr-subscribers-clang

@llvm/pr-subscribers-debuginfo

Author: Michael Buch (Michael137)

Changes

This patch fixes an issue introduced in #71780 where, if EmitGlobalVariable triggered a call to CreateRecordStaticField it would invalidate the StaticDataMemberDefinitionsToEmit iterator that
is currently in-use.

This fixes a crash reported in #71780 (comment)

---

Full diff: https://github.com/llvm/llvm-project/pull/72415.diff

1 Files Affected:

• (modified) clang/lib/CodeGen/CGDebugInfo.cpp (+7-2)

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index a201cf03c22f711..d19e23e1392f4b4 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -5830,8 +5830,13 @@ void CGDebugInfo::setDwoId(uint64_t Signature) {
 }
 
 void CGDebugInfo::finalize() {
-  for (auto const *VD : StaticDataMemberDefinitionsToEmit) {
-    assert(VD->isStaticDataMember());
+  // We can't use a for-each here because `EmitGlobalVariable`
+  // may push new decls into `StaticDataMemberDefinitionsToEmit`,
+  // which would invalidate any iterator.
+  for (size_t i = 0; i < StaticDataMemberDefinitionsToEmit.size(); ++i) {
+    auto const *VD = StaticDataMemberDefinitionsToEmit[i];
+
+    assert(VD && VD->isStaticDataMember());
 
     if (DeclCache.contains(VD))
       continue;

[felipepiovezan]

LGTM. If there are others waiting on the fix, and since this is a fairly trivial change, it's probably ok to push it soonish