[clang] [Clang] Handle structs with inner structs and no fields (PR #89126)

[Bill Wendling via cfe-commits]

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@@ -826,29 +826,32 @@ const FieldDecl *CodeGenFunction::FindFlexibleArrayMemberField(
     ASTContext &Ctx, const RecordDecl *RD, StringRef Name, uint64_t &Offset) {
   const LangOptions::StrictFlexArraysLevelKind StrictFlexArraysLevel =
       getLangOpts().getStrictFlexArraysLevel();
-  unsigned FieldNo = 0;
-  bool IsUnion = RD->isUnion();
+  uint32_t FieldNo = 0;
 
-  for (const Decl *D : RD->decls()) {
-    if (const auto *Field = dyn_cast<FieldDecl>(D);
-        Field && (Name.empty() || Field->getNameAsString() == Name) &&
+  if (RD->isImplicit())
+    return nullptr;
+
+  for (const FieldDecl *FD : RD->fields()) {
+    if ((Name.empty() || FD->getNameAsString() == Name) &&
----------------
bwendling wrote:

I think I did it this way to support searching from either a pointer to the whole struct or pointer to the FAM. I suppose running this when we know we're pointing to the FAM is a bit redundant. And yes, using a `FieldDecl` pointer instead is almost certainly better here.

I think what I want to do though is rework some of the code so that we support `__builtin_dynamic_object_size` for more than just pointing to either the FAM or struct. I'll make that change as well.

https://github.com/llvm/llvm-project/pull/89126