[clang] [clang][dataflow] Correctly handle `InitListExpr` of union type. (PR #82348)

[Gábor Horváth via cfe-commits]

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@@ -1104,12 +1104,22 @@ RecordStorageLocation *getBaseObjectLocation(const MemberExpr &ME,
   return Env.get<RecordStorageLocation>(*Base);
 }
 
-std::vector<FieldDecl *> getFieldsForInitListExpr(const RecordDecl *RD) {
+std::vector<const FieldDecl *>
+getFieldsForInitListExpr(const InitListExpr *InitList) {
+  const RecordDecl *RD = InitList->getType()->getAsRecordDecl();
+  assert(RD != nullptr);
+
+  std::vector<const FieldDecl *> Fields;
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Xazax-hun wrote:

I wonder if a `reserve` call for this vector would be beneficial. Even if we do not know the exact number of fields we want to insert, probably relatively few of them are unnamed bit fields in most code bases. 

https://github.com/llvm/llvm-project/pull/82348