Index: clang/lib/Analysis/FlowSensitive/Transfer.cpp
===================================================================
--- clang/lib/Analysis/FlowSensitive/Transfer.cpp
+++ clang/lib/Analysis/FlowSensitive/Transfer.cpp
@@ -732,7 +732,15 @@
     Env.setValue(Loc, *Val);
 
     if (Type->isStructureOrClassType()) {
-      for (auto It : llvm::zip(Type->getAsRecordDecl()->fields(), S->inits())) {
+      // Unnamed bitfields are only used for padding and are not appearing in
+      // `InitListExpr`'s inits. However, those fields do appear in RecordDecl's
+      // field list, and we thus need to remove them before mapping inits to
+      // fields to avoid mapping inits to the wrongs fields.
+      std::vector<FieldDecl *> Fields;
+      llvm::copy_if(
+          Type->getAsRecordDecl()->fields(), std::back_inserter(Fields),
+          [](const FieldDecl *Field) { return !Field->isUnnamedBitfield(); });
+      for (auto It : llvm::zip(Fields, S->inits())) {
         const FieldDecl *Field = std::get<0>(It);
         assert(Field != nullptr);
 
Index: clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
===================================================================
--- clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
+++ clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
@@ -5080,4 +5080,28 @@
       {BuiltinOptions{ContextSensitiveOptions{}}});
 }
 
+TEST(TransferTest, UnnamedBitfieldInitializer) {
+  std::string Code = R"(
+    struct B {};
+    struct A {
+      unsigned a;
+      unsigned : 4;
+      unsigned c;
+      B b;
+    };
+    void target() {
+      A a = {};
+      A test = a;
+      (void)test.c;
+    }
+  )";
+  runDataflow(
+      Code,
+      [](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
+         ASTContext &ASTCtx) {
+        // This doesn't need a body because this test was crashing the framework
+        // before handling correctly Unnamed bitfields in `InitListExpr`.
+      });
+}
+
 } // namespace