[clang][Interp] Fix scalar inits of void type (#69868)

Author: tbaederr

clang/lib/AST/Interp/ByteCodeExprGen.cpp

@@ -1597,8 +1597,12 @@ bool ByteCodeExprGen<Emitter>::VisitOffsetOfExpr(const OffsetOfExpr *E) {
 template <class Emitter>
 bool ByteCodeExprGen<Emitter>::VisitCXXScalarValueInitExpr(
     const CXXScalarValueInitExpr *E) {
-  return this->visitZeroInitializer(classifyPrim(E->getType()), E->getType(),
-                                    E);
+  QualType Ty = E->getType();
+
+  if (Ty->isVoidType())
+    return true;
+
+  return this->visitZeroInitializer(classifyPrim(Ty), Ty, E);
 }
 
 template <class Emitter> bool ByteCodeExprGen<Emitter>::discard(const Expr *E) {

clang/test/AST/Interp/literals.cpp

@@ -56,6 +56,15 @@ namespace ScalarTypes {
   };
   static_assert(getScalar<E>() == First, "");
   /// FIXME: Member pointers.
+
+#if __cplusplus >= 201402L
+  constexpr void Void(int n) {
+    void(n + 1);
+    void();
+  }
+  constexpr int void_test = (Void(0), 1);
+  static_assert(void_test == 1, "");
+#endif
 }
 
 namespace IntegralCasts {