llvm-project/clang/test/Sema/va_arg_x86_32.c

// RUN: clang-cc -fsyntax-only -verify -triple=i686-pc-linux-gnu %s

int a() {
  __builtin_va_arg((char*)0, int); // expected-error {{expression is not assignable}}
  __builtin_va_arg((void*){0}, int); // expected-error {{first argument to 'va_arg' is of type 'void *'}}
}