c - 铿锵声中是否有“积分常数溢出”警告？

Question

考虑以下片段：

short x = 2000000000;

short x = (short)2000000000;

int x = 1000000000 * 1000000000;

我们可以在 Clang 中得到警告（/错误）吗？如何？从什么版本开始？

谢谢，西普里安。

Answer 1

至少从 clang 3.3 开始，您在这两种情况下都会收到警告，甚至无需尝试：

/* main.c */
short x = 2000000000;
int y = 1000000000 * 1000000000;

int main()
{
    return 0;
}

编译：

$ clang -c main.c
main.c:1:11: warning: implicit conversion from 'int' to 'short' changes value
      from 2000000000 to -27648 [-Wconstant-conversion]
short x = 2000000000;
      ~   ^~~~~~~~~~
main.c:2:20: warning: overflow in expression; result is -1486618624 with type
      'int' [-Winteger-overflow]
int y = 1000000000 * 1000000000;
                   ^
2 warnings generated.