gcc 编译参数求教

[hu_jiajun1979]

// a.c
int main(int argc, char **argv) {
double d = -1.5;
unsigned int i;

j = i; // 这里有强制类型转换，我希望能打印出警告

return j;
}


不知道打印强制类型转换需要加什么参数
我用gcc -Wall -W a.c 也不会打印相应警告

[steptodream]

j在哪儿定义了？

[hu_jiajun1979]

哦，代码错了
是i = d; // 这里有强制类型转换，我希望能打印出警告
return i;

就是希望报强制类型转换的警告

[brookmill]

gcc -Wconversion a.c

$ man gcc
......
-Wconversion
Warn for implicit conversions that may alter a value. This includes conversions
between real and integer, like "abs (x)" when "x" is "double"; conversions between
signed and unsigned, like "unsigned ui = -1"; and conversions to smaller types, like
"sqrtf (M_PI)". Do not warn for explicit casts like "abs ((int) x)" and "ui =
(unsigned) -1", or if the value is not changed by the conversion like in "abs
(2.0)". Warnings about conversions between signed and unsigned integers can be
disabled by using -Wno-sign-conversion.

[Linux-Torvalds]

先-Wall，不会提示的话，再试一下楼上说的。

[mars199]

gcc -Wconversion a.c

[hu_jiajun1979]

-Wconversion只能报出 unsigned ui = -1的错误
如果是 int i = -1;
unsigned ui = i;
这种写法，-Wconversion 报不出来的

[hu_jiajun1979]

结贴了，虽然没有找到答案