GCC - 不应该警告发出？ [英] GCC - shouldn't a warning be issued?

问题描述

我最近成立了一个MinGW的MSYS +环境中的我的笔记本电脑来检查的事情是如何使用Netbeans C / C ++的支持。一切似乎都很好地工作，但是，我的测试过程中，我注意到GCC和微软的编译器的cl.exe之间的差异。

I've recently set up a MinGW + MSYS environment on my laptop to check how things are with Netbeans C/C++ support. Everything seems to work fine, however, during my testing I have noticed a difference between GCC and Microsoft's cl.exe compiler.

下面是一个示例程序：

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>

int main(void) {
    int i_max = INT_MAX;
    char c_max = CHAR_MAX, c;

    c = i_max;
    printf("i_max: %d, c_max: %d, c: %d\n", i_max, c_max, c);
    return EXIT_SUCCESS;
}

输出是：

i_max: 2147483647, c_max: 127, c: -1

正如你可以在上面的code看到，我分配一个int为char。不应该这样产生可能发生可能导致数据丢失的警告？微软的编译器（我已经配置是非常严格）不发出警告的同时GCC没有。

As you can see in the code above, I assign an int to a char. Shouldn't this produce a warning that a possible data loss may occur? Microsoft's compiler (which I have configured to be very strict) does issue the warning while GCC doesn't.

下面是我使用GCC选项：

Here are the GCC options I use:

-g -Werror -ansi -pedantic -Wall -Wextra

我缺少一些GCC选项进行编译时检查更严格？

Am I missing some GCC option to make the compile time checks even stricter?

推荐答案

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-Wconversion

您得问一个gcc开发商为什么一些警告，不包含在 -Wall 或 -Wextra 。

You'd have to ask a gcc developer for the specific reasons why some warnings aren't included in -Wall or -Wextra.

不管怎样，这些都是我用的标志：

Anyway, these are the flags I use:

-Wall -Wextra -Wmissing-prototypes -Wmissing-declarations -Wshadow
-Wpointer-arith -Wcast-align -Wwrite-strings -Wredundant-decls -Wnested-externs
-Winline -Wno-long-long -Wconversion -Wstrict-prototypes

至于其他的人士指出， -Wconversion 的行为用的 4.3版 - 老警告有关原型强制类型转换，现在可作为 -Wtraditional转换

As other's have pointed out, the behaviour of -Wconversion changed with version 4.3 - the old warning about prototypes forcing a type conversion is now available as -Wtraditional-conversion.

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