c - 如何从 GCC-6 中捕获类似 `-Wduplicated-cond` 的重复项

Question

正如标题所说，对于那些已经知道以 GCC-6 开头的人你可以在 if 中找到重复项使用此标志的语句 -Wduplicated-cond像这样:

#include <stdio.h>

int main(void){
    int a = 5;

    if( a == 5){
        printf("First  condition is True, A = %d\n", a);
    }else if( a == 5 ){
        printf("Second condition is True, A = %d\n", a);
    }
}

输出将是:

program.c:8:17: warning: duplicated ‘if’ condition [-Wduplicated-cond]
     }else if( a == 5 ){
               ~~^~~~
program.c:6:11: note: previously used here
     if( a == 5){
         ~~^~~~

现在我知道以下内容:

else if( (a > 4) && (a < 6) )

不一样

else if( a == 5 )

但如果 a == 5，我会检查相同的条件.

我的问题是，是否有机会捕捉(避免)这种重复？

Answer 1

-Wduplicated-cond 确实捕获了这种情况。您必须明确启用它。

main.cpp: In function 'int main()':

main.cpp:8:11: warning: duplicated 'if' condition [-Wduplicated-cond]

 }else if( a == 5 ){
       ^~

main.cpp:6:5: note: previously used here

 if( a == 5){

原来是enabled by -Wall但不再是因为 PR67819 :

Given that the new warning currently breaks bootstrap [*] and I see no simple way how to resolve PR67819 derived out of the bootstrap failure, I'm moving -Wduplicated-cond out of -Wall and skipping one of the tests for the time being. I'm also reverting the hack in genemit.c.