Compiler flag "-Wshadow" doesn't work in CodeBloks

Question

I realized that I need compiler flag -Wshadow after I mess up some code, so I decide to use it in Codeblocks too, but it doesn't work and I can't figure out why.

The following code:

#include <stdio.h>

int main(void){
    int i = 0;
    int arr[] = {1,2,3};

    for (int i=0 ; i < 3 ; i++){
        printf("%d ",arr[i]);
    }

    printf("\nI = %d\n",i);
}

If I try to compile it in my Terminal with the following flags :

-Wall -Wextra -Werror -Wstrict-prototypes -Wconversion -Wmissing-prototypes -Wold-style-definition -Wshadow -O0 -g

I get the following Output, which is OK:

program.c: In function ‘main’:
program.c:7:14: error: declaration of ‘i’ shadows a previous local [-Werror=shadow]
     for (int i=0 ; i < 3 ; i++){
              ^
program.c:4:9: note: shadowed declaration is here
     int i = 0;
         ^
cc1: all warnings being treated as errors

Now using the same Compiler Flags doesn't seems to work, compiles fine with no warnings, just like the flag -Wshadow is not present.

Does anyone know how to fix this?

GCC version is:

gcc (Ubuntu 5.3.0-3ubuntu1~14.04) 5.3.0 20151204

Answer 1

When you add compiler flags via the IDE, it doesn't automatically mark any existing object files or executable as out-of-date.

You need to click on "Rebuild" to do a full rebuild of your code using the new flags.