GCC Exclude User-Defined Warnings from -Werror

I want to pass the -Werror argument to gcc during compilation. The issue is that the code I am compiling has pragma statements such as:

#pragma GCC warning "Custom warning message"

I should be able to add an argument like -Wno-error=pragmas to the command line to enable retaining these lines as warnings. However, when I grepped the output of gcc --help=warnings for pragma, user, and explicit, I can't find the name of the warning switch I need to use. Does anyone know how to exclude explicit #pragma warnings from being errors when -Werror is enabled?

I've also tried to modify the #pragma to the following, which the GCC documentation seems to indicate should also accomplish this:

#pragma GCC diagnostic push
#pragma GCC diagnostic warning "-Wall"
#pragma GCC warning "Custom warning message"
#pragma GCC diagnostic pop

My GCC version is 11.4.0.

Solution

Reasons can be adduced from the GCC documentation why the things you have attempted do not work but I take it you don't need further convincing and just want a solution.

Replace:

#pragma GCC diagnostic push
#pragma GCC diagnostic warning "-Wall"
#pragma GCC warning "Custom warning message"
#pragma GCC diagnostic pop

with:

#pragma GCC diagnostic push
#pragma GCC diagnostic warning "-Wcpp" 
#warning "Custom warning message"
#pragma GCC diagnostic pop

as in e.g.:

$ cat main.c
#pragma GCC diagnostic push
#pragma GCC diagnostic warning "-Wcpp" 
#warning "Custom warning message"
#pragma GCC diagnostic pop 

int main(void)
{
    int x; // unused
    return 0;
}

-Wcpp is enabled by default and in man gcc is documented only negatively:

-Wno-cpp

(C, Objective-C, C++, Objective-C++ and Fortran only)

Suppress warning messages emitted by "#warning" directives

Compile like:

$ gcc -c -Wunused -Werror main.c
main.c:3:2: warning: #warning "Custom warning message" [-Wcpp]
    3 | #warning "Custom warning message"
      |  ^~~~~~~
main.c: In function ‘main’:
main.c:8:13: error: unused variable ‘x’ [-Werror=unused-variable]
    8 |         int x; // unused
      |             ^
cc1: all warnings being treated as errors

You custom warning remains a warning in the presence of -Werror. That is because such custom warnings are enabled by -Wcpp; they are promoted to errors by -Werror, but can be demoted to warnings again, for the duration, by:

#pragma GCC diagnostic warning "-Wcpp"

The error: unused variable ‘x’ shows that -Werror comes back into effect after:

#pragma GCC diagnostic pop

promoting the -Wunused warning to an error.