How can I disable a specific gcc pedantic warning?

Question

I've googled and googled and either google is failing me or you can't do this. This warning comes up when you turn on -Wpedantic...

ISO C++ forbids zero-size array ‘variable’ [-Wpedantic]

I want to turn off this one warning, not all pedantic warnings. Normally, I'd just add -Wno-xyz but I can't find the flag name that relates to that warning. It's just not listed anywhere.

Are the pedantic warnings special in that you can't remove them individually?

Answer 1

The good news: You can do this. The bad news: You can't use any commandline option. The [-Wpedantic] at the end of the diagnostic tells you that -Wno-pedantic is the narrowest option that will disable the diagnostic, and that's no use to you if you want to preserve all other pedantic diagnostics.

You'll have to do it case-by-case with pragmas.

main.cpp

int main(int argc, char *argv[])
{
    int a[0];
    int b[argc];
    return sizeof(a) + sizeof(b);
}

This program provokes two -Wpedantic diaqnostics:

$ g++ -Wpedantic -c main.cpp
main.cpp: In function ‘int main(int, char**)’:
main.cpp:6:12: warning: ISO C++ forbids zero-size array ‘a’ [-Wpedantic]
     int a[0];
            ^
main.cpp:8:15: warning: ISO C++ forbids variable length array ‘b’ [-Wvla]
     int b[argc];
               ^

-Wno-vla will suppress the second one. To suppress the first, you have to resort to:

main.cpp (revised)

int main(int argc, char *argv[])
{
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic"
    int a[0];
#pragma GCC diagnostic pop
    int b[argc];
    return sizeof(a) + sizeof(b);
}

With which:

$ g++ -Wpedantic -c main.cpp
main.cpp: In function ‘int main(int, char**)’:
main.cpp:8:15: warning: ISO C++ forbids variable length array ‘b’ [-Wvla]
     int b[argc];
               ^