Put multiple pragma directives into one preprocessor define

Question

I need to push/pop several gcc diagnostics in my code. If that was needed in a single file I would do the following:

#pragma GCC diagnostic push
#pragma GCC diagnostic error "-Wformat"
#pragma GCC diagnostic error "-Wuninitialized"

...some code...

#pragma GCC diagnostic push

But I need this in multiple locations. So I want to have a #define or something similar. I thought about the following but c preprocessor does not allow #pragmas in #define.

#define PushWarnings \
    #pragma GCC diagnostic push \
    #pragma GCC diagnostic error "-Wformat" \
    #pragma GCC diagnostic error "-Wuninitialized"

Is there a way of achieving this?

The code is *enabling* warnings (or rather, turning them into errors), not disabling them. — melpomene, Dec 16 '17 at 19:48
@melpomene - Compile the code so that all warnings are errors and not need to play around with bits of code not having that protection — Ed Heal, Dec 16 '17 at 19:48
Why don't you just fix the code so that those warnings don't fire? — Jesper Juhl, Dec 16 '17 at 19:48

score 12 · Accepted Answer · answered Dec 16 '17 at 19:42

Yes, there is a way to do this. C99 introduced the _Pragma operator (also available in C++ since C++11).

A pragma such as

#pragma GCC diagnostic error "-Wformat"

can also be written as

_Pragma("GCC diagnostic error \"-Wformat\"")

The latter is not a # preprocessor directive, so it can be generated from macros:

#define PushWarnings \
    _Pragma("GCC diagnostic push") \
    _Pragma("GCC diagnostic error \"-Wformat\"") \
    _Pragma("GCC diagnostic error \"-Wuninitialized\"")

Great. Happy to learn about _Pragma. – Paul Dec 16 '17 at 21:03 — Paul, Dec 16 '17 at 21:03

Put multiple pragma directives into one preprocessor define

1 Answers1