如何取消对源文件中特定宏定义的零参数的GCC可变参数宏参数警告

Question

I want to suppress GCC variadic macro argument warning for zero arguments, produced for example by:

// for illustration purposes only:
int foo(int i) { return 0; };
#define FOO(A, ...) foo(A, ##__VA_ARGS__)
FOO(1);
     ^  warning: ISO C++11 requires at least one argument for the "..." in a variadic macro

for a particular macro definition within a source file when using GCC 5.3.0.

In clang this is done as follows:

// ... large file
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wgnu-zero-variadic-macro-arguments"
#define FOO(A, ...) foo(A, ##__VA_ARGS__)
#pragma clang diagnostic pop
// ... large file

// not necessary on the same file
FOO(1);  // doesnt trigger the warning

In gcc it looks like -pedantic is a magical kind of warning type so the following just doesn't work:

// ... large file
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic"
#define FOO(A, ...) foo(A, ##__VA_ARGS__)
#pragma GCC diagnostic pop
// ... large file

Just to be clear, the warning should be enabled in the whole program except in this particular snippet of code. This is about fine grained control. Disabling the warning in GCC for the whole program can be achieved by just not passing -pedantic to the compiler.

Answer 1

You should be able to suppress this using

#pragma GCC system_header

But that applies for the rest of the file, and you cannot only use it in included files. So doesn't provide perfect scoping and may require some reshuffling / indirect inclusion of header files.

(But quite frankly, if you can't fix the header file to be standards-conforming, you might as well consider the whole header a system_header, which excludes it from producing most warnings.)

See https://gcc.gnu.org/onlinedocs/cpp/System-Headers.html

Answer 2

You can try to use this:

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wvariadic-macros"
#define FOO(A, ...) foo(A, ##__VA_ARGS__)
#pragma GCC diagnostic pop