__int64 for GCC as a Preprocessor Option

Question

Usually Microsoft code uses __int64 which is not understood by GCC. I know I can write it as a macro like this:

#define __int64 long long

But I don't want to do this, due to code portability. I'm trying to give GCC the following Preprocessor Option:

-D__int64="long long"

I get the following error due to the space between the two long's:

gcc.exe: error: long: No such file or directory

How to fix it ?

Answer 1

You could use int64_t, the standard name for that type, but it will only work if the code does #include <stdint.h>, and that's perhaps hoping for too much.

Otherwise you could try to "sneak" in a typedef in some common header:

typedef long long __int64;

Perhaps doing that only if GCC is detected.

Fixing it "your way" should certainly be possible, it looks like some quoting issue.

Answer 2

Sounds like you have a double-eval issue if your example doesn't work. If you can't figure out why that is happening you can try using gcc's -include or -imacros option. You would create a new file gcc_extra_definess with the #defines you want to add, and call gcc -include gcc_extra_defines ... to get gcc to read that file and include it before reading the source file. This is a bit easier than a bunch of -D options for defining multiple things, particularly if you have quoting issues or want things other than macros.