Re: Linux Kernel include files

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Kyle Moffett wrote:

Gah, this particular topic and a few other similar header-compatibility ones show up once a month on LKML; I should probably just make a patch to fix all the types.h files and be done with it. The proper solution is this:

# if __STDC_VERSION__ >= 19901L
typedef   signed long long __s64;
typedef unsigned long long __u64;
# elif defined(__GNUC__)
__extension__ typedef   signed long long __s64;
__extension__ typedef unsigned long long __u64;
# else
# error "Your compiler doesn't support long long (IOW: It sucks). Please get a new one"
# endif

That way if you have any kind of vaguely-long-long-compatible compiler then it will work, and otherwise you'll get a nice useful error message. It also makes sure that GCC doesn't spew warnings/errors when in c89-pedantic mode. The "__extension__" keyword is designed for use in implementation header files which want to use GCC-isms unconditionally.


__extension__ should be macroized if so.

However, since something that doesn't have "long long" won't be able to compile those headers, there is absolutely no reason to not simply use it -- you get an error message on that line, which is good enough. There is definitely no reason to use a test like the one above, which is wrong for several supportable compilers.

	-hpa

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