Re: C99 support

[Roger Leigh]

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Bob Friesenhahn <address@hidden> writes:

> On Mon, 29 Nov 2004, Roger Leigh wrote:
>>
>> It would be great if in the next year, AC_PROG_CC could default to
>> using a C99 compiler.  Since it should be backward-compatible with C89
>> (??), this shouldn't be required, but I would really like to see C99
>> as the default, with some means of choosing an older standard if so
>> required.
>
> Do you have a purpose for using C99 other than to intentionally write
> non-portable software?

Yes: I would like to use C99 features, and the current autoconf
support isn't adequate.  I can portably make use of _Bool, inline and
restrict, but that's it.  The things I currently use, or would like to
use, are:

- - C++-style comments
- - long long
- - Mixed declarations and code
- - Declarations in for loops.
- - Named Initialisers for structs

None of these are strictly /necessary/, but I do believe the latter
three do make for cleaner, more maintainable code.

> Is C99 really 100% upward compatible with the previous version of the
> standard, or is it possibly more strict and include type changes which
> might impact library ABIs?

I believe that it's entirely compatible, providing you don't use the
new datatypes.

C99 support is nearly fully complete:

http://gcc.gnu.org/c99status.html

and the remaining issues are library issues, hopefully to come with a
future glibc.  I do think autoconf should support it--it is the
current C standard.


Regards,
Roger

- -- 
Roger Leigh
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