[PATCH] hsakmt: allow building with gcc 4.x

[Bridgman, John]

>-----Original Message-----
>From: Emil Velikov [mailto:emil.l.velikov at gmail.com]
>Sent: Tuesday, March 29, 2016 4:08 PM
>To: Bridgman, John
>Cc: dri-devel at lists.freedesktop.org
>Subject: Re: [PATCH] hsakmt: allow building with gcc 4.x
>
>Hi John,
>
>On 29 March 2016 at 16:39, Bridgman, John <John.Bridgman at amd.com>
>wrote:
>> The hsakmt code requires c99 support, however gcc 4.x defaults to
>> c89 while gcc 5 defaults to c11. Adding this macro provides c99
>> support on older gcc while not forcing gcc 5 back from c11 to c99.
>>
>> Signed-off-by: John Bridgman <john.bridgman at amd.com>
>> ---
>>  configure.ac | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/configure.ac b/configure.ac index b8e9bea..8f32cbb 100644
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -66,6 +66,7 @@ AC_CANONICAL_HOST
>>  AC_PROG_AWK
>>  test_CFLAGS=${CFLAGS+set} # We may override autoconf default CFLAGS.
>>  AC_PROG_CC
>> +AC_PROG_CC_STDC
>Some versions of autoconf have AC_PROG_CC_STDC as obsolete, while
>others will silently fall back to C89 (according to the autoconf ML).
>
>I've used AC_PROG_CC_C99 and $ac_cv_prog_cc_c99 for libdrm [1]. Did not
>have old enough compiler to test it against though :-\

Hi Emil,

I looked at both AC_PROG_CC_STDC and _C99 options, but found more anecdotal concerns about _C99 so went with _STDC for the patch... but after sending it out I realized that the concerns I found seemed to apply to both STDC and C99 equally. I read about _STDC being obsoleted but also noticed that it was "unobsoleted" in autoconf 2.60, the same release where AC_PROG_CC_C99 was apparently added.

I did run across a 2013 email suggesting that _C99 and _STDC were *both* going to be obsoleted, but was not able to find any further discussion and did not see any mention of either macro in subsequent autoconf release notes. 

Anyways, if you are using AC_PROG_CC_C99 in libdrm then I think it makes sense to do the same in libhsakmt. I will spin a v2 of the patch.

Thanks,
John
>
>-Emil
>
>[1]
>https://cgit.freedesktop.org/mesa/drm/commit/?id=e59f00fb43c2b83bdadb1
>7fa35c3018f817a3806