Re: AC_PROG_CC wrongly setting $GCC=yes while clang is used

[Marko Lindqvist]

On 8 September 2014 17:29, Eric Blake <address@hidden> wrote:
> On 09/08/2014 02:44 AM, Thomas Jahns wrote:
>> On 09/08/14 06:24, Paul Smith wrote:
>>> In particular, this:
>>>
>>>   configure:3666: checking whether we are using the GNU C compiler
>>>   configure:3685: clang -c -mmacosx-version-min=10.6    conftest.c >&5
>>>   configure:3685: $? = 0
>>>   configure:3694: result: yes
>>>
>>> Appears to show that clang is defining the __GNUC__ built-in compiler
>>> flag, presumably for compatibility with GCC source code.  So IF there's
>>> any real problem here, which I'm not sure there is, the problem is in
>>> clang claiming to be something it's not.
>>
>> Happens just the same for icc and since the Intel compiler supports enough of
>> the pragma's and non-std features of gcc, this works out fine for me so far.
>
> Maybe it's as simple as patching autoconf to change the message to
> "checking whether the compiler understands GNU C extensions", to match
> the reality of how it works these days.
>

 The $GCC example brings up another problem, though. Even though
autoconf itself works perfectly by treating clang as gcc (and clang++
as g++), user scripts may not. Is there need to update documentation
abour $GCC to say that it should not be taken literally, but just to
mean some kind of gcc compatibility.


 - ML