[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: visibility.m4
From: |
Simon Josefsson |
Subject: |
Re: visibility.m4 |
Date: |
Tue, 20 Apr 2010 08:39:55 +0200 |
User-agent: |
Gnus/5.110011 (No Gnus v0.11) Emacs/23.1 (gnu/linux) |
Bruno, the patch looks simple to me, any objections to pushing it? I'm
seeing a lot of useless warnings when building for Windows without it.
/Simon
Simon Josefsson <address@hidden> writes:
> Bruno, ping? Ok to push?
>
> /Simon
>
> Simon Josefsson <address@hidden> writes:
>
>> Mike Gran <address@hidden> writes:
>>
>>> Hello-
>>>
>>> If I use visibility.m4 on a platform with a recent GCC (4.x) on
>>> Cygwin, the visibility.m4 correctly discovers that gcc can compile with
>>> -fvisibility="hidden". But, on Cygwin (and probably most non-ELF) gcc does
>>> not actualy implement the visibility and emits the warning "visibility
>>> attribute not supported in this configuration" instead. Even so, the tests
>>> in visibility.m4 pass, and HAVE_VISIBILITY is set in the affirmative.
>>>
>>> In my humble opinion, it would be a good idea to add a "-werror" to the
>>> test in visibility.m4 so that it won't set CFLAGS_VISIBILITY and
>>> HAVE_VISIBILITY on those platforms that don't actually support it.
>>>
>>> What do you think?
>>
>> I agree, and I recall that this was also suggested earlier. The current
>> approach leads to one warning per compiled source file, which is rather
>> annoying.
>>
>> Bruno, how about this patch?
>>
>> /Simon
>>
>> diff --git a/m4/visibility.m4 b/m4/visibility.m4
>> index 35a6dc0..06537d6 100644
>> --- a/m4/visibility.m4
>> +++ b/m4/visibility.m4
>> @@ -29,7 +29,11 @@ AC_DEFUN([gl_VISIBILITY],
>> AC_MSG_CHECKING([for simple visibility declarations])
>> AC_CACHE_VAL([gl_cv_cc_visibility], [
>> gl_save_CFLAGS="$CFLAGS"
>> - CFLAGS="$CFLAGS -fvisibility=hidden"
>> + # We use -Werror here because Cygwin/MinGW gives a warning
>> + # 'visibility attribute not supported in this configuration'
>> + # instead of doing what we want. Using -Werror makes gcc fail
>> + # instead, so we detect the problem.
>> + CFLAGS="$CFLAGS -fvisibility=hidden -Werror"
>> AC_TRY_COMPILE(
>> [extern __attribute__((__visibility__("hidden"))) int hiddenvar;
>> extern __attribute__((__visibility__("default"))) int exportedvar;
- Re: visibility.m4,
Simon Josefsson <=