[FFmpeg-devel] [PATCH 1/3] configure: use c++11 and fallback to c++0x for c++ files

James Almer jamrial at gmail.com
Sun Mar 26 16:29:48 EEST 2017


On 3/26/2017 7:22 AM, Marton Balint wrote:
> 
> On Sat, 25 Mar 2017, James Almer wrote:
> 
>> On 3/25/2017 8:51 PM, Marton Balint wrote:
>>> Needed for the C+11 atomics. Also change add_cxxflags to check_cxxflags.
>>>
>>> Signed-off-by: Marton Balint <cus at passwd.hu>
>>> ---
>>>  configure | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/configure b/configure
>>> index c1aeb6e..6823894 100755
>>> --- a/configure
>>> +++ b/configure
>>> @@ -4648,7 +4648,7 @@ fi
>>>
>>>  add_cppflags -D_ISOC99_SOURCE
>>>  add_cxxflags -D__STDC_CONSTANT_MACROS
>>> -add_cxxflags -std=c++98
>>> +check_cxxflags -std=c++11 || check_cxxflags -std=c++0x
>>
>> Do compilers that support setting --std=c++0x (Old provisional name for C++11)
>> have actual support for std::atomic? They have by definition experimental and
>> incomplete support for the standard in question.
> 
> Yes, gcc supports it since 4.4.
> https://gcc.gnu.org/projects/cxx-status.html
> 
> Also MSVC 2012 (which AFAIK does not even support -std) has support for it:
> https://msdn.microsoft.com/en-us/library/hh874894(v=vs.110).aspx
> 
> Clang since 3.1:
> https://clang.llvm.org/cxx_status.html

Ok, cool then.

> 
>> Maybe an actual check for it would be needed if --std=c++11 isn't available.
> 
> Well, only decklink_enc needs this, so if we really want to check this, and fail, if not, then it should be done somewhere after checking for decklink stuff. I don't particularly think that is very useful, but can do it if you think so.

No, it's ok. Patch LGTM as is.

Thanks for handling this.



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