[OE-core] gcc 6.1+ and isystem

[Andreas Müller]

On Tue, Aug 30, 2016 at 7:00 PM, Richard Purdie
<richard.purdie at linuxfoundation.org> wrote:
> On Tue, 2016-08-30 at 16:37 +0100, Jack Mitchell wrote:
>> Some of the headers shipped with gcc 6.1 and above now use
>> #include_next
>> to try to and do clever things with munging system header files. Our
>> injection of isystem into the build at 'meta/conf/bitbake.conf' seems
>> to
>> be causing some programs to fail to compile. A full explanation can
>> be
>> found at [1], a bug report from GCC specifying that it should only be
>> used in extreme cases at [2].
>>
>> Since we seem to be adding -isystem unconditionally to BUILD_CFLAGS
>> from
>> bitbake, and that the default behavior has now changed should this be
>> revisited? I'll admit that I am no where near experienced enough with
>> GCC and friends internals to make a call on this one, I'm just
>> looking
>> for some input.
>
If I read the bug correct, the error occurs only for c++ when
including STL headers (and for us on native recipes). As this
combination is not that common (meta-qtx?) we have not seen fallout so
far.
> Its been a long time since we've looked at the native build flags and
> the world is a different place from when they were first implemented
> around a decade ago. I did cull some bits occasionally but more cleanup
> remains and it could be we can change it. A build of all the native
> recipes trying to replace it with a -I flag would likely be the first
> step...
>
a bit off topic: I did prepare similar for cmake-native. I saw much
fallout and helped myself by patching cmake-native. Will send out a
patch as RFC.

Andreas