[OE-core] gcc 6.1+ and isystem

[Richard Purdie]

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.

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...

Cheers,

Richard