"namespace linux" clashes with GNU C++14 extensions

[wflohry]

Using gcc 6.3.0, compiling with linux fails if "-std=gnu++14" is used. Compiling with "-std=c++14" works fine.

The GCC manual (see 2.2 C++ Language) says:

By default, GCC also provides some additional extensions to the C++ language that on rare occasions conflict with the C++ standard. The default, if no C++ language dialect options are given, is
-std=gnu++14.

Specifically, the lines referring to "namespace linux" cause the following error:

/root/.jenkins/cinder/include/cinder/linux/FreeTypeUtil.h:38:30: error: expected identifier before numeric constant
 namespace cinder { namespace linux { namespace ftutil {
                              ^
compilation terminated due to -Wfatal-errors.

To replicate, compile with "-std=gnu++14".
I was able to fix it by either:

1. compiling with "-std=c++14" and not gnu++14, or
2. replacing all uses of the namespace linux with ci_linux

[richardeakin]

So is linux made to be a reserved keyword when gnu++14 is used then? Does the compiler complain for other places where there is a namespace linux, like here? This seems pretty non-standard, but I don't see changing the name of that namespace to be a big deal (though I'd hope we could think of a good alternative within an underscore in it, for consistency).

[MikeGitb]

Can't check, but sounds like linux is a macro in that mode.

[wflohry]

Does the compiler complain for other places where there is a namespace linux, like here?

It seems that any use of namespace linux results in an error.

To test, I created a simple main.cpp file:

namespace cinder { namespace linux { } }
int main() { return 0; }

I tested with gcc 6.3.0 and gcc 7.2.0.

Running c++ main.cpp -std=gnu++14 or c++ main.cpp results in the error.

Running c++ main.cpp -std=c++14 doesn't result in the error.

[PetrosKataras]

I m wondering why the GNU version is pulled in by default since -std=c++14 should be already explicitly set here .

[wflohry]

It's not necessarily a problem with compiling Cinder itself, but using it in software that has the GNU++14 extensions. If namespace linux only appeared in Cinder's compiled files it wouldn't be a problem, but since it appears in the header files, it will clash with the GNU++14 extensions in software using it.

[MikeGitb]

@richardeakin , @andrewfb : Is there any consensus to rename that namespace is this a won't fix and people just can't use cinder with -std=gnu++14 / gnu++17?