Re: USE_LANGUAGES+= c++ in bl3 files?

[Greg Troxel <gdt%lexort.com@localhost>]

Edgar Fuß <ef%math.uni-bonn.de@localhost> writes:

> In case a package exposes a library implemented in C++, should the bl3 file 
> set USE_LANGUAGES+= c++?
> I compile C++ with lang/gcc6, and I got strange build errors because 
> lib/gcc6/libatomic was not buildlink-ed.

This is messy.

Just because a library is *implemented* in C++ does not mean that the
depending package needs a a C++ compiler.

However, if you mean "not only is the library in C++, but when you link
it you also have to link some libstc++ and maybe some other libraries,
and you have to use a C++ compiler to call the linker to get that
right", then the question is whether programs not written in C++ are
expected to be able to use this at all, or if they basically have to be
C++ programs already.

An interesting example is geos, which is written in C++, but has a C
library.  The C library does depend on the C++ library, but one can link
it normally, in C -- and that's the point.  In fact it's the official
interface to geos.

So in general, I am not in favor of putting USE_LANGUAGES into bl3
files, and would consider that perhaps controversial.