The surrounding discussion is is pretty much the old battle between C++ proponents (who point out its many merits) and opponents (who point out its many flaws). Concerns about speed and the need to teach GCC devs to use C++. Concerns about 'misuse of C++ features.' I find the slowness argument especially amusing since Clang/LLVM is written in C++ and it does not appear to be suffer from severe performance problems.
And of course there are those who suggest only to use a subset of C++ that would not incur performance penalty nor contain features that are 'easily misused'. I hear many software projects claiming to use C++ are actually written in different, mutually incompatible subsets of C++ (using or not using exceptions, RTTI, templates, etc.) This seems to be encouraged by the historically bad conformance of C++ compilers to the language standard.
Looking away from the rather amusing bickering, does this change affect me, a mere mortal user? Well normally I couldn't care less. When I compile GCC on Linux this certainly does not present any problem. From HelenOS point of view, this is more interesting.
To make HelenOS self-hosting, we need to be able to have some compiler which can be compiled within the system. Question is, which compiler should it be? Today GCC is still a hot candidate -- it is probably the only compiler supporting all the CPU architectures and other features we need. Another selling point was it being written in C -- which it will now lose. In the future it would be necessary to implement or port the C++ standard library (and STL) to HelenOS in order to compile GCC in it.
This makes GCC drop closer to Clang/LLVM on our suitability ladder. (Clang/LLVM is also written in C++). Practically the only remaining deficiency of Clang/LLVM w.r.t GCC is that unlike LLVM itself, which should have good support for several architectures, Clang currently only has good support for i386/x86_64. It should not be hard to improve Clang support for other targets, but still there must be sufficient demand to drive the development (Apple does not need it).
Another player in the field is the Portable C Compiler. It is written in C, but it is a relatively small project and supports only a few CPU architectures. (Interestingly neither LLVM nor PCC support Intel Itanium architecture). I have some misgivings against depending on such project whose future is not very certain.
In any case, the choice of a (first) C compiler to run in HelenOS remains open for now.