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Using C++ in GCC is OK

From: Mark Mitchell <mark at codesourcery dot com>

To: GCC <gcc at gcc dot gnu dot org>

Date: Sun, 30 May 2010 17:26:16 -0700

Subject: Using C++ in GCC is OK

I am pleased to report that the GCC Steering Committee and the FSF have approved the use of C++ in GCC itself. Of course, there's no reason for us to use C++ features just because we can. The goal is a better compiler for users, not a C++ code base for its own sake. Before we start to actually use C++, we need to determine a set of coding standards that will apply to use of C++ within GCC. At first, I believe that we should keep the set of C++ features permitted small, in part so that GCC developers not familiar with C++ are not rapidly overwhelmed by a major change in the implementation language for the compiler itself. We can always use more of C++ later if it seems appropriate to do so, then. For example, I think it goes without question that at this point we are limiting ourselves to C++98 (plus "long long" so that we have a 64-bit integer type); C++0x features should not be used. Using multiple inheritance, templates (other than when using the C++ standard library, e.g. std::list<X>), or exceptions also seems overly aggressive to me. We should use features that are relatively easy for C programmers to understand and relatively hard for new C++ programmers to misuse. (For example, I think constructors and destructors are pretty easy and hard to misuse.) Because C++ is a big language, I think we should try to enumerate what is OK, rather than what is not OK. But, at the same time, I don't think we should try to get overly legalistic about exactly what is in and what is out. We need information guidelines, not an ISO standard. Is there anyone who would like to volunteer to develop the C++ coding standards? I think that this could be done as a Wiki page. (If nobody volunteers, I will volunteer myself.) Whoever ends up doing this, I would urge the rest of us not to spend too much time in the C++ coding-standards bikeshed; we're not going to win or lose too much because we do or do not permit default parameters. -- Mark Mitchell CodeSourcery mark@codesourcery.com (650) 331-3385 x713