Side effects of enabling C++0x support in gcc

Question

Following link, I'm wondering if there're some side effects of enabling C++0x in GCC.

According to gcc: "GCC's support for C++0x is experimental".

What I'm afraid of is that for example compiler will generate some code differently or standard library uses some C++0x feature which is broken in gcc.

So if I don't explicitly use any of C++0x features, may it break my existing code?

Answer 1

The C++0x support has been, and is under heavy development. One thing this means is that bugs get fixed quickly, another thing it means is that there might be small bugs present. I say small, because of two reasons:

1. libstdc++ has not been rewritten from scratch, so all the old elements are just as stable as it was before any of this c++0x was available, if not more stable, because of several years of bug fixes.

2. There's corner cases in the new/old Standard that haven't yet been ironed out. Are these the runtime quirks you talk about? No. C++0x support has been under development for 4 releases now, don't worry.

Most of the impact from that flag will be felt in the new language features, the library features like move constructors and std::thread (on posix platforms) don't affect code not using them.

Bottom line, experimental is too strict a word in daily production. The standard has changed in the three/four years GCC has been working on support. Old revisions of c++0x will be broken in a newer GCC, but that's a good thing. C++0x is finished as far as the non-paying-for-a-pdf-world is concerned, so no breaking changes should be added. Decide if you want the new stuff or not beforehand, because you won't be able to jsut switch it off once you've gotten used to using it.