Re: [boost] Review Request: Singularity

Subject: Re: [boost] Review Request: Singularity
From: Stephan T. Lavavej (stl_at_[hidden])
Date: 2011-08-23 16:26:01

[Mathias Gaunard]
> which is simple, short, fast to compile, and thread-safe.

[John Maddock]
> Not thread safe on the majority of compilers surely?

[Mathias Gaunard]
> Isn't MSVC the only one that doesn't do it?
> And MSVC11 does it, I believe.
> I thought I had read that somewhere, but I can't find the source anymore
> so maybe I'm just confusing it with something else.
> Hopefully it will be the case though.

You're thinking of C++11 "magic statics" (my term), http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2660.htm "Dynamic Initialization and Destruction with Concurrency".

Neither VC10 nor GCC 4.6 implement magic statics (see http://blogs.msdn.com/b/vcblog/archive/2010/04/06/c-0x-core-language-features-in-vc10-the-table.aspx and http://gcc.gnu.org/gcc-4.6/cxx0x_status.html ). I've heard (but don't take my word for it) that GCC currently ensures correctness here by taking a lock, which is far less desirable than the novel magic statics algorithm. VC does not ensure correctness here.

We haven't yet revealed VC11's Core Language features, except for the bugfix-level ones that I've mentioned in passing (e.g. lambdas v1.1).

Stephan T. Lavavej
Visual C++ Libraries Developer