Re: [boost] [static_if] Is there interest in a `static if` emulation library?

Subject: Re: [boost] [static_if] Is there interest in a `static if` emulation library?
From: Sebastian Redl (sebastian.redl_at_[hidden])
Date: 2014-09-01 18:42:04

On 02 Sep 2014, at 24:06, Robert Ramey <ramey_at_[hidden]> wrote:

> FWIW - I'm extremely skeptical of performance claims based on 
> speculation.  It wouldn't surprise me of compilers are already
> skipping compilation of dead branches for which it can be easily
> determined that there are no compile-time side-effects.  In fact
> since I generally have very little problem with compile times these
> days - in spite of writing a lot of template code - I'll bet that
> compiler writers already do this.  Not that it matters because
> it's just not a problem except in contrived pathological cases.

I know for a fact that Clang doesn’t (it doesn’t even have a notion of dead branches until long after all template instantiation is done), and I would be very surprised if any other compiler does - after all, that would be non-conformant, as it would allow erroneous programs to compile.

Either way, my need for static if is to conditionally have specific declarations in a class template or not, so unless the library can do this (the suggested usage won’t work in a pure declaration context), it’s no use to me.

Sebastian