Re: [boost] C++03 unique_ptr emulation

Subject: Re: [boost] C++03 unique_ptr emulation
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2009-01-08 20:54:15

AMDG

Howard Hinnant wrote:
> The first como failure 
> (unique.ptr\unique.ptr.runtime\unique.ptr.runtime.ctor\default02.pass.cpp) 
> looks like a test bug.  B<D>::B() should be outlined next to ~B() 
> instead of inlined.

Confirmed.  I made the change and it passes now.

> I started going through the rest of the como failures and they all 
> look like a failure in detail::is_convertible.  My best guess is that 
> this version of como hasn't implemented CWG issue 291 
> (http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#291), 
> which is understandable considering this issue is C++0X targeted, not 
> C++03 targeted (accepted Oct. 05).  <sigh> is_convertible is a tricky 
> area and apparently my implementation is depending on a dark corner 
> that won't be official until C++0X.  I do not know if changing "test1" 
> to "test2" on line 50 of unique_ptr.hpp would help or not.  It doesn't 
> help on g++.  It might help on Como.  This is a dark corner of the 
> language <shrug>.  If it doesn't help, I don't have a backup plan.

It doesn't help.

> In this case it would appear that there is no C++03 technique for 
> implementing is_convertible for move-only types (that I'm aware of).  
> And if that is the case, a C++03 emulation of move seems very much in 
> jeopardy.  A working is_convertible is the foundation upon which this 
> move emulation is built.

In Christ,
Steven Watanabe