Re: [boost] C++03 unique_ptr emulation

Subject: Re: [boost] C++03 unique_ptr emulation
From: Howard Hinnant (hinnant_at_[hidden])
Date: 2009-01-08 18:33:50

On Jan 8, 2009, at 4:53 PM, Steven Watanabe wrote:

> AMDG
>
> Howard Hinnant wrote:
>> *  No doubt others (and myself) will find good ways to improve both  
>> the implementation and testsuite.  But this is the first version  
>> I'm willing to call fairly complete.  I believe there are 151  
>> tests:  63 that are supposed to pass and 88 that are supposed to  
>> fail.
>>
>> *  This was all tested on g++ 4.0.  I have no idea what it will  
>> take to get it working on other compilers.  To the best of my  
>> knowledge, it should work on any conforming C++03 compiler.
>
> There are 9 failures on on msvc 9.0 Express and 17 on como.
> Output attached.
>
> In Christ,
> Steven Watanabe

Thanks Steven,

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.

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.  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.

-Howard