Re: [boost] [TypeIndex] Peer review period for library acceptance begins, ending Thurs 21st Nov

Subject: Re: [boost] [TypeIndex] Peer review period for library acceptance begins, ending Thurs 21st Nov
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2013-11-14 16:50:11

AMDG

On 11/14/2013 12:29 PM, Niall Douglas wrote:
> On 14 Nov 2013 at 7:01, Steven Watanabe wrote:
> 
>> No, it is not harmless.  You cannot safely assume
>> that undefined behavior is ever harmless, just
>> because you can't think of anything that can go wrong.
>> In particular, the compiler is free to make assumptions
>> that can cause your code to miscompile with optimizations on.
> 
> For the purposes of my peer review report, can you say if you know of 
> any misoperation which any major compiler might do in this 
> circumstance?
> 

I believe that this was a problem for Boost.Move with gcc,
which does something similar.  It's actually quite common
for old C code that casts between different structs to fail
with newer compilers.  For instance, Python does not work
without -fno-strict-aliasing.

In Christ,
Steven Watanabe