Re: [boost] [function] Placement new warnings from gcc 6

Subject: Re: [boost] [function] Placement new warnings from gcc 6
From: Peter Dimov (lists_at_[hidden])
Date: 2016-04-01 12:37:20

Steven Watanabe wrote:
> On 04/01/2016 02:11 AM, Andrey Semashev wrote:
> >
> > In my tests on gcc 6 I'm seeing these warnings which stem from 
> > Boost.Function:
> >
> > ../boost/function/function_template.hpp:572:11: warning: placement new 
> > constructing an object of type '<snip>'
> > and size '8' in a region of type 'char' and size '1' [-Wplacement-new=]

> The 'char' in question is the first element of an array of sufficient 
> size.

The buffer does have sufficient size but the char is not an array element. 
It's a char member of a union.

We could make this clearer by making function_buffer::data be an array with 
a sufficient size by, for instance, duplicating the definition of "union 
function_buffer" and taking its sizeof... or just by using &functor instead 
of &functor.data at line 572, although this might trigger aliasing warnings 
with other g++ versions.