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

Subject: Re: [boost] [function] Placement new warnings from gcc 6
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2016-04-02 08:10:21

On 2016-04-01 19:37, Peter Dimov wrote:
> 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...

Thanks. I've made a patch with a similar idea:

https://github.com/boostorg/function/pull/9

It passes tests on gcc 5.2 and MSVC-14, but unfortunately I don't have 
gcc 6 locally to verify that the warnings are actually gone.