Re: [boost] questions regarding visibility and b2

Subject: Re: [boost] questions regarding visibility and b2
From: Robert Ramey (ramey_at_[hidden])
Date: 2018-10-27 19:19:56

On 10/27/18 10:45 AM, Steven Watanabe via Boost wrote:
> AMDG
> 
> On 10/27/2018 11:29 AM, Robert Ramey via Boost wrote:
>> I've got a few questions about the "visibility" changes for boost.
>>
>> My understanding is that "visibility" for gcc and clang are "sort of the
>> same thing" as dll import and export are for windows.
>>
>> Now we've made "visibility" the "default".
>>
>> But this seems kind of weird.  This has been made a b2 feature.  In
>> order to run tests, this feature is applied to the b2 command line.
>> What's weird is that it's applied to the tests/executables and
>> propogated down to libraries which are built.  I actually don't know
>> what "visibility" means in the context of building and executable.
> 
> It means the same thing that it means for a shared library.
> It's possible for a shared library to import symbols from
> the main executable.  (This usually happens for dynamically
> loaded extensions.)  visibility controls which symbols are exported.

Hmmm - this is itself very weird.  How do we know that something likes 
this actually works.  Does is work with windows exe?  I've never seen 
anything like this explained.

Robert Ramey