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Subject: Re: [boost] questions regarding visibility and b2
From: Robert Ramey (ramey_at_[hidden])
Date: 2018-10-27 19:58:14

On 10/27/18 12:19 PM, Robert Ramey via Boost wrote:
> On 10/27/18 10:45 AM, Steven Watanabe via Boost wrote:
>> 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.

And would't it imply that any program compiled which gcc and uses a
shared library is a huge security risk?
> Robert Ramey
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