[boost] [config] does BOOST_ATTRIBUTE_UNUSED defined implies __attribute__((used)) exists ?

Subject: [boost] [config] does BOOST_ATTRIBUTE_UNUSED defined implies __attribute__((used)) exists ?
From: Raffi Enficiaud (raffi.enficiaud_at_[hidden])
Date: 2018-09-17 20:46:23

Hi,

I have a problem with symbol visibility in boost.test:
https://github.com/boostorg/boost/pull/190

I am wondering if __attribute__((used)) is a portable way to flag a 
static const ref as being used, or there are variations 
(__attribute__((used)) vs __attribute__((__used__))).

I am also wondering if __attribute__((used)) can be considered as 
available if BOOST_ATTRIBUTE_UNUSED is defined.

Would it make sense to have an BOOST_ATTRIBUTE_USED in boost.config?

Thanks,
Raffi