On 27.03.19 20:38, Andrey Semashev via Boost wrote:
On 3/27/19 10:16 PM, Raffi Enficiaud via Boost wrote:
[snip]
You can add -d+2 to the b2 command line to see the commands it is using while building Boost.
I'm guessing that the compiler is correct in that different visibility modes are used for different TUs, since I don't see visibility flags in your project's command line and visibility is likely set to hidden when building Boost. The particular complaint in the warnings you quoted is about the function-local static `null` in `basic_cstring<CharT>::null_str()`, which is not explicitly marked as visible and therefore has different visibility when it is compiled in Boost and your project.
I suggest changing the code so that `null` is instead a static class member of `basic_cstring` and mark it with `BOOST_SYMBOL_VISIBLE`. Also, it might make sense to make it a const array instead of a single character, and change `null_str` to return a const pointer instead of a mutable one.
I am not doing any change to the code that is not related to the warning. To follow up: https://github.com/boostorg/test/commit/04006ad5bdab92ad3f0eb23fb264a9141731... Lessons learned: * template classes should have their forward declaration with visibility settings * local visibility does not work (I do not know if this is the language or a compiler limitation), so the static variables need to get out. For instance: static lazy_ostream& instance() { BOOST_SYMBOL_VISIBLE static lazy_ostream inst; return inst; } is not setting the visibility of the static variable. I guess all those things are compiler specific, and not at all indicated in the standard? Thanks for the quick help, Tests are running, I will need to get this in the next release, Raffi