Description
When using static libraries, a variety of things don't work. On macOS, any attempted use fails with
In file included from /Users/runner/work/stacktrace/boost-root/libs/stacktrace/test/cmake_install_test/main.cpp:6:
In file included from /Users/runner/.local/include/boost/stacktrace/stacktrace.hpp:27:
In file included from /Users/runner/.local/include/boost/stacktrace/safe_dump_to.hpp:[22](https://github.com/boostorg/stacktrace/actions/runs/9615275190/job/26522048559#step:8:23)1:
/Users/runner/.local/include/boost/stacktrace/detail/collect_unwind.ipp:33:2: error: "Boost.Stacktrace requires `_Unwind_Backtrace` function. Define `_GNU_SOURCE` macro or `BOOST_STACKTRACE_GNU_SOURCE_NOT_REQUIRED` if _Unwind_Backtrace is available without `_GNU_SOURCE`."
#error "Boost.Stacktrace requires `_Unwind_Backtrace` function. Define `_GNU_SOURCE` macro or `BOOST_STACKTRACE_GNU_SOURCE_NOT_REQUIRED` if _Unwind_Backtrace is available without `_GNU_SOURCE`."
^
whereas shared libraries work. Under Linux and Windows, things "work", but for instance test_noop.cpp fails when linked with boost_stacktrace_noop statically, even though it succeeds when linked dynamically.
I believe this is caused by the library incorrectly setting its configuration macros. safe_dump_to.hpp includes the implementation .ipp files when BOOST_STACKTRACE_LINK is not defined:
BOOST_STACKTRACE_LINK is a nonstandard macro that is set in push_options.h when the standard one BOOST_STACKTRACE_DYN_LINK is defined:
It is, however, not set when building static libraries (whose standard configuration macro is BOOST_STACKTRACE_STATIC_LINK, which CMakeLists.txt sets.)
Consequently, the library "thinks" it's in header only mode when static libraries are used, which is wrong and causes the issues above.
I don't know what the correct fix is; maybe BOOST_STACKTRACE_LINK needs to be defined when BOOST_STACKTRACE_STATIC_LINK is set, maybe something else. But currently things aren't right. (I think that this also presents problems on MinGW and Cygwin.)