Travis CI shows linking errors on Linux and OS X when __cxa_uncaught_exceptions
is used to implement uncaught_exceptions. There's probably some library missing,
which should be linked in implicitly by the compiler, or the library indeed
does not export the symbol. In any case, __cxa_get_globals-based implementation
should provide the same effect.
Apparently, gcc < 4.7 on Linux also don't have __cxa_get_globals
declaration in cxxabi.h. Declare the function ourselves.
Also, on OpenBSD it seems there is no declaration either, and
on that platform the function implementation has no exception
specification, like on FreeBSD. Add a declaration of that platform.
Lastly, changed __cxa_get_globals and _getptd-based implementations
to avoid violating strict aliasing rules. This is still formally UB
to access structure fields like we do, but this is one less reason to
cause miscompilation or compiler warnings.
This should resolve gcc errors caused by mismatch of the return types of
aur declaration of __cxa_get_globals and the original in cxxabi.h.
Fixes https://github.com/boostorg/core/issues/45.
The uncaught_exceptions function is functionally equivalent to
unhandled_exceptions_count in Boost.Log and implements functionality
similar to the same named C++17 standard function. Tests and docs are
also included.
One notable difference from std::uncaught_exceptions is that the return
type is unsigned rather than signed. This is deliberate as uncaught_exceptions
must never return a negative value and unsigned int better documents that.
Theoretically, as a counter, it may also overflow.
The new output is no less useful, and not potentially misleading (for example in the case of BOOST_TEST_LT(1, nan) failing, it was not right to say that 1 >= nan).
* Work in progress, some tests fail
* adding tests
* missing header
* moved close_to to detail, added constness, replaced predicates from <functional> with custom ones, new code does not rely on partial template specialization
* renamed predicates and removed close_to predicate
* removing now superfluous headers
* unpatching the fix to put in a separate PR
* move predicate to first argument
* call op and anti_op as normal methods
