Add a new routine to libc++abi to get the number of uncaught exceptions

[mclow.lists]

Summary

In http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4259, the method std::uncaught_exceptions() (note the 's') on the end was added to the C++ working paper. This returns the number of currently uncaught exceptions.

The old routine uncaught_exception was deprecated.
libc++abi knows the number, but the call __cxa_uncaught_exception just returns if it is != 0.

Add a new call __cxa_uncaught_exceptions, (with an 's') and make __cxa_uncaught_exception call it.

After this is landed, there will need to be changes to libc++ to use it.

[jroelofs]

Seems reasonable to me. Mind writing testcases for both functions?

include/cxxabi.h

164

s/addition/extension/ while you're here?

[EricWF]

I think that this patch should bump the value of _LIBCPPAPI_VERSION. libc++ is going to need to know when libc++abi supports __cxa_uncaught_exceptions() and when it doesn't in order to provide std::uncaught_exceptions(). Using the value of _LIBCPPABI_VERSION seems like an appropriate approach.

Other than that and @jroelofs request for tests this patch LGTM.

[mclow.lists]

Added basic tests.
Bumped the version # for libc++abi

[jroelofs]

cool... LGTM.

test/uncaught_exceptions.pass.cpp

1 ↗

(On Diff #26834)

catch_ptr_02.cpp --> uncaught_exceptions.pass.cpp

[mclow.lists]

Committed as r238827.

include/cxxabi.h

 extern void __cxa_decrement_exception_refcount(void* primary_exception) throw();
 
 // Apple addition to support std::uncaught_exception()
-extern bool __cxa_uncaught_exception() throw();
+extern bool          __cxa_uncaught_exception () throw();
+extern unsigned int  __cxa_uncaught_exceptions() throw();
 
 #ifdef __linux__
 // Linux TLS support. Not yet an official part of the Itanium ABI.

src/cxa_exception.cpp

 }
 
 bool
-__cxa_uncaught_exception() throw()
+__cxa_uncaught_exception() throw() { return __cxa_uncaught_exceptions() != 0; }
+
+unsigned int
+__cxa_uncaught_exceptions() throw()
 {
     // This does not report foreign exceptions in flight
     __cxa_eh_globals* globals = __cxa_get_globals_fast();
     if (globals == 0)
         return false;
-    return globals->uncaughtExceptions != 0;
+    return globals->uncaughtExceptions;
 }
 
 }  // extern "C"