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

catch_ptr_02.cpp --> uncaught_exceptions.pass.cpp

[mclow.lists]

Committed as r238827.

include/cxxabi.h

 
 #include <__cxxabi_config.h>
 
-#define _LIBCPPABI_VERSION 1001
+#define _LIBCPPABI_VERSION 1002
 #define LIBCXXABI_NORETURN  __attribute__((noreturn))
 
 #ifdef __cplusplus

 extern void __cxa_increment_exception_refcount(void* primary_exception) throw();
 extern void __cxa_decrement_exception_refcount(void* primary_exception) throw();
 
-// Apple addition to support std::uncaught_exception()
-extern bool __cxa_uncaught_exception() throw();
+// Apple extension to support std::uncaught_exception()
+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"

test/uncaught_exceptions.pass.cpp

+//===------------------------- catch_ptr_02.cpp ---------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <cxxabi.h>
+#include <exception>
+#include <cassert>
+
+// namespace __cxxabiv1 {
+//      extern bool          __cxa_uncaught_exception () throw();
+//      extern unsigned int  __cxa_uncaught_exceptions() throw();
+// }
+
+struct A {
+    ~A() { assert( __cxxabiv1::__cxa_uncaught_exception()); }
+    };
+
+struct B {
+    B(int cnt) : data_(cnt) {}
+    ~B() { assert( data_ == __cxxabiv1::__cxa_uncaught_exceptions()); }
+    int data_;
+    };
+
+int main ()
+{
+    try { A a; throw 3; assert (false); }
+    catch (int) {}
+    
+    try { B b(1); throw 3; assert (false); }
+    catch (int) {}
+}