ambiguities with make_shared() function pointers with C++0x

[Georg Fritzsche <georg.fritzsche@…>]

Trying to store a function pointer to make_shared<Arg1> results in ambiguity errors in gcc (4.3.) with C++0x support being enabled.

The following:

typedef boost::shared_ptr<int>(*FP)();
FP fp = boost::make_shared<int>;

leads to:

error: converting overloaded function ‘make_shared’ to type ‘class boost::shared_ptr<int> (*)()’ is ambiguous
boost_1_41_0/boost/smart_ptr/make_shared.hpp:100: error: candidates are: boost::shared_ptr<X> boost::make_shared() [with T = int]
boost_1_41_0/boost/smart_ptr/make_shared.hpp:138: error: boost::shared_ptr<X> boost::make_shared(Args&& ...) [with T = int, Args = ]

[Georg Fritzsche <georg.fritzsche@…>]

simple test case

[Peter Dimov]

I can remove the nullary overload, but this will make the test at source:trunk/libs/smart_ptr/test/make_shared_test.cpp#L57 to fail on gcc 4.3.x (and maybe some 4.4 versions, I haven't checked.)

[Peter Dimov]

(In [62248]) Resolve the ambiguity between the zero argument make_shared and the variadic one. Refs #3856.

[Peter Dimov]

(In [63827]) Merge [62248] to release. Fixes #3856.