http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49609
--- Comment #4 from Stephen Kell <srk31 at srcf dot ucam.org> 2011-07-01 18:09:07 UTC --- (In reply to comment #2) > That paragraph says that if template argument deduction succeeds then an > instantiation is generated. In your case deduction doesn't succeed because the > target type is not available. The note added by DR 115 says that the > specialization can be identified if there's a template argument list, which is > what happens in your example, but it doesn't say that the function template is > instantiated in that case. Ah, I see... I was thinking that the error was spurious because I hadn't overloaded the function, but I guess the template argument-dependence defines a family of overloads. > > You can make it work by using an explicit type conversion to the correct > > type > > before doing the reinterpret_cast: > > > > void *(*my_function_ptr)(void*, void *) > > = reinterpret_cast<void*(*)(void*,void*)>( > > (void*(*)(float*,float*))&(value_convert_function<float, float>) ); > > You can also make it work by not specifying an explicit template argument list > and letting them be deduced: > > void *(*my_function_ptr)(void*, void *) > = reinterpret_cast<void*(*)(void*,void*)>( > (void*(*)(float*,float*))&value_convert_function); Cool -- thanks for this! That teaches me for thinking I can get away without ever using C-style casts in C++....
