On Sat, Sep 5, 2009 at 8:51 AM, Christopher Schmidt<mr.chr.schmidt@online.de> wrote:
I think gcc behaves correctly.
The non-0x pair has a two-argument constructor taking const references to T1 and T2 (20.2.2p2). Therefore the 0 you pass is directly regarded be the null pointer constant. The 0x pair has a 1...N argument _template_ constructor (20.2.2p6 of the current draft). The 0 is regarded to be an int, and therefore you are passing an actual int to initialize a pointer.
std::pair<int, int*> x(0,nullptr); or std::pair<int, int*> x(0,static_cast<void*>(0));
should work fine though.
Since nullptr is a C++0x feature, that won't work for code that also has to run on c++03 compilers. static_cast<void*>(0) isn't valid since a conversion from void* to int* isn't valid. static_cast<int*>(0) works OK. What about a macro "#define nullptr 0" that is only defined if the compiler does not support C++0x nullptr? It usually is a really bad idea to give a macro a lowercase name, but isn't this a really special case because nullptr is a C++0x keyword? --Beman