Explicitly initializing vector of pointers results in conversion error?
c++, visual-c++
Solution
It looks like g++ actually wrong here. See C++98 23.1.1/9:
For every sequence defined in this clause and in clause 21:
— the constructor template X(InputIterator f, InputIterator l, const Allocator& a = Allocator())
shall have the same effect as: `X(static_cast<typename X::size_type>(f), static_cast<typename X::value_type>(l), a)` if InputIterator is an integral type.
Note that `InputIterator` is a template parameter to the constructor, which in this case will be `int` for your example, and thus an integral type. The g++ library actually has specific code to handle all the cases where the type being stored in the `vector` is integral as well and those will all work properly. In this case, only because you used `0` would the `static_cast` dictated by the standard actually be legal. I tried compiling the code that the standard says should be equivalent and it compiles with g++ 4.5.
Problem
Consider this: ``` std::vector<int*> v(1, 0); ``` This compiles fine with VC++10 (no warnings even at max warning level). However, it doesn't compile with llvm on mac or gcc on linux, giving an error like "assigning to int* from incompatible type const int." I'm not looking for solutions -- I know the second parameter is unnecessary or that a static_cast fixes the error. I thought zero was implicitly convertible to any pointer type. What gives? I can do the following: ``` int* i = 0; int* const& ii = 0; const int t = 0; i = t; ``` I understand that the vector constructor signature takes a `const T&` which when expanded for `vector<int*>` becomes `int* const&` correct? Can someone explain what is going on here, and whether the VC++ or non-VC++ compiler is correct?