const to non-const pointer template argument conversion

Question

VC10 and GCC 4.4 accept the following, while Sun Studio 12 does not:

std::pair<char*, int> p1;
std::pair<char* const, int> p2;
p1 = p2

Sun Studio 12 complains:

Error: Cannot use std::pair<char*const, int> to initialize std::pair<char*, int>.

Any ideas why this is happening and how I can get Sun Studio to ignore this. I am working with a third party library, which would be a pain to rewrite just for this sort of thing.

Answer 1

It seems to be a known issue with Sun's std library.

Your best bet may be to convince the author of the code to replace the assignment with:

p1 = std::make_pair(p2.first, p2.second);

Or at construction time:

std::pair<char*, int> p1(p2.first, p2.second);

Answer 2

Are you making sure to use libstlport rather than libCstd? See: https://stackoverflow.com/a/4481452/196844

This is definitely an error in the STL implementation. Section 20.2.2, Pairs, of the C++98 Standard provides for the template constructor template <class U, class V> pair(const pair<U, V>& p) which initializes members first and second from the corresponding members of p, performing implicit conversions as needed.