[cfe-dev] const-ness in libc++ allocator

[redballoon36 at gmail.com]

Hello,

I've encountered a compiler error using shared_ptr and allocator from the
libc++ header <memory>.  I'm running OS X 10.7.2, and I first noticed this
while using the libc++ implementation with Xcode 4.2.1, though I believe
this still exists in svn 147357.

The problem is caused by instantiating std::allocator<> (in the memory
header) with a const type.  This causes the pointer and const_pointer types
to be the same, which results in methods using these to have the same
signatures, which gives a compiler error (as it should, given that methods
are colliding).  Is this supposed to happen? I haven't read the standard,
but it seems like it should work, that is, that std::allocator<const int>
should be allowed to exist.

A bit of background. This gets triggered when using:
std::shared_ptr<const int> ptr(new const int(4));
which also seems like a reasonable thing to do.

Thanks,
Paul O'Neil
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