Re: Old Meyers C++ compiler test no longer valid?
On 17 Jul., 23:26, Russ Bryan <rbryan.nay...@gmail.com> wrote:
Maybe the compilers now refuse to deduce T to the member function
closure type "dereferenced member function pointer in C". After all,
what would they do if you then declared a variable of that type?
I've got it. There actually is a bug in the original code. The
second member of null needs to return a const T:
const class {
public:
template <class T>
operator T*() const {return 0;}
template <class C, class T>
operator const T C::*() const {return 0;}
} null = {};
This looks wrong to me. Doesn't it say that it's a
"pointer to member of C of type const function taking () const and
returning ..."
and therefor qualify as a documented deduction failure? 14.8.2 lists
it as "Attempting to create a cv-qualified function type". But C++1x
changes that, and says the "const" there before "T" will be silently
ignored. If this indeed works on your compiler, then i think this is
only "luck" (depending how you look at it...). Looks like it misses to
test a case which it tests elsewhere when the const isn't there.
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