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Re: c++/950: Template lookup problem
- From: Wolfgang Bangerth <bangerth at ticam dot utexas dot edu>
- To: gcc-bugs at gcc dot gnu dot org, <gcc-gnats at gcc dot gnu dot org>
- Date: Sun, 10 Nov 2002 14:46:04 -0600 (CST)
- Subject: Re: c++/950: Template lookup problem
A reduced testcase for this one is
--------------------------------------------
struct B { void a (int n); };
struct D: public B {};
template <typename T> struct X {
template<typename Y>
static void foo (const Y&, void (T::*)(Y));
};
int main () {
int n = 3;
X<D>::foo(n, &D::a);
}
--------------------------------------
The error I get is this one:
x.cc: In function `int main()':
x.cc:11: error: no matching function for call to `X<D>::foo(int&, void
(B::*)(int))'
Thus, the compiler cannot find a match for X::foo, since &D::a is
immediately converted to &B::a, i.e. to a pointer to member function of
the _base_ class, although we have taken a p-t-m-f of the derived class. I
don't know what the standard says on this one, but at least the failure
mode is clear now.
The problem can be worked around using a temporary variable of type
void (D::*)(int)
or an explicit cast.
Regards
Wolfgang
-------------------------------------------------------------------------
Wolfgang Bangerth email: bangerth@ticam.utexas.edu
www: http://www.ticam.utexas.edu/~bangerth