------- Additional Comments From bangerth at dealii dot org 2004-10-13 12:50 -------
I'm not sure this is a bug: the standard quite unmistakably says that
default arguments aren't evaluated unless used. Now, if I try to
use the default argument in your testcase, like so
------------------
template<typename> struct A {};
template<typename T> struct B
{
A<T> a;
void foo(A<T> = a);
};
void bar ()
{
B<int>().foo();
}
--------------------------
then I do get a sensible error:
g/x> /home/bangerth/bin/gcc-4.0-pre/bin/c++ -c x.cc
x.cc:5: error: invalid use of non-static data member `B<int>::a'
x.cc:12: error: from this location
Can you say why the compiler should diagnose this earlier rather than
later, given what the standard says?
For reference:
14.7.2/9 says
An explicit instantiation does not constitute a use of a default
argument, so default argument instantiation is not done. [Example:
char* p = 0;
template<class T> T g(T = &p);
template int g<int>(int); // OK even though &p isn't an int.
--end example]
and there are more places like this.
W.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17971
