[Bug libstdc++/39405] [4.3 regression] std::shared_ptr barfs on incomplete template class that boost::shared_ptr accepts

["d dot frey at gmx dot de" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #17 from d dot frey at gmx dot de  2009-03-13 16:41 -------
(In reply to comment #16)
> Note, just tweaking is_function like this, doesn't completely fix the issue for
> me, only the reduced testcase using is_abstract...

And actually I don't even understand why it works even in the reduced testcase
:(

Anyway, I think there might be a more basic problem here, which simply raises
the question how instantiations should work. To explain, I created the
following which has *no* includes:

template< typename T >
struct ptr
{
  typename T::type dummy();
};

template< typename T >
struct foo
{
  typedef void type;
  ptr< foo > p;
};

int main()
{
  foo< int > f; // fails without this line
  ptr< foo< int > > p;
}

Note that this does *not* depend on c++0x, it shows the exact same problem with
"normal" C++. Is the compiler correct to reject the code when the marked line
is removed? Guess this needs to be taken to the language lawyers.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39405