------- Comment #8 from rguenth at gcc dot gnu dot org 2009-02-19 15:20 -------
Note that the patch only affects extern explicit template instantiations.
/* Check to see whether we know that this template will be
instantiated in some other file, as with "extern template"
extension. */
external_p = (DECL_INTERFACE_KNOWN (d) && DECL_REALLY_EXTERN (d));
/* In general, we do not instantiate such templates... */
if (external_p
/* ... but we instantiate inline functions so that we can inline
them and ... */
&& ! (TREE_CODE (d) == FUNCTION_DECL
&& DECL_DECLARED_INLINE_P (d))
For them we would no longer inline (or rather instantiate) not inline declared
members. This may affect parts of libstdc++, but I don't know.
In YCP the extern trick seems to be used to break a dependency cycle, so the
situation is somewhat special.
The ultimate question is of course if the standard allows (or even requires)
an error here.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39242
