With this testcase the code in template_args_equal to treat aliases as
distinct wasn't sufficient, because it only looked at the top level, whereas
here we have a reference to the alias. So let's also handle treating them
as distinct in structural_comptypes. For GCC 10 I have a more comprehensive
patch, but for GCC 9 let's go with this smaller change.
* typeck.c (structural_comptypes): When comparing_specializations,
aliases are unequal.
(comptypes): When comparing_specializations, do structural
comparison.
git://gcc.gnu.org / gcc.git / commit