c++: __is_trivially_xible and multi-arg aggr paren init [PR102535]
is_xible_helper assumes only 0- and 1-argument ctors can be trivial, but
C++20 aggregate paren init means multi-arg ctors can now be trivial too.
This patch relaxes the relevant early exit check accordingly.
PR c++/102535
gcc/cp/ChangeLog:
* method.c (is_xible_helper): Don't exit early for multi-arg
ctors in C++20.
gcc/testsuite/ChangeLog:
* g++.dg/ext/is_trivially_constructible7.C: New test.
(cherry picked from commit
9845c52db38f15740861435f38f7e5ad8a8de2ec)