PR c++/90532 Ensure __is_constructible(T[]) is false
An array of an unknown bound is an incomplete type, so no object of such
a type can be constructed. This means __is_constructible should always
be false for an array of unknown bound.
This patch also changes the std::is_default_constructible trait to use
std::is_constructible, which now gives the right answer for arrays of
unknown bound.
gcc/cp:
PR c++/90532 Ensure __is_constructible(T[]) is false
* method.c (is_xible_helper): Return error_mark_node for construction
of an array of unknown bound.
gcc/testsuite:
PR c++/90532 Ensure __is_constructible(T[]) is false
* g++.dg/ext/90532.C: New test.