c++: build initializer_list<string> in a loop [PR105838]

I previously applied this change in r13-4565 but reverted it due to
PR108071.  That PR was then fixed by r13-4712, but I didn't re-apply this
change then because we weren't making the array static; since r14-1500 for
PR110070 we now make the initializer array static, so let's bring this back.

In situations where the maybe_init_list_as_range optimization isn't viable,
we can build an initializer_list<string> with a loop over a constant array
of string literals.

This is represented using a VEC_INIT_EXPR, which required adjusting a couple
of places that expected the initializer array to have the same type as the
target array and fixing build_vec_init not to undo our efforts.

	PR c++/105838

gcc/cp/ChangeLog:

	* call.cc (convert_like_internal) [ck_list]: Use
	maybe_init_list_as_array.
	* constexpr.cc (cxx_eval_vec_init_1): Init might have
	a different type.
	* tree.cc (build_vec_init_elt): Likewise.
	* init.cc (build_vec_init): Handle from_array from a
	TARGET_EXPR.  Retain TARGET_EXPR of a different type.

gcc/testsuite/ChangeLog:

	* g++.dg/tree-ssa/initlist-opt5.C: New test.

0 files changed, 0 insertions, 0 deletions