c++: Fix up calls to immediate functions returning reference [PR99507]

build_cxx_call calls convert_from_reference at the end, so if an immediate
function returns a reference, we were constant evaluating not just that
call, but that call wrapped in an INDIRECT_REF.  That unfortunately means
it can constant evaluate to something non-addressable, so if code later
needs to take its address it will fail.

The following patch fixes that by undoing the convert_from_reference
wrapping for the cxx_constant_value evaluation and readdding it ad the end.

2021-03-12  Jakub Jelinek  <jakub@redhat.com>

	PR c++/99507
	* call.c (build_over_call): For immediate evaluation of functions
	that return references, undo convert_from_reference effects before
	calling cxx_constant_value and call convert_from_reference
	afterwards.

	* g++.dg/cpp2a/consteval19.C: New test.

0 files changed, 0 insertions, 0 deletions