PR libstdc++/85466
* real.h (real_nextafter): Declare.
* real.c (real_nextafter): New function.
* fold-const-call.c (fold_const_nextafter): New function.
(fold_const_call_sss): Call it for CASE_CFN_NEXTAFTER and
CASE_CFN_NEXTTOWARD.
(fold_const_call_1): For CASE_CFN_NEXTTOWARD call fold_const_call_sss
even when arg1_mode is different from arg0_mode.
* gcc.dg/nextafter-1.c: New test.
* gcc.dg/nextafter-2.c: New test.
* gcc.dg/nextafter-3.c: New test.
* gcc.dg/nextafter-4.c: New test.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@259921 138bc75d-0d04-0410-961f-82ee72b054a4