This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
Use recently added hlfir.associate/hlfir.end_associate to deal
with the cases where the actual argument is an expression.
Differential Revision: https://reviews.llvm.org/D139009
Move genCallOpAndResult from ConvertExpr.cpp into a new file so that
it can be shared with lowering to FIR and HLFIR during the transition.
After the transition, call lowering to HLFIR will be implemented in
this new file.
Differential Revision: https://reviews.llvm.org/D138643