[IR] Use std::nullopt instead of None (NFC)

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

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp
index 9d23910..d443f2c 100644
--- a/llvm/lib/IR/ConstantRange.cpp
+++ b/llvm/lib/IR/ConstantRange.cpp
@@ -705,7 +705,7 @@ ConstantRange::exactIntersectWith(const ConstantRange &CR) const {
   ConstantRange Result = intersectWith(CR);
   if (Result == inverse().unionWith(CR.inverse()).inverse())
     return Result;
-  return None;
+  return std::nullopt;
 }
 
 Optional<ConstantRange>
@@ -714,7 +714,7 @@ ConstantRange::exactUnionWith(const ConstantRange &CR) const {
   ConstantRange Result = unionWith(CR);
   if (Result == inverse().intersectWith(CR.inverse()).inverse())
     return Result;
-  return None;
+  return std::nullopt;
 }
 
 ConstantRange ConstantRange::castOp(Instruction::CastOps CastOp,