[flang] 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, 1 insertions, 1 deletions

diff --git a/flang/tools/f18-parse-demo/f18-parse-demo.cpp b/flang/tools/f18-parse-demo/f18-parse-demo.cpp
index d251154381a1..ae0a3c4fb987 100644
--- a/flang/tools/f18-parse-demo/f18-parse-demo.cpp
+++ b/flang/tools/f18-parse-demo/f18-parse-demo.cpp
@@ -111,7 +111,7 @@ void Exec(std::vector<llvm::StringRef> &argv, bool verbose = false) {
     ErrMsg = Program.getError().message();
   if (!Program ||
       llvm::sys::ExecuteAndWait(
-          Program.get(), argv, llvm::None, {}, 0, 0, &ErrMsg)) {
+          Program.get(), argv, std::nullopt, {}, 0, 0, &ErrMsg)) {
     llvm::errs() << "execvp(" << argv[0] << ") failed: " << ErrMsg << '\n';
     exit(EXIT_FAILURE);
   }