[clang] [mlir] [mlir] Migrate away from std::nullopt (NFC) (PR #145523)

[River Riddle via cfe-commits]

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@@ -1060,7 +1060,7 @@ makeMatcherAutoMarshall(ReturnType (*Func)(), StringRef MatcherName) {
   BuildReturnTypeVector<ReturnType>::build(RetTypes);
   return std::make_unique<FixedArgCountMatcherDescriptor>(
       matcherMarshall0<ReturnType>, reinterpret_cast<void (*)()>(Func),
-      MatcherName, RetTypes, std::nullopt);
+      MatcherName, RetTypes, ArrayRef<ArgKind>());
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River707 wrote:

Was this meant to be included (given the `mlir` in the title)

https://github.com/llvm/llvm-project/pull/145523