[clang] [ASTMatchers] Migrate away from ArrayRef(std::nullopt) (NFC) (PR #145840)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Kazu Hirata (kazutakahirata)

<details>
<summary>Changes</summary>

ArrayRef has a constructor that accepts std::nullopt.  This
constructor dates back to the days when we still had llvm::Optional.

Since the use of std::nullopt outside the context of std::optional is
kind of abuse and not intuitive to new comers, I would like to move
away from the constructor and eventually remove it.

This patch migrates away from std::nullopt in favor of ArrayRef<T>().
Note that {} would be ambiguous for perfect forwarding to work here.


---
Full diff: https://github.com/llvm/llvm-project/pull/145840.diff


1 Files Affected:

- (modified) clang/lib/ASTMatchers/Dynamic/Marshallers.h (+1-1) 


``````````diff
diff --git a/clang/lib/ASTMatchers/Dynamic/Marshallers.h b/clang/lib/ASTMatchers/Dynamic/Marshallers.h
index 0e640cbada726..d44e42a524f27 100644
--- a/clang/lib/ASTMatchers/Dynamic/Marshallers.h
+++ b/clang/lib/ASTMatchers/Dynamic/Marshallers.h
@@ -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>());
 }
 
 /// 1-arg overload

``````````

</details>


https://github.com/llvm/llvm-project/pull/145840