[clang] [Wasm][Clang] Add __builtin_wasm_ref_is_null_extern (PR #139580)

[Sam Clegg via cfe-commits]

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@@ -52,14 +52,33 @@ static bool CheckWasmBuiltinArgIsInteger(Sema &S, CallExpr *E,
 }
 
 bool SemaWasm::BuiltinWasmRefNullExtern(CallExpr *TheCall) {
-  if (TheCall->getNumArgs() != 0)
+  if (TheCall->getNumArgs() != 0) {
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sbc100 wrote:

Maybe a comment explaining why `checkArgCount` not used, and maybe like an open bug?

https://github.com/llvm/llvm-project/pull/139580