[clang] [APINotes] Match function-like Where.Parameters in Sema (PR #205307)

[Gábor Horváth via cfe-commits]

================
@@ -993,6 +993,119 @@ UnwindTagContext(TagDecl *DC, api_notes::APINotesManager &APINotes) {
   return std::nullopt;
 }
 
+static void stripAPINotesParameterNullability(QualType &ParamType) {
+  while (true) {
+    if (!AttributedType::stripOuterNullability(ParamType))
+      return;
+  }
+}
+
+struct APINotesParameterSelector {
+  SmallVector<std::string, 4> Parameters;
+
+  SmallVector<StringRef, 4> getParameterRefs() const {
----------------
Xazax-hun wrote:

Not necessarily for this PR, but I am wondering if we can avoid materializing yet another data structure at some point. Two ways I can think of:
* Create an iterator and begin/end, which lazily creates a `StringRef` during iteration and pass ranges of StringRefs around.
* Keep the `std::string` representation and instead of passing around `SmallVector<StringRef>`, we could pass `ArrayRef<std::string>`s. 

https://github.com/llvm/llvm-project/pull/205307