[clang] [APINotes] Diagnose invalid Where.Parameters selectors (PR #209408)

[John Hui via cfe-commits]

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@@ -1072,6 +1073,69 @@ getAPINotesParameterSelectorCandidates(const Sema &S, const FunctionDecl *FD) {
   return Candidates;
 }
 
+static api_notes::APINotesFunctionSelectorKey
+getBroadAPINotesSelectorKey(api_notes::APINotesFunctionSelectorKey Key) {
+  Key.ParameterTypeIDs = std::nullopt;
+  return Key;
+}
+
+static APINotesSelectorDiagnosticReaderState &
+getAPINotesSelectorDiagnosticState(Sema &S, api_notes::APINotesReader *Reader) {
+  if (!S.APINotesSelectorDiagnostics)
+    S.APINotesSelectorDiagnostics =
+        std::make_unique<APINotesSelectorDiagnosticState>();
+  auto &State = S.APINotesSelectorDiagnostics->Readers[Reader];
+  if (State.Initialized)
+    return State;
+
+  State.Initialized = true;
+  SmallVector<api_notes::APINotesFunctionSelector, 4> Selectors;
+  if (!Reader->collectExactFunctionParameterSelectors(Selectors))
+    return State;
+
+  State.Selectors.reserve(Selectors.size());
+  State.SelectorIndices.reserve(Selectors.size());
+  State.SeenNames.reserve(Selectors.size());
+  for (auto &Selector : Selectors) {
+    unsigned Index = State.Selectors.size();
+    APINotesSelectorDiagnosticEntry Entry;
+    Entry.BroadKey = getBroadAPINotesSelectorKey(Selector.Key);
+    Entry.Parameters = std::move(Selector.Parameters);
+    State.Selectors.push_back(std::move(Entry));
+    State.SelectorIndices.insert({Selector.Key, Index});
+  }
+  return State;
+}
+
+static void noteSeenAPINotesSelectorName(
----------------
j-hui wrote:

This function (as well as `markAPINotesSelectorUsed` and `markAPINotesSelectorCandidatesUsed`) seem like they should be methods of `APINotesSelectorDiagnosticReaderState`.

https://github.com/llvm/llvm-project/pull/209408