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

[Gábor Horváth via cfe-commits]

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@@ -893,6 +911,59 @@ APINotesReader::Implementation::getIdentifier(llvm::StringRef Str) {
   return *Known;
 }
 
+std::optional<llvm::StringRef>
+APINotesReader::Implementation::getIdentifierString(IdentifierID ID) {
+  if (!IdentifierTable)
+    return std::nullopt;
+
+  if (ID == IdentifierID(0))
+    return llvm::StringRef();
+
+  if (!IdentifierStrings) {
+    IdentifierStrings.emplace();
+    // keys() and data() iterate over the same serialized entries in lockstep.
+    // The serialized hash-table order is not guaranteed to be identifier-ID
+    // order, so keep an explicit ID-to-string map rather than indexing a vector
+    // by ID.
+    auto Identifiers = IdentifierTable->keys();
+    auto IDs = IdentifierTable->data();
+    auto Identifier = Identifiers.begin();
+    auto KnownID = IDs.begin();
+    auto IdentifierEnd = Identifiers.end();
+    auto KnownIDEnd = IDs.end();
+    for (; Identifier != IdentifierEnd && KnownID != KnownIDEnd;
+         ++Identifier, ++KnownID)
+      IdentifierStrings->try_emplace(static_cast<uint32_t>(*KnownID),
+                                     *Identifier);
+  }
+
+  auto Known = IdentifierStrings->find(static_cast<uint32_t>(ID));
+  if (Known == IdentifierStrings->end())
+    return std::nullopt;
+  return Known->second;
+}
+
+template <typename TableT>
+bool APINotesReader::Implementation::collectExactFunctionParameterSelectors(
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Xazax-hun wrote:

We seem to always return true from this function. Should we remove the return type or is there a typo somewhere?

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