Fix indexed access in function arguments (facebook#55645)

Summary:
Pull Request resolved: facebook#55645

Changelog: [Internal]

Updates the C++ api snapshot generator to correctly handle arrays of fixed size.

Reviewed By: cipolleschi

Differential Revision: D93407605

fbshipit-source-id: b64d30db04696ea54109258d7d4c4fbf43a4cc69

Author: j-piasecki

scripts/cxx-api/parser/main.py

@@ -230,6 +230,30 @@ def get_doxygen_params(
             resolve_ref_text_name(param.defval).strip() if param.defval else None
         )
 
+        # Doxygen splits array dimensions into a separate <array> element.
+        # For complex declarators like "PropNameID (&&propertyNames)[N]",
+        # doxygen gives type="PropNameID(&&)", name="propertyNames",
+        # array="[N]".  We must reconstruct the full declarator with the
+        # name embedded inside the grouping parentheses:
+        #   PropNameID(&&propertyNames)[N]
+        param_array = param.array
+        if param_array:
+            # Match type ending with a pointer/reference declarator group:
+            # e.g. "PropNameID(&&)", "int(&)", "void(*)"
+            m = re.search(r"\([*&]+\)\s*$", param_type)
+            if m and param_name:
+                # Insert name before the closing ')' and append array
+                insert_pos = m.end() - 1  # position of trailing ')'
+                param_type = (
+                    param_type[:insert_pos]
+                    + param_name
+                    + param_type[insert_pos:]
+                    + param_array
+                )
+                param_name = None
+            else:
+                param_type += param_array
+
         qualifiers, core_type = extract_qualifiers(param_type)
         arguments.append((qualifiers, core_type, param_name, param_default))
 

scripts/cxx-api/tests/snapshots/should_handle_array_param/snapshot.api

@@ -0,0 +1,8 @@
+struct test::Node {
+  public void setArray(int(&arr)[10]);
+  template <size_t N>
+  public static std::vector< test::PropNameID > names(PropNameID(&&propertyNames)[N]);
+}
+
+struct test::PropNameID {
+}

scripts/cxx-api/tests/snapshots/should_handle_array_param/test.h

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+namespace test {
+
+struct PropNameID {};
+
+struct Node {
+  template <size_t N>
+  static std::vector<PropNameID> names(PropNameID (&&propertyNames)[N]);
+
+  void setArray(int (&arr)[10]);
+};
+
+} // namespace test