Fix handling of member function pointers in the API snapshot (#56069)

Summary:

Changelog: [Internal]

Fixes handling of member function pointers in the C++ Api snapshot.

Differential Revision: D96279461

Author: j-piasecki

scripts/cxx-api/parser/builders.py

@@ -317,6 +317,21 @@ def get_doxygen_params(
             else:
                 param_type += param_array
 
+        # Handle pointer-to-member-function types where the name must be
+        # embedded inside the declarator group.  Doxygen gives:
+        #   type = "void(ns::*)() const", name = "asFoo"
+        # We need to produce:
+        #   "void(ns::*asFoo)() const"
+        if param_name:
+            m = re.search(r"\([^)]*::\*\)", param_type)
+            if m:
+                # Insert name before the closing ')' of the ptr-to-member group
+                insert_pos = m.end() - 1
+                param_type = (
+                    param_type[:insert_pos] + param_name + param_type[insert_pos:]
+                )
+                param_name = None
+
         qualifiers, core_type = extract_qualifiers(param_type)
         arguments.append((qualifiers, core_type, param_name, param_default))
 

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

@@ -0,0 +1,6 @@
+struct folly::dynamic {
+}
+
+
+template <typename R, typename... T>
+R test::jsArg(const folly::dynamic& arg, R(folly::dynamic::*asFoo)() const, const T &... desc);

scripts/cxx-api/tests/snapshots/should_handle_pointer_to_member_function_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 folly {
+
+struct dynamic {};
+
+} // namespace folly
+
+namespace test {
+
+template <typename R, typename... T>
+R jsArg(const folly::dynamic &arg, R (folly::dynamic::*asFoo)() const, const T &...desc);
+
+} // namespace test