Handle constexpr functions (#55801)

Summary:
Pull Request resolved: #55801

Changelog: [Internal]

Handle `constexpr` functions in the C++ API snapshot

Reviewed By: javache

Differential Revision: D94658128

fbshipit-source-id: 9e380de951e46dff72ba40c8726e46c01340a9a8

Author: j-piasecki

scripts/cxx-api/parser/main.py

@@ -316,6 +316,7 @@ def get_function_member(
     function_arg_string = function_def.get_argsstring()
     is_pure_virtual = function_def.get_virt() == "pure-virtual"
     function_virtual = function_def.get_virt() == "virtual" or is_pure_virtual
+    is_constexpr = function_def.constexpr == "yes"
 
     # Doxygen incorrectly merges "=0" into the return type for pure-virtual
     # functions using trailing return types (e.g. "auto f() -> T = 0").
@@ -333,6 +334,7 @@ def get_function_member(
         is_pure_virtual,
         is_static,
         doxygen_params,
+        is_constexpr,
     )
 
     function.add_template(get_template_params(function_def))

scripts/cxx-api/parser/member.py

@@ -206,11 +206,13 @@ def __init__(
         is_pure_virtual: bool,
         is_static: bool,
         doxygen_params: list[Argument] | None = None,
+        is_constexpr: bool = False,
     ) -> None:
         super().__init__(name, visibility)
         self.type: str = type
         self.is_virtual: bool = is_virtual
         self.is_static: bool = is_static
+        self.is_constexpr: bool = is_constexpr
         parsed_arguments, self.modifiers = parse_arg_string(arg_string)
         self.arguments = (
             doxygen_params if doxygen_params is not None else parsed_arguments
@@ -258,6 +260,9 @@ def to_string(
         if self.is_static:
             result += "static "
 
+        if self.is_constexpr:
+            result += "constexpr "
+
         if self.type:
             result += f"{self.type} "
 

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

@@ -0,0 +1 @@
+constexpr int test::makeValue();

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

@@ -0,0 +1,14 @@
+/*
+ * 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 {
+
+constexpr int makeValue();
+
+} // namespace test

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

@@ -0,0 +1,4 @@
+class test::Clss {
+  public constexpr int getValue() const;
+  public static constexpr int getDefault();
+}

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

@@ -0,0 +1,18 @@
+/*
+ * 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 {
+
+class Clss {
+ public:
+  constexpr int getValue() const;
+  static constexpr int getDefault();
+};
+
+} // namespace test