[Cpp Parser] Implement free function declarations

cpp/libclang/docs/ast-traversal.md

@@ -45,7 +45,7 @@ not filtered out, it dispatches to the relevant specialized visitor:
 | --- | --- |
 | `ClassDecl`, `StructDecl`, `ClassTemplate`, and `ClassTemplatePartialSpecialization` | Extract class/struct entities, members, aliases, bases, and relationship inputs. |
 | `EnumDecl` | Extract enum entities and literals. |
-| `FunctionDecl`, `FunctionTemplate`, and `Method` | Extract callable definitions and their body control flow. Function templates are classified as free functions, methods, or static methods according to their scope. |
+| `FunctionDecl`, `FunctionTemplate`, `Method`, `Constructor`, and `Destructor` | Extract callable definitions and their body control flow. Function templates are classified as free functions, methods, or static methods according to their scope. Constructors and destructors are routed through the same callable visitor and participate in body extraction when they have a direct compound body. |
 
 After traversal, class relationship resolution uses the collected base,
 variable, and method type information to populate the class-diagram

cpp/libclang/docs/function-extraction.md

@@ -195,15 +195,17 @@ The top-level visitor currently dispatches these cursor kinds to
 | `FunctionDecl` | `Free` |
 | `FunctionTemplate` | `Free` at global or namespace scope; `Method` or `StaticMethod` at type scope |
 | `Method` | `Method` or `StaticMethod` |
+| `Constructor` | `Constructor` |
+| `Destructor` | `Destructor` |
 
 C++ member operator overloads such as `operator+` and `operator[]` are normally
 reported as `Method`; the current model does not use a distinct operator-method
 kind.
 
 `FunctionVisitor` has internal kind mappings for `Constructor`, `Destructor`,
-and `ConversionFunction`, but the top-level visitor currently logs and ignores
-those cursor kinds. Therefore they do not currently produce `FunctionDef`
-entries. A conversion operator such as `operator bool()` is a
+and `ConversionFunction`. The top-level visitor currently dispatches
+constructors and destructors for extraction, but still logs and ignores
+`ConversionFunction`. A conversion operator such as `operator bool()` is a
 `ConversionFunction` and is distinct from a normal operator overload.
 
 Namespace-level function templates are extracted as `FunctionDef` entries with

cpp/libclang/integration_test/cases/definition_then_forward_decl/BUILD

@@ -0,0 +1,32 @@
+# *******************************************************************************
+# Copyright (c) 2026 Contributors to the Eclipse Foundation
+#
+# See the NOTICE file(s) distributed with this work for additional
+# information regarding copyright ownership.
+#
+# This program and the accompanying materials are made available under the
+# terms of the Apache License Version 2.0 which is available at
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# SPDX-License-Identifier: Apache-2.0
+# *******************************************************************************
+load("//cpp/libclang/integration_test:test_rules.bzl", "cpp_parser_integration_test")
+
+cc_library(
+    name = "definition_then_forward_decl",
+    srcs = [
+        "first.cpp",
+        "second.cpp",
+    ],
+    hdrs = [
+        "widget_forward.h",
+        "widget_full.h",
+    ],
+    visibility = ["//cpp/libclang:__subpackages__"],
+)
+
+cpp_parser_integration_test(
+    name = "test_definition_then_forward_decl",
+    expected_output = ["expected.json"],
+    target = ":definition_then_forward_decl",
+)

cpp/libclang/integration_test/cases/definition_then_forward_decl/expected.json

@@ -0,0 +1,33 @@
+{
+  "types": {
+    "util::Widget": {
+      "id": "util::Widget",
+      "name": "Widget",
+      "enclosing_namespace_id": "util",
+      "stereotypes": [],
+      "entity_type": "Class",
+      "type_aliases": [],
+      "variables": [
+        {
+          "name": "value",
+          "data_type": "int",
+          "visibility": "public",
+          "is_static": false,
+          "source_location": {
+            "file": "cpp/libclang/integration_test/cases/definition_then_forward_decl/widget_full.h",
+            "line": 19
+          }
+        }
+      ],
+      "methods": [],
+      "template_parameters": null,
+      "enum_literals": [],
+      "relationships": [],
+      "source_location": {
+        "file": "cpp/libclang/integration_test/cases/definition_then_forward_decl/widget_full.h",
+        "line": 17
+      }
+    }
+  },
+  "functions": []
+}

cpp/libclang/integration_test/cases/definition_then_forward_decl/first.cpp

@@ -0,0 +1,14 @@
+/********************************************************************************
+ * Copyright (c) 2026 Contributors to the Eclipse Foundation
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License Version 2.0 which is available at
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ********************************************************************************/
+
+#include "widget_forward.h"

cpp/libclang/integration_test/cases/definition_then_forward_decl/run_test.rs

@@ -0,0 +1,19 @@
+// *******************************************************************************
+// Copyright (c) 2026 Contributors to the Eclipse Foundation
+//
+// See the NOTICE file(s) distributed with this work for additional
+// information regarding copyright ownership.
+//
+// This program and the accompanying materials are made available under the
+// terms of the Apache License Version 2.0 which is available at
+// <https://www.apache.org/licenses/LICENSE-2.0>
+//
+// SPDX-License-Identifier: Apache-2.0
+// *******************************************************************************
+
+use test_framework::run_parser_case;
+
+#[test]
+fn test_definition_then_forward_decl() {
+    run_parser_case();
+}

cpp/libclang/integration_test/cases/definition_then_forward_decl/second.cpp

@@ -0,0 +1,14 @@
+/********************************************************************************
+ * Copyright (c) 2026 Contributors to the Eclipse Foundation
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License Version 2.0 which is available at
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ********************************************************************************/
+
+#include "widget_full.h"

cpp/libclang/integration_test/cases/definition_then_forward_decl/widget_forward.h

@@ -0,0 +1,18 @@
+/********************************************************************************
+ * Copyright (c) 2026 Contributors to the Eclipse Foundation
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License Version 2.0 which is available at
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ********************************************************************************/
+
+#pragma once
+
+namespace util {
+class Widget;
+}  // namespace util

cpp/libclang/integration_test/cases/definition_then_forward_decl/widget_full.h

@@ -0,0 +1,21 @@
+/********************************************************************************
+ * Copyright (c) 2026 Contributors to the Eclipse Foundation
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License Version 2.0 which is available at
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ********************************************************************************/
+
+#pragma once
+
+namespace util {
+class Widget {
+public:
+    int value;
+};
+}  // namespace util

cpp/libclang/integration_test/cases/dependent_decltype_base/expected.json

@@ -148,5 +148,60 @@
             }
         }
     },
+    "free_function_declarations": [
+        {
+            "name": "declval",
+            "enclosing_namespace_id": null,
+            "return_type": "T",
+            "parameters": [],
+            "template_parameters": [
+                {
+                    "Type": {
+                        "name": "T",
+                        "is_pack": false
+                    }
+                }
+            ],
+            "source_location": {
+                "file": "cpp/libclang/integration_test/cases/dependent_decltype_base/dependent_base.cpp",
+                "line": 19
+            }
+        },
+        {
+            "name": "is_maplike_container_impl",
+            "enclosing_namespace_id": null,
+            "return_type": "decltype(value.begin())",
+            "parameters": [
+                {
+                    "name": "value",
+                    "param_type": "T",
+                    "is_variadic": false
+                }
+            ],
+            "template_parameters": [
+                {
+                    "Type": {
+                        "name": "T",
+                        "is_pack": false
+                    }
+                }
+            ],
+            "source_location": {
+                "file": "cpp/libclang/integration_test/cases/dependent_decltype_base/dependent_base.cpp",
+                "line": 22
+            }
+        },
+        {
+            "name": "make_widget",
+            "enclosing_namespace_id": null,
+            "return_type": "Widget",
+            "parameters": [],
+            "template_parameters": null,
+            "source_location": {
+                "file": "cpp/libclang/integration_test/cases/dependent_decltype_base/dependent_base.cpp",
+                "line": 43
+            }
+        }
+    ],
     "functions": []
 }

cpp/libclang/integration_test/function_cases/class_method_template_body/expected.json

@@ -1,4 +1,17 @@
 {
+  "free_function_declarations": [
+    {
+      "name": "notify",
+      "enclosing_namespace_id": null,
+      "return_type": "void",
+      "parameters": [],
+      "template_parameters": null,
+      "source_location": {
+        "file": "cpp/libclang/integration_test/function_cases/class_method_template_body/functions.cpp",
+        "line": 14
+      }
+    }
+  ],
   "functions": [
     {
       "id": {

cpp/libclang/integration_test/function_cases/explicit_specialization/expected.json

@@ -1,20 +1,63 @@
 {
+  "types": {},
+  "free_function_declarations": [
+    {
+      "name": "specialized",
+      "enclosing_namespace_id": "utility",
+      "return_type": "T",
+      "parameters": [
+        {
+          "name": "value",
+          "param_type": "T",
+          "is_variadic": false
+        }
+      ],
+      "template_parameters": [
+        {
+          "Type": {
+            "name": "T",
+            "is_pack": false
+          }
+        }
+      ],
+      "source_location": {
+        "file": "cpp/libclang/integration_test/function_cases/explicit_specialization/specialization.h",
+        "line": 21
+      }
+    },
+    {
+      "name": "specialized",
+      "enclosing_namespace_id": "utility",
+      "return_type": "int",
+      "parameters": [
+        {
+          "name": "value",
+          "param_type": "int",
+          "is_variadic": false
+        }
+      ],
+      "template_parameters": null,
+      "source_location": {
+        "file": "cpp/libclang/integration_test/function_cases/explicit_specialization/specialization.h",
+        "line": 25
+      }
+    }
+  ],
   "functions": [
     {
       "id": {
-        "name": "specialized",
         "scope": {
           "Namespace": [
             "utility"
           ]
-        }
+        },
+        "name": "specialized"
       },
       "kind": "Free",
       "return_type": {
         "Builtin": "int"
       },
       "body": []
     }
-  ],
-  "types": {}
-}
+  ]
+}

cpp/libclang/integration_test/function_cases/free_function_identity/BUILD

@@ -14,7 +14,8 @@ load("//cpp/libclang/integration_test:test_rules.bzl", "cpp_parser_integration_t
 
 cc_library(
     name = "free_function_identity",
-    srcs = glob(["*.cpp"]),
+    srcs = ["functions.cpp"],
+    hdrs = ["functions.hpp"],
     visibility = ["//cpp/libclang:__subpackages__"],
 )