[rules score] warn instead of panic if libclang hits unknown types

cpp/libclang/integration_test/cases/inherit_external_base/BUILD

@@ -0,0 +1,28 @@
+# *******************************************************************************
+# 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 = "inherit_external_base",
+    srcs = ["inherit_external.cpp"],
+    visibility = ["//cpp/libclang:__subpackages__"],
+    deps = [
+        "@flatbuffers//:runtime_cc",
+    ],
+)
+
+cpp_parser_integration_test(
+    name = "test_inherit_external_base",
+    expected_output = ["expected.json"],
+    target = ":inherit_external_base",
+)

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

@@ -0,0 +1,26 @@
+{
+    "types": {
+        "my_ns::MyNativeObject": {
+            "id": "my_ns::MyNativeObject",
+            "name": "MyNativeObject",
+            "enclosing_namespace_id": "my_ns",
+            "entity_type": "Class",
+            "enum_literals": [],
+            "methods": [],
+            "relationships": [],
+            "template_parameters": null,
+            "type_aliases": [],
+            "variables": [
+                {
+                    "name": "value",
+                    "data_type": "int",
+                    "is_static": false,
+                    "visibility": "public"
+                }
+            ],
+            "source_file": "cpp/libclang/integration_test/cases/inherit_external_base/inherit_external.cpp",
+            "source_line": 23
+        }
+    },
+    "functions": []
+}

cpp/libclang/integration_test/cases/inherit_external_base/inherit_external.cpp

@@ -0,0 +1,28 @@
+/********************************************************************************
+ * 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
+ ********************************************************************************/
+
+// Regression test: a workspace class that inherits from an external-library
+// base class must not cause the AST parser to panic.  The base class is
+// filtered out during the visit phase (path contains "external/"), so it is
+// not present in the type map.  The expected result is that the workspace
+// class is emitted without any inheritance relationship.
+#include "flatbuffers/flatbuffers.h"
+
+namespace my_ns {
+
+class MyNativeObject : public flatbuffers::NativeTable {
+public:
+  int value{};
+};
+
+} // namespace my_ns

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

@@ -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
+// *******************************************************************************
+
+use test_framework::run_parser_case;
+#[test]
+fn test_inherit_external_base() {
+    run_parser_case();
+}

cpp/libclang/src/visitor/src/class_visitor.rs

@@ -357,12 +357,17 @@ fn build_relationships_for_class(ctx: &mut VisitContext, builder: &ParsedClassIn
             )
         });
 
-        let target_class = ctx.types.get(resolved_base).unwrap_or_else(|| {
-            panic!(
-                "Resolved base type '{}' missing in type map for '{}'",
+        let Some(target_class) = ctx.types.get(resolved_base) else {
+            // Base type is not in the type map — it is likely an external dependency
+            // that was filtered out during the visit phase. Skip the relationship
+            // rather than panicking so analysis of workspace classes can proceed.
+            eprintln!(
+                "Warning: base type '{}' not found in type map for '{}'; \
+                 skipping inheritance relationship (external dependency?)",
                 resolved_base, builder.id
-            )
-        });
+            );
+            continue;
+        };
 
         let relation_type = if target_class.entity_type == EntityType::Interface {
             RelationType::Implementation