[rules score] Refactor libclang parser and Reuse in unit rule

refactor(cpp/libclang): extract reusable parser action

Move the C++ parser action setup into shared Starlark plumbing so it can be reused by both cpp_parser and other Bazel rules.
Switch parser outputs from an output directory to explicit class FlatBuffer and optional debug JSON files, and update the Rust CLI and docs to use those paths.
test(cpp/libclang): centralize parser integration case wiring

Add a shared integration test macro that wires the parser, expected output filegroup, debug JSON provider, and Rust comparison test for each case.
Update all parser integration BUILD files to use the macro and make the test framework consume the explicit debug JSON output path.
feat(rules_score): generate implementation class FBS in unit rule

Wire the libclang C++ parser action into the unit rule for implementation targets that provide parser inputs.
Collect generated class diagram FBS files in DefaultInfo, and add the parser toolchain attrs/aspects required by the reused action.

Author: melodyoncode

bazel/rules/rules_score/private/unit.bzl

@@ -19,12 +19,32 @@ following S-CORE process guidelines. A unit is the smallest testable
 software element with associated design, implementation, and tests.
 """
 
+load("@bazel_skylib//rules:common_settings.bzl", "BuildSettingInfo")
 load("@lobster//:lobster.bzl", "subrule_gtest_report")
+load("@rules_cc//cc:find_cc_toolchain.bzl", "use_cc_toolchain")
 load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
 load("@rules_rust//rust:defs.bzl", "rust_common")
 load("//bazel/rules/rules_score:providers.bzl", "CcDependencyInfo", "CertifiedScope", "SphinxSourcesInfo", "UnitDesignInfo", "UnitInfo")
+load("//cpp/libclang:cpp_parser.bzl", "cpp_parser_action_internal_attrs", "cpp_parser_target_aspects", "has_cpp_parser_inputs", "run_cpp_parser_action")
 load(":cc_dependency_aspect.bzl", "cc_dependencies_aspect")
 
+def _run_implementation_cpp_parser(ctx, impl, output_prefix):
+    return run_cpp_parser_action(
+        ctx,
+        target = impl,
+        output_prefix = output_prefix,
+        tool = ctx.attr._tool,
+        libclang = ctx.file._libclang,
+        llvm_cxx_builtin_include = ctx.attr._llvm_cxx_builtin_include,
+        llvm_extra_config_site = ctx.attr._llvm_extra_config_site,
+        log_level = ctx.attr._log_level[BuildSettingInfo].value,
+    )
+
+def _target_output_prefix(ctx, target):
+    package_name = target.label.package.replace("/", "_")
+    target_name = target.label.name.replace("/", "_")
+    return "{}_{}_{}".format(ctx.label.name, package_name, target_name)
+
 # ============================================================================
 # Private Rule Implementation
 # ============================================================================
@@ -59,28 +79,41 @@ def _unit_impl(ctx):
     design_static_fbs_depset = depset(transitive = design_static_fbs)
     design_dynamic_fbs_depset = depset(transitive = design_dynamic_fbs)
 
+    # Generate FBS files for implementation targets supported by the libclang parser.
+    implementation_class_fbs = []
+    collected_dependent_labels = []
+    for impl in ctx.attr.implementation:
+        if CcDependencyInfo in impl:
+            collected_dependent_labels.append(impl[CcDependencyInfo].dependencies)
+
+        if not has_cpp_parser_inputs(impl):
+            continue
+
+        output_prefix = _target_output_prefix(ctx, impl)
+        parser_outputs = _run_implementation_cpp_parser(ctx, impl, output_prefix)
+        implementation_class_fbs.append(parser_outputs.class_fbs)
+
     # Run each test executable via subrule_gtest_report and collect the XML outputs
     xml_files = []
     for test_target in ctx.attr.tests:
-        pkg = test_target.label.package.replace("/", "_")
-        test_name = test_target.label.name.replace("/", "_")
-        unique_name = "{}_{}_{}_gtest_report".format(ctx.label.name, pkg, test_name)
-        xml = subrule_gtest_report(unique_name, test_target.files_to_run.executable, test_target.default_runfiles.files)
+        unique_name = "{}_gtest_report".format(
+            _target_output_prefix(ctx, test_target),
+        )
+        xml = subrule_gtest_report(
+            unique_name,
+            test_target.files_to_run.executable,
+            test_target.default_runfiles.files,
+        )
         xml_files.append(xml)
 
     tests_depset = depset(xml_files)
 
     # Combine all files for DefaultInfo
     all_files = depset(
-        xml_files,
+        xml_files + implementation_class_fbs,
         transitive = [design_depset],
     )
 
-    collected_dependent_labels = []
-    for impl in ctx.attr.implementation:
-        if CcDependencyInfo in impl:
-            collected_dependent_labels.append(impl[CcDependencyInfo].dependencies)
-
     return [
         DefaultInfo(files = all_files),
         CertifiedScope(transitive_scopes = depset(ctx.attr.scope)),
@@ -104,32 +137,38 @@ def _unit_impl(ctx):
 # Rule Definition
 # ============================================================================
 
+_unit_attrs = {
+    "unit_design": attr.label_list(
+        mandatory = True,
+        providers = [UnitDesignInfo],
+        doc = "Unit design artifacts (unit_design targets only)",
+    ),
+    "implementation": attr.label_list(
+        mandatory = True,
+        providers = [[CcInfo], [rust_common.crate_info]],
+        aspects = [cc_dependencies_aspect] + cpp_parser_target_aspects(),
+        doc = "Implementation targets (cc_library, cc_binary, rust_library, rust_binary, etc.).",
+    ),
+    "scope": attr.string_list(
+        default = [],
+        doc = "Additional not explicitly named targets which are needed for the unit implementation",
+    ),
+    "tests": attr.label_list(
+        mandatory = True,
+        cfg = "exec",
+        doc = "Test targets that verify the unit (cc_test, py_test, rust_test, etc.)",
+    ),
+}
+
+_unit_attrs.update(cpp_parser_action_internal_attrs())
+
 _unit = rule(
     implementation = _unit_impl,
     doc = "Defines a software unit with design, implementation, and tests for S-CORE process compliance",
     subrules = [subrule_gtest_report],
-    attrs = {
-        "unit_design": attr.label_list(
-            mandatory = True,
-            providers = [UnitDesignInfo],
-            doc = "Unit design artifacts (unit_design targets only)",
-        ),
-        "implementation": attr.label_list(
-            mandatory = True,
-            providers = [[CcInfo], [rust_common.crate_info]],
-            aspects = [cc_dependencies_aspect],
-            doc = "Implementation targets (cc_library, cc_binary, rust_library, rust_binary, etc.)",
-        ),
-        "scope": attr.string_list(
-            default = [],
-            doc = "Additional not explicitly named targets which are needed for the unit implementation",
-        ),
-        "tests": attr.label_list(
-            mandatory = True,
-            cfg = "exec",
-            doc = "Test targets that verify the unit (cc_test, py_test, rust_test, etc.)",
-        ),
-    },
+    attrs = _unit_attrs,
+    toolchains = use_cc_toolchain(),
+    fragments = ["cpp"],
 )
 
 # ============================================================================

cpp/libclang/BUILD

@@ -32,9 +32,6 @@ rust_binary(
     data = [
         "@llvm_toolchain_llvm//:libclang",
     ],
-    env = {
-        "LIBCLANG_PATH": "$(rootpath @llvm_toolchain_llvm//:libclang)",
-    },
     visibility = ["//visibility:public"],
     deps = [
         "//cpp/libclang/src/utils",

cpp/libclang/README.md

@@ -26,7 +26,6 @@ cpp_parser(
   extra_args = [
   ],
   target = "//cpp/libclang/integration_test/cases/include_3rdparty",
-  tool = ":clang_rs_parser",
 )
 ```
 
@@ -38,9 +37,9 @@ Where:
 Expected result:
 
 - Bazel creates parser output artifact:
-  - `bazel-bin/cpp/libclang/cpp_parser_include_3rdparty_result.fbs.bin`
+  - `bazel-bin/cpp/libclang/cpp_parser_include_3rdparty_class_diagram.fbs.bin`
 - When `emit_debug_json = True`, the parser also writes:
-  - `bazel-bin/cpp/libclang/cpp_parser_include_3rdparty_result/debug.json`
+  - `bazel-bin/cpp/libclang/cpp_parser_include_3rdparty_debug.json`
 
 ## Configure debug logging
 
@@ -55,6 +54,6 @@ Accepted values are: `error`, `warn`, `info`, `debug`, `trace`.
 ## Quick check (optional)
 
 ```bash
-ls -l bazel-bin/cpp/libclang/cpp_parser_include_3rdparty_result.fbs.bin
-ls -l bazel-bin/cpp/libclang/cpp_parser_include_3rdparty_result/debug.json
+ls -l bazel-bin/cpp/libclang/integration_test/cases/include_3rdparty/parser_class_diagram.fbs.bin
+ls -l bazel-bin/cpp/libclang/integration_test/cases/include_3rdparty/parser_debug.json
 ```