fix(cpp): extract union specifiers as class-like type nodes

[rajatnagda45]

Closes #4051

Problem

A named C++ union is dropped from the graph entirely — the type and all its members vanish:

union Value { int i; float f; };
struct Point { int x; };

Point and its members are in the graph; Value / i / f are not.

Cause

union_specifier was missing from _CPP_CONFIG.class_types. class_specifier, struct_specifier, and enum_specifier are all there, so a union was the only class-like container that fell through and was dropped.

Fix

Add union_specifier to class_types. It shares struct_specifier's name/body fields (type_identifier + field_declaration_list), so the existing generic container handling gives it a type node, a contains edge from its file, and a data member per field — exactly like a struct. An anonymous union has no type_identifier and is skipped by the existing name guard, like an anonymous enum.

Tests

Added test_cpp_union_specifier_is_extracted: a named union becomes a type node with defines edges to its members, and a typedef union { ... } Anon mints no nameless node. Fails on current v8, passes with the fix. Full suite: 6345 passed, 15 skipped. ruff clean; pyright on extract.py unchanged (119 errors before and after, 0 added).

[github-actions]

Thanks for the pull request, @rajatnagda45. A maintainer will review it soon.

Want to talk it through while it is in review? Come join us on our Discord server. For longer-form discussion there is also GitHub Discussions.

A couple of things that speed up review: make sure the test suite passes on Python 3.10 and 3.13, and that the change keeps extraction deterministic.

[graphify-labs]

Graphify reviewed this change.

Looks safe to merge — no coupling regressions and no blocking issues, checked against the code graph (not a self-assessment).

---

Graphify review — findings

Adds union_specifier to the C++ class_types, so a named union { ... } now becomes a type node with its data members (file contains the union, the union defines each field) instead of vanishing entirely. Anonymous unions such as typedef union { ... } Anon have no type name and are still skipped, matching anonymous enums.

No blocking issues surfaced.

Analysis details — impact, health, verification

Impact & health

Graphify review

Impact — 2349 functions depend on the 289 functions this change touches.

Health — this change adds coupling hotspots:

• new: extract() — 753 callers, 50 callees
• new: _rebuild_code() — 149 callers, 56 callees
• new: extract_js() — 87 callers, 4 callees
• new: extract_xaml() — 19 callers, 17 callees
• new: main() — 99 callers, 3 callees
• new: dispatch_command() — 2 callers, 127 callees
• new: _get_extractor() — 27 callers, 6 callees
• new: collect_files() — 19 callers, 6 callees
• …and 35 more — each is listed as a finding

Verification — 2349 functions in the blast radius were not formally verified this run (proofs are advisory here).

Gate & verification

graphify gate

PASS — objectively clean (no health regressions, tests not run — proofs not run this pass (advisory)). Grounded, not self-assessed.

Advisory (not blocking):

• verification_scope: 2164 function(s) in the blast radius were not formally verified this run

Test selection

Test selection

142 of 326 test file(s) selected (44%) via static blast radius.

• tests/test_astro_extraction.py — impact
• tests/test_astro_import_ids.py — impact
• tests/test_blade_extractor.py — impact
• tests/test_build.py — impact
• tests/test_builtin_global_type_refs.py — impact
• tests/test_case_sensitive_resolution.py — impact
• tests/test_cjs_module_extension.py — impact
• tests/test_cobol_extractor.py — impact
• tests/test_cpp_method_declarations.py — impact
• tests/test_cpp_nested_and_cli.py — impact, changed-test
• tests/test_cpp_objc_cross_file_calls.py — impact
• tests/test_cross_extension_reexport_self_cycle.py — impact
• tests/test_cross_language_call_resolution.py — impact
• tests/test_cross_repo_external_call_guards.py — impact
• tests/test_cross_repo_member_calls.py — impact
• tests/test_csharp_call_site_generic_args.py — impact
• tests/test_csharp_enum_members.py — impact
• tests/test_csharp_field_generic_args.py — impact
• tests/test_csharp_generic_callsites.py — impact
• tests/test_csharp_interface_dispatch.py — impact
• tests/test_csharp_member_calls.py — impact
• tests/test_csharp_member_nodes.py — impact
• tests/test_csharp_object_creation.py — impact
• tests/test_csharp_partial_classes.py — impact
• tests/test_csharp_tuple_type_refs.py — impact
• tests/test_csharp_type_resolution.py — impact
• tests/test_definition_file_portability.py — impact
• tests/test_detect.py — impact
• tests/test_dotnet.py — impact
• tests/test_duplicate_annotation_edges.py — impact
• tests/test_elixir_import_resolution.py — impact
• tests/test_elixir_unqualified_call_scope.py — impact
• tests/test_erlang_extractor.py — impact
• tests/test_extract.py — impact
• tests/test_extract_cache_location.py — impact
• tests/test_extract_php_closures.py — impact
• tests/test_file_label_disambiguation.py — impact
• tests/test_file_node_id_spec.py — impact
• tests/test_forwarding_review_findings.py — impact
• tests/test_go_builtin_call_targets.py — impact
• tests/test_go_import_repoint.py — impact
• tests/test_go_interface_methods.py — impact
• tests/test_go_qualified_resolution.py — impact
• tests/test_import_extension_resolution.py — impact
• tests/test_import_self_loops.py — impact
• tests/test_imported_export_forwarding.py — impact
• tests/test_incremental.py — impact
• tests/test_indirect_call_arrow_single_param_shadow.py — impact
• tests/test_indirect_call_block_scoped_shadow.py — impact
• tests/test_indirect_call_catch_binding_shadow.py — impact
• … and 92 more

Selection is safe under the controlled-regression assumption; always-run tests + a periodic full run are the backstops. Advisory — it never changes the check verdict.

· 43 more finding(s) on lines outside this diff (see the check run).

[safishamsi]

Shipped in v0.9.76 (live on PyPI as graphifyy==0.9.76). Landed on v8 via an authorship-preserving cherry-pick, so your original commit authorship is kept. Thanks @rajatnagda45 for C++ union specifiers 🙏

Closing as shipped.