feat(lang): add C and C++ language support

[davehenton]

Summary

• Add tree-sitter-based C and C++ language implementations for maintainability analysis (complexity, duplication, nested control flow, etc.)
• Wire up tree-sitter dependencies, language registration in ALL_LANGS, file type/extension mappings, and protobuf enum mappings
• Add integration test fixtures and test registration for both C and C++

Test plan

• Unit tests pass for both C and C++ language modules (11 tests)
• Integration tests pass for both c_tests and cpp_tests
• cargo check passes cleanly
• CI passes

🤖 Generated with Claude Code

[qltysh]

Coverage Impact - ubuntu-latest

⬆️ Merging this pull request will increase total coverage on main by 0.14%.

Modified Files with Diff Coverage (3)

Rating	File	% Diff	Uncovered Line #s
	qlty-types/src/lib.rs	100.0%
	qlty-analysis/src/lang/c.rs	99.0%	205, 227
	qlty-analysis/src/lang/cpp.rs	99.1%	229, 243
	Total	99.0%

🤖 Increase coverage with AI coding...

In the `feat/c-cpp-maintainability-support` branch, add test coverage for this new code:

- `qlty-analysis/src/lang/c.rs` -- Lines 205 and 227
- `qlty-analysis/src/lang/cpp.rs` -- Lines 229 and 243

🚦 See full report on Qlty Cloud »

🛟 Help

• Diff Coverage: Coverage for added or modified lines of code (excludes deleted files). Learn more.

• Total Coverage: Coverage for the whole repository, calculated as the sum of all File Coverage. Learn more.

• File Coverage: Covered Lines divided by Covered Lines plus Missed Lines. (Excludes non-executable lines including blank lines and comments.)

  • Indirect Changes: Changes to File Coverage for files that were not modified in this PR. Learn more.

[qltysh]

Coverage Impact - macos-15

⬆️ Merging this pull request will increase total coverage on main by 0.13%.

Modified Files with Diff Coverage (3)

Rating	File	% Diff	Uncovered Line #s
	qlty-types/src/lib.rs	100.0%
	qlty-analysis/src/lang/c.rs	99.0%	205, 227
	qlty-analysis/src/lang/cpp.rs	99.1%	229, 243
	Total	99.0%

🤖 Increase coverage with AI coding...

In the `feat/c-cpp-maintainability-support` branch, add test coverage for this new code:

- `qlty-analysis/src/lang/c.rs` -- Lines 205 and 227
- `qlty-analysis/src/lang/cpp.rs` -- Lines 229 and 243

🚦 See full report on Qlty Cloud »

🛟 Help

• Diff Coverage: Coverage for added or modified lines of code (excludes deleted files). Learn more.

• Total Coverage: Coverage for the whole repository, calculated as the sum of all File Coverage. Learn more.

• File Coverage: Covered Lines divided by Covered Lines plus Missed Lines. (Excludes non-executable lines including blank lines and comments.)

  • Indirect Changes: Changes to File Coverage for files that were not modified in this PR. Learn more.

[claude]

⚠️ Code review skipped — your organization's overage spend limit has been reached.

Code review is billed via overage credits. To resume reviews, an organization admin can raise the monthly limit at claude.ai/admin-settings/claude-code.

Once credits are available, reopen this pull request to trigger a review.

[Copilot]

Pull request overview

Adds first-class C and C++ support to qlty’s tree-sitter-based maintainability analysis pipeline, wiring language registration/config globs and providing CLI integration fixtures to exercise the end-to-end flow.

Changes:

• Introduce new c and cpp language implementations in qlty-analysis and register them in ALL_LANGS.
• Add workspace dependencies (tree-sitter-c, tree-sitter-cpp) and protobuf/enum + default config mappings for c/cpp.
• Add CLI integration fixtures and test registration for C and C++.

Reviewed changes

Copilot reviewed 28 out of 29 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
qlty-types/src/lib.rs	Maps "c"/"cpp" string names to protobuf Language enums.
qlty-config/default.toml	Adds file_types and language glob mappings for C/C++.
qlty-cli/tests/lang/cpp/basic.toml	Adds a basic C++ CLI integration test case.
qlty-cli/tests/lang/cpp/basic.in/Returns.cpp	C++ fixture for return-statements behavior.
qlty-cli/tests/lang/cpp/basic.in/parameters.cpp	C++ fixture for parameter counting behavior.
qlty-cli/tests/lang/cpp/basic.in/NestedControl.cpp	C++ fixture for nested control-flow behavior.
qlty-cli/tests/lang/cpp/basic.in/Identical.cpp	C++ fixture for identical-code behavior.
qlty-cli/tests/lang/cpp/basic.in/FunctionComplexity.cpp	C++ fixture for function complexity behavior.
qlty-cli/tests/lang/cpp/basic.in/FileComplexity.cpp	C++ fixture for file complexity behavior.
qlty-cli/tests/lang/cpp/basic.in/BooleanLogic.cpp	C++ fixture for boolean-logic behavior.
qlty-cli/tests/lang/cpp/basic.in/.qlty/qlty.toml	Minimal per-fixture qlty config for C++ tests.
qlty-cli/tests/lang/cpp/basic.in/.gitignore	Ignores generated .qlty/ outputs in C++ fixtures.
qlty-cli/tests/lang/c/basic.toml	Adds a basic C CLI integration test case.
qlty-cli/tests/lang/c/basic.in/returns.c	C fixture for return-statements behavior.
qlty-cli/tests/lang/c/basic.in/parameters.c	C fixture for parameter counting behavior.
qlty-cli/tests/lang/c/basic.in/nested_control.c	C fixture for nested control-flow behavior.
qlty-cli/tests/lang/c/basic.in/identical.c	C fixture for identical-code behavior.
qlty-cli/tests/lang/c/basic.in/function_complexity.c	C fixture for function complexity behavior.
qlty-cli/tests/lang/c/basic.in/file_complexity.c	C fixture for file complexity behavior.
qlty-cli/tests/lang/c/basic.in/boolean_logic.c	C fixture for boolean-logic behavior.
qlty-cli/tests/lang/c/basic.in/.qlty/qlty.toml	Minimal per-fixture qlty config for C tests.
qlty-cli/tests/lang/c/basic.in/.gitignore	Ignores generated .qlty/ outputs in C fixtures.
qlty-cli/tests/lang.rs	Registers c_tests and cpp_tests in the CLI test suite.
qlty-analysis/src/lang/cpp.rs	Implements C++ AST node kinds + queries and identifier extraction via tree-sitter-cpp.
qlty-analysis/src/lang/c.rs	Implements C AST node kinds + queries and identifier extraction via tree-sitter-c.
qlty-analysis/src/lang.rs	Adds mod c; mod cpp; and registers them in ALL_LANGS.
qlty-analysis/Cargo.toml	Adds tree-sitter-c and tree-sitter-cpp workspace dependencies.
Cargo.toml	Adds workspace package versions for tree-sitter-c and tree-sitter-cpp.
Cargo.lock	Locks new tree-sitter C/C++ crates and their transitive deps.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[marschattha]

Follow-up fix: .h header routing + LCOM bare member call tracking

Two bugs were identified and fixed in b7e5fb3:

1. .h headers analyzed as C instead of C++ (High)

*.h was only in the C file_type/language globs, so C++ headers like Header.h were routed to the C parser — which can't parse class, namespace, template, etc. This caused those files to silently produce classes: 0, functions: 0.

Fix: Moved *.h from C-only to C++ globs in default.toml. The C++ tree-sitter grammar is a superset of C, so pure C headers still parse correctly. C++ headers now get the correct parser.

2. LCOM drops bare member calls in C++ (Medium)

call_identifiers() returned (None, "b") for bare b() calls inside methods. Since LCOM only records calls where receiver == self_keyword ("this"), all implicit member calls were silently dropped — producing lcom4: 0 for classes that should have had cohesion.

Fix: Bare identifier calls now return (Some("this"), name), matching the established Python/C# pattern. Also added field_expression to field_nodes() so explicit this->x field access is visible to LCOM's visit_field.

Local repro confirmed: class Foo { int x; void a() { x = 1; b(); } void b() { x = 2; } } now correctly reports lcom4: 1.