feat(codegraph): extract call graph from Rust function bodies - #1025

Greptile Summary

This PR fixes the long-standing gap where _extract_symbols_rust built Symbol objects for function_item nodes but always left Symbol.calls empty. The fix wires the existing _extract_calls helper into the Rust extractor by reading the function body node and passing deduped results to the Symbol constructor.

• core.py — two lines added to the function_item branch: child_by_field_name(\"body\") retrieves the block, and _extract_calls traverses it for call_expression nodes; result is deduped with list(set(...)), mirroring the JS extraction pattern.
• test_multilang.py — two new @_skip_no_rust tests using the next(..., None) guard pattern, one verifying \"multiply_internal\" in multiply.calls and one verifying empty calls for no-call bodies.
• .pre-commit-config.yaml — gptme-codegraph added to the mypy exclusion list.

Confidence Score: 5/5

Safe to merge — the change is a two-line addition to an isolated Rust extractor function with no effect on Python or JS/TS extraction paths.

The fix reuses the battle-tested _extract_calls helper already used for Python and JS extractors, and the new tests properly guard against regressions. No existing behaviour is altered.

No files require special attention.

Important Files Changed

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["_extract_symbols_rust(root, filepath)"] --> B{node.type == function_item?}
    B -- Yes --> C["name = child_by_field_name('name')"]
    C --> D["body_node = child_by_field_name('body')"]
    D --> E{"body_node is not None?"}
    E -- Yes --> F["_extract_calls(body_node)"]
    F --> G["Walk body via cursor looking for call_expression nodes"]
    G --> H["calls.append(_text(func_node))"]
    E -- No --> I["calls = []"]
    H --> J["calls = list(set(calls))"]
    I --> J
    J --> K["Symbol(..., calls=calls)"]
    B -- No --> L["Recurse into children (impl_item passes parent_kind='impl')"]
    L --> B

_{Reviews (2): Last reviewed commit: "test(codegraph): improve Rust call-extra..." | Re-trigger Greptile}

Codecov Report

✅ All modified and coverable lines are covered by tests.

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Thanks for the review!

Addressed in 112acfc:

• bare next() → next(..., None) + assertion — both test_parse_rust_function_calls and test_parse_rust_impl_method_calls now give a clear AssertionError message (e.g. "multiply symbol not found in parse result") instead of a cryptic StopIteration
• trivially-passing with_max.calls is not None — fixed to assert with_max.calls == []; the with_max body is self.max_value = max; self which has no call_expression nodes, so the correct assertion is an empty list
• gptme-codegraph added to mirrors-mypy exclude list — the typecheck-packages local hook already runs mypy for the package with the correct env; the mirrors-mypy isolated venv doesn't have gptme-codegraph installed, which caused a fresh pre-commit failure when the test file was touched

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