fix(tsconfig): dedupe project reference dependencies

[CPunisher]

Summary

• Store tsconfig file dependencies in insertion-ordered sets so extended configs and project references are deduplicated without rebuilding a temporary set on each merge.
• Precompute flattened transitive project references while loading tsconfig references, preserving the existing nested-reference-first resolution order.
• Make TsConfig::resolve iterate the flattened reference list directly, removing per-resolve recursive traversal and visited-set hashing.

Verification

• cargo fmt --check
• cargo test tsconfig_project_references --lib

cargo test --lib was also run; non-tsconfig PnP tests fail in this local environment (src/tests/pnp.rs), while 143 other tests pass.

Local downstream validation

Earlier in this investigation, built a local Rspack binding against the resolver fix and verified the ccweb Platform build with:

NAPI_RS_NATIVE_LIBRARY_PATH=/Users/bytedance/Projects/rspack/crates/node_binding/rspack.darwin-arm64.node DEBUG=1 IS_OVERSEA=true BUILD_TYPE=online emo run build --filter platform --skip-cache

Result: exit 0, peak RSS around 12.6 GB. Before the dependency dedupe fix, the same validation still hit exit 137 / memory pressure after only adding the reference traversal visited set.

[coderabbitai]

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Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 6bfefbcf-1826-4c27-824b-c0075adccb48

📥 Commits

Reviewing files that changed from the base of the PR and between a94f6ea and 7a8f251.

📒 Files selected for processing (2)

• src/lib.rs
• src/tsconfig.rs

📝 Walkthrough

Walkthrough

TsConfig now stores file dependencies in an IndexSet-backed FileDependencies alias, inserts config paths into that set during parsing, and merges dependencies through a new crate-visible helper. resolve and find_reference_paths now carry a visited set to stop recursive traversal on repeated tsconfig paths. load_references uses the helper, and a new unit test checks deduplication and ordering.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 37.50% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly reflects the main change: deduplicating tsconfig project reference dependencies.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description check	✅ Passed	The description accurately summarizes the tsconfig dependency deduplication and resolution changes, matching the code changes.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/dedupe-tsconfig-reference-deps

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[codspeed-hq]

Merging this PR will not alter performance

✅ 12 untouched benchmarks

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_{Comparing codex/dedupe-tsconfig-reference-deps (7a8f251) with main (b50ffec)}

[Copilot]

Pull request overview

This PR improves tsconfig project-reference resolution by preventing redundant work and growth in tracked tsconfig dependency lists, reducing repeated traversals and memory pressure when resolving transitive project references.

Changes:

• Deduplicate TsConfig.file_dependencies when merging extended configs and project references via a shared helper.
• Add a visited set to TsConfig::find_reference_paths to avoid re-walking already-seen reference nodes during transitive traversal.
• Add a regression unit test to ensure dependency deduplication behavior is preserved.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/tsconfig.rs	Adds file-dependency dedupe helper and a visited-set guard for reference-path traversal to prevent repeated walking.
src/lib.rs	Switches project-reference dependency merging to the new dedupe helper.
src/tests/tsconfig_project_references.rs	Adds a regression test verifying file dependency deduplication.

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