fix(inference): handle import cycles

[ematipico]

Summary

Adds cycle-safe Salsa inference for imported modules. Imports inside the active strongly connected component resolve conservatively while dependencies outside the cycle remain inferred.

Test Plan

Moved cycle coverage to a focused test file and passed all module-graph tests and all-target clippy.

Docs

N/A

This PR was created with AI assistance (OpenCode).

[ematipico]

• refactor(inference): remove the legacy type engine #10937
• refactor(inference): prepare legacy type removal #11010
• refactor(analyzer): cut over inferred type consumers #11009
• fix(inference): handle import cycles #11008 👈 (View in Graphite)
• refactor(inference): port Salsa module inference #11006
• refactor(inference): add canonical inferred globals #11005
• refactor(inference): add structural type mapping #11004
• refactor(inference): separate raw type collection #11003
• refactor(lint): extract return type relation #10973
• fix(inference): suppress incomplete type results #10972
• fix(inference): improve member and Promise inference #10971
• fix(inference): improve overload selection #10970
• fix(inference): improve imported and aliased types #10936
• main

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Latest commit: 0e32611

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[coderabbitai]

Walkthrough

Implemented cycle-aware module type inference using SCC analysis and ImportResolution::CycleFallback. Standard inference explicitly uses full import resolution, while cycle fallback blocks recursive modules and continues resolving non-cyclic dependencies. Updated tests now verify unknown types for cyclic bindings and number inference for an acyclic export.

Possibly related PRs

• biomejs/biome#10888: Implements the related cycle/SCC inference and ImportResolution flow.
• biomejs/biome#11006: Refactors the resolver’s imported-module type inference path.

Suggested labels: A-Type-Inference

Suggested reviewers: denbezrukov

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarises the main change: handling import cycles in inference.
Description check	✅ Passed	The description matches the changeset and describes cycle-safe inference and the test move.
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.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 15-handle-inference-import-cycles

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[coderabbitai]

🧹 Nitpick comments (1)

crates/biome_module_graph/src/db/type_inference/mod.rs (1)

158-177: 📐 Maintainability & Code Quality | 🔵 Trivial

Consider a short doc comment.

inference_scc next door has a solid rustdoc explaining the cycle-fallback contract, but this function (the actual Salsa cycle_result entry point) has none. A one-liner noting it's the fallback invoked when Salsa detects an import cycle, and that it delegates to inference_scc for blocking, would help future readers who aren't already steeped in Salsa cycle-recovery semantics.

📝 Suggested doc comment

+/// Salsa cycle-recovery fallback for `infer_module_types`, invoked when
+/// inferring `module` would otherwise recurse into itself. Computes the
+/// enclosing strongly connected component and re-resolves `module` with
+/// cyclic imports blocked, leaving acyclic dependencies fully inferred.
 pub(super) fn infer_module_types_cycle_result<'db>(
     db: &'db dyn ModuleDb,
     _id: salsa::Id,
     module: ModuleInfo,
 ) -> Option<InferredModuleTypes<'db>> {

As per coding guidelines: "Write comments only when they convey information not recoverable from code: /// documents contracts... // provides rationale."

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@crates/biome_module_graph/src/db/type_inference/mod.rs` around lines 158 -
177, Add a concise Rustdoc comment above infer_module_types_cycle_result
documenting that it is the Salsa cycle-result fallback invoked when an import
cycle is detected and that it delegates blocking decisions to inference_scc. Do
not alter the function’s behavior.

Source: Coding guidelines

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@crates/biome_module_graph/src/db/type_inference/mod.rs`:
- Around line 158-177: Add a concise Rustdoc comment above
infer_module_types_cycle_result documenting that it is the Salsa cycle-result
fallback invoked when an import cycle is detected and that it delegates blocking
decisions to inference_scc. Do not alter the function’s behavior.

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📥 Commits

Reviewing files that changed from the base of the PR and between f0ebdbb and 0e32611.

📒 Files selected for processing (5)

• crates/biome_module_graph/src/db/queries/type_inference.rs
• crates/biome_module_graph/src/db/type_inference/mod.rs
• crates/biome_module_graph/src/db/type_inference/resolver.rs
• crates/biome_module_graph/tests/spec_tests_v2.rs
• crates/biome_module_graph/tests/spec_tests_v2/cycles.test.rs