fix: stabilize capped rechecks in dependency order#4190
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A finite chain of cyclic module pairs can consume the incremental epoch budget and reach commit with recorded export changes still pending. Keep the current failure as an expected-panic regression so a separate scheduler fix can remove the annotation and verify propagation reaches the final importer.
The epoch cap discarded its live export-change frontier, so its final invalidation could leave a new change pending at commit. Preserve that frontier, condense its affected reverse-dependency graph into SCCs, and stabilize each component dependency-first before committing.
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Merging main restored the reproducer's expected-panic marker after the scheduler fix. Remove it again so CI verifies the transaction converges and reaches the final importer error.
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Mutable-cycle detection still used a single coarse recomputation, which could leave transaction state pending and lose recursive diagnostics. Reuse the dependency-first SCC fallback already used at the epoch cap so each affected component stabilizes before commit. Fixes facebook#4216. Signed-off-by: teerth sharma <teerths57@gmail.com>
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According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅ |
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@stroxler or @samwgoldman you guys might be best suited to look at this one |
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Summary
Why
The old capped fallback reread
TransactionData.changedafter the epoch loop had already drained it, so it invalidated an empty set and could commit with a newly pending change.The mutable-cycle fallback had a related gap: it coarsely invalidated the closure but ran only one additional step. A recursive two-module inference cycle could therefore retain pending transaction state or, after a different fallback, commit while losing its
non-convergent-recursionwarning (#4216).For the affected graph
G[A], the condensationG[A] / ~is a DAG. With edgesimporter -> dependency, Tarjan's SCC order is dependency-first, so every dependency component reaches a fixed point before its importers run. Pending work for later components is preserved, and no residual transaction state is cleared.No new dependency is added; the normal fine-grained path is unchanged. Tarjan recovery runs only after repeated overlapping export changes or the existing epoch cap.
Verification
Transaction has uncommitted changesnon-convergent-recursionwarningcargo test -p pyrefly --lib test::incremental(76 passed)cargo +stable fmt --all -- --checkpython3 test.py --no-test --no-tensor-shapes --no-conformance --no-jsonschemagit diff --checkBuilt on #4180. Fixes #4171. Fixes #4216.