[ty] Avoid redundant constraint saturation work#25786
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Typing conformance resultsNo changes detected ✅Current numbersThe percentage of diagnostics emitted that were expected errors held steady at 92.23%. The percentage of expected errors that received a diagnostic held steady at 87.42%. The number of fully passing files held steady at 92/134. |
Memory usage reportSummary
Significant changesClick to expand detailed breakdownflake8
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Summary
The constraint-set subtype checks introduced in #25778 can be repeated many times while saturating pairs of constraints. On pytest-robotframework, that increased median check time from 105.8 ms on main to 159.9 ms with #25778.
This caches those checks for the lifetime of a constraint-set builder.
As a separate, semantics-preserving optimization, this also skips calling
add_nested_typevar_sequentswhen neither constraint has a type variable in its bounds. In that case, the method cannot derive any sequents: all of its variance checks returnBivariant. The precheck visits lazy types to match the traversal performed byvariance_of.With this change, pytest-robotframework takes 108.5 ms, 2.6% above main, with byte-for-byte identical diagnostics. The full
ty_python_semantictest suite, focused Clippy, and repository hooks pass.