[ty] [testing impact of proposed typeshed change]

[AlexWaygood]

Testing the impact for us if python/typeshed#14583 were merged upstream

[github-actions]

Diagnostic diff on typing conformance tests

Changes were detected when running ty on typing conformance tests

--- old-output.txt	2025-08-18 13:51:17.962702396 +0000
+++ new-output.txt	2025-08-18 13:51:20.444706451 +0000
@@ -1,5 +1,5 @@
 WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
-fatal[panic] Panicked at /home/runner/.cargo/git/checkouts/salsa-e6f3bb7c2a062968/918d35d/src/function/execute.rs:215:25 when checking `/home/runner/work/ruff/ruff/typing/conformance/tests/aliases_typealiastype.py`: `infer_definition_types(Id(9637)): execute: too many cycle iterations`
+fatal[panic] Panicked at /home/runner/.cargo/git/checkouts/salsa-e6f3bb7c2a062968/918d35d/src/function/execute.rs:215:25 when checking `/home/runner/work/ruff/ruff/typing/conformance/tests/aliases_typealiastype.py`: `infer_definition_types(Id(9640)): execute: too many cycle iterations`
 _directives_deprecated_library.py:15:31: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `int`
 _directives_deprecated_library.py:30:26: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `str`
 _directives_deprecated_library.py:36:41: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `Self@__add__`

[github-actions]

mypy_primer results

No ecosystem changes detected ✅
No memory usage changes detected ✅

[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #19969 will degrade performances by 5.3%

_{Comparing typeshed-experiment (cf51684) with main (e4f1b58)}

Summary

❌ 1 regressions
✅ 41 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
❌	ty_micro[many_string_assignments]	68.3 ms	72.1 ms	-5.3%