[ty] rollback preferring declared type on invalid TypedDict creation#21169
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[ty] rollback preferring declared type on invalid TypedDict creation#21169
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carljm
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Diagnostic diff on typing conformance testsChanges were detected when running ty on typing conformance tests--- old-output.txt 2025-10-31 15:52:43.080086460 +0000
+++ new-output.txt 2025-10-31 15:52:46.243119858 +0000
@@ -927,7 +927,6 @@
typeddicts_operations.py:29:42: error[invalid-argument-type] Invalid argument to key "year" with declared type `int` on TypedDict `Movie`: value of type `float`
typeddicts_operations.py:32:36: error[invalid-key] Invalid key for TypedDict `Movie`: Unknown key "other"
typeddicts_operations.py:37:20: error[missing-typed-dict-key] Missing required key 'name' in TypedDict `Movie` constructor
-typeddicts_operations.py:47:1: error[unresolved-attribute] Object of type `Movie` has no attribute `clear`
typeddicts_operations.py:62:1: error[unresolved-attribute] Object of type `MovieOptional` has no attribute `clear`
typeddicts_readonly.py:24:4: error[invalid-assignment] Cannot assign to key "members" on TypedDict `Band`: key is marked read-only
typeddicts_readonly.py:50:4: error[invalid-assignment] Cannot assign to key "title" on TypedDict `Movie1`: key is marked read-only
@@ -947,5 +946,5 @@
typeddicts_usage.py:28:17: error[missing-typed-dict-key] Missing required key 'name' in TypedDict `Movie` constructor
typeddicts_usage.py:28:18: error[invalid-key] Invalid key for TypedDict `Movie`: Unknown key "title"
typeddicts_usage.py:40:24: error[invalid-type-form] The special form `typing.TypedDict` is not allowed in type expressions. Did you mean to use a concrete TypedDict or `collections.abc.Mapping[str, object]` instead?
-Found 949 diagnostics
+Found 948 diagnostics
WARN A fatal error occurred while checking some files. Not all project files were analyzed. See the diagnostics list above for details. |
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Summary
Discussion with @ibraheemdev clarified that #21168 was incorrect. In a case of failed inference of a dict literal as a
TypedDict, we should store the context-less inferred type of the dict literal as the type of the dict literal expression itself; the fallback to declared type should happen at the level of the overall assignment definition.The reason the latter isn't working yet is because currently we (wrongly) consider a homogeneous dict type as assignable to a
TypedDict, so we don't actually consider the assignment itself as failed. So the "bug" I observed (and tried to fix) will naturally be fixed by implementing TypedDict assignability rules.Rollback #21168 except for the tests, and modify the tests to include TODOs as needed.
Test Plan
Updated mdtests.