[crypt0lith]

Summary

Fixes #11810.

Pyright reports a field annotation that refers back to the alias as a variable in a type expression, and discards the declared type of a TypedDict field.

Root cause

Evaluating the value of a TypeAliasType call builds the fields of the TypedDict or NamedTuple classes it refers to, and those fields look up the alias while it is still being evaluated. getTypeOfTypeAliasCommon creates a placeholder for this, but registers it as a partial type only when the alias name has a declaration, and the binder attaches no declaration to the target of an assignment. The lookup then fails the recursion check in getTypeOfSymbolForDecls and produces Unknown. The failed check also invalidates the symbols being resolved above it, including the field whose annotation is being evaluated.

Fix

• In getTypeOfTypeAliasCommon, find the declaration through the alias symbol when the name node has none.
• In getTypeOfSymbolForDecls, check for a partial type before the recursion check, as getDeclaredTypeOfSymbol already does.

Test

Adds a test sample typeAliasType3.py that reveals the field types of TypedDict and NamedTuple classes that refer to each other through a TypeAliasType. Without the fix, it reports 3 errors.

[github-actions]

Compared candidate 6c2717743bfaca53583abe79aa49c964bb54c1a2 against its first parent fe14a8e051c63f1ea1b76ac08227f73aa923032f.

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Execution time history

Peak memory history

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Type checker benchmark

🟢 No performance regressions detected.

Regression threshold: 20.0%
Statistic: median
Variance guard: >1.0s time and >100.0 MB memory

Package	Checker	Files checked	Time	Time delta	Peak memory	Memory delta	Status
ansible	pyright	583	18.139s	-0.0%	1107.5 MB	+2.2%	🟢 Pass
click	pyright	17	2.137s	+0.1%	354.7 MB	+0.2%	🟢 Pass
homeassistant	pyright	9850	123.668s	-8.0%	6220.9 MB	+2.3%	🟢 Pass
numpy	pyright	356	31.813s	-5.8%	1293.4 MB	-3.3%	🟢 Pass
pandas	pyright	1459	101.701s	+5.5%	3667.5 MB	-7.6%	🟢 Pass
pytest	pyright	243	12.803s	-0.0%	848.4 MB	+0.3%	🟢 Pass
requests	pyright	19	2.237s	-0.9%	342.2 MB	-0.1%	🟢 Pass
torch	pyright	2400	136.722s	-2.3%	5029.1 MB	+6.1%	🟢 Pass
transformers	pyright	2901	88.659s	+4.1%	5063.2 MB	-3.5%	🟢 Pass

Pyright stats

Package	Parsed/bound	Checked	Find	Read	Tokenize	Parse	Imports	Bind	Check	Cycles
ansible	989	583	0.040s	0.087s	0.383s	0.737s	0.223s	0.947s	14.900s	0.000s
click	111	17	0.000s	0.010s	0.080s	0.163s	0.027s	0.183s	1.440s	0.000s
homeassistant	11147	9850	0.353s	0.723s	2.787s	4.457s	1.903s	5.873s	107.700s	0.000s
numpy	603	356	0.010s	0.070s	0.353s	0.687s	0.240s	0.800s	29.203s	0.000s
pandas	1895	1459	0.050s	0.197s	0.923s	2.080s	0.250s	2.190s	94.833s	0.000s
pytest	542	243	0.020s	0.057s	0.387s	0.557s	0.113s	0.727s	10.517s	0.000s
requests	168	19	0.000s	0.017s	0.110s	0.203s	0.057s	0.247s	1.293s	0.000s
torch	3079	2400	0.140s	0.387s	2.230s	3.600s	0.567s	4.483s	121.670s	0.000s
transformers	3535	2901	0.077s	0.393s	1.777s	2.733s	0.687s	6.833s	77.627s	0.000s

[Heejae Chang (heejaechang)]

🟢 Pyright CLI QA — ab0c5c67 — verdict: green

Automated CLI checks compared this change with its base revision.
33 focused check(s) completed.

No new behavior difference was detected.