Fix bug in SequenceValue / KnownValue interaction (#701)

quora · Oct 18, 2023 · 7214b26 · 7214b26
1 parent fc3f543
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diff --git a/docs/changelog.md b/docs/changelog.md
@@ -1,5 +1,10 @@
 # Changelog
 
+## Unreleased
+
+- Fix bug in type compatibility check between known-length sequence
+  types and literal values (#701)
+
 ## Version 0.11.0 (October 3, 2023)
 
 - Partial support for PEP 695-style type aliases. Scoping changes

diff --git a/pyanalyze/test_value.py b/pyanalyze/test_value.py
@@ -238,6 +238,10 @@ def test_sequence_value() -> None:
         ),
     )
 
+    assert_can_assign(val, KnownValue((1, "x")))
+    assert_cannot_assign(val, KnownValue((1, 2)))
+    assert_cannot_assign(val, KnownValue((1, "x", "y")))
+
     assert str(val) == "tuple[int, str]"
     assert str(value.SequenceValue(tuple, [(False, TypedValue(int))])) == "tuple[int]"
     assert (

diff --git a/pyanalyze/value.py b/pyanalyze/value.py
@@ -1057,6 +1057,7 @@ def make_or_known(
             return SequenceValue(typ, members)
 
     def can_assign(self, other: Value, ctx: CanAssignContext) -> CanAssign:
+        other = replace_known_sequence_value(other)
         if isinstance(other, SequenceValue):
             can_assign = self.get_type_object(ctx).can_assign(self, other, ctx)
             if isinstance(can_assign, CanAssignError):