diff --git a/mypy/checkexpr.py b/mypy/checkexpr.py index 95ab75e24585..c132b35e5a2a 100644 --- a/mypy/checkexpr.py +++ b/mypy/checkexpr.py @@ -4093,7 +4093,10 @@ def visit_assignment_expr(self, e: AssignmentExpr) -> Type: value = self.accept(e.value) self.chk.check_assignment(e.target, e.value) self.chk.check_final(e) - self.chk.store_type(e.target, value) + if not has_uninhabited_component(value): + # TODO: can we get rid of this extra store_type()? + # Usually, check_assignment() already stores the lvalue type correctly. + self.chk.store_type(e.target, value) self.find_partial_type_ref_fast_path(e.target) return value diff --git a/test-data/unit/check-python38.test b/test-data/unit/check-python38.test index d83f29f2186a..1e99c760b67a 100644 --- a/test-data/unit/check-python38.test +++ b/test-data/unit/check-python38.test @@ -826,3 +826,11 @@ main:5: error: Dict entry 0 has incompatible type "str": "str"; expected "str": main:5: error: Unpacked dict entry 1 has incompatible type "Dict[str, str]"; expected "SupportsKeysAndGetItem[str, int]" dct: Dict[str, int] = {"a": "b", **other} ^~~~~ + +[case testWalrusAssignmentEmptyCollection] +from typing import List + +y: List[int] +if (y := []): + reveal_type(y) # N: Revealed type is "builtins.list[builtins.int]" +[builtins fixtures/list.pyi]