diff --git a/mypy/checker.py b/mypy/checker.py
index 62acfc9e3abe..81f125e89ead 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -5309,10 +5309,16 @@ def get_types_from_except_handler(self, typ: Type, n: Expression) -> list[Type]:
def visit_for_stmt(self, s: ForStmt) -> None:
"""Type check a for statement."""
+ lvalue_type, b, c = self.check_lvalue(s.index)
+ if lvalue_type is not None:
+ context: Type | None = self.named_generic_type("typing.Iterable", [lvalue_type])
+ else:
+ context = None
+
if s.is_async:
- iterator_type, item_type = self.analyze_async_iterable_item_type(s.expr)
+ iterator_type, item_type = self.analyze_async_iterable_item_type(s.expr, context)
else:
- iterator_type, item_type = self.analyze_iterable_item_type(s.expr)
+ iterator_type, item_type = self.analyze_iterable_item_type(s.expr, context)
s.inferred_item_type = item_type
s.inferred_iterator_type = iterator_type
@@ -5324,10 +5330,12 @@ def visit_for_stmt(self, s: ForStmt) -> None:
),
)
- def analyze_async_iterable_item_type(self, expr: Expression) -> tuple[Type, Type]:
+ def analyze_async_iterable_item_type(
+ self, expr: Expression, context: Type | None = None
+ ) -> tuple[Type, Type]:
"""Analyse async iterable expression and return iterator and iterator item types."""
echk = self.expr_checker
- iterable = echk.accept(expr)
+ iterable = echk.accept(expr, context)
iterator = echk.check_method_call_by_name("__aiter__", iterable, [], [], expr)[0]
awaitable = echk.check_method_call_by_name("__anext__", iterator, [], [], expr)[0]
item_type = echk.check_awaitable_expr(
@@ -5335,10 +5343,12 @@ def analyze_async_iterable_item_type(self, expr: Expression) -> tuple[Type, Type
)
return iterator, item_type
- def analyze_iterable_item_type(self, expr: Expression) -> tuple[Type, Type]:
+ def analyze_iterable_item_type(
+ self, expr: Expression, context: Type | None = None
+ ) -> tuple[Type, Type]:
"""Analyse iterable expression and return iterator and iterator item types."""
iterator, iterable = self.analyze_iterable_item_type_without_expression(
- self.expr_checker.accept(expr), context=expr
+ self.expr_checker.accept(expr, context), context=expr
)
int_type = self.analyze_range_native_int_type(expr)
if int_type:
diff --git a/mypy/checkpattern.py b/mypy/checkpattern.py
index c71d83324694..936c844abc9b 100644
--- a/mypy/checkpattern.py
+++ b/mypy/checkpattern.py
@@ -307,6 +307,9 @@ def visit_sequence_pattern(self, o: SequencePattern) -> PatternType:
narrowed_inner_types = []
inner_rest_types = []
for inner_type, new_inner_type in zip(inner_types, new_inner_types):
+ # TODO: for loop type context should narrow on "assignment"?
+ assert inner_type is not None
+
(narrowed_inner_type, inner_rest_type) = (
self.chk.conditional_types_with_intersection(
inner_type, [get_type_range(new_inner_type)], o, default=inner_type
diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index 7219d5d5e708..a3ea1c5c7165 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -2317,15 +2317,15 @@ def decompose_union_helper(
rest_items.append(item)
exit_block = BasicBlock()
result = Register(result_type)
- for i, item in enumerate(fast_items):
+ for i, inst in enumerate(fast_items):
more_types = i < len(fast_items) - 1 or rest_items
if more_types:
# We are not at the final item so we need one more branch
- op = self.isinstance_native(obj, item.class_ir, line)
+ op = self.isinstance_native(obj, inst.class_ir, line)
true_block, false_block = BasicBlock(), BasicBlock()
self.add_bool_branch(op, true_block, false_block)
self.activate_block(true_block)
- coerced = self.coerce(obj, item, line)
+ coerced = self.coerce(obj, inst, line)
temp = process_item(coerced)
temp2 = self.coerce(temp, result_type, line)
self.add(Assign(result, temp2))
diff --git a/mypyc/test-data/irbuild-set.test b/mypyc/test-data/irbuild-set.test
index c42a1fa74a75..43134f7bad38 100644
--- a/mypyc/test-data/irbuild-set.test
+++ b/mypyc/test-data/irbuild-set.test
@@ -736,10 +736,8 @@ def not_precomputed() -> None:
[out]
def precomputed():
r0 :: set
- r1, r2 :: object
- r3 :: str
- _ :: object
- r4 :: bit
+ r1, r2, _ :: object
+ r3 :: bit
L0:
r0 = frozenset({'False', 'None', 'True'})
r1 = PyObject_GetIter(r0)
@@ -747,12 +745,11 @@ L1:
r2 = PyIter_Next(r1)
if is_error(r2) goto L4 else goto L2
L2:
- r3 = cast(str, r2)
- _ = r3
+ _ = r2
L3:
goto L1
L4:
- r4 = CPy_NoErrOccurred()
+ r3 = CPy_NoErrOccurred()
L5:
return 1
def precomputed2():
diff --git a/test-data/unit/check-inference-context.test b/test-data/unit/check-inference-context.test
index 17ae6d9934b7..41c4136afc55 100644
--- a/test-data/unit/check-inference-context.test
+++ b/test-data/unit/check-inference-context.test
@@ -1495,3 +1495,12 @@ def g(b: Optional[str]) -> None:
z: Callable[[], str] = lambda: reveal_type(b) # N: Revealed type is "builtins.str"
f2(lambda: reveal_type(b)) # N: Revealed type is "builtins.str"
lambda: reveal_type(b) # N: Revealed type is "builtins.str"
+
+[case testInferenceForForLoops]
+from typing import Literal
+
+def func2() -> None:
+ b: Literal["foo", "bar", "baz"]
+ for b in ["foo", "bar"]:
+ # TODO: this should narrow to "foo" | "bar" ideally?
+ reveal_type(b) # N: Revealed type is "Union[Literal['foo'], Literal['bar'], Literal['baz']]"
diff --git a/test-data/unit/check-inference.test b/test-data/unit/check-inference.test
index 42b5a05ab39a..670a079abb73 100644
--- a/test-data/unit/check-inference.test
+++ b/test-data/unit/check-inference.test
@@ -1149,11 +1149,11 @@ for x, (y, z) in [(A(), (B(), C()))]:
a = x
b = y
c = z
-for xx, yy, zz in [(A(), B())]: # E: Need more than 2 values to unpack (3 expected)
+for x2, y2, z2 in [(A(), B())]: # E: Need more than 2 values to unpack (3 expected)
pass
-for xx, (yy, zz) in [(A(), B())]: # E: "B" object is not iterable
+for x3, (y3, z3) in [(A(), B())]: # E: "B" object is not iterable
pass
-for xxx, yyy in [(None, None)]:
+for x4, y4 in [(None, None)]:
pass
[builtins fixtures/for.pyi]