diff --git a/mypy/constraints.py b/mypy/constraints.py
index 9da4f04d2277..2a278995e142 100644
--- a/mypy/constraints.py
+++ b/mypy/constraints.py
@@ -108,6 +108,12 @@ def _infer_constraints(template: Type, actual: Type,
template = get_proper_type(template)
actual = get_proper_type(actual)
+ # Type inference shouldn't be affected by whether union types have been simplified.
+ if isinstance(template, UnionType):
+ template = mypy.typeops.make_simplified_union(template.items)
+ if isinstance(actual, UnionType):
+ actual = mypy.typeops.make_simplified_union(actual.items)
+
# Ignore Any types from the type suggestion engine to avoid them
# causing us to infer Any in situations where a better job could
# be done otherwise. (This can produce false positives but that
diff --git a/test-data/unit/check-inference.test b/test-data/unit/check-inference.test
index b2050a127ba6..5366de858018 100644
--- a/test-data/unit/check-inference.test
+++ b/test-data/unit/check-inference.test
@@ -2924,3 +2924,18 @@ reveal_type(q2(z)) # N: Revealed type is '__main__.B*'
reveal_type(q1(Z(b))) # N: Revealed type is '__main__.B*'
reveal_type(q2(Z(b))) # N: Revealed type is '__main__.B*'
[builtins fixtures/isinstancelist.pyi]
+
+[case testUnionInvariantSubClassAndCovariantBase]
+from typing import Union, Generic, TypeVar
+
+T = TypeVar('T')
+T_co = TypeVar('T_co', covariant=True)
+
+class Cov(Generic[T_co]): ...
+class Inv(Cov[T]): ...
+
+X = Union[Cov[T], Inv[T]]
+
+def f(x: X[T]) -> T: ...
+x: Inv[int]
+reveal_type(f(x)) # N: Revealed type is 'builtins.int*'
diff --git a/test-data/unit/check-overloading.test b/test-data/unit/check-overloading.test
index 6574cd9e730c..0351111c8fa0 100644
--- a/test-data/unit/check-overloading.test
+++ b/test-data/unit/check-overloading.test
@@ -3646,7 +3646,7 @@ def test_narrow_none() -> None:
a: Optional[int]
if int():
a = narrow_none(a)
- reveal_type(a) # N: Revealed type is 'Union[builtins.int, None]'
+ reveal_type(a) # N: Revealed type is 'builtins.int'
b: int
if int():
@@ -3710,7 +3710,7 @@ def test_narrow_none_v2() -> None:
a: Optional[int]
if int():
a = narrow_none_v2(a)
- reveal_type(a) # N: Revealed type is 'Union[builtins.int, None]'
+ reveal_type(a) # N: Revealed type is 'builtins.int'
b: int
if int():
diff --git a/test-data/unit/pythoneval.test b/test-data/unit/pythoneval.test
index fad202d50d1e..d6df7ece9899 100644
--- a/test-data/unit/pythoneval.test
+++ b/test-data/unit/pythoneval.test
@@ -1490,3 +1490,12 @@ reveal_type(A().b)
[out]
_testNamedTupleAtRunTime.py:5: error: NamedTuple type as an attribute is not supported
_testNamedTupleAtRunTime.py:7: note: Revealed type is 'Any'
+
+[case testAsyncioFutureWait]
+# mypy: strict-optional
+from asyncio import Future, wait
+from typing import List
+
+async def foo() -> None:
+ f = [] # type: List[Future[None]]
+ await wait(f)
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