From 234b1613f81429d17a8345874182563d39583e82 Mon Sep 17 00:00:00 2001
From: Ivan Levkivskyi <levkivskyi@gmail.com>
Date: Sun, 14 Aug 2022 18:51:34 +0100
Subject: [PATCH] Fix type inference for tuples in iterable context (#13406)

It is a minor change to fix the example in https://github.com/python/typeshed/issues/7904
---
 mypy/checkexpr.py                   |  5 +++--
 test-data/unit/check-inference.test | 16 ++++++++++++++++
 test-data/unit/pythoneval.test      | 18 ++++++++++++++++++
 3 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/mypy/checkexpr.py b/mypy/checkexpr.py
index 598fe952fafa..7f72a21ebc18 100644
--- a/mypy/checkexpr.py
+++ b/mypy/checkexpr.py
@@ -132,6 +132,7 @@
 )
 from mypy.types import (
     LITERAL_TYPE_NAMES,
+    TUPLE_LIKE_INSTANCE_NAMES,
     AnyType,
     CallableType,
     DeletedType,
@@ -3848,7 +3849,7 @@ def visit_tuple_expr(self, e: TupleExpr) -> Type:
                 t
                 for t in get_proper_types(type_context.items)
                 if (isinstance(t, TupleType) and len(t.items) == len(e.items))
-                or is_named_instance(t, "builtins.tuple")
+                or is_named_instance(t, TUPLE_LIKE_INSTANCE_NAMES)
             ]
             if len(tuples_in_context) == 1:
                 type_context = tuples_in_context[0]
@@ -3859,7 +3860,7 @@ def visit_tuple_expr(self, e: TupleExpr) -> Type:
 
         if isinstance(type_context, TupleType):
             type_context_items = type_context.items
-        elif type_context and is_named_instance(type_context, "builtins.tuple"):
+        elif type_context and is_named_instance(type_context, TUPLE_LIKE_INSTANCE_NAMES):
             assert isinstance(type_context, Instance)
             if type_context.args:
                 type_context_items = [type_context.args[0]] * len(e.items)
diff --git a/test-data/unit/check-inference.test b/test-data/unit/check-inference.test
index f094bf36b8c5..04c710af10d1 100644
--- a/test-data/unit/check-inference.test
+++ b/test-data/unit/check-inference.test
@@ -3248,3 +3248,19 @@ reveal_type(x)  # N: Revealed type is "builtins.bytes"
 if x:
     reveal_type(x)  # N: Revealed type is "builtins.bytes"
 [builtins fixtures/dict.pyi]
+
+[case testTupleContextFromIterable]
+from typing import TypeVar, Iterable, List, Union
+
+T = TypeVar("T")
+
+def foo(x: List[T]) -> List[T]: ...
+x: Iterable[List[Union[int, str]]] = (foo([1]), foo(["a"]))
+[builtins fixtures/tuple.pyi]
+
+[case testTupleContextFromIterable2]
+from typing import Dict, Iterable, Tuple, Union
+
+def foo(x: Union[Tuple[str, Dict[str, int], str], Iterable[object]]) -> None: ...
+foo(("a", {"a": "b"}, "b"))
+[builtins fixtures/dict.pyi]
diff --git a/test-data/unit/pythoneval.test b/test-data/unit/pythoneval.test
index a79e8743fb97..7991ee75d03e 100644
--- a/test-data/unit/pythoneval.test
+++ b/test-data/unit/pythoneval.test
@@ -1612,3 +1612,21 @@ class Foo(Enum):
 _testEnumValueWithPlaceholderNodeType.py:5: error: Incompatible types in assignment (expression has type "object", variable has type "Foo")
 _testEnumValueWithPlaceholderNodeType.py:6: error: Incompatible types in assignment (expression has type "object", variable has type "Foo")
 _testEnumValueWithPlaceholderNodeType.py:6: error: Name "Missing" is not defined
+
+[case testTypeshedRecursiveTypesExample]
+# flags: --enable-recursive-aliases
+from typing import List, Union
+
+Recursive = Union[str, List["Recursive"]]
+
+def foo(r: Recursive) -> None:
+    if not isinstance(r, str):
+        if r:
+            foo(r[0])
+    if not isinstance(r, list):
+        r.casefold()
+
+foo("")
+foo(list(""))
+foo(list((list(""), "")))
+[out]