From 0be6f608e6490946c5aadf9b44e633f1f2541161 Mon Sep 17 00:00:00 2001
From: dnwpark <dnwpark@protonmail.com>
Date: Fri, 9 Jan 2026 09:45:49 -0800
Subject: [PATCH] Fix duplicate Iter in type being cached.

---
 tests/test_type_eval.py           | 18 +++++++++++++++++-
 typemap/type_eval/_eval_typing.py |  6 +++++-
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/tests/test_type_eval.py b/tests/test_type_eval.py
index 77829f4..ea851bc 100644
--- a/tests/test_type_eval.py
+++ b/tests/test_type_eval.py
@@ -640,7 +640,7 @@ def test_never_is():
     assert d is True
 
 
-def test_eval_iter():
+def test_eval_iter_01():
     d = eval_typing(Iter[tuple[int, str]])
     assert tuple(d) == (int, str)
 
@@ -654,6 +654,22 @@ def test_eval_iter():
     assert tuple(d) == ()
 
 
+type DuplicateTuple[T] = tuple[*[x for x in Iter[T]], *[x for x in Iter[T]]]
+type ConcatTupleWithSelf[T] = ConcatTuples[T, T]
+
+
+def test_eval_iter_02():
+    # ensure iterating duplicate tuples can be iterated multiple times
+    d = eval_typing(ConcatTuples[tuple[int, str], tuple[int, str]])
+    assert d == tuple[int, str, int, str]
+
+    d = eval_typing(DuplicateTuple[tuple[int, str]])
+    assert d == tuple[int, str, int, str]
+
+    d = eval_typing(ConcatTupleWithSelf[tuple[int, str]])
+    assert d == tuple[int, str, int, str]
+
+
 def test_eval_length_01():
     d = eval_typing(Length[tuple[int, str]])
     assert d == Literal[2]
diff --git a/typemap/type_eval/_eval_typing.py b/typemap/type_eval/_eval_typing.py
index bab4cce..a8ab683 100644
--- a/typemap/type_eval/_eval_typing.py
+++ b/typemap/type_eval/_eval_typing.py
@@ -1,5 +1,6 @@
 import annotationlib
 
+import collections.abc
 import contextlib
 import contextvars
 import dataclasses
@@ -231,7 +232,10 @@ def _eval_types(obj: typing.Any, ctx: EvalContext):
         ctx.resolved |= {x: x for x in child_ctx.known_recursive_types.keys()}
         ctx.known_recursive_types |= child_ctx.known_recursive_types
 
-    ctx.resolved[obj] = evaled
+    # Don't cache iterators as they are stateful and can only be consumed once.
+    # This is important for Iter results that may be used multiple times.
+    if not isinstance(evaled, collections.abc.Iterator):
+        ctx.resolved[obj] = evaled
     return evaled