From b867c8a1df2460b73b23b3dd2294292403c3a3aa Mon Sep 17 00:00:00 2001
From: Sean Doherty <smaster7772@gmail.com>
Date: Sat, 16 May 2026 23:04:52 -0500
Subject: [PATCH] Avoid match subject star unpack crash

---
 mypy/checker.py                     |  2 ++
 test-data/unit/check-python310.test | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/mypy/checker.py b/mypy/checker.py
index 80402e71dce6..4cef19b98315 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -6033,6 +6033,8 @@ def _get_recursive_sub_patterns_map(
         typ_ = get_proper_type(typ)
         if isinstance(expr, TupleExpr) and isinstance(typ_, TupleType):
             # When matching a tuple expression with a sequence pattern, narrow individual tuple items
+            if any(isinstance(item, StarExpr) for item in expr.items):
+                return sub_patterns_map
             assert len(expr.items) == len(typ_.items)
             for item_expr, item_typ in zip(expr.items, typ_.items):
                 sub_patterns_map[item_expr] = item_typ
diff --git a/test-data/unit/check-python310.test b/test-data/unit/check-python310.test
index 03a0934b662c..afc9677f98f5 100644
--- a/test-data/unit/check-python310.test
+++ b/test-data/unit/check-python310.test
@@ -479,6 +479,16 @@ match m, (n, o), (p, (q, r)):
         reveal_type(r)  # N: Revealed type is "Literal[5]"
 [builtins fixtures/tuple.pyi]
 
+[case testMatchSequencePatternSubjectWithStarExprNoCrash]
+# flags: --strict-equality --warn-unreachable
+foo: int
+bar: tuple[int, int]
+
+match foo, *bar:
+    case _:
+        pass
+[builtins fixtures/tuple.pyi]
+
 [case testMatchSequencePatternSequencesLengthMismatchNoNarrowing]
 # flags: --strict-equality --warn-unreachable
 m: int