From dad3851d55f9e87e35c18163dec664dd12dcad68 Mon Sep 17 00:00:00 2001
From: Kadir Can Ozden <101993364+bysiber@users.noreply.github.com>
Date: Fri, 20 Feb 2026 05:26:13 +0300
Subject: [PATCH 1/3] raises: fix stale loop variable in RaisesGroup error
 reporting

In _check_exceptions, the diagnostic loop at line 1368 uses i_exp
(last value from the earlier enumerate loop) instead of i_failed
(the current loop variable). This causes incorrect result lookups
when building the failure message for unmatched expected exceptions.
---
 src/_pytest/raises.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/_pytest/raises.py b/src/_pytest/raises.py
index 7c246fde280..c979b599df3 100644
--- a/src/_pytest/raises.py
+++ b/src/_pytest/raises.py
@@ -1365,7 +1365,7 @@ def _check_exceptions(
                 f"\n{indent_1}{self._repr_expected(self.expected_exceptions[i_failed])}"
             )
             for i_actual, actual in enumerate(actual_exceptions):
-                if results.get_result(i_exp, i_actual) is None:
+                if results.get_result(i_failed, i_actual) is None:
                     # we print full repr of match target
                     s += (
                         f"\n{indent_2}It matches {backquote(repr(actual))} which was paired with "

From 2063856b1d26a094e87163afb8e9a6017ee4a7ed Mon Sep 17 00:00:00 2001
From: Kadir Can Ozden <101993364+bysiber@users.noreply.github.com>
Date: Fri, 20 Feb 2026 15:47:24 +0300
Subject: [PATCH 2/3] Add regression test for stale loop variable in
 RaisesGroup error message

Tests that the error message for failed expected exceptions uses the
correct index (i_failed) rather than a stale i_exp from a prior loop.
---
 testing/python/raises_group.py | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/testing/python/raises_group.py b/testing/python/raises_group.py
index e5e3b5cd2dc..e6fe2086529 100644
--- a/testing/python/raises_group.py
+++ b/testing/python/raises_group.py
@@ -1355,3 +1355,31 @@ def test_tuples() -> None:
         ),
     ):
         RaisesGroup((ValueError, IndexError))  # type: ignore[call-overload]
+
+
+def test_stale_loop_variable_in_error_message() -> None:
+    """Regression test: error message for failed expected exceptions should
+    reference the correct expected index, not a stale loop variable from
+    a previous enumerate() loop."""
+    # We need multiple expected exceptions where a non-last expected fails.
+    # Expected: [RaisesExc(ValueError, match='foo'), TypeError, RuntimeError]
+    # Actual:   [ValueError('bar'), TypeError(), KeyError()]
+    # Greedy matching: TypeError() pairs with TypeError (index 1->1)
+    # Failed expected: index 0 (match fails) and index 2 (KeyError is not RuntimeError)
+    # Remaining actual: index 0 (ValueError('bar')) and index 2 (KeyError())
+    #
+    # With the stale-variable bug, the error message for the first failed
+    # expected (index 0) would use results from the last expected (index 2)
+    # instead of its own, potentially showing incorrect "It matches" lines.
+    with pytest.raises(Failed) as exc_info:
+        with RaisesGroup(
+            RaisesExc(ValueError, match="foo"), TypeError, RuntimeError
+        ):
+            raise ExceptionGroup(
+                "",
+                [ValueError("bar"), TypeError(), KeyError()],
+            )
+    # Verify the error message references the correct expected exceptions
+    message = str(exc_info.value)
+    assert "RaisesExc(ValueError, match='foo')" in message
+    assert "RuntimeError" in message

From 4c947b384c1fe70ac08923863f8a5439f3fe2c0f Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Fri, 20 Feb 2026 12:47:53 +0000
Subject: [PATCH 3/3] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 testing/python/raises_group.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/testing/python/raises_group.py b/testing/python/raises_group.py
index e6fe2086529..5f6dbfebb79 100644
--- a/testing/python/raises_group.py
+++ b/testing/python/raises_group.py
@@ -1372,9 +1372,7 @@ def test_stale_loop_variable_in_error_message() -> None:
     # expected (index 0) would use results from the last expected (index 2)
     # instead of its own, potentially showing incorrect "It matches" lines.
     with pytest.raises(Failed) as exc_info:
-        with RaisesGroup(
-            RaisesExc(ValueError, match="foo"), TypeError, RuntimeError
-        ):
+        with RaisesGroup(RaisesExc(ValueError, match="foo"), TypeError, RuntimeError):
             raise ExceptionGroup(
                 "",
                 [ValueError("bar"), TypeError(), KeyError()],