From 78229ed62070154d0a72cecbb61079066daa4876 Mon Sep 17 00:00:00 2001
From: solaluset <60041069+solaluset@users.noreply.github.com>
Date: Thu, 6 Nov 2025 16:54:08 +0200
Subject: [PATCH 1/7] Fix internal error when source is modified

---
 src/_pytest/_code/source.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/_pytest/_code/source.py b/src/_pytest/_code/source.py
index 99c242dd98e..d0a5df4457f 100644
--- a/src/_pytest/_code/source.py
+++ b/src/_pytest/_code/source.py
@@ -216,6 +216,7 @@ def getstatementrange_ast(
             pass
 
     # The end might still point to a comment or empty line, correct it.
+    end = min(end, len(source.lines))
     while end:
         line = source.lines[end - 1].lstrip()
         if line.startswith("#") or not line:

From 6ac721c70ddbc30f6dc39f0182aa6cdca935f48a Mon Sep 17 00:00:00 2001
From: solaluset <60041069+solaluset@users.noreply.github.com>
Date: Sat, 8 Nov 2025 18:45:44 +0200
Subject: [PATCH 2/7] Fix IndexError when retrieving start lineno

---
 src/_pytest/_code/source.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/_pytest/_code/source.py b/src/_pytest/_code/source.py
index d0a5df4457f..cbadf667907 100644
--- a/src/_pytest/_code/source.py
+++ b/src/_pytest/_code/source.py
@@ -168,6 +168,8 @@ def get_statement_startend2(lineno: int, node: ast.AST) -> tuple[int, int | None
                     values.append(val[0].lineno - 1 - 1)
     values.sort()
     insert_index = bisect_right(values, lineno)
+    if insert_index == 0:
+        return 0, None
     start = values[insert_index - 1]
     if insert_index >= len(values):
         end = None

From c4848a445eb075ebee95f7dd8071fe65f41714bd Mon Sep 17 00:00:00 2001
From: solaluset <60041069+solaluset@users.noreply.github.com>
Date: Sat, 8 Nov 2025 18:47:31 +0200
Subject: [PATCH 3/7] Add test_patched_compile

pytest should not crash when source is dynamically modified
---
 testing/code/test_source.py | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/testing/code/test_source.py b/testing/code/test_source.py
index e413af3766e..3704687ad75 100644
--- a/testing/code/test_source.py
+++ b/testing/code/test_source.py
@@ -7,6 +7,7 @@
 import sys
 import textwrap
 from typing import Any
+from unittest.mock import patch
 
 from _pytest._code import Code
 from _pytest._code import Frame
@@ -647,3 +648,26 @@ def __init__(self, *args):
     # fmt: on
     values = [i for i in x.source.lines if i.strip()]
     assert len(values) == 4
+
+
+def test_patched_compile() -> None:
+    # ensure Source doesn't break
+    # when compile() modifies code dynamically
+    from builtins import compile
+
+    def patched_compile1(_, *args, **kwargs):
+        return compile("", *args, **kwargs)
+
+    with patch("builtins.compile", new=patched_compile1):
+        Source(patched_compile1).getstatement(1)
+
+    # fmt: off
+    def patched_compile2(_, *args, **kwargs):
+# first line of this function must not start with spaces
+# LINES must be equal to number of lines of this function
+        LINES = 4
+        return compile("\ndef a():\n" + "\n" * LINES + "    pass", *args, **kwargs)
+    # fmt: on
+
+    with patch("builtins.compile", new=patched_compile2):
+        Source(patched_compile2).getstatement(1)

From 60d4d82dd29062dd0a72814bb468774d9187fb43 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 8 Nov 2025 19:03:12 +0000
Subject: [PATCH 4/7] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 testing/code/test_source.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/testing/code/test_source.py b/testing/code/test_source.py
index 3704687ad75..1afcd906b61 100644
--- a/testing/code/test_source.py
+++ b/testing/code/test_source.py
@@ -663,8 +663,8 @@ def patched_compile1(_, *args, **kwargs):
 
     # fmt: off
     def patched_compile2(_, *args, **kwargs):
-# first line of this function must not start with spaces
-# LINES must be equal to number of lines of this function
+    # first line of this function must not start with spaces
+    # LINES must be equal to number of lines of this function
         LINES = 4
         return compile("\ndef a():\n" + "\n" * LINES + "    pass", *args, **kwargs)
     # fmt: on

From 24dd541821363c1f6169b4919fd5a6a5ed4ccede Mon Sep 17 00:00:00 2001
From: solaluset <60041069+solaluset@users.noreply.github.com>
Date: Tue, 18 Nov 2025 05:29:41 +0200
Subject: [PATCH 5/7] Fix source IndexError test

---
 testing/code/test_source.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/testing/code/test_source.py b/testing/code/test_source.py
index 1afcd906b61..3512a86f9a8 100644
--- a/testing/code/test_source.py
+++ b/testing/code/test_source.py
@@ -663,9 +663,10 @@ def patched_compile1(_, *args, **kwargs):
 
     # fmt: off
     def patched_compile2(_, *args, **kwargs):
-    # first line of this function must not start with spaces
-    # LINES must be equal to number of lines of this function
-        LINES = 4
+
+        # first line of this function (the one above this one) must be empty
+        # LINES must be equal or higher than number of lines of this function
+        LINES = 99
         return compile("\ndef a():\n" + "\n" * LINES + "    pass", *args, **kwargs)
     # fmt: on
 

From e422b605c5299c5d8a8f384dcb72ed3b52d76d2f Mon Sep 17 00:00:00 2001
From: solaluset <60041069+solaluset@users.noreply.github.com>
Date: Thu, 20 Nov 2025 23:00:42 +0200
Subject: [PATCH 6/7] Add changelog entry for #13884

---
 changelog/13884.bugfix.rst | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog/13884.bugfix.rst

diff --git a/changelog/13884.bugfix.rst b/changelog/13884.bugfix.rst
new file mode 100644
index 00000000000..3f7fb465603
--- /dev/null
+++ b/changelog/13884.bugfix.rst
@@ -0,0 +1 @@
+Fixed rare internal IndexError caused by `builtins.compile` being overriden in client code.

From 59021758e6e4f4894528ca696365ba03f39b2af7 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Thu, 20 Nov 2025 21:05:54 +0000
Subject: [PATCH 7/7] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 changelog/13884.bugfix.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/changelog/13884.bugfix.rst b/changelog/13884.bugfix.rst
index 3f7fb465603..af0f08eb00c 100644
--- a/changelog/13884.bugfix.rst
+++ b/changelog/13884.bugfix.rst
@@ -1 +1 @@
-Fixed rare internal IndexError caused by `builtins.compile` being overriden in client code.
+Fixed rare internal IndexError caused by `builtins.compile` being overridden in client code.