From fcffcd724afe1a45e2c79f79ed0ca465869f10f8 Mon Sep 17 00:00:00 2001
From: kobarity <kobarity@gmail.com>
Date: Sat, 16 Sep 2023 23:14:45 +0900
Subject: [PATCH] Fix Python mode error caused by incorrect indentation

* lisp/progmodes/python.el (python-indent--calculate-indentation):
Guard against negative indentation.  (Bug #65870)

* test/lisp/progmodes/python-tests.el
(python-indent-badly-indented-block-end): New test.

(cherry picked from commit c03cafba390603de653def097fdcf9566d502061)
---
 lisp/progmodes/python.el            | 2 +-
 test/lisp/progmodes/python-tests.el | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index b5c00385ef3..bb2bf1731b4 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -1819,7 +1819,7 @@ possibilities can be narrowed to specific indentation points."
         (`(:after-block-end . ,start)
          ;; Subtract one indentation level.
          (goto-char start)
-         (- (current-indentation) python-indent-offset))
+         (max 0 (- (current-indentation) python-indent-offset)))
         (`(:at-dedenter-block-start . ,_)
          ;; List all possible indentation levels from opening blocks.
          (let ((opening-block-start-points
diff --git a/test/lisp/progmodes/python-tests.el b/test/lisp/progmodes/python-tests.el
index 73fbd9a5bba..f8873bdd0db 100644
--- a/test/lisp/progmodes/python-tests.el
+++ b/test/lisp/progmodes/python-tests.el
@@ -2116,6 +2116,15 @@ def test_re(string):
    (python-tests-look-at "else:")
    (should (= (python-indent-calculate-indentation) 4))))
 
+(ert-deftest python-indent-badly-indented-block-end ()
+  "Test BUG 65870 regression."
+  (python-tests-with-temp-buffer
+   "
+return
+"
+   (goto-char (point-max))
+   (should (= (python-indent-calculate-indentation) 0))))
+
 
 ;;; Filling
 
-- 
2.39.2