bug#56600: 29.0.50; Python navigation problem with an empty line in nested defun

[kobarity <kobarity@gmail.com>]

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Hello,

I'm afraid this is a bug in my patch to fix #56105.  It initialized
`min-indentation' using `current-indentation' of the current line.
However, it was not adequate for an empty line as
`current-indentation' of an empty line is zero.

Attached is a patch to fix this issue.

Best Regards,

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commit 3b23ee92fab820497e90038b9eab5c030b989de4
Author: kobarity <kobarity@gmail.com>
Date:   Sat Jul 16 22:30:31 2022 +0900

    Fix python navigation problem with an empty line in nested defun
    
    * lisp/progmodes/python.el (python-nav--beginning-of-defun): Fix
    bug when point is on an empty line (bug#56600).

diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index 1c99937c4b..f31832fec9 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -1454,21 +1454,24 @@ python-nav--beginning-of-defun
          (line-beg-pos (line-beginning-position))
          (line-content-start (+ line-beg-pos (current-indentation)))
          (pos (point-marker))
-         (min-indentation (+ (current-indentation)
-                             (if (python-info-looking-at-beginning-of-defun)
-                                 python-indent-offset 0)))
+         (min-indentation (if (python-info-current-line-empty-p)
+                              most-positive-fixnum
+                            (current-indentation)))
          (body-indentation
           (and (> arg 0)
-               (save-excursion
-                 (while (and
-                         (or (not (python-info-looking-at-beginning-of-defun))
-                             (>= (current-indentation) min-indentation))
-                         (setq min-indentation
-                               (min min-indentation (current-indentation)))
-                         (python-nav-backward-block)))
-                 (or (and (python-info-looking-at-beginning-of-defun)
-                          (+ (current-indentation) python-indent-offset))
-                     0))))
+               (or (and (python-info-looking-at-beginning-of-defun)
+                        (+ (current-indentation) python-indent-offset))
+                   (save-excursion
+                     (while
+                         (and
+                          (python-nav-backward-block)
+                          (or (not (python-info-looking-at-beginning-of-defun))
+                              (>= (current-indentation) min-indentation))
+                          (setq min-indentation
+                                (min min-indentation (current-indentation)))))
+                     (or (and (python-info-looking-at-beginning-of-defun)
+                              (+ (current-indentation) python-indent-offset))
+                         0)))))
          (found
           (progn
             (when (and (python-info-looking-at-beginning-of-defun nil t)
diff --git a/test/lisp/progmodes/python-tests.el b/test/lisp/progmodes/python-tests.el
index 92c20288c8..b2cccdd956 100644
--- a/test/lisp/progmodes/python-tests.el
+++ b/test/lisp/progmodes/python-tests.el
@@ -1876,7 +1876,7 @@ python-nav-beginning-of-defun-2
                 (beginning-of-line)
                 (point))))
    ;; Nested defuns should be skipped.
-   (python-tests-look-at "return a" -1)
+   (forward-line -1)
    (should (= (save-excursion
                 (python-nav-beginning-of-defun)
                 (point))
@@ -1885,6 +1885,15 @@ python-nav-beginning-of-defun-2
                 (beginning-of-line)
                 (point))))
    ;; Defuns on same levels should be respected.
+   (python-tests-look-at "if True:" -1)
+   (forward-line -1)
+   (should (= (save-excursion
+                (python-nav-beginning-of-defun)
+                (point))
+              (save-excursion
+                (python-tests-look-at "def a():" -1)
+                (beginning-of-line)
+                (point))))
    (python-tests-look-at "def a():" -1)
    (should (= (save-excursion
                 (python-nav-beginning-of-defun)
@@ -1893,8 +1902,16 @@ python-nav-beginning-of-defun-2
                 (python-tests-look-at "def b():" -1)
                 (beginning-of-line)
                 (point))))
-   ;; Jump to a top level defun.
+   ;; Jump to an upper level defun.
    (python-tests-look-at "def b():" -1)
+   (should (= (save-excursion
+                (python-nav-beginning-of-defun)
+                (point))
+              (save-excursion
+                (python-tests-look-at "def m(self):" -1)
+                (beginning-of-line)
+                (point))))
+   (forward-line -1)
    (should (= (save-excursion
                 (python-nav-beginning-of-defun)
                 (point))
@@ -2009,6 +2026,15 @@ python-nav-end-of-defun-1
                 (python-tests-look-at "def c(self):")
                 (forward-line -1)
                 (point))))
+   (should (= (save-excursion
+                (python-tests-look-at "def b():")
+                (forward-line -1)
+                (python-nav-end-of-defun)
+                (point))
+              (save-excursion
+                (python-tests-look-at "def c(self):")
+                (forward-line -1)
+                (point))))
    (should (= (save-excursion
                 (python-tests-look-at "def b():")
                 (python-nav-end-of-defun)
@@ -2017,6 +2043,10 @@ python-nav-end-of-defun-1
                 (python-tests-look-at "def b():")
                 (forward-line 2)
                 (point))))
+   (should (not (save-excursion
+                  (python-tests-look-at "def a():")
+                  (forward-line -1)
+                  (python-nav-end-of-defun))))
    (should (= (save-excursion
                 (python-tests-look-at "def c(self):")
                 (python-nav-end-of-defun)