Respect field boundaries in indent-line-to (Bug#32014)

* lisp/indent.el (indent-line-to): Use the back-to-indentation point
as the end-point of whitespace removal, rather than
backward-to-indentation which doesn't respect field boundaries.
* test/lisp/emacs-lisp/lisp-mode-tests.el
(lisp-indent-with-read-only-field): Don't expect to fail.

1 files changed, 3 insertions, 2 deletions

diff --git a/lisp/indent.el b/lisp/indent.el
index 398585e1f90..db811cf35cc 100644
--- a/lisp/indent.el
+++ b/lisp/indent.el
@@ -300,8 +300,9 @@ only if necessary.  It leaves point at end of indentation."
                               (progn (skip-chars-backward " ") (point))))
            (indent-to column))
           ((> cur-col column) ; too far right (after tab?)
-           (delete-region (progn (move-to-column column t) (point))
-                          (progn (backward-to-indentation 0) (point)))))))
+           (let ((cur-indent (point)))
+             (delete-region (progn (move-to-column column t) (point))
+                            cur-indent))))))
 
 (defun current-left-margin ()
   "Return the left margin to use for this line.