gptel-rewrite diff fails in modified buffer

[ekenberg]

Please update gptel first -- errors are often fixed by the time they're reported.

• I have updated gptel to the latest commit and tested that the issue still exists

Bug Description

gptel-rewrite diff fails to show a correct diff when buffer is modified since last saved

Note: ediff works as expected

Backend

None

Steps to Reproduce

Put this code in a .py file and save it:

for i in range(1, 11):
    print(i)

Change the code to this but do not save the buffer:

for i in range(1, 10 + 1):
    print(i)

Run gptel-rewrite on the code, tell it to simplify and (hopefully) get this suggested result:

for i in range(1, 11):
    print(i)

Now, run diff (RET d or C-c C-d) and the result shows no changes (except for a missing newline which is issue #552)

diff -u --label /home/johan/tmp/gptel-test.py --label \#\<buffer\ \*gptel-diff\*\> /home/johan/tmp/gptel-test.py /tmp/buffer-content-mdiIZ5
--- /home/johan/tmp/gptel-test.py
+++ #<buffer *gptel-diff*>
@@ -3,5 +3,4 @@
 
 for i in range(1, 11):
     print(i)
-
 # more code

Diff finished.  Tue Jan  7 11:43:08 2025

Note: ediff works as expected

Additional Context

Emacs version: "GNU Emacs 29.3 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.33, cairo version 1.16.0) of 2024-05-03"
gptel version: 20250107.34

Backtrace

No response

Log Information

No response