How to troubleshoot problem with M-x diff-buffers
reddit / emacs

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MaherVelousSc2 · 2022-06-29 00:51

Hello,

I'm having a problem with M-x diff-buffers, in that I have two buffers
which are definitely different, and calling diff-buffers on the two of
them returns that they are identical.

How should I go about troubleshooting this issue? It seems like it's
writing the contents to two temp files and then diffing these two
files, and I'm not familiar with debugging elisp at all [tracing
functions? inspecting stuff that's running?]. Is there a way to get to
the bottom of this which doesn't involve learning how to debug elisp
and debugging `diff`?

Thanks in advance, sorry if the problem is badly posed.

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redguardtoo · 2022-06-29 04:07

Make sure the cli program `diff` exists and is added into the OS
envrionment variable `PATH` (see https://duckduckgo.com/?q=environment
+variable+path&atb=v320-1&ia=web). You might need install diff and
setup `PATH` if you are using Windows.

If the issue is still not resolved,
- `M-x togggle-debug-on-error` and reproduce the issue
- report the bug to the emacs core team, `M-x report-emacs-bug`

Besides, https://github.com/redguardtoo/diff-lisp provides a pure
Emacs Lisp solution which needs no setup. You can use its region
comparing command as a fallback.

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samsjj · 2022-06-29 06:27

Try ediff

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Phil-Hudson · 2022-06-29 07:23

This. Usually the better solution IME.

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wargxs · 2022-07-01 06:48

Can you do diff buffer with file for both of them? And if different,
save them? or ediff :-)