Re: master e67f03bf35b: lisp/gnus/mm-encode.el (mm-default-buffer-type): Obey the mode hierarchy

[Robert Pluim]

>>>>> On Tue, 25 Mar 2025 11:24:01 -0400 (EDT), Stefan Monnier via Mailing list 
>>>>> for Emacs changes <emacs-diffs@gnu.org> said:

    Stefan> diff --git a/lisp/gnus/mm-encode.el b/lisp/gnus/mm-encode.el
    Stefan> index 021c56e26ef..ef75b6da6e1 100644
    Stefan> --- a/lisp/gnus/mm-encode.el
    Stefan> +++ b/lisp/gnus/mm-encode.el
    Stefan> @@ -110,7 +110,8 @@ This variable should never be set directly, but 
bound before a call to
    Stefan>  (defun mm-default-buffer-type (buffer)
    Stefan>    "Return a default content type for BUFFER, a buffer name."
    Stefan>    (if-let* ((buf (get-buffer buffer))
    Stefan> -            ((eq (buffer-local-value 'major-mode buf) 'diff-mode)))
    Stefan> +            ((provided-mode-derived-p (buffer-local-value 
'major-mode buf)
    Stefan> +                                      'diff-mode)))
    Stefan>        "text/x-patch" "text/plain"))

Do we want to cater for `magit-diff-mode' here? It doesnʼt derive from 
`diff-mode'.

Robert
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