bug#70307: [PATCH] Allow preview to work in non-file buffers

[Arash Esbati]

Paul Nelson <ultrono@gmail.com> writes:

> This patch allows preview.el to work in LaTeX-mode non-file buffers
> for which TeX-master has been set to the name of a valid tex file.
>
> This patch might appear to be adding a new feature, but if I
> understand correctly, it's really fixing an ancient bug.  From what I
> can tell, preview.el was carefully designed to support non-file
> buffers, but this support was broken unintentionally in the commit
> 3651776f5a57283f97af54a53a6106519bef41b0.
>
> In more detail, when preview-region is called on a non-file buffer,
> the file name "<none>" is passed along to TeX-region-create.  Since
> that commit, the file name is subsequently relativized to the master
> file, even when it is "<none>".  As a result, in
> preview-parse-messages, the checks (string= file "<none>") fail in
> cases where they should succeed.  This patch makes it so that
> TeX-region-create only relativizes the file name when it is not equal
> to "<none>", so that the checks in question succeed, as was intended.
>
> As motivation, I have been using something equivalent to this patch
> for a while, and have found it very useful in, e.g., indirect org-mode
> source blocks.

Paul, thanks for the patch, the motivation and the change sound
reasonable to me.

@David and Keita: WDYT, any comments?

Best, Arash