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Re: [PATCH] cc-mode: don't tread dir-local and file-local variables diff
From: |
Stefan Monnier |
Subject: |
Re: [PATCH] cc-mode: don't tread dir-local and file-local variables differently |
Date: |
Mon, 25 May 2020 22:28:15 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) |
> 1) /tmp/foo/.dir-locals.el exists and contains a single line:
>
> ((nil . ((c-file-style . "bsd"))))
>
> Opening an empty /tmp/foo/foo.c file results in ‘c-basic-offset’
> being four and ‘c-file-style’ being "bsd".
>
> 2) /tmp/bar/.dir-locals.el does not exist but /tmp/bar/bar.c does and
> contains a single line:
>
> /* -*- c-file-style: "bsd" -*- */
>
> Opening that file results in ‘c-basic-offset’ being eight and
> ‘c-file-style’ being "bsd". (Value of eight for the offset comes
> from "bsd" style).
I haven't thought very deeply about those two cases, so I'm not sure
whether I'd consider it a problem or a feature.
> I maintain that in both cases ‘c-basic-offset’ should be the same.
> I further maintain that its value should be eight. Alan disagrees and
> maintains that cc-mode-hook should overwrite settings in dir-local
> variables but should be overwritten by settings in file-local variables.
Not sure what `cc-mode-hook` has to do with it since your above example
didn't use it.
>> Just as it is sensible that a hook setting takes precedence over a
>> dir-local setting.
> No, it doesn’t. dir-local and file-local configuration is both located
> closer to the file being open than settings specified in a hook. Values
> in a hook apply to anything user opens anywhere. dir-local and
> file-local variables are narrower in scope and thus should have higher
> priority.
A hook setting can perform any test it likes to adjust the setting to
any detail of the situation. So it is definitely more specific than
a dir-locals.el setting which applies blindly to all files underneath.
> It’s highly relevant that c-file-style variable behave completely
> different whether it’s dir-local or file-local.
IIUC your example shows a different interaction between a global setting
and file-vs-dir setting. FWIW, I do find it surprising that file-local
would be treated differently from dir-local when faced with a global setting.
Stefan