GNU bug report logs -
#77256
Treesit language-at-point
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Reported by: Juri Linkov <juri <at> linkov.net>
Date: Tue, 25 Mar 2025 18:44:02 UTC
Severity: normal
Fixed in version 31.0.50
Done: Juri Linkov <juri <at> linkov.net>
Bug is archived. No further changes may be made.
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Message #67 received at 77256 <at> debbugs.gnu.org (full text, mbox):
> On Apr 8, 2025, at 11:18 PM, Juri Linkov <juri <at> linkov.net> wrote:
>
>>>> This would make sure the `treesit-language-at-point-function` is good
>>>> enough to implement the default behavior and it makes it possible to use
>>>> `add-function` on `treesit-language-at-point-function`.
>>>
>>> Unfortunately, it's too late to add a non-nil default value.
>>
>> Is it?
>> I can't find any code out there that seems to care what is its default
>> value (all users set it but doesn't look at it, AFAICT).
The default value shouldn't matter. What’s the difference between a major-mode-set non-nil value and a default non-nil value?
>
> This case looks problematic:
>
> ;; LANG can be nil. We don't want to use the fallback
> ;; in `treesit-language-at', so here we call
> ;; `treesit-language-at-point-function' directly.
> (let* ((lang (and treesit-language-at-point-function
> (funcall treesit-language-at-point-function
> pos)))
>
> But I believe this whole 'let*' can be replaced by just
> the 'treesit-parsers-at' call. I hope Yuan could confirm this.
Why is this problematic? And yes, treesit-parsers-at is a good fit.
>
>>> I already tried to do the same by adding 'forward-sexp-default-function'
>>> to 'forward-sexp-function', but failed spectacularly (bug#70426),
>>
>> Yes, that one is much harder (it's one of the first I tried to change),
>
> If no more code outside relies on the default value,
> the default function could be added like this:
> diff --git a/lisp/treesit.el b/lisp/treesit.el
> index 8e57a6dae14..a010ff24afb 100644
> --- a/lisp/treesit.el
> +++ b/lisp/treesit.el
> @@ -165,7 +165,8 @@ treesit-primary-parser
> The primary parser should be a parser that parses the entire buffer, as
> opposed to embedded parsers which parses only part of the buffer.")
>
> -(defvar-local treesit-language-at-point-function nil
> +(defvar-local treesit-language-at-point-function
> + #'treesit-language-at-point-default
> "A function that returns the language at point.
> This is used by `treesit-language-at', which is used by various
> functions to determine which parser to use at point.
> @@ -183,10 +184,13 @@ treesit-language-at
> the most relevant parser (hence language) by their embed level.
> If `treesit-language-at-point-function' is non-nil, return
> the return value of that function instead."
> - (if treesit-language-at-point-function
> - (funcall treesit-language-at-point-function position)
> - (treesit-parser-language
> - (car (treesit-parsers-at position)))))
> + (funcall treesit-language-at-point-function position))
> +
> +(defun treesit-language-at-point-default (position)
> + "Default function for `treesit-language-at-point-function'.
> +Return the deepest parser by embed level."
> + (treesit-parser-language
> + (car (treesit-parsers-at position))))
>
> ;;; Node API supplement
>
LGTM.
> BTW, I noticed now that indentation of the default value
> in defvar-local is incorrect and differs from defvar and defcustom.
> Here is the fix:
>
> diff --git a/lisp/subr.el b/lisp/subr.el
> index be847aab28a..164ed2a6f63 100644
> --- a/lisp/subr.el
> +++ b/lisp/subr.el
> @@ -197,7 +197,7 @@ defvar-local
> Like `defvar' but additionally marks the variable as being automatically
> buffer-local wherever it is set.
> \n(fn SYMBOL &optional VALUE DOCSTRING)"
> - (declare (debug defvar) (doc-string 3) (indent 2))
> + (declare (debug defvar) (doc-string 3) (indent defun))
> ;; Can't use backquote here, it's too early in the bootstrap.
> (let ((value (car-safe args))
> (docstring (car-safe (cdr-safe args))))
This bug report was last modified 91 days ago.
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