Re: When is a syntax-propertize-function called when parse-sexp-lookup-properties is t for a current buffer?

[Stefan Monnier via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

> 1 -> (my-syntax-propertize 980 1555)
> 1 <- my-syntax-propertize: nil
> ======================================================================
> 1 -> (my-syntax-propertize 980 1556)
> 1 <- my-syntax-propertize: nil
> ======================================================================
> 1 -> (my-syntax-propertize 1043 1616)
> 1 <- my-syntax-propertize: nil
> ======================================================================
> 1 -> (my-syntax-propertize 1043 1617)
> 1 <- my-syntax-propertize: nil

So, IIUC even though the function is called, the relevant char doesn't
get the corresponding `syntax-table` text property?

Maybe the major-mode is getting in the way?

You can try to use:

      (defun my-syntax-propertize (beg end)
        (funcall
         (syntax-propertize-rules
           ("\\(<\\)<"
            (1 (progn
                 (message "OPEN at %S" (match-beginning 1))
                 (string-to-syntax "(>")))))
           (">\\(>\\)"
            (1 (progn
                 (message "CLOSE at %S" (match-beginning 1))
                 (string-to-syntax "(>")))))
         beg end))

Then check your *Messages* buffer to see where the function placed the
property, then look at these positions (e.g. with `C-u C-x =`) to see if
the `syntax-table` text property is still present.

If the property is absent (i.e. has been removed after your function
added it), then you may want to check your `syntax-propertize-function`
and search for `syntax-table` in erlong-mode's code to see what might be
interfering (e.g. maybe this property is added to
`font-lock-extra-properties`?).


        Stefan