bug#19397: incorrect handling of / in a character class in js-mode

bug#19397: incorrect handling of / in a character class in js-mode

[Paul Pogonyshev]

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Try to type the following code in a JS buffer:

function test ()
{
    return /[/]/.test ('/')
}

This function is legal in JS and returns true. However, Emacs is badly
confused: indentation, syntax highlighting, C-M-f over the regex all don't
work correctly.

Note that while _this_ regex is silly, it is based on a real-life one that
uses a character class with a slash in it.

Recent Emacs trunk.

Paul

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bug#19397: incorrect handling of / in a character class in js-mode

[Stefan Monnier]

> Try to type the following code in a JS buffer:
> function test ()
> {
>     return /[/]/.test ('/')
> }

Indeed, there are two problems here: js-mode treats the first / as
a division operation, and even if you change the code to avoid this
problem, you bump into the fact that js-mode doesn't know there can be
"unescaped / in character class".

I installed a fix for the first problem into emacs-24.
For the second problem, I recommend you escape the slash for now (IIUC
the syntax of regexps in ecmascript, that will DTRT).


        Stefan

bug#19397: incorrect handling of / in a character class in js-mode

[Stefan Monnier]

Version: 25.1

> function test ()
> {
>     return /[/]/.test ('/')
> }

OK, I installed a patch into master which should handle the "unescaped slash in
character classes".  Together with the previous patch installed in
emacs-24, it should handle at least the above case.


        Stefan