Division sometimes breaks syntax highlighting in ruby-mode

Question

Interesting bug in ruby-mode. When a variable called index is followed by a slash /, syntax highlighting breaks.

Here's a screenshot to show you what I mean:

I'm not really sure how to file a ticket on the ruby-mode repo since I've never used SVN. Anyone know where to go from here?

To report a bug in ruby-mode, you should `M-x report-emacs-bug`. ruby-mode is distributed with Emacs. I can reproduce the problem, but the way to fix it is non-obvious, and it doesn't seem inappropriate to have that discussion in StackExchange. Thanks. — Dmitry, Jun 07 '16 at 21:14
`it doesn't seem inappropriate to have that discussion in StackExchange`. Was that an intentional double-negative? Are you saying it *is* appropriate to have that discussion here? — harumph, Jun 07 '16 at 21:50
Interestingly it only happens with `index`, if you change the var's name is goes ok. — Henry Mazza, Apr 09 '20 at 13:07

score 3 · Accepted Answer · answered Jun 07 '16 at 22:43

3

In short, it is because Ruby's syntax is ambiguous, and because String#index accepts a regexp in its first argument.

There are different tradeoffs different editors take regarding regular expressions in Ruby. We can discuss improving Emacs's tradeoff in a bug report.

answered Jun 07 '16 at 22:43

Dmitry

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I'm not sure I understand why distinguishing between a method on a string and a variable name is ambiguous. Wouldn't any variable name that also happens to be a method on a literal be problematic, in that case? – harumph Jun 07 '16 at 23:00
Also, I am going to submit a bug report. – harumph Jun 07 '16 at 23:01
The ambiguity I'm referring to here is between regexp delimiters and division. – Dmitry Jun 07 '16 at 23:05
Upvotes are nice and all, but would somebody file the bug? – Dmitry Jun 15 '16 at 12:20
Filed the bug with `M-x report-emacs-bug` last week, right after creating this post. – harumph Jun 15 '16 at 18:05
@harumph Do you have a bug number? Or, better, a URL? – Dmitry Jun 15 '16 at 19:36
I do not, and I can't find it in the bug tracker. First time filing an emacs bug, maybe I messed something up. I'll try again. – harumph Jun 15 '16 at 23:53
@harumph Are you using Mac Port, by any chance? It hijacks the bug reporting mechanism, and never forwards any reports to the official list. – Dmitry Jun 16 '16 at 00:19
using homebrew. – harumph Jun 16 '16 at 14:03
Homebrew allows installing different versions. – Dmitry Jun 16 '16 at 14:23
In any case, when you report a bug, you should get a reply email with the link to the created bug. No need to look for the bug tracker. – Dmitry Jun 16 '16 at 14:24
I'm running 24.5.1. Sent again, but no response yet. – harumph Jun 16 '16 at 14:28
You're either running the NS port, or the Mac Port. There are probably articles on the Internet that tell how to tell which one you have. – Dmitry Jun 16 '16 at 14:34

score 0 · Answer 2 · answered Jun 08 '16 at 11:30

0

FWIW, if you use enh-ruby-mode, that problem doesn't occur.

https://github.com/zenspider/enhanced-ruby-mode

answered Jun 08 '16 at 11:30

Trevoke

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Division sometimes breaks syntax highlighting in ruby-mode

2 Answers2