From: "mame (Yusuke Endoh) via ruby-core" <ruby-core@...>
Date: 2024-11-07T10:34:01+00:00
Subject: [ruby-core:119802] [Ruby master Bug#20785] Should `a in b, and c` `a in b, or c` `a in b, rescue c` be syntax ok?

Issue #20785 has been updated by mame (Yusuke Endoh).


Discussed at the dev meeting. Matz says that, in principle, the trailing comma of a pattern should be allowed.

```ruby
a in b, and c    # Prism should accept this as `(a in b,) and c`
a in b, or c     # Prism should accept this as `(a in b,) or c`
```

In terms of rescue after a comma, it should be handled as a modifier.

```ruby
a in b, rescue c # (a in b,) rescue c
```

In terms of a newline after a comma, it should be handled as an end of a sentence.

```ruby
a in b, # This line should be a complete sentence
and c   # This is an invalid line
```

However, if there are implementation difficulties with the parser, he would consider compromises.

@yui-knk @kddnewton Do you think if matz's expectation is feasible?

----------------------------------------
Bug #20785: Should `a in b, and c` `a in b, or c` `a in b, rescue c` be syntax ok?
https://bugs.ruby-lang.org/issues/20785#change-110486

* Author: tompng (tomoya ishida)
* Status: Open
* Assignee: matz (Yukihiro Matsumoto)
* ruby -v: ruby 3.4.0dev (2024-10-04T03:22:53Z master 939ec9f080) +YJIT +MN +PRISM [arm64-darwin22]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN
----------------------------------------
This code is accepted in parse.y but rejected in prism
~~~ruby
tap do
  a in b, and c
  a in b, or c
  a in b, rescue c
end

# parsed as
tap do
  (a in b,;) and c
  (a in b,;) or c
  a in b,;
rescue c
end
~~~

I think these should be rejected like prism (parse.y accepts)
~~~ruby
a in b, and c

a in b,
and c

tap do
  a in b, rescue c
end
~~~


I think these should be accepted like parse.y (prism rejects)
~~~ruby
tap do
  a in b,
end

tap do
  a in b,
rescue
end
~~~



-- 
https://bugs.ruby-lang.org/
 ______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
 ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/