From: merch-redmine@...
Date: 2019-07-09T15:56:52+00:00
Subject: [ruby-core:93642] [Ruby master Bug#10463] :~@ and :!@ are not	parsed correctly

Issue #10463 has been updated by jeremyevans0 (Jeremy Evans).


nobu (Nobuyoshi Nakada) wrote:
> If `:!@` and `:!`  are different things, also `!foo` and `foo.!` are different things.

I don't believe that is true.  With the above patch:

```ruby
class A
  def !; :! end
  def ~; :~ end
end

!A.new
# :!
A.new.!
# :!
~A.new
# :~
A.new.~
# :~
```

The `@` in `:!@` and `def !@; end` was ignored during lexing before, it doesn't affect the semantics.  This is different than `+@` and `+`:

```ruby
class A
  def +; :+ end
  def +@; :+@ end
end

+A.new
# :+@
A.new.+
# :+
```

> This means a backward incompatibility.

The backward incompatibility should be limited to making the following invalid syntax:

```ruby
def !@; end
def ~@; end
alias foo !@
alias bar ~@
:!@
:~@
```

Currently, `:!@` is different than `:"!@"`, which very much appears to be a bug.  With the above patch `:!@` is a syntax error (`:"!@"` is still valid).

----------------------------------------
Bug #10463: :~@ and :!@ are not parsed correctly
https://bugs.ruby-lang.org/issues/10463#change-79250

* Author: sawa (Tsuyoshi Sawada)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: 2.1.4
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
The at mark in literal symbols `:~@` and `:!@` are ignored.

~~~ruby
:~@  # => :~
:!@  # => :!
~~~



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