From: merch-redmine@...
Date: 2021-02-26T21:59:17+00:00
Subject: [ruby-core:102622] [Ruby master Bug#9931] irb: Really weird behavior for x = "#{x\"}" (ex: irb(main:009:-4))

Issue #9931 has been updated by jeremyevans0 (Jeremy Evans).

Status changed from Assigned to Closed

As of Ruby 3.0, I think this is fixed:

```
$ irb30
irb(main):001:0" x = "#{x\"}"
irb(main):002:0"
irb(main):003:0" }
irb(main):004:0" "
Traceback (most recent call last):
        3: from /usr/local/bin/irb30:23:in `<main>'
        2: from /usr/local/bin/irb30:23:in `load'
        1: from /usr/local/lib/ruby/gems/3.0/gems/irb-1.3.0/exe/irb:11:in `<top (required)>'
SyntaxError ((irb):1: syntax error, unexpected backslash)
x = "#{x\"}"
        ^
```

This behavior makes sense.  It's invalid syntax, so it is reasonable that irb would expect that after `"#{x\"}"`, you are still in an interpolation inside a string, and as soon as it knows the interpolation has ended, it evaluates the string and you get a syntax error.

----------------------------------------
Bug #9931: irb: Really weird behavior for x = "#{x\"}" (ex: irb(main:009:-4))
https://bugs.ruby-lang.org/issues/9931#change-90616

* Author: jesserayadkins (Jesse Adkins)
* Status: Closed
* Priority: Normal
* Assignee: aycabta (aycabta .)
* ruby -v: ruby 1.9.3p484 (2013-11-22 revision 43786) [x86_64-linux]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
# Our journey starts off rather simple:
irb(main):001:0> x = "#{x}"
=> ""
# Okay, makes sense.
irb(main):002:0> x = "#{x\"}"
irb(main):003:0" 
# Hmm...Still in a string? That's weird.
irb(main):003:0" "
irb(main):004:0> 
# Things seem back to normal but...
irb(main):004:0> x
# Nothing? But x is defined!
irb(main):005:0> 
# Nothing? Hmm...
irb(main):005:0> end
irb(main):006:-1> end
# Uhh...I don't think that's supposed to do that.
irb(main):007:-2> end
irb(main):008:-3> end
irb(main):009:-4> 
# ...I'm afraid to go deeper.
# Get me out of here!
irb(main):009:-4> quit
irb(main):010:-4> 
# O.O
irb(main):010:-4> ^C
irb(main):010:0> 
# ...Can I go now?
irb(main):010:0> quit
# Success!

# Additionally, if I put this in a file:
x = "#{x\"}"

# I get two syntax errors (ruby 1.9.3):
test.rb:1: syntax error, unexpected $undefined, expecting '}'
x = "#{x\"}"
         ^
test.rb:1: syntax error, unexpected $end, expecting '}'
x = "#{x\"}"
            ^




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