[ruby-core:72789] [Ruby trunk - Bug #11970] Multiple Assignment Into a Hash with Destructuring causes segfault

Issue #11970 has been updated by Nobuyoshi Nakada.


https://github.com/nobu/ruby/tree/bug/11970-massign-lhs-splat

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Bug #11970: Multiple Assignment Into a Hash with Destructuring causes segfault
https://bugs.ruby-lang.org/issues/11970#change-56034

* Author: Davis Wahl
* Status: Open
* Priority: Normal
* Assignee: 
* ruby -v: ruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-linux]
* Backport: 2.0.0: REQUIRED, 2.1: REQUIRED, 2.2: REQUIRED, 2.3: REQUIRED
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Segfaults in 2.2.3 and 2.3.0, In 2.1.0 and below, produces `{[:foo]=>:bar}`

~~~ruby
foo = [:foo]
bar = [:bar]

h = {}
h[*foo], _tail = *bar # Segfault
~~~

Using hash assignment/destructuring in this way may very well be undefined. I am surprised that the hash key `h[*foo]` destructures in later examples, but I'm not really sure what the behavior should be. A number of similar constructs
produce consistent behavior, which leads me to believe the above syntax should work (or at least not segfault).

Below examples produce the same output in ruby 1.9.3, 2.1.0, 2.2.3, and 2.3.0

~~~ruby
h = {}
h[:foo], _tail = *bar
puts h
# => {:foo => :bar}

h = {}
h[foo[0]], _tail = *bar
puts h
# => {:foo => :bar}

h = {}
h[*foo] = :bar
puts h
# => {:foo => :bar}
~~~

Rubies Tested:

~~~
ruby 1.9.3p550 (2014-10-27 revision 48165) [x86_64-linux]
ruby 2.1.0p0 (2013-12-25 revision 44422) [x86_64-linux]
ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-linux]
ruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-linux]
~~~


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