[ruby-core:112897] [Ruby master Bug#4040] SystemStackError with Hash[*a] for Large _a_

Issue #4040 has been updated by Eregon (Benoit Daloze).


My opinion as a TruffleRuby implementer is I don't TruffleRuby will or can support that.
So at least it should be clear that's not something really supported by the Ruby language in general.

User code shouldn't pass a million arguments, if it's say > 20 arguments or so one should pass an array, splatting on both sides is silly, it just creates extra copies and is slower.
It's a Ruby anti-pattern.

So IMO there is no point to fix or support this, such code doesn't make sense and changing the user code is the best fix, for performance and simplicity.

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Bug #4040: SystemStackError with Hash[*a] for Large _a_
https://bugs.ruby-lang.org/issues/4040#change-102414

* Author: runpaint (Run Paint Run Run)
* Status: Open
* Priority: Normal
* Assignee: ko1 (Koichi Sasada)
* ruby -v: ruby 1.9.3dev (2010-11-09 trunk 29737) [x86_64-linux] 
* Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN
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=begin
 I've been hesitating over whether to file a ticket about this, so please feel free to close if I've made the wrong choice.
 
 I often use Hash[*array.flatten] in IRB to convert arrays of arrays into hashes. Today I noticed that if the array is big enough, this would raise a SystemStackError. Puzzled, I looked deeper. I assumed I was hitting the maximum number of arguments a method's argc can hold, but realised that the minimum size of the array needed to trigger this exception differed depending on whether I used IRB or not. So, presumably this is indeed exhausting the stack...
 
 In IRB, the following is the minimal reproduction of this problem:
 
   Hash[*130648.times.map{ 1 }]; true
 
 I haven't looked for the minimum value needed with `ruby -e`, but the following reproduces:
 
   ruby -e 'Hash[*1380888.times.map{ 1 }]'
 
 I suppose this isn't technically a bug, but maybe it offers another argument for either #666 or an extension of #3131.
=end




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