[ruby-core:90362] [Ruby trunk Bug#15389] 9 elements or more larger Hash doesn't show an entry

[hanmac@gmx.de]

Issue #15389 has been updated by Hanmac (Hans Mackowiak).


@kou you need to debug what sym is, it looks like that it thinks that some of them are already existing

it might also be a bad idea to use such objects as hash keys?

Or debug why hash thinks it already has that key?

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Bug #15389: 9 elements or more larger Hash doesn't show an entry
https://bugs.ruby-lang.org/issues/15389#change-75473

* Author: kou (Kouhei Sutou)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: ruby 2.6.0dev (2018-12-05 trunk 66213) [x86_64-linux]
* Backport: 2.4: UNKNOWN, 2.5: UNKNOWN
----------------------------------------
I don't know this problem is a problem of Racc or Ruby itself yet but I'll share this.

Here is a Ruby script that reproduce this case:

```ruby
require "racc/grammar"

hash = {}
[
  [false, 0],
  [:error, 1],
  [:END, 2],
  [:CLASS, 3],
  [:RULE, 4],
  [:"<", 5],
  [:SYMBOL, 6],
  [:":", 7],
  [:CONV, 8],
].each do |value, ident|
  sym = Racc::Sym.new(value, false)
  sym.ident = ident
  hash[sym] = ident
end
p hash
```

It outputs the following:

```text
{error=>1, END=>2, CLASS=>3, RULE=>4, <=>5, SYMBOL=>6, :=>7, CONV=>8}
```

It doesn't have an entry for `[false, 0]`.

If we reduce the last entry (`[:CONV, 8]`), we can see the entry for `[false, 0]`:

```ruby
require "racc/grammar"

hash = {}
[
  [false, 0],
  [:error, 1],
  [:END, 2],
  [:CLASS, 3],
  [:RULE, 4],
  [:"<", 5],
  [:SYMBOL, 6],
  [:":", 7],
].each do |value, ident|
  sym = Racc::Sym.new(value, false)
  sym.ident = ident
  hash[sym] = ident
end
p hash
```

```text
{$end=>0, error=>1, END=>2, CLASS=>3, RULE=>4, <=>5, SYMBOL=>6, :=>7}
```

(`$end=>0` is the entry for `[false, 0]`.)

This is occurred since r65454.



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