[ruby-core:114628] [Ruby master Bug#19862] argument stack underflow compile error happens for the combination of and/or & one line pattern matching

5 Sep 2023

      Issue #19862 has been reported by yui-knk (Kaneko Yuichiro).

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Bug #19862: argument stack underflow compile error happens for the combination of and/or & one line pattern matching
https://bugs.ruby-lang.org/issues/19862

* Author: yui-knk (Kaneko Yuichiro)
* Status: Open
* Priority: Normal
* ruby -v: ruby 3.3.0dev (2023-09-04T18:01:33Z master db3b814cb0) [arm64-darwin21]
* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
This code raises argument stack underflow compile error on ruby 3.3 which is under development.

```ruby
# test3.rb
if true or {a: 0} in {a:}
  p 1
else
  p 0
end
```

```shell
% ruby -v test3.rb
ruby 3.3.0preview1 (2023-05-12 master a1b01e7701) [arm64-darwin21]
test3.rb:2: warning: assigned but unused variable - a
-- raw disasm--------
   trace: 1
   0000 jump                 <L000>                                      (   2)
 <L006> [sp: 0]
 <L004> [sp: 0]
*  0002 pop                                                              (   2)
   0003 pop                                                              (   2)
   0004 jump                 <L001>                                      (   2)
 <L000> [sp: 0]
   trace: 1
   0006 putself                                                          (   3)
   0007 putobject_INT2FIX_1_                                             (   3)
   0008 opt_send_without_block <calldata:p, 1>                           (   3)
   0010 leave                                                            (   5)
 <L001> [sp: -1]
   trace: 1
   0011 putself                                                          (   5)
   0012 putobject_INT2FIX_0_                                             (   5)
   0013 opt_send_without_block <calldata:p, 1>                           (   5)
   0015 leave                                                            (   5)
---------------------
test3.rb:2: argument stack underflow (-1)
test3.rb: compile error (SyntaxError)

% ./ruby -v ../../test3.rb
ruby 3.3.0dev (2023-09-04T18:01:33Z master db3b814cb0) [arm64-darwin21]
`RubyGems' were not loaded.
`error_highlight' was not loaded.
`did_you_mean' was not loaded.
`syntax_suggest' was not loaded.
../../test3.rb:2: warning: assigned but unused variable - a
-- raw disasm--------
   trace: 1
   0000 jump                 <L000>                                      (   2)
 <L006> [sp: 0]
 <L004> [sp: 0]
*  0002 pop                                                              (   2)
   0003 pop                                                              (   2)
   0004 jump                 <L001>                                      (   2)
 <L000> [sp: 0]
   trace: 1
   0006 putself                                                          (   3)
   0007 putobject_INT2FIX_1_                                             (   3)
   0008 opt_send_without_block <calldata:p, 1>                           (   3)
   0010 leave                                                            (   5)
 <L001> [sp: -1]
   trace: 1
   0011 putself                                                          (   5)
   0012 putobject_INT2FIX_0_                                             (   5)
   0013 opt_send_without_block <calldata:p, 1>                           (   5)
   0015 leave                                                            (   5)
---------------------
../../test3.rb:2: argument stack underflow (-1)
../../test3.rb: compile error (SyntaxError)
```

This also raises same error.

```ruby
# test4.rb
if false and {a: 0} in {a:}
  p 1
else
  p 0
end
```

As far as I checked, 3.0.0, 3.1.0, 3.2.0 don't raise the error.

-- 
https://bugs.ruby-lang.org/