Bug #21168: Prism doesn't require argument parentheses (in some cases) when a block is present but parse.y does

• Status: Open
• Assignee: prism
• Target version: -
• ruby -v: ruby 3.4.2 (2025-02-15 revision d2930f8e7a) +PRISM [x86_64-linux]
• Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN

[Earlopain (Earlopain _)]

It's a bit more than that but explaining it in full would be a bit much. Instead, see this:

foo(
  bar baz do
  end
)

$ ruby -c --parser=prism test.rb
Syntax OK
$ ruby -c --parser=parse.y test.rb
ruby: test.rb:2: syntax error, unexpected 'do' for block, expecting ')' (SyntaxError)
  bar baz do
          ^~

OTOH, this is consistently rejected:

[
  foo bar do
  end,
]
# And also
foo || bar baz do
end

[tenderlovemaking (Aaron Patterson)]

• Assignee set to prism