Bug #18629: block args array splatting assigns to higher scope _ var

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: 3.0.2
• Backport: 2.7: REQUIRED, 3.0: REQUIRED, 3.1: DONE

[Nakilon (Victor Maslov)]

v = 1; [[2]].each{ |(v)| }; p v
_ = 1; [[2]].each{ |(_)| }; p _

prints

1
2

You can see here that v is still 1 but _ isn't shadowed properly and is being assigned 2.
Reproducible from 2.3.8 to 3.0.2 (macOS rbenv)

[jeremyevans0 (Jeremy Evans)]

I'm guessing this isn't a bug, because variables prefixed by _ (including _ itself) are supposed to be used in cases where you are ignoring the values. There are other cases where _ prefixed variables are special:

def a(b, b) end   # SyntaxError
def a(_b, _b) end # no error

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN to 2.7: REQUIRED, 3.0: REQUIRED, 3.1: REQUIRED

[mame (Yusuke Endoh)]

This ticket was discussed at the dev meeting, and @matz (Yukihiro Matsumoto) said it should be fixed. @nobu (Nobuyoshi Nakada) has already committed a fix 3ddf6ad4d2f6dae4caa00b8c407768c7062099a0

[mame (Yusuke Endoh)]

• Status changed from Open to Closed

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.7: REQUIRED, 3.0: REQUIRED, 3.1: REQUIRED to 2.7: REQUIRED, 3.0: REQUIRED, 3.1: DONE

ruby_3_1 536f5ba0d48c033e63398d1751aebd0a11bcc6ff merged revision(s) 3ddf6ad4d2f6dae4caa00b8c407768c7062099a0.