Bug #21776: Binding#local_variable_defined? still supports numbered parameters

• Status: Open
• Assignee: -
• Target version: -
• ruby -v: ruby 4.0.0dev (2025-12-11T18:57:06Z master d02c971574) +PRISM [x86_64-linux]
• Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN

[zverok (Victor Shepelev)]

On the freshest master:

[1].each {_1; p binding.local_variable_defined?(:_1) }
#=> true

It is inconsistent with changes in #local_variables/#local_variable_get/#local_variable_set. And inconsistent with handling of it:

[1].each { it; p binding.local_variable_defined?(:it) }
#=> false