Issue #19619 has been reported by okuramasafumi (Masafumi OKURA). ---------------------------------------- Bug #19619: Endless method definition with parameters for an instance given as numbered parameters doesn't work https://bugs.ruby-lang.org/issues/19619 * Author: okuramasafumi (Masafumi OKURA) * Status: Open * Priority: Normal * ruby -v: 3.2.2 * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- This works: ```ruby class Foo def bar(baz) = 'foo' end p Foo.new.bar('baz') ``` This also works: ```ruby o = Object.new o.tap { |obj| def obj.bar(baz) = 'foo' } p o.bar('baz') ``` Even this works: ```ruby o = Object.new o.tap { def _1.bar = 'foo' } p o.bar ``` But this DOESN'T work: ```ruby o = Object.new o.tap { def _1.bar(baz) = 'foo' } p o.bar('baz') ``` So, when we define a method with parameters on an instance given as numbered parameters, it doesn't work. If we change one condition (definition way, parameter existence, and so on), it works. -- https://bugs.ruby-lang.org/