Bug #21010: Endless method definition of `[]=` is SyntaxError in parse.y but allowed in Prism

• Status: Closed
• Assignee: prism
• Target version: -
• ruby -v: ruby 3.5.0dev (2025-01-06T01:50:53Z master c8e3d745fa) +PRISM [x86_64-linux]
• Backport: 3.1: DONTNEED, 3.2: DONTNEED, 3.3: DONTNEED, 3.4: REQUIRED

[tompng (tomoya ishida)]

These codes is SyntaxError in parse.y but accepted in Prism

def []=(k,v)=1
def obj.[]=(k,v)=1

These are both SyntaxError in parse.y and Prism by design.

# invalid method name; a setter method cannot be defined in an endless method definition
def f=(k,v)=1
def obj.f=(k,v)=1

I think endless method definition of []= should be also rejected.

[eileencodes (Eileen Uchitelle)]

• Assignee set to prism

[eileencodes (Eileen Uchitelle)]

Fixed in https://github.com/ruby/prism/pull/3377

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

[nobu (Nobuyoshi Nakada)]

• Backport changed from 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN to 3.1: DONTNEED, 3.2: DONTNEED, 3.3: DONTNEED, 3.4: REQUIRED