Bug #21714: Prism and parse.y inconsistency in `def a = a b do 1 end`

• Status: Assigned
• Assignee: prism
• Target version: -
• ruby -v: ruby 4.0.0dev (2025-11-26T06:41:42Z master 43ed35de6c) +YJIT +MN +PRISM [arm64-darwin24]
• Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN

[tompng (tomoya ishida)]

Endless method definition and command with block are syntax error in parse.y, accepted in Prism.

def a = a b do 1 end

Related to https://bugs.ruby-lang.org/issues/17398 and https://bugs.ruby-lang.org/issues/21711

[mame (Yusuke Endoh)]

• Status changed from Open to Assigned
• Assignee set to prism