[ruby-core:123916] [Ruby Bug#21714] Prism and parse.y inconsistency in `def a = a b do 1 end`

Issue #21714 has been reported by tompng (tomoya ishida). ---------------------------------------- Bug #21714: Prism and parse.y inconsistency in `def a = a b do 1 end` https://bugs.ruby-lang.org/issues/21714 * Author: tompng (tomoya ishida) * Status: Open * 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 ---------------------------------------- Endless method definition and command with block are syntax error in parse.y, accepted in Prism. ~~~ruby def a = a b do 1 end ~~~ Related to https://bugs.ruby-lang.org/issues/17398 and https://bugs.ruby-lang.org/issues/21711 -- https://bugs.ruby-lang.org/