Issue #20784 has been reported by tompng (tomoya ishida). ---------------------------------------- Bug #20784: `?\` followed by EOF is parsed wrong https://bugs.ruby-lang.org/issues/20784 * Author: tompng (tomoya ishida) * Status: Open * ruby -v: ruby -v: ruby 3.4.0dev (2024-10-05T02:36:21Z master e939f28cc9) +YJIT +MN +PRISM [arm64-darwin22] * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- `?\` at EOF should be syntax error ~~~ % printf "p ?\\" | ruby --parser=parse.y [nothing shown] % printf "1 in a ?\\" | ruby --parser=parse.y -c Syntax OK ~~~ With `--parser=prism`, `?\` at EOF is parsed as empty string, reported in https://github.com/ruby/prism/issues/3144 -- https://bugs.ruby-lang.org/