Issue #19881 has been updated by mame (Yusuke Endoh). My uncertain understanding is that an expression (called "arg" in parse.y) must come after the unary minus. Since `foo 1, 2, 3` is not an expression but a statement (called "command" in parse.y), `- foo 1, 2, 3` is not acceptable. ---------------------------------------- Bug #19881: Unary operators on calls without parentheses https://bugs.ruby-lang.org/issues/19881#change-104597 * Author: kddnewton (Kevin Newton) * Status: Open * Priority: Normal * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- At the moment it appears that you can't use unary operators when you have a call without parentheses. For example: ``` ruby - foo 1, 2, 3 ``` This seems useful, particularly for methods that perform calculations. I'm also asking because I thought this *was* allowed, so YARP allows it. If it's not, I need to explicitly add a syntax error for it. -- https://bugs.ruby-lang.org/