Bug #21622: Prism wrongly accepts command call to be a key of keyword argument

• Status: Closed
• Assignee: prism
• Target version: -
• ruby -v: ruby 3.5.0dev (2025-10-02T03:48:32Z master 88222caaa9) +PRISM [x86_64-linux]
• Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN

[tompng (tomoya ishida)]

These are syntax error in parse.y but accepted in Prism

p(p a, x: b => value)
p(p a, x: => value)
p(p a, &block => value)
p(p a, *args => value)
p(p a, **kwargs => value)

Maybe as a result, Prism accepts command call within command call

p p 1, &block => 2, &block
p p p 1 => 2 => 3 => 4

[Earlopain (Earlopain _)]

The first code examples are parsed like p((p a, &block) => value). https://github.com/ruby/prism/pull/3669 should fix this (and the other two as well)

[alanwu (Alan Wu)]

• Assignee set to prism

[Earlopain (Earlopain _)]

• Status changed from Open to Closed

Applied in changeset git|2870b7d7df30bc227f40a4c04c97050b90f1f25b.

---

[ruby/prism] Reject p(p a, &block => value) and similar

They were being parsed as p((p a, &block) => value).
When we get to this point, we must not just have parsed a command call, always consuming the => is not correct.

Closes [Bug #21622]

https://github.com/ruby/prism/commit/796ab0edf4