Bug #21819: A Data object should be frozen even if it has no members

• Status: Open
• Assignee: -
• Target version: -
• ruby -v: ruby 4.0.0 (2025-12-25 revision 553f1675f3) +PRISM [arm64-darwin25]
• Backport: 3.2: REQUIRED, 3.3: REQUIRED, 3.4: REQUIRED, 4.0: REQUIRED

[dazuma (Daniel Azuma)]

Data objects with at least one member are currently automatically frozen on construction, and shareable if all members are shareable. However, a Data object with no members is not frozen on construction. I would expect such an object similarly to be frozen (and also shareable since it has no non-shareable members).

Foo = Data.define(:foo)
Foo.new(1).frozen? # => true

Bar = Data.define
Bar.new.frozen? # => false

[nobu (Nobuyoshi Nakada)]

• Backport changed from 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN to 3.2: REQUIRED, 3.3: REQUIRED, 3.4: REQUIRED, 4.0: REQUIRED

[nobu (Nobuyoshi Nakada)]

GH-15792