[ruby-core:112984] [Ruby master Bug#19416] Inconsistent behaviour for Struct.new without any member_names

Issue #19416 has been updated by jeremyevans0 (Jeremy Evans).


matz (Yukihiro Matsumoto) wrote in #note-3:
> After consideration, I think we should allow empty `Struct` even without the name for consistency.

I submitted a pull request to implement this: https://github.com/ruby/ruby/pull/7587

----------------------------------------
Bug #19416: Inconsistent behaviour for Struct.new without any member_names
https://bugs.ruby-lang.org/issues/19416#change-102515

* Author: herwin (Herwin W)
* Status: Open
* Priority: Normal
* ruby -v: ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [x86_64-linux-gnu]
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
When I simply declare a Struct without any arguments, I get an error:
```
irb(main):001:0> Struct.new
(irb):1:in `new': wrong number of arguments (given 0, expected 1+) (ArgumentError)
        from (irb):1:in `<main>'                        
```
But Struct has an option to pass a class name as the first argument, which will create the struct as a constant in the Struct namespace. If this argument is given, there is no ArgumentError
```
irb(main):002:0> Struct.new('Foo')
=> Struct::Foo
```
This results in a rather pointless class
```
irb(main):003:0> Struct::Foo.new(1)
(irb):3:in `initialize': struct size differs (ArgumentError)
        from (irb):3:in `new'                                
irb(main):004:0> Struct::Foo.new
=> #<struct Struct::Foo>
```

This behaviour is not documented in the Struct class, but I would guess this is not how it is intended to be.



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