[ruby-core:112312] [Ruby master Bug#19427] Marshal.load(source, freeze: true) doesn't freeze in some cases

9 Feb 2023

      Issue #19427 has been updated by byroot (Jean Boussier).
...
`deep_freeze`
As always the tricky part it circular references etc. But I guess in the case of freeze it's easy to use the frozen flag can be used to void cycles.

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Bug #19427: Marshal.load(source, freeze: true) doesn't freeze in some cases
https://bugs.ruby-lang.org/issues/19427#change-101753

* Author: andrykonchin (Andrew Konchin)
* Status: Open
* Priority: Normal
* ruby -v: 3.1
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
I've noticed that the `freeze` option doesn't work in the following cases:
- when dumped object extends a module
- when dumped object responds to `#marshal_dump` and `#marshal_load` methods
- when dumped object responds to `#_dump` method

Is it expected behaviour or maybe a known issue?

Examples:

```ruby
module M
end

object = Object.new
object.extend(M)

object = Marshal.load(Marshal.dump(object), freeze: true)
object.frozen? # => false
```

```ruby
class UserMarshal
  attr_accessor :data

  def initialize
    @data = 'stuff'
  end
  def marshal_dump() :data end
  def marshal_load(data) @data = data end
end

object = Marshal.load(Marshal.dump(UserMarshal.new), freeze: true)
object.frozen? # => false
```

```ruby
class UserDefined
  attr_reader :a, :b

  def initialize
    @a = 'stuff'
    @b = @a
  end

  def _dump(depth)
    Marshal.dump [:stuff, :stuff]
  end

  def self._load(data)
    a, b = Marshal.load data

    obj = allocate
    obj.instance_variable_set :@a, a
    obj.instance_variable_set :@b, b

    obj
  end
end

object = Marshal.load(Marshal.dump(UserDefined.new), freeze: true)
object.frozen? # => false
```

-- 
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