From: marcandre-ruby-core@...
Date: 2020-12-17T03:59:33+00:00
Subject: [ruby-core:101491] [Ruby master Feature#17397] `shareable_constant_value: literal` should check at runtime, not at parse time

Issue #17397 has been updated by marcandre (Marc-Andre Lafortune).


nobu (Nobuyoshi Nakada) wrote in #note-5:
> Your proposal seems `shareable_constant_value: everything` (it's prefixed with `experimental_` now though).

No, that value deep-freezes implicitly all constants. Non-literals are not frozen in my proposal.

Here's a code summary of the differences (scenarios 2, 3 or 5 == 2+3):

```ruby
# shareable_constant_value: experimental_everything (current, ok)

X = [1, 2, 3]
p X.frozen? # => true
Y = Set[4, 5, 6]
p Y.frozen? # => true

# shareable_constant_value: literal (2) or literal_strict (5)

X = [1, 2, 3]
p X.frozen? # => true
(Y = Set[4, 5, 6]) rescue :error # => :error (at runtime, currently at parse time)
Z = Set[8, 9].freeze # => no error (currently parse error)

# shareable_constant_value: literal (3 or 5)

X = [1, 2, 3]
p X.frozen? # => true
Y = Set[4, 5, 6] # => no error (currently parse error)
p Y.frozen? # => false
```

----------------------------------------
Feature #17397: `shareable_constant_value: literal` should check at runtime, not at parse time
https://bugs.ruby-lang.org/issues/17397#change-89269

* Author: marcandre (Marc-Andre Lafortune)
* Status: Open
* Priority: Normal
* Assignee: ko1 (Koichi Sasada)
----------------------------------------
I think `shareable_constant_value: literal` is too strict because it has too crude checks at parse time.

I wish the following code would parse and run:

```ruby
# shareable_constant_value: literal

class Foo < RuntimeError
end

# Similar code, but does not parse:
Bar = Class.new(RuntimeError) # => unshareable expression

Baz = Ractor.make_shareable(anything_here) # => unshareable expression

Qux = Set[1, 2, 3].freeze # => unshareable expression
```

Could we instead raise some sort of RuntimeError when an assignment is made that is not shareable?



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