From: XrXr@users.noreply.github.com
To: ruby-core@ruby-lang.org
Subject: [ruby-core:99313] [Ruby master Bug#17048] Calling initialize_copy on live modules leads to crashes
Date: Fri, 24 Jul 2020 17:23:59 +0000 (UTC) [thread overview]
Message-ID: <redmine.journal-86707.20200724172359.16806@ruby-lang.org> (raw)
In-Reply-To: redmine.issue-17048.20200724160919.16806@ruby-lang.org
Issue #17048 has been updated by alanwu (Alan Wu).
I'm not proposing that we remove `initialize_copy`, but to make it raise when the receiver has children. So this is what it would look like:
```ruby
module A
end
A.send(:initialize_copy, Module.new) # fine, no one inherits from A
class B
include A
A.send(:initialize_copy, Module.new) # raise, since A now has one child
end
```
Admittedly this proposed behavior is designed to sidestep the problem that the current implementation has.
Though maybe it's fine since this is a seldom used private method and other Ruby implementations don't have to follow this behavior?
Now that you've mentioned it, removing the method and moving the logic into `Module#{dup,clone}` feels like the cleanest solution. It's more likely to be a breaking change though.
----------------------------------------
Bug #17048: Calling initialize_copy on live modules leads to crashes
https://bugs.ruby-lang.org/issues/17048#change-86707
* Author: alanwu (Alan Wu)
* Status: Open
* Priority: Normal
* ruby -v: ruby 2.8.0dev (2020-07-23T14:44:25Z master 098e8c2873) [x86_64-linux]
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN
----------------------------------------
Here's a repro script
```ruby
loop do
m = Module.new do
prepend Module.new
def hello
end
end
klass = Class.new { include m }
m.send(:initialize_copy, Module.new)
GC.start
klass.new.hello rescue nil
end
```
Here's a script that shows that it has broken semantics even
when it happens to not crash.
```ruby
module A
end
class B
include A
end
module C
Const = :C
end
module D
Const = :D
end
A.send(:initialize_copy, C)
p B::Const # :C, makes sense
A.send(:initialize_copy, D)
p B::Const # :D, makes sense
A.send(:initialize_copy, Module.new)
p (begin B::Const rescue NameError; 'NameError' end) # NameError, makes sense
A.send(:initialize_copy, C)
p B::Const # still NameErorr. Weird
```
This example shows that the problem exists [as far back as 2.0.0](https://wandbox.org/permlink/4dVDY9sNXJ803jh8).
I think the easiest way to fix this is to forbid calling `:initialize_copy`
on modules that have children. Another option is to try to decide on
the semantics of this. Though I don't think it's worth the effort as this
has been broken for a long time and people don't seem to to be using it.
Thoughts?
--
https://bugs.ruby-lang.org/
next prev parent reply other threads:[~2020-07-24 17:24 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-24 16:09 [ruby-core:99311] [Ruby master Bug#17048] Calling initialize_copy on live modules leads to crashes XrXr
2020-07-24 16:40 ` [ruby-core:99312] " merch-redmine
2020-07-24 17:23 ` XrXr [this message]
2020-07-24 17:52 ` [ruby-core:99314] " merch-redmine
2020-07-24 22:29 ` [ruby-core:99317] " XrXr
2020-07-25 2:35 ` [ruby-core:99321] " nobu
2020-07-25 10:32 ` [ruby-core:99331] " eregontp
2020-07-25 18:33 ` [ruby-core:99336] " XrXr
2020-07-26 6:21 ` [ruby-core:99343] " nobu
2020-07-26 16:23 ` [ruby-core:99349] " eregontp
2020-07-28 23:45 ` [ruby-core:99379] " XrXr
2020-08-12 7:30 ` [ruby-core:99567] " ko1
2020-08-26 20:27 ` [ruby-core:99715] " XrXr
2021-07-02 17:11 ` [ruby-core:104475] " merch-redmine
2021-09-16 7:18 ` [ruby-core:105288] " nobu (Nobuyoshi Nakada)
2021-09-16 16:03 ` [ruby-core:105312] " jeremyevans0 (Jeremy Evans)
2021-09-16 21:00 ` [ruby-core:105314] " alanwu (Alan Wu)
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