[ruby-core:108742] [Ruby master Bug#18779] `GC.compact` and other compaction related methods should be defined as rb_f_notimplement on non supported platforms.

["jaruga (Jun Aruga)" <noreply@ruby-lang.org>]

Issue #18779 has been updated by jaruga (Jun Aruga).


> I'm marking 3.0 and 3.1 for backport. The two commits are:
> 
>    6ddec1082d06431111123c03b18ca41e7a2cec12
>    e9623f7432b4603735c74b6f0bb683a9bf19c2c6

Did you backport to ruby_3_0 and ruby_3_1 branches? I cannot find the 2 commit hashes above.


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Bug #18779: `GC.compact` and other compaction related methods should be defined as rb_f_notimplement on non supported platforms. 
https://bugs.ruby-lang.org/issues/18779#change-97802

* Author: byroot (Jean Boussier)
* Status: Closed
* Priority: Normal
* Backport: 2.7: WONTFIX, 3.0: REQUIRED, 3.1: REQUIRED
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I received several bug report on native gems using `GC.verify_compaction_references` in their test suite.

Examples:

  - https://github.com/msgpack/msgpack-ruby/pull/275/files
  - https://github.com/Shopify/bootsnap/pull/414/files

I think that when `!GC_COMPACTION_SUPPORTED`, rather than raise `NotImplementedError`, we should instead define these methods as `rb_f_notimplement` like `Process.fork` on Windows.

This way `GC.respond_to?(:compact)` would be a proper way to test for compaction support.

Unfortunately, these methods are defined through `.rb` files with `Primitive`, and I don't know wether it's possible to check `GC_COMPACTION_SUPPORTED` from there, nor if it's possible to define a `rb_f_notimplement` method.

cc @tenderlovemaking 



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