[ruby-core:116889] [Ruby master Bug#20285] Stale inline method caches when refinement modules are reloaded

21 Feb 2024

      Issue #20285 has been updated by jhawthorn (John Hawthorn).

Backport changed from 3.0: DONTNEED, 3.1: DONTNEED, 3.2: DONTNEED, 3.3: UNKNOWN to 3.0: DONTNEED, 3.1: DONTNEED, 3.2: DONTNEED, 3.3: REQUIRED

Fixed by https://github.com/ruby/ruby/pull/10037

I'll mark this as requiring a backport for 3.3, but I think there's probably minimal impact from this issue.

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Bug #20285: Stale inline method caches when refinement modules are reloaded
https://bugs.ruby-lang.org/issues/20285#change-106924

* Author: jhawthorn (John Hawthorn)
* Status: Assigned
* Priority: Normal
* Assignee: jhawthorn (John Hawthorn)
* Backport: 3.0: DONTNEED, 3.1: DONTNEED, 3.2: DONTNEED, 3.3: REQUIRED
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This is essentially the same issue as #11672, but for inline method caches rather than class caches.

In Ruby 3.3 we started using inline caches for refinements. However, we weren't clearing inline caches when defined on a reopened refinement module.

``` ruby
class C
end

module R
  refine C do
    def m
      :foo
    end
  end
end

using R
def m
  C.new.m
end

raise unless :foo == m()

module R
  refine C do
    alias m m
    def m
      :bar
    end
  end
end

v = m()
raise "expected :bar, got #{v.inspect}" unless :bar == v
```

This will raise in Ruby 3.3 as the inline cache finds a stale refinement, but passes in previous versions.

-- 
https://bugs.ruby-lang.org/