From: "mugikurash (Shuta Mugikura) via ruby-core" <ruby-core@...>
Date: 2026-08-28T14:14:50+00:00
Subject: [ruby-core:126540] [Ruby Bug#22018] ISeq created via `RubyVM::InstructionSequence.compile`  don't support coverage

Issue #22018 has been updated by mugikurash (Shuta Mugikura).


I found an unintended interaction with `Coverage.line_stub` after this change: calling `line_stub` while coverage is running can reset already-collected coverage counters.

I opened #22269 for this issue:
https://bugs.ruby-lang.org/issues/22269

Just linking it here since it is related to this change.


----------------------------------------
Bug #22018: ISeq created via `RubyVM::InstructionSequence.compile`  don't support coverage
https://bugs.ruby-lang.org/issues/22018#change-118723

* Author: byroot (Jean Boussier)
* Status: Closed
* Backport: 3.3: WONTFIX, 3.4: DONE, 4.0: DONE
----------------------------------------
Reproduction:

```ruby
require "coverage"

File.write("/tmp/a.rb", <<~RUBY)
  module CoverableRaw
    def self.call
      "cover up"
    end
  end

  CoverableRaw.call
RUBY

Coverage.start
require "/tmp/a.rb"
p Coverage.result

File.write("/tmp/b.rb", <<~RUBY)
  module Coverable
    def self.call
      "cover up"
    end
  end

  Coverable.call
RUBY

class RubyVM::InstructionSequence
  def self.load_iseq(path)
    compile_file(path)
  end
end

Coverage.start
require "/tmp/b.rb"
p Coverage.result
```

Expected:

```ruby
{"/tmp/a.rb" => [1, 1, 1, nil, nil, nil, 1]}
{"/tmp/b.rb" => [1, 1, 1, nil, nil, nil, 1]}
```

Actual:

```ruby
{"/tmp/a.rb" => [1, 1, 1, nil, nil, nil, 1]}
{}
```

Patch: https://github.com/ruby/ruby/pull/16805




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