[ruby-core:122112] [Ruby Bug#21339] Namespace: `RubyVM::InstructionSequence.load_iseq` isn't called for the root namespace

15 May 2025

      Issue #21339 has been updated by mame (Yusuke Endoh).

It works as expected with `--disable=gems`.

```
$ RUBY_NAMESPACE=1 ./local/bin/ruby --disable=gems test.rb
./local/bin/ruby: warning: Namespace is experimental, and the behavior may change in the future!
See doc/namespace.md for known issues, etc.
main:
[:load_iseq, "/tmp/test-file.rb"]
namespace:
[:load_iseq, "/tmp/test-file.rb"]
```

But it does not by default.

```
$ RUBY_NAMESPACE=1 ./local/bin/ruby test.rb
./local/bin/ruby: warning: Namespace is experimental, and the behavior may change in the future!
See doc/namespace.md for known issues, etc.
main:
namespace:
[:load_iseq, "/tmp/test-file.rb"]
```

The reason seems to be that rubygems's require monkey patch does not work in sub namespace.

```ruby
# with RUBY_NAMESPACE=1
puts "main:"
require "csv" #=> OK

if ENV["RUBY_NAMESPACE"]
  puts "namespace:"
  ns = Namespace.new
  # csv is a bundled gem, so rubygems is needed to require it
  ns.require("csv") #=> cannot load such file -- csv (LoadError)
end
```

Thus, there are two problems

* load_iseq does not fire via RubyGems require monkey patch.
* RubyGems require monkey patch does not work in sub namespaces.

----------------------------------------
Bug #21339: Namespace: `RubyVM::InstructionSequence.load_iseq` isn't called for the root namespace
https://bugs.ruby-lang.org/issues/21339#change-113265

* Author: byroot (Jean Boussier)
* Status: Assigned
* Assignee: tagomoris (Satoshi Tagomori)
* ruby -v: ruby 3.5.0dev (2025-05-14T12:41:46Z master b5575a80bc) +PRISM [arm64-darwin24]
* Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
```ruby
File.write("/tmp/compile-cache.rb", <<~'RUBY')
  class << RubyVM::InstructionSequence
    def load_iseq(path)
      p [:load_iseq, path]
      RubyVM::InstructionSequence.compile_file(path)
    end
  end
RUBY
File.write("/tmp/test-file.rb", "")

puts "main:"
require "/tmp/compile-cache.rb"
require "/tmp/test-file.rb"

if ENV["RUBY_NAMESPACE"]
  puts "namespace:"
  ns = Namespace.new
  ns.require("/tmp/compile-cache.rb")
  ns.require("/tmp/test-file.rb")
end
```

Expected behavior:

I would expect `load_iseq` to be invoked both in the root namespace and the user namespace when `RUBY_NAMESPACE=1`.

Actual behavior:

Somehow it's only invoked in the user namespace:

```bash
main:
[:compile_cache_setup]
[:load_iseq, "/tmp/test-file.rb"]
```

```bash
main:
[:compile_cache_setup]
namespace:
[:compile_cache_setup]
[:load_iseq, "/tmp/test-file.rb"]
```

But I don't understand why.

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