CodeQL Ruby parser fails on bare & block forwarding in multi-line method calls
- Dominant language
- CodeQL
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Description
# 🖼️ Context
CodeQL's Ruby parser encounters parse errors when using Ruby 3.1+'s anonymous block forwarding syntax (&) in specific contexts, despite this being valid Ruby syntax.
## Reproduction Case
```ruby
module TestCase
def method_with_bare_ampersand(&)
some_method_call(
keyword_arg1: "value1",
keyword_arg2: "value2",
keyword_arg3: "value3",
& # <-- CodeQL parse error occurs here
)
end
# This works fine - single line call
def working_method(&)
simple_call(&)
end
private
def some_method_call(keyword_arg1:, keyword_arg2:, keyword_arg3:, &block)
yield if block_given?
end
def simple_call(&block)
yield if block_given?
end
end
```
### Environment
- Repo: [rubygems/rubygems.org](https://github.com/rubygems/rubygems.org)
- recent [workflow run](https://github.com/rubygems/rubygems.org/actions/runs/17104368086/job/48509269173?pr=5925))
- [offending file](https://github.com/rubygems/rubygems.org/blob/ae3f654e67d74122a692de4e7832fa6657d98a7a/app/controllers/concerns/avo_auditable.rb#L26)
- [offending file](https://github.com/rubygems/rubygems.org/blob/ae3f654e67d74122a692de4e7832fa6657d98a7a/app/controllers/concerns/maintenance_tasks_auditable.rb#L26)
- CodeQL CLI version: 2.15.5
- Ruby version: 3.4.x
- Syntax: Valid Ruby (confirmed with ruby -c)
### 📝 Notes
- The issue only occurs with multi-line method calls where & appears on its own line
- Single-line calls with & work correctly
- Named block parameters (e.g., &block) work in all contexts
- This is valid Ruby 3.1+ anonymous block forwarding syntax
### Impact
This prevents CodeQL security analysis on codebases using modern Ruby block forwarding patterns, forcing developers to use less idiomatic code or exclude files from analysis.
Contributor guide
Research direction
Start by reproducing CodeQL analysis against app/controllers/concerns/avo_auditable.rb and app/controllers/concerns/maintenance_tasks_auditable.rb, then compare the result with ruby -c and the supplied reproduction. Done means the CodeQL Ruby parser accepts anonymous block forwarding on its own line in a multi-line call and analysis proceeds without a parse error.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- ruby
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100