Ruby: add qltest documenting implicit return dataflow gaps

[Copilot]

Ruby's dataflow ExprReturnNode only recognises implicit returns that are direct statements of the method body (c.getBody().getAStmt()), missing cases where the returned value is in a rescue, else, or a body with ensure present.

New test: implicit-return

Six cases, all using implicit returns (no return keyword):

# Works: simple body return
def m_body
  source(1)
end
sink(m_body) # $ hasValueFlow=1

# Missing: body return when ensure is present
def m_body_ensure
  source(2)
ensure
  nil
end
sink(m_body_ensure) # $ MISSING: hasValueFlow=2

# Missing: rescue clause
def m_rescue
  raise "error"
rescue
  source(3)
end
sink(m_rescue) # $ MISSING: hasValueFlow=3

# Also MISSING: rescue+ensure, else, else+ensure

MISSING: annotations document known gaps without causing test failures; the framework will emit "Fixed missing result" when the bug is eventually addressed.

[aschackmull]

Tweaks

[Copilot]

Pull request overview

Adds a focused Ruby data-flow regression test documenting known implicit-return gaps.

Changes:

• Covers method body, rescue, and else implicit returns with optional ensure.
• Marks known missing flows without failing the test.

Show a summary per file

File	Description
implicit-return.ql	Defines the path query.
implicit-return.expected	Records current results.
implicit_return.rb	Provides inline flow cases and expectations.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 1
• Review effort level: Balanced