Complete Grammar structure transformation in optimizer

[EffortlessSteven]

Summary

The IR optimizer has incomplete Grammar structure transformation code with a TODO comment indicating the implementation needs to be fixed for the new Grammar structure.

Location

• File: ir/src/optimizer.rs
• Line: 527-528
• Code:

  // TODO: Fix this for new Grammar structure
  // grammar.rules.retain(|_, r| r.lhs \!= original_symbol);

Issue

The optimizer cannot properly transform grammar rules due to incomplete implementation. The commented-out code suggests this functionality existed but was disabled during a Grammar structure refactor.

Impact

• Grammar optimizations may not work correctly
• Left-recursion elimination may be incomplete
• Could lead to incorrect parser generation

Proposed Solution

1. Review the current Grammar structure and determine correct API
2. Implement proper rule retention/removal logic
3. Add tests to verify optimization correctness
4. Update related optimization passes that may depend on this

Priority

High - This affects core grammar transformation functionality

Context

Found during codebase analysis. This appears to be a remnant from a Grammar structure refactor that wasn't fully completed.

Related Files

• ir/src/lib.rs - Grammar structure definition
• ir/src/optimizer.rs - Other optimization passes that may be affected