# Sprint 3: Remaining Issues for 100% Book Compatibility

## Current Status
- **Book Compatibility**: ~98% (estimated after Sprint 1 & 2 fixes)
- **Sprint 1**: ✅ RETURN-STMT-001 fixed (13/13 tests passing)
- **Sprint 2**: ✅ ARRAY-SYNTAX-001 partially fixed (8/12 tests passing)

## Remaining Technical Issues

### 1. Array Literal vs Array Type Mismatch
**Problem**: Array literals `[1, 2, 3]` are transpiled to `vec![1, 2, 3]` but array-typed parameters expect `[i32; N]`
**Impact**: Functions with array parameters cannot be called with array literals
**Solution Required**: 
- Type-directed transpilation of array literals
- When passing to `[T; N]` parameter, transpile to array syntax
- When passing to `Vec<T>` parameter, transpile to vec! macro

### 2. Local Array Variable Declarations
**Problem**: Cannot declare local variables with array types `let arr: [i32; 10];`
**Impact**: 1 test failing (test_local_array_declaration)
**Solution Required**:
- Extend variable declaration parsing to support array types
- Handle uninitialized array declarations

### 3. Array Initialization Syntax
**Problem**: Array initialization syntax `[0; 4]` not supported
**Impact**: 1 test failing (test_ch15_array_initialization)
**Solution Required**:
- Parse `[value; size]` syntax in expressions
- Transpile to Rust array initialization

### 4. Constant Size Resolution
**Problem**: Constants used in array sizes (e.g., `[i32; SIZE]`) not resolved
**Impact**: 1 test failing (test_array_length_constant)
**Solution Required**:
- Implement constant evaluation for array size expressions
- Track const declarations and resolve at parse time

### 5. Array Processing in Ch15
**Problem**: Complex array operations in binary compilation chapter
**Impact**: 1 test failing (test_ch15_array_processing)
**Solution Required**:
- May be related to array literal/type mismatch
- Needs investigation after fixing issue #1

## Priority Order for Sprint 3

1. **HIGH**: Fix array literal vs type mismatch (enables most use cases)
2. **MEDIUM**: Add array initialization syntax `[value; size]`
3. **LOW**: Local array declarations (less common pattern)
4. **LOW**: Constant size resolution (edge case)

## Expected Outcome
- Fixing issue #1 should resolve most practical array usage
- Full array support would bring us to 100% book compatibility
- Estimated effort: 1-2 days for complete resolution

## Test Coverage Status
- `return_statement_tdd.rs`: 13/13 ✅
- `array_syntax_tdd.rs`: 8/12 ⚠️
  - ✅ Fixed-size array parameters
  - ✅ Array return types
  - ✅ Multiple array parameters
  - ✅ Nested array types
  - ❌ Local array declarations
  - ❌ Array initialization
  - ❌ Constant sizes
  - ❌ Array processing

## Next Steps
1. Implement type-directed array literal transpilation
2. Run full book test suite to measure actual improvement
3. Address remaining array syntax issues
4. Achieve 100% book compatibility