feat: add Epic 8-10 roadmap for complete compiler implementation

Extend BACKLOG.md with comprehensive roadmap to transform FortFC from
infrastructure-complete project to actual working Fortran compiler:

Epic 8: Real MLIR C API Implementation
- Replace all stub implementations with real MLIR C API calls
- Integrate with actual LLVM/MLIR libraries
- Generate verifiable MLIR IR and object code

Epic 9: Complete Compiler Implementation
- Add full Fortran language support
- Implement executable generation and linking
- Create comprehensive end-to-end testing

Epic 10: Production Readiness
- Complete CLI interface matching gfortran patterns
- Add comprehensive error handling and diagnostics
- Create distribution and documentation

Goal: Transform from "infrastructure complete" to "ffc hello.f90 -o hello && ./hello"

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: krystophny

BACKLOG.md

@@ -19,6 +19,31 @@ Tasks are organized by epic and follow a strict RED/GREEN/REFACTOR test-driven d
 - Use src/mlir_c/, src/dialects/, src/builder/ modules exclusively
 - Text output only for final debugging/verification
 
+## Current Status Summary
+
+### ✅ COMPLETED (Infrastructure Ready):
+- **Epic 1-3**: Complete MLIR C API Foundation, Dialects, IR Builder (using stubs)
+- **Epic 4**: Complete AST to MLIR Conversion Pipeline (using stubs)
+- **Epic 5**: Complete Pass Management and Optimization (using stubs)
+- **Epic 6**: Complete Backend Integration and Memory Management
+- **Epic 7**: Complete Testing, Documentation, and CI/CD
+
+### 🎯 NEXT PHASE (Make it a Real Compiler):
+- **Epic 8**: Replace ALL stubs with real MLIR C API calls
+- **Epic 9**: Implement complete Fortran language support
+- **Epic 10**: Production-ready CLI and distribution
+
+### 🚀 END GOAL:
+```bash
+$ echo 'program hello; print *, "Hello, World!"; end program' > hello.f90
+$ ffc hello.f90 -o hello
+$ ./hello
+Hello, World!
+```
+
+**Current Reality**: All infrastructure exists but uses stubs - cannot compile real Fortran yet
+**After Epic 8-10**: Full working Fortran compiler with MLIR backend
+
 ## Epic 1: MLIR C API Foundation
 
 ### 1.1 Create Basic C Bindings Module [5 story points]
@@ -443,7 +468,208 @@ Tasks are organized by epic and follow a strict RED/GREEN/REFACTOR test-driven d
 - Integrated existing memory leak detection from Epic 6.2 into CI pipeline
 - Added build configuration script with requirement checking and automated setup
 
-## Prioritization
+## Epic 8: Real MLIR C API Implementation
+
+### 8.1 Replace MLIR C API Stubs [21 story points]
+**RED Tests:**
+- [x] Test MLIR context creation and destruction (currently using stubs)
+- [x] Test MLIR module creation (currently using stubs)
+- [x] Test MLIR type creation (currently using stubs)
+- [x] Test MLIR operation creation (currently using stubs)
+- [ ] Test real MLIR context with actual LLVM libraries
+- [ ] Test real MLIR module with verifiable IR
+- [ ] Test real MLIR type system integration
+- [ ] Test real MLIR operation verification
+
+**GREEN Implementation:**
+- [ ] Link against actual LLVM/MLIR development libraries
+- [ ] Replace `mlir_c_stubs.c` with real MLIR C API calls
+- [ ] Update `mlir_c_core.f90` to use real MLIR context functions
+- [ ] Update `mlir_c_types.f90` to use real MLIR type system
+- [ ] Update `mlir_c_operations.f90` to use real MLIR operation builders
+- [ ] Update CMakeLists.txt to require and link MLIR libraries
+- [ ] Test with actual MLIR IR generation and verification
+
+**REFACTOR:**
+- [ ] Optimize MLIR C API usage patterns
+- [ ] Add comprehensive error handling for real MLIR operations
+- [ ] Implement MLIR diagnostic handling
+- [ ] Add MLIR pass registration and execution
+
+### 8.2 Real Frontend Integration [13 story points]
+**RED Tests:**
+- [ ] Test fortfront AST parsing integration
+- [ ] Test AST to HLFIR conversion with real data
+- [ ] Test Fortran type system mapping to MLIR types
+- [ ] Test function signature generation from AST
+
+**GREEN Implementation:**
+- [ ] Integrate with fortfront for real Fortran AST parsing
+- [ ] Implement AST traversal for HLFIR generation
+- [ ] Create real type mapping from Fortran to MLIR
+- [ ] Generate actual HLFIR operations from AST nodes
+
+**REFACTOR:**
+- [ ] Optimize AST traversal performance
+- [ ] Add comprehensive Fortran language feature support
+- [ ] Implement advanced type conversion edge cases
+
+### 8.3 Real HLFIR/FIR Generation [21 story points]
+**RED Tests:**
+- [ ] Test real HLFIR.declare operation generation
+- [ ] Test real HLFIR.assign operation generation
+- [ ] Test real HLFIR.elemental operation generation
+- [ ] Test FIR.alloca operation generation
+- [ ] Test FIR.load/store operation generation
+- [ ] Test function call generation
+- [ ] Test control flow generation (if/do/select)
+
+**GREEN Implementation:**
+- [ ] Generate real HLFIR operations using MLIR C API
+- [ ] Implement HLFIR to FIR lowering with real passes
+- [ ] Create actual FIR operations for memory management
+- [ ] Generate proper function signatures and calls
+- [ ] Implement control flow structures in HLFIR/FIR
+
+**REFACTOR:**
+- [ ] Optimize HLFIR operation patterns
+- [ ] Add comprehensive Fortran intrinsic support
+- [ ] Implement array operations and elemental functions
+
+### 8.4 Real Lowering Pipeline [13 story points]
+**RED Tests:**
+- [ ] Test HLFIR to FIR lowering with verification
+- [ ] Test FIR to LLVM IR lowering
+- [ ] Test LLVM optimization passes
+- [ ] Test object code generation
+
+**GREEN Implementation:**
+- [ ] Implement real HLFIR to FIR lowering passes
+- [ ] Configure FIR to LLVM IR lowering
+- [ ] Set up LLVM optimization pipeline
+- [ ] Generate actual object files (.o)
+
+**REFACTOR:**
+- [ ] Optimize compilation pipeline performance
+- [ ] Add configurable optimization levels (-O0, -O1, -O2, -O3)
+- [ ] Implement debug information generation
+
+## Epic 9: Complete Compiler Implementation
+
+### 9.1 Executable Generation [8 story points]
+**RED Tests:**
+- [ ] Test object file to executable linking
+- [ ] Test runtime library integration
+- [ ] Test main program generation
+- [ ] Test executable execution
+
+**GREEN Implementation:**
+- [ ] Implement linking stage for executables
+- [ ] Integrate Fortran runtime libraries
+- [ ] Generate proper main program wrapper
+- [ ] Create working executable files
+
+**REFACTOR:**
+- [ ] Optimize linking performance
+- [ ] Add static/dynamic linking options
+- [ ] Implement cross-compilation support
+
+### 9.2 Complete Fortran Language Support [21 story points]
+**RED Tests:**
+- [ ] Test basic arithmetic operations
+- [ ] Test variable declarations and assignments
+- [ ] Test function/subroutine definitions and calls
+- [ ] Test array operations and allocations
+- [ ] Test derived types and modules
+- [ ] Test I/O operations (print, read, write)
+- [ ] Test control flow (if, do, select case)
+- [ ] Test intrinsic functions
+- [ ] Test character string operations
+
+**GREEN Implementation:**
+- [ ] Implement complete expression evaluation
+- [ ] Add full variable and type system
+- [ ] Create function/subroutine call infrastructure
+- [ ] Implement array operations and memory management
+- [ ] Add derived type and module support
+- [ ] Create I/O operation infrastructure
+- [ ] Implement all control flow constructs
+- [ ] Add intrinsic function library
+- [ ] Implement character operations
+
+**REFACTOR:**
+- [ ] Optimize code generation patterns
+- [ ] Add advanced Fortran features (parameterized types, etc.)
+- [ ] Implement Fortran 2018+ features
+
+### 9.3 End-to-End Integration Testing [13 story points]
+**RED Tests:**
+- [ ] Test Hello World program compilation and execution
+- [ ] Test scientific computation programs
+- [ ] Test array manipulation programs
+- [ ] Test modular programs with multiple files
+- [ ] Test I/O intensive programs
+- [ ] Test numerical computation accuracy
+- [ ] Test performance against gfortran
+
+**GREEN Implementation:**
+- [ ] Create comprehensive integration test suite
+- [ ] Validate against reference Fortran programs
+- [ ] Test compilation of real-world Fortran code
+- [ ] Benchmark performance vs other compilers
+
+**REFACTOR:**
+- [ ] Optimize overall compilation performance
+- [ ] Add comprehensive error reporting
+- [ ] Implement debugging support
+
+## Epic 10: Production Readiness
+
+### 10.1 Command Line Interface [8 story points]
+**RED Tests:**
+- [ ] Test command line argument parsing
+- [ ] Test multiple input file handling
+- [ ] Test output file specification
+- [ ] Test compilation flags and options
+
+**GREEN Implementation:**
+- [ ] Create complete CLI interface
+- [ ] Implement file handling and processing
+- [ ] Add compilation option support
+- [ ] Create user-friendly error messages
+
+**REFACTOR:**
+- [ ] Add advanced CLI features
+- [ ] Implement configuration file support
+- [ ] Add progress reporting
+
+### 10.2 Error Handling and Diagnostics [13 story points]
+**RED Tests:**
+- [ ] Test syntax error reporting
+- [ ] Test semantic error detection
+- [ ] Test runtime error handling
+- [ ] Test warning generation
+
+**GREEN Implementation:**
+- [ ] Implement comprehensive error detection
+- [ ] Create clear diagnostic messages
+- [ ] Add source location tracking
+- [ ] Generate helpful error suggestions
+
+**REFACTOR:**
+- [ ] Optimize error reporting performance
+- [ ] Add IDE integration features
+- [ ] Implement advanced diagnostics
+
+### 10.3 Documentation and Distribution [8 story points]
+**Tasks:**
+- [ ] Create user manual and installation guide
+- [ ] Document command line interface
+- [ ] Create example programs and tutorials
+- [ ] Set up binary distribution
+- [ ] Create release process
+
+## Updated Prioritization
 
 ### Phase 1 (Weeks 1-2): Foundation
 1. Epic 1.1: Basic C Bindings Module
@@ -481,14 +707,39 @@ Tasks are organized by epic and follow a strict RED/GREEN/REFACTOR test-driven d
 3. Epic 7.2: Documentation
 4. Epic 7.3: CI/CD Integration
 
+### Phase 7 (Weeks 12-16): Real Compiler Implementation
+1. Epic 8.1: Replace MLIR C API Stubs
+2. Epic 8.2: Real Frontend Integration
+3. Epic 8.3: Real HLFIR/FIR Generation
+4. Epic 8.4: Real Lowering Pipeline
+
+### Phase 8 (Weeks 17-20): Complete Compiler
+1. Epic 9.1: Executable Generation
+2. Epic 9.2: Complete Fortran Language Support
+3. Epic 9.3: End-to-End Integration Testing
+
+### Phase 9 (Weeks 21-22): Production Readiness
+1. Epic 10.1: Command Line Interface
+2. Epic 10.2: Error Handling and Diagnostics
+3. Epic 10.3: Documentation and Distribution
+
 ## Success Metrics
 
+### Infrastructure Complete (✅ DONE):
 - All existing tests pass with C API implementation
 - No memory leaks detected by valgrind
 - Compilation time improved by >20%
 - Code coverage >90%
 - Zero text-based MLIR generation remaining
 
+### Compiler Complete (🎯 TARGET):
+- **Can compile Fortran hello world to executable**
+- **Generated executables run correctly**
+- **Supports core Fortran language features**
+- **Performance comparable to other Fortran compilers**
+- **Comprehensive error reporting and diagnostics**
+- **Complete CLI interface matching gfortran usage patterns**
+
 ## Notes
 
 - Each task should start with failing tests (RED)