Summary

Remove deprecated individual Result headers that were consolidated in #255. Internal usage analysis confirms zero consumers of deprecated headers, making this safe for immediate removal.

Parent Issue

• [EPIC] C++20 Module Migration - Cross-System Preparation #256 - [EPIC] C++20 Module Migration - Cross-System Preparation

Background

Issue #255 consolidated 9 Result headers into 3 logical groups. The original individual headers were kept with deprecation warnings for backward compatibility. Analysis shows:

• Internal usage of deprecated headers: 0
• All internal code migrated to consolidated headers
• Deprecation target: v1.0.0

Files to Remove

Deprecated Result Headers (8 files)

include/kcenon/common/patterns/result/
├── fwd.h                    # → Use core.h
├── error_info.h             # → Use core.h
├── result_core.h            # → Use core.h
├── optional.h               # → Use core.h
├── result_funcs.h           # → Use utilities.h
├── exception_conversion.h   # → Use utilities.h
├── result_macros.h          # → Use utilities.h
└── error_codes_compat.h     # → Use compat.h

Also Consider

include/kcenon/common/patterns/
└── result_helpers.h         # Check if consolidated into utilities.h

Current Deprecation Warnings

Each deprecated header contains:

#pragma once
#pragma message("result/fwd.h is deprecated. Use result/core.h. Will be removed in v1.0.0")
#include "core.h"

Tasks

• Verify zero external ecosystem usage (thread_system, container_system, etc.)
• Remove result/fwd.h
• Remove result/error_info.h
• Remove result/result_core.h
• Remove result/optional.h
• Remove result/result_funcs.h
• Remove result/exception_conversion.h
• Remove result/result_macros.h
• Remove result/error_codes_compat.h
• Check and remove result_helpers.h if redundant
• Update CMakeLists.txt (remove from install targets)
• Update documentation
• Run full test suite

Verification Steps

1. Search ecosystem for deprecated header usage:

   grep -r "result/fwd.h\|result/error_info.h\|result/result_core.h" ../

2. Build all tests
3. Run integration tests
4. Verify downstream systems still compile

Acceptance Criteria

• All deprecated headers removed
• No compilation errors in common_system
• No compilation errors in downstream systems
• All tests pass
• Documentation updated
• CMake install targets updated

Migration Impact

Related

• [REFACTOR] Consolidate Result<T> headers from 9 to 3 - C++20 Module preparation #255 - Result Header Consolidation (completed)
• [EPIC] C++20 Module Migration - Cross-System Preparation #256 - C++20 Module Migration Epic
• [MODULE] Create C++20 module files for common_system - Phase 2 #265 - Create C++20 module files