# Qt5/C++11 → Qt6/C++17 Migration Status

**Last Updated**: 2026-08-22 12:45  
**Session**: 009-build-rti-dds-guard-fixes-comp  
**Branch**: main → `qt-migration-legatus` submodule → `feature/qt6-migration-basis-modules`

---

## 📊 Current Status

### Build Validation Summary

| Configuration | Status | Notes |
|---------------|--------|-------|
| **BUILD_RTI=OFF** | ✅ **SUCCESS** (0 errors) | Completed in previous session |
| **BUILD_RTI=ON** | ✅ **DDS Core SUCCESS** | libddsconnector.so built successfully |
| **C++ Standard** | **C++17** | Enforced due to RTI DDS 7.7.0 incompatibility with C++20+ |

### Latest Commit

- **Submodule**: `d7c8c9e6` → `feature/qt6-migration-basis-modules`
- **Main Repo**: `4340d47a` → `main`
- **Changes**: BUILD_RTI=ON DDS header includes and logger initialization fixes

---

## ✅ Completed Work

### Session 009: BUILD_RTI=ON DDS Fixes

#### Fixed Files (6 files changed, 22 insertions, 20 deletions)

1. **Lts/DDS/Generic/dynamic_data_reader.h**
   - Added `#include <rti/core/xtypes/DynamicDataImpl.hpp>`
   - Resolved incomplete type error when deleting `DynamicDataImpl*` pointers
   - Added `m_logger` member variable declaration

2. **Lts/DDS/DTS/generic_dts_impl.h**
   - Added `m_logger` member variable declaration (`LOGGER_T&`)

3. **Lts/DDS/DDSConnector/pub_sub_base.cpp**
   - Fixed logger initialization pattern
   - Changed from non-existent `NGL::getNGLLogger()` to `NGL::NGLLoggerBootstrap::getNGLRootLogger().getNGLLogger()`

4. **Lts/Common/LtsSession/lts_session_data_dds.h**
   - Added `DataPluginBase::Interface` forward declaration to both `#ifdef BUILD_RTI` and `#else` blocks
   - Ensures consistent compilation across both build configurations

5. **Lts/Common/LtsUtils/LtsUtilsCore/CMakeLists.txt**
   - Fixed include path from `/..` to `/../..` for `LtsUtilsCoreHeaderOnly` target

6. **tests/CMakeLists.txt**
   - Moved Grantlee test filtering BEFORE executable creation
   - Prevents build failures when Grantlee is disabled

#### Build Results

```
✅ BUILD_RTI=OFF: 0 errors, 0 warnings (new)
✅ BUILD_RTI=ON: DDS core components compile successfully
   - libddsconnector.so created
   - ddsconnector library links successfully
⚠️  Remaining errors in unrelated modules (pre-existing):
   - IsmDataPluginInterface: linker error -lsvcIsmCommon
   - IsmShared: linker error -lsvcIsmCommon
   - BuildingControlBsm: svctabcommon_export.h not found
```

### Session 008: BUILD_RTI=OFF Validation

- Fixed Qt6 API compatibility issues (~558 QJsonObject initializer list fixes)
- Fixed Header struct member access patterns
- Fixed BatteryState/BatteryAlarm toJson()/fromJson() methods
- Fixed UAVAction, UAVStatus, and other telegram methods
- Added missing `#include <iomanip>` to lts_coordinate.cpp
- Fixed Qt6 include paths throughout codebase
- **Result**: 0 errors, only pre-existing warnings remain

---

## 🎯 Key Technical Decisions

### C++17 Standard Enforcement

**Decision**: All build configurations enforce C++17 standard.

**Rationale**: RTI Connext DDS 7.7.0 has known header bugs with C++20/C++23 that cause compilation failures. While Qt 6.10.2 fully supports C++23, the RTI dependency is a hard blocker.

| Component | C++14 | C++17 | C++20 | C++23 |
|-----------|-------|-------|-------|-------|
| RTI Connext DDS 7.7.0 | ✅ | ✅ | ❌ | ❌ |
| Qt 6.10.2 | ✅ | ✅ | ✅ | ✅ |
| **Project Standard** | - | **✅** | - | - |

**Impact**: All CMakeLists.txt, presets, toolchains, and compiler flags unified to C++17.

### RTI DDS Integration Pattern

**Strategy**: RTI Connext DDS is treated as an optional dependency with clean separation:

1. **BUILD_RTI=OFF**: All RTI code excluded via `#ifdef BUILD_RTI` guards
2. **BUILD_RTI=ON**: RTI headers included with stable guards/stubs
3. **No vendor header patches**: RTI headers used as-is, compatibility handled in wrapper code
4. **Forward declarations**: Minimize header dependencies for faster compilation

---

## 📋 Migration Progress

### Completed Modules

| Module | Status | BUILD_RTI=OFF | BUILD_RTI=ON | Notes |
|--------|--------|---------------|--------------|-------|
| Lts/Common | ✅ Complete | ✅ | ✅ | All submodules compile |
| Lts/DDS/Core | ✅ Complete | ✅ | ✅ | DDS core infrastructure |
| Lts/DDS/DTS | ✅ Complete | ✅ | ✅ | Generic DTS implementation |
| Lts/DDS/Generic | ✅ Complete | ✅ | ✅ | Dynamic data handling |
| Lts/DDS/DDSConnector | ✅ Complete | ✅ | ✅ | Pub/sub base classes |
| Lts/DDS/Discovery | 🟡 Partial | ✅ | ⏳ | Pending full validation |
| TetraIF | 🟡 Partial | ⏳ | ⏳ | Migration in progress |
| Z-Modules | 🟡 Partial | ⏳ | ⏳ | Some submodules complete |

### Remaining Modules

- Lts/Plugins (60 submodules)
- Lts/Projects (5 submodules)
- Lts/Proxies (13 submodules)
- Lts/Services (47 submodules)
- TetraIF (completion)
- Z-Modules (completion)

---

## 🔧 Infrastructure

### Git Configuration

```
Main Repo: git@devel:lifemaps/qt6-migration-pipeline.git (main)
Submodule: git@devel:lifemaps/qt-migration-legatus.git (feature/qt6-migration-basis-modules)
SSH Config: devel → gitea.life-maps.com:2223 (IdentityFile: ~/.ssh/twi-devel.gitea)
```

### Docker Build Environment

```bash
Image: migration-pipeline:ubuntu26.04
Base: Ubuntu 26.04
Qt: 6.10.2
CMake: 3.16+
C++: 17 (enforced)
RTI: Connext DDS 7.7.0
```

### Build Commands

```bash
# BUILD_RTI=OFF (default)
docker run --rm -v $(pwd):/repo migration-pipeline:ubuntu26.04 \
  cmake --build /repo/build --parallel

# BUILD_RTI=ON
docker run --rm -v $(pwd):/repo migration-pipeline:ubuntu26.04 \
  cmake --build /repo/build-rti --parallel
```

---

## ⏭️ Next Steps

### Immediate (Next 4 hours)

1. ⏳ **Resolve non-DDS build issues**
   - IsmDataPluginInterface: Fix -lsvcIsmCommon linker dependency
   - IsmShared: Fix -lsvcIsmCommon linker dependency
   - BuildingControlBsm: Fix svctabcommon_export.h include path

2. ⏳ **Complete Lts/DDS module validation**
   - Build and test remaining DDS submodules
   - Verify integration with Qt6 event loop

3. ⏳ **Update MIGRATION_STATUS.md**
   - Auto-commit every 4 hours or at milestones
   - Track build status and blockers

### Short-term (This week)

4. ⏳ **Resume Lts module migration**
   - Lts/Plugins: Prioritize core functionality submodules
   - Lts/Proxies: Complete TrainingAreaBase and related modules
   - Lts/Services: Address InfrastructureManagement dependencies

5. ⏳ **TetraIF completion**
   - Finish Qt6 migration
   - Validate with existing tests

6. ⏳ **Z-Modules completion**
   - Identify remaining unmigrated submodules
   - Complete migration and validation

### Medium-term (Next 2 weeks)

7. ⏳ **Full build validation**
   - Complete BUILD_RTI=ON with all modules
   - Integration testing with RTI DDS

8. ⏳ **CI/CD pipeline**
   - Validate GitHub Actions workflow
   - Ensure submodule checkout works correctly
   - Test artifact generation

---

## 📝 Auto-Update Policy

This document is automatically updated:
- **Every 4 hours** during active migration work
- **At each milestone** (successful build, module completion, blocker resolution)
- **On every commit** to main branch or submodule

**Automation**: Manual updates committed with migration work until automation script is implemented.

---

## 📞 Contact & References

- **Repository**: `lifemaps/qt6-migration-pipeline`
- **Submodule**: `lifemaps/qt-migration-legatus`
- **Branch**: `feature/qt6-migration-basis-modules`
- **Session Log**: Checkpoints 001-009 in `.git/` directory
- **Migration Scripts**: `./migration/`, `./final-migration/`

---

**Generated**: 2026-08-22 12:45  
**Session**: 009-build-rti-dds-guard-fixes-comp  
**Status**: BUILD_RTI=ON DDS Core ✅ | Non-DDS Issues ⏳