# BUILD_RTI=ON Validation Report

## Executive Summary

The Lts/DDS module has been successfully migrated to Qt6 with RTI Connext DDS 7.7 integration enabled (`BUILD_RTI=ON`). All core DDS targets compile and link successfully in the Docker build environment.

**Date:** 2026-09-06  
**Build Environment:** Ubuntu 26.04, Qt 6.10.2, RTI Connext DDS 7.7  
**C++ Standard:** C++17 (required for RTI 7.7 compatibility)

---

## Build Results

### Successfully Built Targets

| Target | Library | Size | Status |
|--------|---------|------|--------|
| ddscore | libddscore.so | 4.3M | ✅ |
| ddsftccore | libddsftccore.so | 550K | ✅ |
| ddsQoS | libddsQoS.so | 1.6M | ✅ |
| ddsconnector | libddsconnector.so | 4.4M | ✅ |
| ddsgen | libddsgen.so | 3.1M | ✅ |

### Build Configuration

```bash
# Docker image
legatus-qt6-build:latest

# CMake configuration
cmake -DBUILD_RTI=ON -DCMAKE_CXX_STANDARD=17 ..

# RTI License
/home/torsten/swy/sandbox/rti_license.dat (empty development license)
```

---

## Issues Resolved

### 1. Qt5 API Deprecations (Qt6 Migration)

**Problem:** `QByteArray::number()` is deprecated/removed in Qt6

**Solution:** Replace with `QString::number(value).toLatin1()`

**Files Modified:**
- `Lts/DDS/FTC/generic_ftc_impl.h` (2 occurrences)
- `Lts/DDS/FTS/connext.h` (1 occurrence)
- `Lts/DDS/Routing/routing_plugin.h` (1 occurrence)
- `Lts/DDS/Generic/generic_data_reader.h` (1 occurrence)

### 2. C++ Standard Compatibility

**Problem:** RTI 7.7 requires C++17, not C++23

**Solution:** Changed `CMAKE_CXX_STANDARD` from 23 to 17 in parent CMakeLists.txt (line 99)

### 3. AUTOMOC vs Codegen Timing

**Problem:** AUTOMOC runs at configure time, but codegen macros run at build time. Generated files like `core_dtc.h` don't exist when moc tries to process them.

**Solution:** 
```cmake
# Skip AUTOMOC for generated files
set_source_files_properties(${CMAKE_CURRENT_BINARY_DIR}/core_dtc.h SKIP_AUTOMOC ON)

# Manually invoke QT6_WRAP_CPP with proper dependencies
qt6_wrap_cpp(NGLEXTRA_SOURCES ${CMAKE_CURRENT_BINARY_DIR}/core_dtc.h
    OPTIONS -I${CMAKE_SOURCE_DIR}/include -I${CMAKE_SOURCE_DIR}/Lts)
```

### 4. RTI Library Path Resolution

**Problem:** RTI libraries exist on host at `/home/torsten/swy/sandbox/external/rti_connext_dds-7.7.0/lib/x64Linux4gcc8.5.0/` but must be mounted to `/workspace/external/rti_connext_dds-7.7.0` in container.

**Solution:** Updated `cmake/FindRTI.cmake` to search `${CMAKE_SOURCE_DIR}/../../../external/` path

### 5. PartitionType Enum Conversion

**Problem:** Both `LtsSession::PartitionType` and `IDL::PartitionType` exist with different naming conventions (SCREAMING_SNAKE_CASE vs PascalCase)

**Solution:** Added conversion functions in `lts_session_data_dds.h/.cpp`:
```cpp
IDL::PartitionType toIdlPartitionType(PartitionType type);
PartitionType toPartitionType(IDL::PartitionType type);
```

### 6. Missing Fetcher Class

**Problem:** Legacy version has `Fetcher` inline helper class and `m_guiPluginInterfaces` member that were missing from migrated version.

**Solution:** Added to `lts_session_data_dds.h`:
- `m_guiPluginInterfaces` member variable
- `getForeignGuiInterface<S>()` template method
- `Fetcher` class inline definition

### 7. Missing generic_dtc_impl.h

**Problem:** File was missing from migrated version's `include/DDS/DTC/` directory, causing incomplete type errors.

**Solution:** Copied from legacy version to migrated version.

### 8. RTI Header Conflicts

**Problem:** `generic_dtc.h` had stub definitions for `LoanedSamples` and `SampleInfo` that conflicted with RTI's actual headers.

**Solution:** Added conditional compilation guards:
```cpp
#ifdef BUILD_RTI
    #include <dds/sub/LoanedSamples.hpp>
    #include <dds/sub/SampleInfo.hpp>
#else
    // Stub definitions for BUILD_RTI=OFF
#endif
```

### 9. DataModification Enum Conflict

**Problem:** Stub enum in `generic_dtc.h` (Added, Modified, Removed) conflicted with `LtsUtilsCore/data_modification_enum.h` (eAdded, eModified, eRemoved).

**Solution:** Only define stub enum when `BUILD_RTI=OFF`.

---

## File Changes Summary

| File | Change Type | Description |
|------|-------------|-------------|
| `CMakeLists.txt` | Modified | C++17 standard, RTI path resolution |
| `cmake/FindRTI.cmake` | Modified | Added external/ directory search path |
| `Lts/DDS/Core/CMakeLists.txt` | Modified | AUTOMOC skip, manual QT6_WRAP_CPP |
| `Lts/DDS/QosProfile/CMakeLists.txt` | Modified | Fixed include path |
| `Lts/DDS/DDSConnector/CMakeLists.txt` | Modified | INTERFACE to PUBLIC include |
| `Lts/Common/LtsSession/CMakeLists.txt` | Modified | Added ddsQoS link, fixed include path |
| `Lts/Common/LtsSession/lts_session_data_dds.h` | Modified | Added members, Fetcher class, conversion functions |
| `Lts/Common/LtsSession/lts_session_data_dds.cpp` | Modified | Implemented conversion functions |
| `Lts/DDS/FTC/generic_ftc_impl.h` | Modified | Qt5 API fixes |
| `Lts/DDS/FTS/connext.h` | Modified | Qt5 API fix |
| `Lts/DDS/Routing/routing_plugin.h` | Modified | Qt5 API fix |
| `Lts/DDS/Generic/generic_data_reader.h` | Modified | Qt5 API fix |
| `include/DDS/Core/core.hpp` | Renamed | → core.hpp.stub (was blocking generated file) |
| `include/DDS/Core/core_dtc_types.h` | Renamed | → core_dtc_types.h.stub (was blocking generated files) |
| `include/DDS/DTC/generic_dtc_impl.h` | Added | Copied from legacy |
| `include/DDS/DTC/generic_dtc.h` | Modified | Conditional RTI headers, enum fix |
| `rti_license.dat` | Created | Empty development license |

---

## Known Issues (Out of Scope)

### 1. ddsfts Build Failure

**Status:** ❌ Not Built  
**Cause:** Missing `pdm.idl` from ProjectDataManagement module

**Details:**
The `ddsfts` target depends on IDL files from the ProjectDataManagement module which is not part of the DDS migration scope. The build fails with:
```
File pdm.idl not found
```

**Resolution Path:**
- Requires ProjectDataManagement module to be migrated first
- Or create stub pdm.idl for build purposes only

### 2. ProjectDataManagement Module

**Location:** 
- `Lts/Plugins/ProjectDataManagement/`
- `Lts/Services/ProjectDataManagement/`

**Status:** Not migrated  
**Dependencies:** Required by ddsfts and other Project-related plugins

**Known Issues:**
- pdm.idl not available for DDS codegen
- Potential Qt5 API usage (unverified)
- CMake configuration not updated for Qt6

### 3. Project Plugin Qt6 Migration Issues

**Affected Plugins:**
- ProjectEtsPlugin
- ProjectAhtcPlugin
- ProjectPluginBase
- Other Project* plugins

**Error Type:** `moc "Undefined interface"` errors  
**Status:** Pre-existing issues, unrelated to DDS/RTI migration

---

## Validation Checklist

- [x] RTI license file created and accessible
- [x] RTI libraries mounted and discoverable by CMake
- [x] C++17 standard enforced
- [x] Qt5 API deprecations resolved
- [x] Code generation runs during build (verified via nddsgen warnings in output)
- [x] No stub/placeholder files for generated code
- [x] ddscore builds successfully
- [x] ddsftccore builds successfully
- [x] ddsQoS builds successfully
- [x] ddsconnector builds successfully
- [x] ddsgen builds successfully
- [ ] ddsfts builds (blocked by pdm.idl)
- [ ] ProjectDataManagement migrated (out of scope)
- [ ] Project plugins Qt6 migration (out of scope)

---

## Recommendations

1. **For ddsfts:** Coordinate with ProjectDataManagement team to migrate pdm.idl or create temporary stub
2. **For Project Plugins:** Address Qt6 migration issues in parallel workstream
3. **For Future RTI Updates:** Document RTI version compatibility matrix (RTI 7.7 → C++17)
4. **For Codegen:** Consider caching generated files to speed up clean builds

---

## Contact

For questions about this migration, refer to:
- Migration prompt: `./prompts/combined-migration-subfolder-dds-rti-compact.prompt.md`
- Build documentation: `./app/Dockerfile`
- RTI configuration: `./cmake/FindRTI.cmake`