qt-migration-legatus/qt6-after/qt6-migrated-legatus/KNOWN_ISSUES_DDSFTS_PROJECTDATAMANAGEMENT.md

# Known Issues - ddsfts and ProjectDataManagement

## Overview

This document tracks known issues blocking the complete migration of the DDS module, specifically the ddsfts target and its dependency on ProjectDataManagement.

---

## Issue #1: ddsfts Build Failure

### Status
❌ **Blocked** - Cannot build until pdm.idl is available

### Error Message
```
File pdm.idl not found
[Error from nddsgen codegen step]
```

### Root Cause
The `ddsfts` target depends on IDL files from the ProjectDataManagement module. The file `pdm.idl` is not present in the migrated codebase because:
1. ProjectDataManagement module has not been migrated yet
2. The IDL file may not exist in the expected location
3. CMake IDL search paths may not be configured correctly

### Impact
- ddsfts library cannot be built
- Any code depending on ddsfts is blocked
- Complete DDS module validation is incomplete

### Location
- **Target:** `Lts/DDS/FTS/CMakeLists.txt`
- **Dependency:** `Lts/Plugins/ProjectDataManagement/` or `Lts/Services/ProjectDataManagement/`
- **Missing File:** `pdm.idl`

### Resolution Options

#### Option A: Migrate ProjectDataManagement First (Recommended)
1. Migrate ProjectDataManagement module to Qt6
2. Ensure pdm.idl is in correct location
3. Update ddsfts CMakeLists.txt to reference correct IDL path
4. Rebuild ddsfts

**Pros:** Proper long-term solution  
**Cons:** Requires additional migration work

#### Option B: Create Stub pdm.idl (Temporary)
1. Create minimal pdm.idl stub in `include/DDS/FTS/` or similar
2. Define only the types needed by ddsfts
3. Document as temporary workaround
4. Replace with real pdm.idl after ProjectDataManagement migration

**Pros:** Unblocks ddsfts build quickly  
**Cons:** May not match actual IDL, could cause runtime issues

#### Option C: Exclude ddsfts from Build (Workaround)
1. Wrap ddsfts in additional CMake conditional
2. Build other DDS targets without ddsfts
3. Document ddsfts as temporarily unavailable

**Pros:** Allows other DDS targets to be used  
**Cons:** Incomplete DDS module

### Investigation Steps

1. **Search for pdm.idl in legacy version:**
   ```bash
   find qt-migration-legatus/qt5-before -name "pdm.idl"
   ```

2. **Check ProjectDataManagement directories:**
   ```bash
   ls -la Lts/Plugins/ProjectDataManagement/
   ls -la Lts/Services/ProjectDataManagement/
   ```

3. **Check ddsfts CMakeLists.txt for IDL references:**
   ```bash
   grep -n "pdm" Lts/DDS/FTS/CMakeLists.txt
   grep -n "IDL" Lts/DDS/FTS/CMakeLists.txt
   ```

4. **Search for pdm references in code:**
   ```bash
   grep -r "pdm" Lts/DDS/FTS/ --include="*.h" --include="*.cpp"
   ```

---

## Issue #2: ProjectDataManagement Module Not Migrated

### Status
⚠️ **Not Started** - Requires full Qt6 migration

### Locations
- `Lts/Plugins/ProjectDataManagement/`
- `Lts/Services/ProjectDataManagement/`

### Known Dependencies
- ddsfts (blocks ddsfts build)
- ProjectEtsPlugin (likely depends on ProjectDataManagement)
- ProjectAhtcPlugin (likely depends on ProjectDataManagement)
- Other Project* plugins

### Migration Checklist

#### Phase 1: Assessment
- [ ] Inventory all source files (.h, .cpp)
- [ ] Inventory all IDL files (.idl)
- [ ] Review CMakeLists.txt structure
- [ ] Identify Qt5 API usage
- [ ] Identify code generation requirements

#### Phase 2: Qt6 API Migration
- [ ] Replace QByteArray::number() → QString::number().toLatin1()
- [ ] Replace QRegExp → QRegularExpression
- [ ] Replace QDesktopWidget → QScreen
- [ ] Update signal/slot syntax if needed
- [ ] Update any deprecated Qt classes

#### Phase 3: CMake Configuration
- [ ] Change find_package(Qt5...) to find_package(Qt6...)
- [ ] Add qt_standardize_properties()
- [ ] Configure KTextTemplate for IDL codegen
- [ ] Fix include paths
- [ ] Set CMAKE_CXX_STANDARD to 17

#### Phase 4: RTI Integration
- [ ] Verify BUILD_RTI compatibility
- [ ] Check for RTI header conflicts
- [ ] Test with BUILD_RTI=ON

#### Phase 5: Validation
- [ ] Build without errors
- [ ] No moc warnings
- [ ] Run unit tests if available
- [ ] Verify IDL codegen output

### Potential Issues

#### Qt5 API Usage (Expected)
Based on patterns in other modules, expect to find:
- `QByteArray::number()` - Replace with `QString::number().toLatin1()`
- `QRegExp` - Replace with `QRegularExpression`
- `QApplication::desktop()` - Replace with `QGuiApplication::primaryScreen()`

#### Code Generation
- May use KTextTemplate for IDL → C++ generation
- Check for AUTOMOC timing issues with generated files
- May need SKIP_AUTOMOC + manual QT6_WRAP_CPP pattern

#### Include Paths
- Legacy paths may reference `LtsUtils/` instead of `Lts/`
- Check all `#include` directives after migration

---

## Issue #3: Project Plugin Qt6 Migration Issues

### Status
⚠️ **Pre-existing Issues** - Unrelated to DDS/RTI migration

### Affected Plugins
- ProjectEtsPlugin
- ProjectAhtcPlugin
- ProjectPluginBase
- Project*Plugin (other Project plugins)

### Error Type
```
moc: Undefined interface
```

### Root Cause Analysis Needed
1. Check Q_PLUGIN_METADATA declarations
2. Verify Q_DECLARE_INTERFACE in interface classes
3. Check for missing Q_OBJECT macros
4. Verify AUTOMOC is enabled
5. Check for circular dependencies

### Investigation Commands
```bash
# Find all Project plugins
find Lts/Plugins -name "*Project*Plugin" -type d

# Check for Q_PLUGIN_METADATA
grep -r "Q_PLUGIN_METADATA" Lts/Plugins/Project*Plugin/ --include="*.h"

# Check for Q_DECLARE_INTERFACE
grep -r "Q_DECLARE_INTERFACE" Lts/Plugins/Project*Plugin/ --include="*.h"

# Check CMakeLists.txt for AUTOMOC
grep -r "AUTOMOC" Lts/Plugins/Project*Plugin/CMakeLists.txt
```

### Common Qt6 Plugin Issues

#### Issue: Q_PLUGIN_METADATA requires QJsonDocument
**Qt5:**
```cpp
Q_PLUGIN_METADATA(IID "com.example.PluginInterface" FILE "plugin.json")
```

**Qt6:** May require additional QJsonDocument handling

#### Issue: Interface UUID Changes
Plugin interface UUIDs must be consistent between:
- Q_DECLARE_INTERFACE declaration
- Q_PLUGIN_METADATA IID string
- Plugin loader expectations

#### Issue: Plugin Loading
Qt6 may require both Q_PLUGIN_METADATA and Q_PLUGIN_IMPORT for proper plugin loading.

---

## Resolution Priority

| Priority | Issue | Impact | Effort | Recommendation |
|----------|-------|--------|--------|----------------|
| 1 | ddsfts missing pdm.idl | High (blocks DDS) | Low-Medium | Create stub or migrate ProjectDataManagement |
| 2 | ProjectDataManagement migration | High (enables ddsfts) | High | Full migration required |
| 3 | Project plugin moc errors | Medium (plugins only) | Medium | Fix after DDS module complete |

---

## Action Items

### Immediate (Unblock ddsfts)
- [ ] Search for pdm.idl in legacy codebase
- [ ] If found, copy to migrated version
- [ ] If not found, create minimal stub
- [ ] Update ddsfts CMakeLists.txt if needed
- [ ] Rebuild ddsfts

### Short-term (Complete DDS module)
- [ ] Migrate ProjectDataManagement module
- [ ] Verify all DDS targets build with BUILD_RTI=ON
- [ ] Document any remaining issues

### Long-term (Complete Qt6 migration)
- [ ] Migrate all Project* plugins
- [ ] Fix moc "Undefined interface" errors
- [ ] Verify plugin loading at runtime
- [ ] Run full test suite

---

## References

- BUILD_RTI Validation Report: `BUILD_RTI_VALIDATION_REPORT.md`
- Migration Continuation Prompt: `DDS_RTI_MIGRATION_CONTINUATION_PROMPT.md`
- Migration Instructions: `../prompts/combined-migration-subfolder-dds-rti-compact.prompt.md`
- RTI Configuration: `../cmake/FindRTI.cmake`
- Build Environment: `../app/Dockerfile`