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.

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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:

   find qt-migration-legatus/qt5-before -name "pdm.idl"
   

2. Check ProjectDataManagement directories:

   ls -la Lts/Plugins/ProjectDataManagement/
   ls -la Lts/Services/ProjectDataManagement/
   

3. Check ddsfts CMakeLists.txt for IDL references:

   grep -n "pdm" Lts/DDS/FTS/CMakeLists.txt
   grep -n "IDL" Lts/DDS/FTS/CMakeLists.txt
   

4. Search for pdm references in code:

   grep -r "pdm" Lts/DDS/FTS/ --include="*.h" --include="*.cpp"
   

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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

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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

# 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:

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.

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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

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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

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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