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session 17f09f89 · workflow wf_54002329
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delegated task
CONTEXT — FreeCAD is being ported to WebAssembly (emscripten). Toolchain facts you MUST assume: - Emscripten 4.0.12 (clang/LLVM 22), Binaryen v123, at
▸ Magik
CONTEXT — FreeCAD is being ported to WebAssembly (emscripten). Toolchain facts you MUST assume: - Emscripten 4.0.12 (clang/LLVM 22), Binaryen v123, at /opt/toolchains/emsdk. - Native wasm exceptions (exnref): compile with -fwasm-exceptions -sWASM_LEGACY_EXCEPTIONS=0. NO legacy asyncify-EH for new TUs. - NO pthreads/std::thread (single-threaded wasm build). NO real sockets. Filesystem is emscripten MEMFS. - No subprocess/popen/system (external solvers like ccx/calculix, gmsh are NOT available at runtime). - The build already ships OCCT, Qt6 (widgets), Python 3.14, PySide6, and many FreeCAD Mods (Part, Mesh, Draft, BIM, CAM, Import, etc.). Mesh module was built WITHOUT SMESH (uses OCCT mesher). - FreeCAD source root: /home/magik6k/lcad-wasm/freecad-port/FreeCAD - GOAL: load the example file data/examples/FEMExample.FCStd in the browser. Its objects are: Fem::FemAnalysis(3), Fem::ConstraintForce/Fixed/Displacement, Fem::FemSolverObjectPython(3), Fem::FemMeshObjectPython(3), Fem::FemMeshShapeBaseObjectPython(3), Fem::FemResultObjectPython(3), Fem::FemPostPipeline(3), Fem::FemPostWarpVectorFilter(3), Fem::FeaturePython(2), App::MaterialObjectPython(3), Part::Box/Plane/Line, App::TextDocument, App::DocumentObjectGroup. - Restore currently fails: "No module named 'Fem'" (C++ Fem module not built, BUILD_FEM=OFF) AND a security block in src/App/PropertyPythonObject.cpp isAllowedModule() blocks 'femobjects.material_common'. - KEY: src/Mod/Fem/CMakeLists.txt gates all VTK behind BUILD_FEM_VTK (adds -DFC_USE_VTK). FemPost*/VTKExtensions are VTK-only. You have Read/Grep/Glob/Bash (read-only intent — do NOT modify files, do NOT run long builds; quick greps/find are fine). Return ONLY the requested structured fields. Be concrete: cite exact files, CMake option names, #ifdef guards, class names. YOUR AREA: Can the C++ Fem module build with BUILD_FEM=ON but BUILD_FEM_VTK=OFF, and what of the FEMExample restores in that config? Investigate: 1. Read src/Mod/Fem/CMakeLists.txt fully — what sources are gated by BUILD_FEM_VTK vs always-compiled? List the FemPost*/PropertyPostDataObject/VTKExtensions files (VTK-only) vs FemAnalysis/FemConstraint*/FemSolverObject/FemMesh/FemResultObject (core). 2. grep src/Mod/Fem/App for '#ifdef FC_USE_VTK' — does any CORE class (FemAnalysis, FemMesh, FemResultObject, constraints, solver) have a hard VTK dependency, or is it cleanly ifdef'd to the post-processing? 3. Which of the example's object types (Fem::FemAnalysis, ConstraintForce/Fixed/Displacement, FemSolverObjectPython, FemMeshObjectPython, FemMeshShapeBaseObjectPython, FemResultObjectPython, FemPostPipeline, FemPostWarpVectorFilter) are registered/initFreeCADType'd only under FC_USE_VTK? (Look at AppFem.cpp / the module init.) If FemPostPipeline is VTK-gated, restoring it fails per-object — does the doc still open? 4. What Python is in src/Mod/Fem (App-level femobjects/, feminout/, etc.)? Which Python packages must be PACKAGED for restore (femobjects.material_common etc.)? 5. Does the Fem Gui module need to build, or can we ship App-only Fem (like a headless data load)? What's the minimal target list? Answer: exact CMake config (BUILD_FEM=ON, BUILD_FEM_VTK=?, BUILD_FEM_NETGEN=?) and which example objects survive restore in that config.
Fable
thinking
I'm looking into the FEM module's build setup by examining the CMakeLists.txt file and searching for relevant configuration patterns.
Fable
I'll investigate the FEM module build configuration. Let me start by reading the key files.
Fable
⚙ Read {"file_path": "/home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/Mod/Fem/CMakeLists.txt"}
tool result
1	
2	if(BUILD_FEM_VTK)
3	    add_definitions(-DFC_USE_VTK)
4	
5	    # we may use VTK but do not have the python wrappers available
6	    if(BUILD_FEM_VTK_PYTHON)
7	        add_definitions(-DFC_USE_VTK_PYTHON)
8	    endif(BUILD_FEM_VTK_PYTHON)
9	
10	endif(BUILD_FEM_VTK)
11	
12	
13	# suppress warnings from smesh
14	if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_COMPILER_IS_CLANGXX)
15	    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-overloaded-virtual")
16	endif()
17	
18	
19	# ******************************  …[truncated]
Fable
⚙ Bash {"command": "grep -rn \"FC_USE_VTK\" /home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/Mod/Fem/App/ | head -100", "description": "Find FC_USE_VTK guards in Fem App"}
tool result
/home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/Mod/Fem/App/AppFem.cpp:65:#ifdef FC_USE_VTK
/home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/Mod/Fem/App/AppFem.cpp:196:#ifdef FC_USE_VTK
/home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/Mod/Fem/App/FemPostFilterPyImp.cpp:35:#ifdef FC_USE_VTK_PYTHON
/home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/Mod/Fem/App/FemPostFilterPyImp.cpp:55:#ifdef FC_USE_VTK_PYTHON
/home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/Mod/Fem/App/FemPostFilterPyImp.cpp:121:#  …[truncated]
Fable
thinking
I need to check the App/CMakeLists.txt file to find the actual C++ source list and look at the AppFem.cpp module initialization.
Fable
Now let me read the App/CMakeLists.txt for the actual C++ sources, and the module init file.
Fable
⚙ Read {"file_path": "/home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/Mod/Fem/App/CMakeLists.txt"}
tool result
1	
2	# Many warnings caused by vtk
3	if(CMAKE_COMPILER_IS_CLANGXX)
4	    add_compile_options(-Wno-pedantic) # needed for vtk headers
5	    if (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 4.0)
6	        add_compile_options(-Wno-inconsistent-missing-override)
7	    endif()
8	elseif(CMAKE_COMPILER_IS_GNUCXX)
9	    add_compile_options(-Wno-pedantic) # needed for vtk headers
10	endif()
11	
12	
13	if(BUILD_FEM_NETGEN)
14	    add_definitions(-DFCWithNetgen ${NETGEN_DEFINITIONS})
15	endif(BUILD_FEM_NETGE  …[truncated]
Fable
⚙ Read {"file_path": "/home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/Mod/Fem/App/AppFem.cpp"}
tool result
1	/***************************************************************************
2	 *   Copyright (c) 2023 Peter McB                                          *
3	 *   Copyright (c) 2013 Jürgen Riegel (FreeCAD@juergen-riegel.net)         *
4	 *                                                                         *
5	 *   This file is part of the FreeCAD CAx development system.              *
6	 *                                                                         *
7	 *   This library is fre  …[truncated]
Fable
thinking
I'm seeing that certain FEM types like FemPostPipeline and FemPostWarpVectorFilter are only registered when the VTK build flag is enabled, so they won't be available if BUILD_FEM_VTK is turned off. Meanwhile, core types like FemAnalysis and FeaturePython are always registered regardless of build configuration. FeaturePython is also core and registered at line 138. So the VTK-only objects are FemPostPipeline and FemPostWarpVectorFilter — six objects total that won't be registered. I'm verifying the class name mappings are correct and checking whether FemMesh.cpp and the constraint classes compile without VTK by looking at their ifdef guards. I also need to understand how FreeCAD's document re  …
Fable
This is very informative. Now let me verify the SMESH dependency (critical) and the FemMesh/FemResultObject/netgen VTK-independence.
Fable
⚙ Bash {"command": "cd /home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/Mod/Fem/App\necho \"=== FemMesh.h includes (SMESH?) ===\"\ngrep -n \"include\" FemMesh.h | head -40\necho \"\"\necho \"=== FemMesh.h class member type ===\"\ngrep -n \"SMESH\\…
tool result
=== FemMesh.h includes (SMESH?) ===
25:#include <list>
26:#include <memory>
27:#include <vector>
29:#include <SMDSAbs_ElementType.hxx>
30:#include <SMESH_Version.h>
32:#include <App/ComplexGeoData.h>
33:#include <Base/Quantity.h>
34:#include <Mod/Fem/FemGlobal.h>

=== FemMesh.h class member type ===
29:#include <SMDSAbs_ElementType.hxx>
30:#include <SMESH_Version.h>
37:class SMESH_Gen;
38:class SMESH_Mesh;
39:class SMESH_Hypothesis;
78:using SMESH_HypothesisPtr = std::shared_ptr<SMESH_Hypothesis  …[truncated]
Fable
⚙ Bash {"command": "cd /home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/Mod/Fem/App\necho \"=== FemResultObject.h includes ===\"\ngrep -n \"include\\|vtk\\|VTK\\|SMESH\" FemResultObject.h | head\necho \"\"\necho \"=== FemMeshShapeNetgenObject.cpp …
tool result
=== FemResultObject.h includes ===
25:#include <App/DocumentObject.h>
26:#include <App/FeaturePython.h>
27:#include <Mod/Fem/FemGlobal.h>

=== FemMeshShapeNetgenObject.cpp netgen guards ===
29:#ifdef FCWithNetgen
30:# include <NETGENPlugin_Hypothesis.hxx>
31:# include <NETGENPlugin_Mesher.hxx>
32:#endif
39:#include "FemMeshShapeNetgenObject.h"
45:PROPERTY_SOURCE(Fem::FemMeshShapeNetgenObject, Fem::FemMeshShapeBaseObject)
50:FemMeshShapeNetgenObject::FemMeshShapeNetgenObject()
81:FemMeshShapeNetg  …[truncated]
Fable
thinking
I'm realizing FemMesh.h has a hard dependency on SMESH through its member variable and includes, which means the C++ Fem module can't be built without SMESH even though the Mesh module itself was constructed without it. This is a critical blocker for the build process.
Fable
Critical finding: FemMesh.h hard-depends on SMESH (`SMESH_Mesh* myMesh` member). Let me check SMESH availability and the top-level FEM/VTK CMake option definitions.
Fable
⚙ Bash {"command": "cd /home/magik6k/lcad-wasm/freecad-port/FreeCAD\necho \"=== BUILD_FEM / BUILD_FEM_VTK / NETGEN option definitions ===\"\ngrep -rn \"BUILD_FEM\\b\\|BUILD_FEM_VTK\\|BUILD_FEM_NETGEN\\|BUILD_FEM_VTK_PYTHON\\|BUILD_SMESH\\|FREECAD_…
tool result
=== BUILD_FEM / BUILD_FEM_VTK / NETGEN option definitions ===
cMake/FreeCAD_Helpers/SetupSalomeSMESH.cmake:65:        set(BUILD_FEM_VTK ON)
cMake/FreeCAD_Helpers/SetupSalomeSMESH.cmake:71:            set(BUILD_FEM_VTK_PYTHON 1)
cMake/FreeCAD_Helpers/SetupSalomeSMESH.cmake:86:                set(BUILD_FEM_VTK OFF)
cMake/FreeCAD_Helpers/InitializeFreeCADBuildOptions.cmake:9:    option(FREECAD_USE_EXTERNAL_SMESH "Use system installed smesh instead of the bundled." OFF)
cMake/FreeCAD_Helpers/Initial  …[truncated]
Fable
⚙ Bash {"command": "cd /home/magik6k/lcad-wasm/freecad-port/FreeCAD\necho \"=== cMake options file ===\"\ngrep -rn \"BUILD_FEM\\|SMESH\\|NETGEN\\|BUILD_MESH\" cMake/FreeCAD_Helpers/InitializeFreeCADBuildOptions.cmake 2>/dev/null | head -40\necho \…
tool result
=== cMake options file ===
cMake/FreeCAD_Helpers/InitializeFreeCADBuildOptions.cmake:9:    option(FREECAD_USE_EXTERNAL_SMESH "Use system installed smesh instead of the bundled." OFF)
cMake/FreeCAD_Helpers/InitializeFreeCADBuildOptions.cmake:147:    option(BUILD_FEM "Build the FreeCAD FEM module" ON)
cMake/FreeCAD_Helpers/InitializeFreeCADBuildOptions.cmake:158:    option(BUILD_MESH "Build the FreeCAD mesh module" ON)
cMake/FreeCAD_Helpers/InitializeFreeCADBuildOptions.cmake:159:    option(BUILD_  …[truncated]
Fable
thinking
I'm finding something critical here—looking at the InitializeFreeCADBuildOptions.cmake file around lines 200-230, there's a conditional check that gates SMESH behavior based on whether EMSCRIPTEN is enabled. Specifically, when FEM or MESH_PART builds are requested and EMSCRIPTEN is not active, it enables FREECAD_USE_SMESH and BUILD_SMESH, but this logic appears to change when building for WebAssembly.

The problem is that the Fem module's CMakeLists.txt unconditionally links against SMESH libraries and FemMesh.h directly includes SMESH headers, which means Fem can't actually compile under EMSCRIPTEN without SMESH being available—but SMESH isn't being built in that configuration. I need to ex  …
Fable
Major finding — SMESH is disabled under EMSCRIPTEN. Let me read the exact CMake logic and the BUILD_FEM_VTK gating.
Fable
⚙ Read {"file_path": "/home/magik6k/lcad-wasm/freecad-port/FreeCAD/cMake/FreeCAD_Helpers/InitializeFreeCADBuildOptions.cmake", "offset": 140, "limit": 95}
tool result
140	            set(CMAKE_INSTALL_PREFIX
141	                ${CMAKE_INSTALL_PREFIX}/${PROJECT_NAME}.app/Contents)
142	            set(CMAKE_INSTALL_LIBDIR ${CMAKE_INSTALL_PREFIX}/lib )
143	        endif(FREECAD_CREATE_MAC_APP)
144	        set(CMAKE_MACOSX_RPATH TRUE )
145	    endif(APPLE)
146	
147	    option(BUILD_FEM "Build the FreeCAD FEM module" ON)
148	    option(BUILD_TEMPLATE "Build the FreeCAD template module which is only for testing purposes" OFF)
149	    option(BUILD_ADDONMGR "Build t  …[truncated]
Fable
⚙ Read {"file_path": "/home/magik6k/lcad-wasm/freecad-port/FreeCAD/cMake/FreeCAD_Helpers/SetupSalomeSMESH.cmake"}
tool result
1	macro(SetupSalomeSMESH)
2	# -------------------------------- Salome SMESH --------------------------
3	    # Salome SMESH sources are under src/3rdParty now
4	    if(FREECAD_USE_SMESH)
5	
6	        # set the internal smesh version:
7	        # see src/3rdParty/salomonemesh/CMakeLists.txt and commit https://github.com/FreeCAD/FreeCAD/commit/666a3e5 and https://forum.freecad.org/viewtopic.php?f=10&t=30838
8	        set(SMESH_VERSION_MAJOR 7)
9	        set(SMESH_VERSION_MINOR 7)
10	        set(SM  …[truncated]
Fable
thinking
I'm seeing the CMake configuration now—BUILD_FEM defaults to ON at line 147, while BUILD_FEM_VTK isn't exposed as a user option but gets set to ON inside SetupSalomeSMESH.cmake only when FREECAD_USE_SMESH is enabled.

Under EMSCRIPTEN, the whole chain breaks: FREECAD_USE_SMESH forces OFF, which means BUILD_SMESH doesn't build, the SetupSalomeSMESH macro never runs, BUILD_FEM_VTK stays unset, and critically, SMESH_Version.h never gets configured—so the header that AppFem.cpp and FemMesh.h depend on won't exist in the binary directory.

The key insight is that BUILD_FEM_VTK isn't independently toggleable through the option system; it's a derived variable set only inside the SMESH setup macro,   …
Fable
Now let me confirm the document-restore behavior for an unregistered object type (does the doc still open), and check the Python packaging security block.
Fable
⚙ Bash {"command": "cd /home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/App\necho \"=== Document::restore / addObject unknown type handling ===\"\ngrep -n \"getProducedType\\|not found\\|Cannot create\\|failed to create\\|unknown type\\|addObject(…
tool result
=== Document::restore / addObject unknown type handling ===
1217:                addObject(type.c_str(), name.c_str(), /*isNew=*/false);
1220:                Base::Console().message("Cannot create object '%s'\n", name.c_str());
1646:            // following addObject() generate the correct id for this object.
1674:                addObject(type.c_str(), obj_name, /*isNew=*/false, viewType.c_str(), partial);
1705:            Base::Console().error("Cannot create object '%s': (%s)\n", name.c_st  …[truncated]
Fable
⚙ Bash {"command": "cd /home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/App\necho \"=== isAllowedModule in PropertyPythonObject.cpp ===\"\ngrep -n \"isAllowedModule\\|femobjects\\|material_common\\|allowed\\|Fem\" PropertyPythonObject.cpp | head -…
tool result
=== isAllowedModule in PropertyPythonObject.cpp ===
77: * @brief Check whether a module import should be allowed during document restore.
87: * @return @c true if the module is allowed, @c false otherwise.
89:bool isAllowedModule(const std::string& moduleName)
150:    // Use FreeCAD.__ModDirs__ as the authoritative list of allowed module directories.
176:    // FemMigrateApp (which we will allow).  Check whether the spec's loader itself comes from a
483:                if (!isAllowedModule(  …[truncated]
Fable
thinking
I'm checking the restore behavior in that section to see whether per-object failures allow the document to still open, or if they're fatal.
Fable
Let me read the restore loop to confirm per-object vs fatal failure behavior.
Fable
⚙ Read {"file_path": "/home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/App/Document.cpp", "offset": 1655, "limit": 60}
tool result
1655	        // internal name, and the rest of the link properties will be able to
1656	        // correctly unmap the names.
1657	        auto pos = name.find('@');
1658	        std::string _obj_name;
1659	        const char* obj_name {nullptr};
1660	        if (pos != std::string::npos) {
1661	            _obj_name = name.substr(0, pos);
1662	            obj_name = _obj_name.c_str();
1663	        }
1664	        else {
1665	            obj_name = name.c_str();
1666	        }
1667	
1668	          …[truncated]
Fable
thinking
When an unknown object type is encountered, `addObject` either throws an exception or returns null, which gets caught at the per-object level with an error message, allowing the document to still open while those unregistered objects (like FemPostPipeline and FemPostWarpVectorFilter) are skipped and the rest restore normally. But I need to verify whether `addObject` actually throws or if FreeCAD handles the substitution differently.

Looking at the specific objects in the example, the core Fem types like FemAnalysis, the constraint objects, and the Python-based solvers and mesh objects are all registered in the core module and survive the restore, while the VTK-dependent post-processing obje  …
Fable
Let me confirm SMESH itself pulls VTK (SMDS built on vtkUnstructuredGrid) — this affects whether "BUILD_FEM_VTK=OFF" truly means no VTK.
Fable
⚙ Bash {"command": "cd /home/magik6k/lcad-wasm/freecad-port/FreeCAD/src/3rdParty/salomesmesh\necho \"=== SMDS_Mesh.hxx vtk usage ===\"\ngrep -rln \"vtkUnstructuredGrid\\|#include <vtk\\|#include \\\"vtk\" inc/ 2>/dev/null | head\necho \"\"\necho \…
tool result
=== SMDS_Mesh.hxx vtk usage ===
inc/SMDS_VtkFace.hxx
inc/SMDS_VtkEdge.hxx
inc/SMDS_Mesh.hxx
inc/SMDS_UnstructuredGrid.hxx
inc/SMDS_VtkCellIterator.hxx
inc/SMDS_MeshElement.hxx
inc/SMESH_SMDS.hxx

=== count of vtk includes in salomesmesh inc ===
19

=== SMDS_Mesh member types ===
47:#include "SMDS_UnstructuredGrid.hxx"
75:  //! actual nodes coordinates, cells definition and reverse connectivity are stored in a vtkUnstructuredGrid
76:  inline SMDS_UnstructuredGrid* getGrid() {return myGrid; }
811:  …[truncated]
Fable
thinking
SMDS_Mesh's core storage relies on `vtkUnstructuredGrid`, which means SMESH fundamentally depends on VTK's data model regardless of whether FemPost or FC_USE_VTK is enabled. This is the critical distinction for `vtk_needed`: the FemPost and FemVTKTools code can be cleanly disabled, but the underlying VTK dependency cannot.

The Fem module hard-depends on SMESH (FemMesh wraps SMESH_Mesh), and SMESH's SMDS hard-depends on VTK's data-model subset (vtkCommonCore and vtkCommonDataModel at minimum). So even with BUILD_FEM_VTK=OFF, a buildable Fem module still needs that VTK data-model subset transitively through SMESH — you can't reach zero VTK without also stripping or replacing SMESH entirely. T  …
Fable
I have a complete picture. Let me compile the findings into the structured output.
Fable
⚙ StructuredOutput {"area": "C++ Fem module build with BUILD_FEM=ON / BUILD_FEM_VTK=OFF and which FEMExample objects restore", "verdict": "The VTK post-processing layer (FC_USE_VTK) is cleanly #ifdef-gated so BUILD_FEM_VTK=OFF is fine and all core objects sur…
tool result
Structured output provided successfully