xtemp09

I've just compiled FreeCAD using gcc 12.3 with C++20 option on Ubuntu 22.04. If I set `CMAKE_CXX_STANDARD` to 20, it does not affect `BUILD_ENABLE_CXX_STD`. I don't know what the latter...

Perhaps, the issue is connected to [this crash](http://git.dev.opencascade.org/gitweb/?p=occt.git;a=commit;h=03275c0be165da7abe8e0044d79c10a0038a8340).

I have compiled FreeCAD with the latest OCCT 7.8.0dev, the crash reported here and [here](https://github.com/FreeCAD/FreeCAD/issues/9000) remains. ='(

@Jolbas, one ought to save the file before clicking the Fillet tool. _Refining might not work._

Well, it's my recommendation.

@drcowsley, FreeCAD is known to crash when doing fillet. I export models as STL and do fillet (and chamfer) in Blender.

I've reproduced on Ubuntu. The backtrace is somehow similar to all other crashes involving the fillet. Backtrace ```ruby * thread #1, name = 'FreeCAD', stop reason = signal SIGSEGV: address...

I cannot reproduce it on Linux and Windows. FreeCAD writes, instead of crashing: ```java 13:09:40 Unhandled unknown exception caught in GUIApplication::notify. 13:09:40 Unhandled unknown exception caught in GUIApplication::notify. 13:10:07 top_block_front_fillet:...

Yes, it seems like an OCCT bug. The crash occurs [here](https://github.com/FreeCAD/FreeCAD/blob/c726b69d7ede5b1af82407c515e14375f3358be3/src/Mod/PartDesign/App/FeatureFillet.cpp#L110-L112): ```c++ -> 110 mkFillet.Build(); 111 if (!mkFillet.IsDone()) 112 return new App::DocumentObjectExecReturn("Failed to create fillet"); ```

This is a duplicate of #8179.