Currently in Manjaro/Arch/Linux there's this issue:
```
/.../src/Mod/Raytracing/App/LuxProject.cpp: In member function ‘virtual App::DocumentObjectExecReturn* Raytracing::LuxProject::execute()’:
/.../src/Mod/Raytracing/App/LuxProject.cpp:85:20: error: variable ‘std::ifstream file’ has initializer but incomplete type
85 | ifstream file (fi.filePath().c_str());
| ^~
/.../src/Mod/Raytracing/App/LuxProject.cpp:89:20: error: variable ‘std::ofstream ofile’ has initializer but incomplete type
89 | ofstream ofile(tempName.c_str());
| ^~~~~~~~
```
See https://stackoverflow.com/questions/50355130/variable-stdofstream-outfile-has-initializer-but-incomplete-type.
Also edit `Precompiled.h` as compile fix
Removes the BUILD_QT5 flag and adds a new FREECAD_QT_VERSION option,
which can be set to either "Auto" (default), 5, or 6. Auto detects which
version of Qt is installed on the system and chooses it. If both version
are installed, Qt5 is used.
Note that this DOES NOT implement compiling against Qt6, it only adds
the necessary cMake infrastructure to begin work on the source code
changes that will be required.
This undoes most of the Xerces related part of the commits listed below.
The issue resolved here is that the Xerces include dir *is* set in the
CMakeLists.txt of src/Base, but it got removed from various App and Gui
dirs in src/Mod. If those now include a header from src/Base, which
itself includes xercesc, the build fails using Apple clang version 11.0.0
(clang-1100.0.33.17) on Mojave, configured using cmake 3.22.1, with
errors like the following:
In file included from .../src/Mod/Part/App/FeaturePartBoolean.cpp:34:
In file included from .../src/App/Application.h:33:
.../src/Base/Parameter.h:54:10: fatal error: 'xercesc/util/XercesDefs.hpp' file not found
#include <xercesc/util/XercesDefs.hpp>
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
Finally, a full list of the commits that introduced this spurious include
dir optimization for reference:
- Drawing: commit f4411478d106ba9f4827754a50efa53bd7767a66
- Image: commit e3476815c04c571199779bd1e444b950e6398025
- Import: commit b7b264e52c8fd97e83987c4ce42ce563170c8918
- Inspection: commit 1f64d8b1b8fcabe983c6e5e624d65766b4429ea0
- Mesh: commit 5a8fed0720d681cdbb9fedc840d2532c4f2f6042
- Part: commit 26bb65f11f4b51e5e47b65b2d6049ece10705a83
- PartDesign: commit f4e49f2aecf08f2337e84510ed019b7fa4b685a3
- Path: commit e3d9cc98577d2073297d55ffd8de28dd50f8444c
- Points: commit 09f3e867cdccd31294cced4e3c73015d3add3f4a
- Raytracing: commit 7b92dedc53f09e2ce8365408f3003e5700aebfc8
- ReverseEnginering: commit eeacc51ad0cd82e5f17d63207f78f79eb20bf9a9
- Robot: commit 4d06684cbd0328e4f43c78b5dab7e7fcebab148d
- Sketcher: commit 079125665495a08a7e2e2a4f01da406128dca625
- Spreadsheet: commit 514097954e95c04a7ec9d7e8ec1afc3aac3dd8d
- Start: commit 2ea2bb0dc393d7b8b41e9137c6d4ae40ce29719d
- Surface: commit 272268dd6c0b460ae9aeecdf371495ea26aa044d
- TechDraw: commit c70fdc3e0aa6b409626a6fa6b7266d05f3338c6d
- Test: commit 49a07b121e08e9bf3fef0f414a8da5602533592e
- Web: commit a93a23d7e4da13b2d5c37ac087b2dcf41aae197d
