I am trying to compile of source code for Window10 and by using Qt Creator 5.0.1
Based on Qt 5.15.2 (MSVC 2019, 64 bit), but I got the following errors:
C:\DEV\misc\mygit\LibreCAD\librecad\src\lib\gui\rs_graphicview.h:65: error: invalid conversion from 'int' to 'Qt::WindowType' [-fpermissive]
In file included from lib\actions\rs_preview.cpp:30:
lib/gui/rs_graphicview.h:65:59: error: invalid conversion from 'int' to 'Qt::WindowType' [-fpermissive]
RS_GraphicView(QWidget * parent = 0, Qt::WindowFlags f = 0);
Because 0 is of type (int) but Qt::WindowFlags is an enum of type (Qt::WindowType).
Thus the compiler expects this:
RS_GraphicView(QWidget * parent = 0, Qt::WindowFlags f = Qt::Widget);
Or even better:
RS_GraphicView(QWidget * parent = nullptr, Qt::WindowFlags f = Qt::Widget);
From your deleted post I've seen, that your tool chain is Qt 6.1.3 with GCC 8.1 64-bit.
Iirc our Windows build server uses Qt 5.12 with bundled 32-bit GCC (don't remember Mingw version from top off my head).
So this could evolve to an endless thread if you don't understand the compiler errors.
Qt 6 could rise issues because of removed, obsolete Qt 5 classes and methods, GCC 8 is presumably the cause for this error because it's more strict and I'm not sure if GCC 64 vs 32 bit can rise issues too.