There was a strange error during compilation when including the Windows API header file before 'ui_mainwindow.h'.

[dfger]

[Christian Ehrlicher]

Please provide a minimal, compilable example of your problem. I would guess you use a variable name which is also a define in the windows headers. Nothing Qt can do about it - use another name when you found out which one is causing the problem.

[dfger]

@Christian-Ehrlicher

The reason has been identified, setting PushButton Icon to 'DocumentProperties' will trigger this issue.

[JonB]

@dfger
dwrite.h must be an MSVC header file, including definitions for its own DocumentProperties and it will have a line like

#define DocumentProperties DocumentPropertiesW

which MSVC uses for the "wide character" version. Meanwhile you are trying to use some Qt-defined symbol of DocumentProperties for the theme. And these clash.

Try one of the following:

• Move the #include <dwrite.h> line to after the #include ui_mainwindow.h. That may, or may not, be enough to make it work.

• If you do not need the MSVC DocumentProperties define append line of #undef DocumentProperties immediately after the #include <dwrite.h>.

• Move the #include <dwrite.h> line, and anything which uses its content, into another C++ source file of yours, where there is no UI stuff requiring the theme.

[dfger]

@JonB Thank you for your suggestion. It is feasible for me to move it after "ui_mainwindow.h"