Qmake DEFINES macro with parameter - macros

Question

I want to know how to define C++ preprocessor macro using qmake DEFINES variable. I have tried to do the following:
Project file
TEMPLATE = app
CONFIG += c++14 console
SOURCES += main.cpp
DEFINES += "TEMPORARY_UNUSED(x)=\"(void)x;\""
DEFINES += "BASE_CLASS_UNUSED(x)=\"(void)x;\""
Main.cpp file
int main() {
int hello;
TEMPORARY_UNUSED(hello)
BASE_CLASS_UNUSED(hello)
}
But this resulted in following error: [main.o] Error 2. I have no idea how macro definition (very simple by the way) could cause errors in build process.
This is macro definitions using c++'s #define. They work just as I expected
#define TEMPORARY_UNUSED(x) (void)x;
#define BASE_CLASS_UNUSED(x) (void)x;
The question is: how do I define c++ preprocessor macro using qmake DEFINES and how my macro was able to cause compilation errors.
P.S. I'm perfectly aware of Q_UNUSED macro but I prefer to have a macro that indicates not only that the variable is unused but also why it is unused.
P.S. Code that I have posted is 100% of my project, there no more files that define/redefine anything else.

Answer 1

You need to escape the parentheses and the semicolon with backslashes:
DEFINES += TEMPORARY_UNUSED\\(x\\)=\\(void\\)x\\;
Otherwise the () and the ; in the -D compiler argument will be interpreted as parts of a more complex command.
Note that the /D option of MSVC does not support function-like macro definitions. To overcome this restriction, write your preprocessor directives into a header file and include it with the /FI compiler switch.