If QCoreApplication is passed a negative argc, it converts this to an unsigned integer and tries to allocate the memory unchecked. In the case of win/32, it tries to allocate off 4G when passed -1, and fails trying to do so.

[I] MAF: Memory allocation failure of -1 bytes in new(UINT)

Allocation location
new(UINT) [C:\DEPOT\QT5\QTBASE\BIN\QTCORED5.DLL]
<>=(UINT) [f:\dd\vctools\crt_bld\self_x86\crt\src\newaop.cpp:7]
QCoreApplicationPrivate::QCoreApplicationPrivate(int&,char * *,UINT) [c:\depot\qt5\qtbase\src\corelib\kernel\qcoreapplication.cpp:293]
, in_exec(false)
, aboutToQuitEmitted(false)
, threadData_clean(false)
=> {
app_compile_version = flags & 0xffffff;
static const char *const empty = "";
if (argc == 0 || argv == 0) {
QGuiApplicationPrivate::QGuiApplicationPrivate(int&,char * *,int) [c:\depot\qt5\qtbase\src\gui\kernel\qguiapplication.cpp:379]
QApplicationPrivate::QApplicationPrivate(int&,char * *,Type::QCoreApplication,int) [c:\depot\qt5\qtbase\src\widgets\kernel\qapplication.cpp:161]
QApplication::QApplication(int&,char * *,int) [c:\depot\qt5\qtbase\src\widgets\kernel\qapplication.cpp:555]
DumpIDL [c:\depot\qt5\qtactiveqt\src\activeqt\control\qaxserver.cpp:1127]
dumpIdl [c:\depot\qt5\qtactiveqt\src\tools\idc\main.cpp:176]
runIdc(int,char * *) [c:\depot\qt5\qtactiveqt\src\tools\idc\main.cpp:292]
main [c:\depot\qt5\qtactiveqt\src\tools\idc\main.cpp:334]

please note: the failure is in the code:
#ifdef Q_OS_WIN
, origArgc(aargc)
, origArgv(new char *[aargc])
#endif