qmake processes my pro-file three times instead of one

Question

This is entire pro file:

message("This message should appeare only once!!!")
CONFIG += qt
SOURCES += src/main.cpp

I invoke qmake in the following way:

set QMAKESPEC=win32-msvc2008
set QTDIR=c:\Qt\4.8.4_vs2008\

call "C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\vcvarsall.bat" x86
call "%QTDIR%\bin\qmake.exe" -tp vc Server.pro

And I get following output:

Setting environment for using Microsoft Visual Studio 2008 x86 tools.

Project MESSAGE: This message should be appeared only once!!!

Project MESSAGE: This message should be appeared only once!!!

Project MESSAGE: This message should be appeared only once!!!

Why did the message print THREE times?

Answer 1

Actually, the condition "build_pass" is always true except the first time qmake parses your .pro file, so the following works:

!build_pass:message("This message should appear only once")

I made a helper function, which works fine in my project:

defineTest(print) {
  !build_pass:message($$1)
}

print("This message should appear only once")