Qmake uses toplevel or topbuilddir

sketch

When working in a complex environment based on qmake When a project has multiple subdirectories , Have a pair of top_srcdir and top_builddir Variables are very convenient , for instance :

• INCLUDEPATH = $$top_srcdir/include
• LIBS= -L$$top_builddir/lib -lmylib
• include($$top_srcdir/path/to /config.pri)
  qmake Provide out of the box variables PWD and OUT_PWD, But these variables point to the current .pro / .pri Document and its construction specification , This means that when they return subdirectories