How to get rid of the error when compiling the qt creator plugin?

Question

Qt Creator

XUbuntu QT Creator om created a project with a file (didn't compose anything)

DEFINES += MYPLUGIN_LIBRARY
# MyPlugin files
SOURCES += mypluginplugin. cpp
HEADERS += mypluginplugin. h \
myplugin_global. h \
mypluginconstants. h
# Qt Creator linking
## set the QTC_SOURCE environment variable to override the setting here
QTCREATOR_SOURCES = $$ ( QTC_SOURCE )
isEmpty ( QTCREATOR_SOURCES ): QTCREATOR_SOURCES =/ usr/ src / qtcreator
## set the QTC_BUILD environment variable to override the setting here
IDE_BUILD_TREE = $$ (QTC_BUILD )
isEmpty ( IDE_BUILD_TREE ): IDE_BUILD_TREE =/ tmp /
## uncomment to build plugin into user config directory
## <localappdata>/plugins/<ideversion>
##    where <localappdata> is e.g.
##    "%LOCALAPPDATA%\QtProject\qtcreator" on Windows Vista and later
##    "$XDG_DATA_HOME/data/QtProject/qtcreator" or "~/.local/share/data/QtProject/qtcreator" on Linu
##    "~/Library/Application Support/QtProject/Qt Creator" on Mac
# USE_USER_DESTDIR = yes

Gives errors:

:-1: error: cannot find -lCore
:-1: error: cannot find -lAggregation
:-1: error: cannot find -lExtensionSystem
:-1: error: cannot find -lUtils
:-1: error: collect2: error: ld returned 1 exit status

locate libAggregation
/usr/lib/i386-linux-gnu/qtcreator/libAggregation.so
/usr/lib/i386-linux-gnu/qtcreator/libAggregation.so.1
/usr/lib/i386-linux-gnu/qtcreator/libAggregation.so.1.0
/usr/lib/i386-linux-gnu/qtcreator/libAggregation.so.1.0.0

Tried to point the project to these libs, nothing helps.
What to do?

Answer 1

If still relevant ...
I was helped by an explicit indication of the directory where Qt Creator was compiled.
IDE_BUILD_TREE=