cmake & Qt4: Cannot specify link libraries for target - qt

Question

Following some hello world with qt and cmake, this is my fold structure:
CMakeLists.txt
main.cpp
ui/mainwindow.ui
src/mainwindow.cpp
include/mainwindow.h
and this is CMakeList.txt:
cmake_minimum_required (VERSION 2.8)
# Project
set(PROJECTNAME "Hello")
project(${PROJECTNAME} C CXX)
set(${PROJECTNAME}_MAJOR_VERSION 0)
set(${PROJECTNAME}_MINOR_VERSION 1)
# qt
find_package(Qt4 REQUIRED)
set (QT_USE_QTMAIN TRUE)
include (${QT_USE_FILE})
add_definitions(${QT_DEFINITIONS})
# compilers
#set(CMAKE_CXX_FLAGS "-Wall -std=gnu++0x")
# files
include_directories(${CMAKE_CURRENT_BINARY_DIR})
include_directories(src)
include_directories(include)
set(${PROJECTNAME}_SOURCES
main.cpp
src/mainwindow.cpp
)
set(${PROJECTNAME}_HEADERS
include/mainwindow.h
)
set(${PROJECTNAME}_HEADERS_MOC
include/mainwindow.h
)
set(${PROJECTNAME}_FORMS
ui/mainwindow.ui
)
QT4_WRAP_CPP(${PROJECTNAME}_HEADERS_MOC ${${PROJECTNAME}_HEADERS_MOC})
QT4_WRAP_UI(${PROJECTNAME}_FORMS_HEADERS ${${PROJECTNAME}_FORMS})
QT4_ADD_RESOURCES(${PROJECTNAME}_RESOURCES_RCC ${${PROJECTNAME}_RESOURCES})
# executables and installation
add_executable (
${${PROJECTNAME}_HEADERS}
${${PROJECTNAME}_SOURCES}
${${PROJECTNAME}_HEADERS_MOC}
${${PROJECTNAME}_FORMS_HEADERS}
)
target_link_libraries(${PROJECTNAME} ${QT_LIBRARIES})
tried different ways of add target_link_libraries but still get:
-- The C compiler identification is GNU
-- The CXX compiler identification is GNU
-- Check for working C compiler: /usr/bin/gcc
-- Check for working C compiler: /usr/bin/gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Looking for Q_WS_X11
-- Looking for Q_WS_X11 - found
-- Looking for Q_WS_WIN
-- Looking for Q_WS_WIN - not found.
-- Looking for Q_WS_QWS
-- Looking for Q_WS_QWS - not found.
-- Looking for Q_WS_MAC
-- Looking for Q_WS_MAC - not found.
-- Found Qt4: /usr/bin/qmake (found version "4.8.1")
CMake Error at CMakeLists.txt:61 (target_link_libraries):
Cannot specify link libraries for target "Hello" which is not built by
this project.
-- Configuring incomplete, errors occurred!

Answer 1

You are missing the target name as the first parameter to add_executable.
add_executable(
${PROJECTNAME}
${${PROJECTNAME}_HEADERS}
${${PROJECTNAME}_SOURCES}
${${PROJECTNAME}_HEADERS_MOC}
${${PROJECTNAME}_FORMS_HEADERS}
)