cmake_minimum_required(VERSION 3.6)
project(Splines)

set(CMAKE_CXX_COMPILER "/usr/bin/clang++")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14 -Wall -Wextra -pedantic -static -stdlib=libc++ -lc++abi -v")
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}")
set(SOURCE_FILES main.cpp)

set(CMAKE_AUTOMOC ON)
set(CMAKE_INCLUDE_CURRENT_DIR ON)

set(Qt5_DIR "/usr/local/Qt5_static/")
find_package(Qt5Widgets)

add_executable(Splines ${SOURCE_FILES})

target_link_libraries(Splines Qt5::Widgets)

/usr/bin/ld: attempted static link of dynamic object `/usr/lib/libQt5Widgets.so.5.7.0'
clang-3.8: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [CMakeFiles/Splines.dir/build.make:124: /home/darthvlado/MEGA/MEGAsync/workspace/ClionProjects/Splines/Splines] Ошибка 1
make[1]: *** [CMakeFiles/Makefile2:68: CMakeFiles/Splines.dir/all] Ошибка 2
make: *** [Makefile:84: all] Ошибка 2

/usr/local/Qt5_static/lib/cmake/Qt5Widgets

add_library(LibName STATIC IMPORTED)
SET_PROPERTY(TARGET LibName PROPERTY IMPORTED_LOCATION ${path_to_lib})
TARGET_LINK_LIBRARIES(programName LibName)

set(Qt5Widgets_DIR "/usr/local/Qt5_static/")#или задавать префикс
find_package(Qt5Widgets)
qt5_use_modules(Splines Widgets)

set(Qt5_DIR "/usr/local/Qt5_static/")
find_package(Qt5 REQUIRED Widgets)
target_link_libraries(Splines Qt5::Widgets)

set(CMAKE_CXX_STANDARD 14)