Добавить qtwidgets в файл cmake
cmake_minimum_required(VERSION 3.16)
project(helloworld VERSION 1.0.0 LANGUAGES CXX)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)
set(CMAKE_AUTOUIC ON)
find_package(Qt6 REQUIRED COMPONENTS Widgets)
add_executable(helloworld
mainwindow.ui
mainwindow.cpp
main.cpp
resources.qrc
)
target_link_libraries(helloworld PRIVATE Qt6::Widgets)
Cautious Cowfish