How to link a library .a or dll in my project, with cmake in Qt and windows

[lincoln]

Hello, I have the following problem, when including an external library to my project, in Qt, when using qmake, it was only necessary to do:

INCLUDEPATH + = "$$ PWD / mylib / include"
LIBS + = -L "$$ PWD / mylib / lib"
LIBS + = -lthislib -lotherlib

but in cmake I have no idea how to do it.

I have the following:

cmake_minimum_required(VERSION 3.5)

project(untitled2 VERSION 0.1 LANGUAGES CXX)

set(CMAKE_INCLUDE_CURRENT_DIR ON)

set(CMAKE_AUTOUIC ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)

set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

# QtCreator supports the following variables for Android, which are identical to qmake Android variables.
# Check https://doc.qt.io/qt/deployment-android.html for more information.
# They need to be set before the find_package( ...) calls below.

#if(ANDROID)
#    set(ANDROID_PACKAGE_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/android")
#    if (ANDROID_ABI STREQUAL "armeabi-v7a")
#        set(ANDROID_EXTRA_LIBS
#            ${CMAKE_CURRENT_SOURCE_DIR}/path/to/libcrypto.so
#            ${CMAKE_CURRENT_SOURCE_DIR}/path/to/libssl.so)
#    endif()
#endif()

find_package(QT NAMES Qt6 Qt5 COMPONENTS Widgets REQUIRED)
find_package(Qt${QT_VERSION_MAJOR} COMPONENTS Widgets REQUIRED)

set(PROJECT_SOURCES
        main.cpp
        widget.cpp
        widget.h
        widget.ui
)

include_directories(${CMAKE_CURRENT_SOURCE_DIR}/lib/include)
add_library(MYLIB STATIC IMPORTED)


if(${QT_VERSION_MAJOR} GREATER_EQUAL 6)
    qt_add_executable(untitled2
        MANUAL_FINALIZATION
        ${PROJECT_SOURCES}
    )
else()
    if(ANDROID)
        add_library(untitled2 SHARED
            ${PROJECT_SOURCES}
        )
    else()
        add_executable(untitled2
            ${PROJECT_SOURCES}
        )
    endif()
endif()

target_link_libraries(untitled2 PRIVATE Qt${QT_VERSION_MAJOR}::Widgets)
target_link_libraries(untitled2 PRIVATE  ${MYLIB})

set_target_properties(untitled2 PROPERTIES
    MACOSX_BUNDLE_GUI_IDENTIFIER my.example.com
    MACOSX_BUNDLE_BUNDLE_VERSION ${PROJECT_VERSION}
    MACOSX_BUNDLE_SHORT_VERSION_STRING ${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}
)

if(QT_VERSION_MAJOR EQUAL 6)
    qt_finalize_executable(untitled2)
endif()

I use include_directories, to add the .h files from my library and add_library to add the static library, and at the end target_link_libraries (untitled2 PRIVATE $ {MYLIB}),

but I get this error when I run the program.

code of my main form:

#include "widget.h"
#include "./ui_widget.h"
#include <QMessageBox>
#include "xlsxdocument.h"
#include "xlsxchartsheet.h"
#include "xlsxcellrange.h"
#include "xlsxchart.h"
#include "xlsxrichstring.h"
#include "xlsxworkbook.h"

using namespace QXlsx;

Widget::Widget(QWidget *parent)
  : QWidget(parent)
  , ui(new Ui::Widget)
{
  ui->setupUi(this);
  QXlsx::Document document;
  document.write("A1","Hello Qt!");
  if(!document.saveAs("D:\\ejmplo.xlsx")){
    QMessageBox::critical(this,qApp->applicationName(),"Error al guardar el archivo.\n");
    return;
  }
  QMessageBox::information(this,qApp->applicationName(),"Archivo guardado.");
}

Widget::~Widget()
{
  delete ui;
}

Any suggestions as to why this error appears, or what is the correct way to include third party libraries in cmake, thanks in advance.

[JoeCFD]

unset(MY_LIB CACHE)
FIND_LIBRARY( MY_LIB NAMES libthislib.so
                                PATHS ${PWD}/mylib <===check PWD usage here
                                DOC "MY_LIB library to link with"
                                NO_SYSTEM_ENVIRONMENT_PATH)
target_link_libraries(${PROJECT_NAME} "${MY_LIB}")

[lincoln]

@JoeCFD

Now I get this error.

I take it back so I stay at the end and if it worked, thanks man.

include_directories(${CMAKE_CURRENT_SOURCE_DIR}/lib/include)
unset(MYLIB CACHE)
find_library(MYLIB NAMES libQXlsx.a PATHS ${CMAKE_CURRENT_SOURCE_DIR}/lib NO_SYSTEM_ENVIROMENT_PATH)
target_link_libraries(untitled2 PRIVATE  ${MYLIB})