CMAKE_PREFIX_PATH 不能帮助 CMake 找到 Qt5

Question

从这里：https://stackoverflow.com/a/28327499/462608

我试过了：

cmake_minimum_required(VERSION 2.8.12)

project(qtquick_hello_cmake)

set(CMAKE_PREFIX_PATH "/opt/Qt5.9.1/5.9.1/")

set(CMAKE_INCLUDE_CURRENT_DIR ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)

find_package(Qt5 COMPONENTS Quick Core REQUIRED)

qt5_add_resources(RESOURCES qml.qrc)

add_executable(${PROJECT_NAME} "main.cpp" "qml.qrc")

qt5_use_modules(${PROJECT_NAME} Quick Core)

target_link_libraries(${PROJECT_NAME} Qt5::Core Qt5::Quick)

这是cmake .的输出

:~/junk/qtquick_hello_cmake$ cmake .
CMake Error at CMakeLists.txt:11 (find_package):
  By not providing "FindQt5.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "Qt5", but
  CMake did not find one.

  Could not find a package configuration file provided by "Qt5" with any of
  the following names:

    Qt5Config.cmake
    qt5-config.cmake

  Add the installation prefix of "Qt5" to CMAKE_PREFIX_PATH or set "Qt5_DIR"
  to a directory containing one of the above files.  If "Qt5" provides a
  separate development package or SDK, be sure it has been installed.


-- Configuring incomplete, errors occurred!
See also "/home/.../junk/qtquick_hello_cmake/CMakeFiles/CMakeOutput.log".

这是为了表明/opt/Qt5.9.1/确实存在。

:~/junk/qtquick_hello_cmake$ cd /opt/Qt5.9.1/5.9.1/
:/opt/Qt5.9.1/5.9.1$ ls
android_armv7  android_x86  gcc_64  Src

这里我使用 -DCMAKE 选项运行 cmake，但输出仍然相同：

:~/junk/qtquick_hello_cmake$ cmake -DCMAKE_PREFIX_PATH=/opt/Qt5.9.1/5.9.1/ -DWITH_QT5=1 .
CMake Error at CMakeLists.txt:11 (find_package):
  By not providing "FindQt5.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "Qt5", but
  CMake did not find one.

  Could not find a package configuration file provided by "Qt5" with any of
  the following names:

    Qt5Config.cmake
    qt5-config.cmake

  Add the installation prefix of "Qt5" to CMAKE_PREFIX_PATH or set "Qt5_DIR"
  to a directory containing one of the above files.  If "Qt5" provides a
  separate development package or SDK, be sure it has been installed.


-- Configuring incomplete, errors occurred!
See also "/home/.../junk/qtquick_hello_cmake/CMakeFiles/CMakeOutput.log".

目录内容：

:~/junk/qtquick_hello_cmake$ ls
CMakeCache.txt  CMakeFiles  CMakeLists.txt  main.cpp  main.qml  qml.qrc

Answer 1

我安装了以下缺失的软件包：

sudo apt-get install qtbase5-dev
sudo apt-get install qtdeclarative5-dev

现在不需要附加任何类型的前缀：

CMakeList：

    :~/junk/qtquick_hello_cmake$ cat CMakeLists.txt
    cmake_minimum_required(VERSION 2.8.12)
    
    project(qtquick_hello_cmake)
    
    set(CMAKE_INCLUDE_CURRENT_DIR ON)
    set(CMAKE_AUTOMOC ON)
    set(CMAKE_AUTORCC ON)
    
    find_package(Qt5 COMPONENTS Quick Core REQUIRED)
    
    qt5_add_resources(RESOURCES qml.qrc)
    
    add_executable(${PROJECT_NAME} "main.cpp" "qml.qrc")
    
    qt5_use_modules(${PROJECT_NAME} Quick Core)
    
    target_link_libraries(${PROJECT_NAME} Qt5::Core Qt5::Quick)

新输出：

:~/junk/qtquick_hello_cmake$ ls
build  CMakeLists.txt  main.cpp  main.qml  qml.qrc

:~/junk/qtquick_hello_cmake$ cd build/
:~/junk/qtquick_hello_cmake/build$ rm -rf *

:~/junk/qtquick_hello_cmake/build$ cmake ../
-- The C compiler identification is GNU 4.8.4
-- The CXX compiler identification is GNU 4.8.4
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- 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
-- Configuring done
-- Generating done
-- Build files have been written to: /home/.../junk/qtquick_hello_cmake/build

错误现在消失了。

感谢：
https://answers.ros.org/question/236324/could-not-find-a-package-configuration-file-provided-by-qt5widgets/
https://askubuntu.com/questions/508503/whats-the-development-package-for-qt5-in-14-04

Answer 2

对于 macOS，在终端中导出以下变量。

export CMAKE_PREFIX_PATH=/usr/local/Cellar/qt5/5.15.1/  

可能还有另一个版本，检查你有哪个版本并相应地更改最后一个路径组件。

发布构建重新配置

cmake ../

Answer 3

我最近遇到了这个问题，我通过将它添加到任何产生此错误的 CMakeLists.txt 中来解决这个问题：

set(Qt5_DIR "*PATH TO YOUR QT QT5CONFIG FILE HERE*" CACHE PATH "Initial cache" FORCE)

Answer 4

关于失败 find_package 和设置 CMAKE_PREFIX_PATH 变量的 CMake 错误消息

将“Qt5”的安装前缀添加到CMAKE_PREFIX_PATH

在某种程度上具有误导性。它只谈论“安装前缀”，但此安装仍然要求在内部包含 Qt5Config.cmake 或 qt5-config.cmake 文件，以便 find_package 发现。

但是消息

如果“Qt5”提供了一个 单独的开发包或SDK，请确保已安装。

很清楚：

需要安装一个包含所需配置文件的开发包。

---

以上所有内容仅适用于find_package的CONFIG模式，当“查找”脚本既不是由CMake提供，也不是由使用此命令的CMake项目提供时。

Answer 5

另一种解决方案，例如，如果您在主目录中手动安装了 Qt（而不是使用系统安装的），则在命令行中准确指定要使用的版本。示例：

cmake -DCMAKE_BUILD_TYPE=Release -DBUILD_SAMPLES=TRUE -DBUILD_STATIC_QRC=TRUE -DCMAKE_PREFIX_PATH=/home/anthony/Qt/5.15.2/gcc_64 ..

注意指定版本+您正在使用的目标系统。然后，Qt 会在子目录中找到合适的配置文件。

Answer 6

几年后，我在新的 Android NDK 工具链中遇到了类似的问题。这里提供的解决方案还不够。我找到了一种新方法并在此处发布以下内容：

$ cmake --log-level=DEBUG --debug-find <SRC_DIR>

这将打印出 CMake 找到包文件的查找过程。