与GTest的链接失败 [英] Linking against GTest fails

问题描述

我有以下 CMakeLists.txt ：

cmake_minimum_required(VERSION 3.15)

set(CMAKE_CXX_STANDARD 17)

# adding library
set(ST_SRC simple_tree.cpp)
add_library(st ${ST_SRC})
target_include_directories(st PUBLIC ${PROJECT_SOURCE_DIR}/include/data_structures/simple_tree/)

# adding googletest
set(GOOGLETEST_PATH ~/local/googletest)
set(GTEST_INCLUDE_DIR ~/local/include/)
set(GTEST_LIBRARY ~/local/lib/)
set(GTEST_MAIN_LIBRARY ~/local/lib/)
find_package(GTest REQUIRED)

# adding tests
set(TEST_TARGET test_simple_tree)
add_executable(${TEST_TARGET} test_simple_tree.cpp)
target_include_directories(${TEST_TARGET}
                        PUBLIC
                        ${PROJECT_SOURCE_DIR}/include/data_structures/simple_tree
                        ${GOOGLETEST_PATH}
                        ${GTEST_INCLUDE_DIR})
target_link_libraries(${TEST_TARGET} PUBLIC st)
target_link_libraries(${TEST_TARGET} PUBLIC gtest gtest_main)

基本上，我已将 googletest 安装到我的主目录中，而不是系统范围内。
find_package（）命令显然成功。但是，尝试构建 test_simple_tree 失败，并显示以下内容：

Basically, I've installed googletest into my home directory rather than system-wide. The find_package() command apparently succeeds. However, trying to build test_simple_tree fails with:

/usr/bin/ld: cannot find -lgtest
/usr/bin/ld: cannot find -lgtest_main

在此 CMakeLists.txt 里面，我还能如何告诉链接器在其他地方
查找 gtest ？

Inside this CMakeLists.txt, how else can I tell the linker to look elsewhere for the gtest?

编辑：阅读文档后，我已修复了 Gtest 问题，如下所述。但是，出现了以下问题： CMake导入的目标包含不存在的路径

After reading the docs, I've fixed the Gtest issue as described below. However, the following issue cropped up: CMake imported target includes non-existent path

推荐答案

如果 find_package（）成功找到GTest包括/库，它应该根据CMake为您填充目标 FindGTest 文档：

If find_package() was successful in finding the GTest includes/libraries, it should populate targets for you, per the CMake FindGTest documentation:

此模块定义了以下 IMPORTED 目标：

GTest :: GTest ：
Google测试 gtest 库（如果找到）；自动添加Thread :: Thread

GTest::GTest: The Google Test gtest library, if found; adds Thread::Thread automatically

GTest :: Main ：
Google测试 gtest_main 库（如果找到）

您应该在 target_link_libraries中使用它们（）命令。另外，CMake将填充 GTEST_INCLUDE_DIRS ，但GTest包含目录应从上述导入的目标中拉入。

You should use these in your target_link_libraries() command instead. Also, CMake will populate GTEST_INCLUDE_DIRS, but the GTest include directories should be pulled in from the imported targets mentioned above.

另一个重要说明：我不确定您是否发布了CMake代码的 all ，但在您的代码中看不到 project（）调用。因此， $ {PROJECT_SOURCE_DIR} 变量可能不是您所期望的。通常，优良作法是在CMake顶部使用 project（）声明项目。

Another important note: I'm not sure if you posted all of your CMake code, but I don't see a project() call in your code. As a result, the ${PROJECT_SOURCE_DIR} variable may not be what you expect. In general, it is good practice to declare your project with project() at the top of your CMake.

经过这些修改的CMake文件可能看起来像这样：

Your CMake file with these modifications could look something like this:

cmake_minimum_required(VERSION 3.15)

project(simple_tree_example)

set(CMAKE_CXX_STANDARD 17)

# adding library
set(ST_SRC simple_tree.cpp)
add_library(st ${ST_SRC})
target_include_directories(st PUBLIC 
    ${PROJECT_SOURCE_DIR}/include/data_structures/simple_tree/)

# adding googletest
set(GOOGLETEST_PATH ~/local/googletest)
set(GTEST_INCLUDE_DIR ~/local/include/)
set(GTEST_LIBRARY ~/local/lib/)
set(GTEST_MAIN_LIBRARY ~/local/lib/)
find_package(GTest REQUIRED)

# adding tests
set(TEST_TARGET test_simple_tree)
add_executable(${TEST_TARGET} test_simple_tree.cpp)
target_include_directories(${TEST_TARGET}
                        PUBLIC
                        ${PROJECT_SOURCE_DIR}/include/data_structures/simple_tree
                        ${GOOGLETEST_PATH})
target_link_libraries(${TEST_TARGET} PUBLIC st GTest::GTest GTest::Main)

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