CMake无法正确链接库求助（附作业项目结构）

Let’s work through your CMake issues step by step to get your shared library (src.so) and Google Test setup working properly. First, let’s recap your project structure clearly to make sure we’re on the same page:

.
├── CMakeLists.txt
├── main.c          # Contains only "Hello, world"
├── src
│   ├── CMakeLists.txt
│   ├── game
│   │   ├── game.c
│   │   └── game.h
│   └── main.c
└── test
    ├── CMakeLists.txt
    ├── homework_tests
    │   ├── CMakeLists.txt
    │   ├── gtest.cpp
    │   └── gtest.h
    └── lib
        └── googletest
            └── googletest
                └── [library files (not compiled)]

Step 1: Root CMakeLists.txt Setup #

First, we need to configure the root CMakeLists.txt to set up the project, enable C/C++ support, and point CMake to your source and test directories:

cmake_minimum_required(VERSION 3.10)
project(HomeworkProject C CXX)

# Enforce standard versions for compatibility
set(CMAKE_C_STANDARD 99)
set(CMAKE_CXX_STANDARD 11)

# Add subdirectories to build source and test targets
add_subdirectory(src)
add_subdirectory(test)

# Optional: Build the top-level "Hello World" main.c as a separate executable
add_executable(top_level_main main.c)

This ensures CMake knows about all your code paths and sets consistent standards for compilation.

Step 2: Build src.so from the src Directory #

Your goal here is to create a shared library from the game module (we’ll exclude src/main.c since libraries don’t need a main function). Update src/CMakeLists.txt like this:

# Collect all source files from the game subdirectory
file(GLOB GAME_SOURCES game/*.c)

# Build the shared library (will output as src.so)
add_library(src SHARED ${GAME_SOURCES})

# Make game.h accessible to other targets (like tests)
target_include_directories(src PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/game)

# Optional: If you want to build src/main.c as an executable linked to src.so
add_executable(src_main main.c)
target_link_libraries(src_main PRIVATE src)

The PUBLIC flag ensures any target linking against src.so automatically gets access to the game header directory.

Step 3: Configure Google Test in the test Directory #

Since your Google Test files are uncompiled, we need to tell CMake to build the library from source. Update test/CMakeLists.txt:

# Add the Google Test source directory so CMake compiles it
add_subdirectory(lib/googletest/googletest)

# Include Google Test headers so your test files can find gtest/gtest.h
include_directories(${gtest_SOURCE_DIR}/include ${gtest_SOURCE_DIR})

# Point CMake to your test implementation directory
add_subdirectory(homework_tests)

Step 4: Link Tests to src.so & Google Test #

Finally, update test/homework_tests/CMakeLists.txt to compile your tests and link them to both your shared library and Google Test:

# Collect your test source files
file(GLOB TEST_SOURCES *.cpp)

# Build the test executable
add_executable(homework_tests ${TEST_SOURCES})

# Link against your shared library and Google Test libraries
target_link_libraries(homework_tests PRIVATE src gtest gtest_main)

# Enable test discovery so you can run tests with `ctest`
enable_testing()
add_test(NAME HomeworkTests COMMAND homework_tests)

Key Fixes Explained #

• Shared Library Cleanup: We excluded src/main.c from the library since libraries shouldn’t contain a main function—this avoids unnecessary code and potential conflicts.
• Google Test Compilation: Using add_subdirectory on the Google Test source ensures CMake builds the library for your specific system, eliminating linking mismatches.
• Header Visibility: Using target_include_directories (for src.so) and include_directories (for Google Test) ensures all targets can find the headers they need without hardcoding paths.
• Proper Linking Order: Listing your shared library first in target_link_libraries ensures CMake resolves dependencies correctly when linking the test executable.

Verify the Setup #

To test everything works:

1. Create a build directory and navigate into it:

   mkdir build && cd build
   

2. Generate build files with CMake:

   cmake ..
   

3. Build all targets:

   make -j$(nproc)
   

4. Run your tests:

   ctest
   

You should see src.so in the build/src directory, and your tests should run successfully if your test implementation is correct.

内容的提问来源于stack exchange，提问作者Dennis Barzanoff