在您构建的库上使用 CMake 中的 --whole-archive

Question

我有一个 CMake 项目，同时构建一个静态库并将其与其他代码链接到一个可执行文件中。由于我不会详细介绍的原因，我希望使用 --whole-archive 链接器标志进行此链接。

现在，这个标志很棘手，因为你不能在任何地方添加它 - 你必须切换它，然后列出你想要它应用的库，然后取消它。

我在某处读到（URL 忽略了我），如果您有一个预先存在的库，您可以通过执行以下操作有效地添加此链接器标志：

# Just an example, find_library calls should really be isolated to separate find modules
find_library(FOO_LIBRARY foo)
set(FOO_LIBRARY "-Wl,--whole-archive ${FOO_LIBRARY} -Wl,--no-whole-archive")

add_executable(hello main.c)
target_link_libraries(hello ${FOO_LIBRARY})

这很好。但是，如果 您 正在构建一个静态库，而您没有预先存在的变量（即，您有一个 add_library() CMake 命令的东西）怎么办？您是否必须手动指示其路径而不是 ${FOO_LIBRARY}？或者您是否可以使用其他一些技巧来获取 CMake 为其在命令行上放置的路径？

另外，如果我要使用某种${FOO_LIBRARY}-like 字符串而不是我的静态库目标标识符 - 我相信 CMake 可能会丢失依赖项，即它可能不会重新链接到修改后的库（甚至构建它）因为 target_link_libraries 命令会看到一个奇怪的字符串而不是另一个目标的标识符。

Answer 1

这可以使用：

add_dependencies(the_exe the_static_lib)
set_target_properties(the_exe LINK_FLAGS
    "-L/path/to/the_static_lib -Wl,--whole-archive,-lthe_static_lib,--no-whole-archive")

-L/path/to/the_static_lib 的值透明地遵循您指定的输出目录 要成为的目标，或者目标的默认输出目录（如果不这样做）。例如。如果the_static_lib 是 只需在构建目录中输出，然后-L/path/to/the_static_lib 将是-L.

这是一个以合理一般的方式说明的项目，我们在其中 具有用于源和标题的结构化子目录以及不同的常规 输出目录，bin，lib

$ ls -R
.:
app  build  CMakeLists.txt  foobar  inc

./app:
main.c

./build:

./foobar:
bar.c  foo.c

./inc:
foobar.h

有文件：

app/main.c

#include <foobar.h>

int main(void)
{
    foo();
    bar();
    return 0;
}

foobar/foo.c

#include <foobar.h>
#include <stdio.h>

void foo(void)
{
    puts(__func__);
}

foobar/bar.c

#include <foobar.h>
#include <stdio.h>

void bar(void)
{
    puts(__func__);
}

inc/foobar.h

#ifndef FOOBAR_H
#define FOOBAR_H

void foo(void);
void bar(void);

#endif

CMakeLists.txt (1)

cmake_minimum_required(VERSION 3.0)
project(app)
include_directories(inc)
add_library(foobar STATIC foobar/foo.c foobar/bar.c)
set_target_properties(foobar
    PROPERTIES ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib")
add_executable(app app/main.c)
add_dependencies(app foobar)
set_target_properties(app PROPERTIES
    RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/bin"
    LINK_FLAGS "-Llib -Wl,--whole-archive,-lfoobar,--no-whole-archive")

我们想从./foobar/foo.c 和./foobar/bar.c 生成./build/lib/libfoobar.a。 我们想从./app/main.c制作./build/bin/app，链接整个档案./build/lib/libfoobar.a

生成、构建和运行：

$ cd build; cmake ..; make; ./bin/app
-- The C compiler identification is GNU 8.2.0
-- The CXX compiler identification is GNU 8.2.0
-- 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
-- Detecting C compile features
-- Detecting C compile features - 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
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/imk/develop/so/cmake_prob/build
Scanning dependencies of target foobar
[ 20%] Building C object CMakeFiles/foobar.dir/foobar/foo.c.o
[ 40%] Building C object CMakeFiles/foobar.dir/foobar/bar.c.o
[ 60%] Linking C static library lib/libfoobar.a
[ 60%] Built target foobar
Scanning dependencies of target app
[ 80%] Building C object CMakeFiles/app.dir/app/main.c.o
[100%] Linking C executable bin/app
[100%] Built target app
foo
bar

类似地，例如而不是 CMakeLists.txt 我们有：

CMakeLists.txt (2)

cmake_minimum_required(VERSION 3.0)
project(app)
include_directories(inc)
add_subdirectory(foobar)
add_executable(app app/main.c)
add_dependencies(app foobar)
set_target_properties(app PROPERTIES
    RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/bin"
    LINK_FLAGS "-Llib -Wl,--whole-archive,-lfoobar,--no-whole-archive")

和分开：

foobar/CMakeLists.txt (1)

add_library(foobar STATIC foo.c bar.c)
set_target_properties(foobar
    PROPERTIES ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib")

使用相同的分隔，但默认输出目录，我们将拥有：

CMakeLists.txt (3)

cmake_minimum_required(VERSION 3.0)
project(app)
include_directories(inc)
add_subdirectory(foobar)
add_executable(app app/main.c)
add_dependencies(app foobar)
set_target_properties(app PROPERTIES
    LINK_FLAGS "-Lfoobar -Wl,--whole-archive,-lfoobar,--no-whole-archive")

foobar/CMakeLists.txt (2)

add_library(foobar STATIC foo.c bar.c)

会是这样的：

$ cd build; cmake ..; make; ./app
-- The C compiler identification is GNU 8.2.0
-- The CXX compiler identification is GNU 8.2.0
-- 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
-- Detecting C compile features
-- Detecting C compile features - 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
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/imk/develop/so/cmake_prob/build
Scanning dependencies of target foobar
[ 20%] Building C object foobar/CMakeFiles/foobar.dir/foo.c.o
[ 40%] Building C object foobar/CMakeFiles/foobar.dir/bar.c.o
[ 60%] Linking C static library libfoobar.a
[ 60%] Built target foobar
Scanning dependencies of target app
[ 80%] Building C object CMakeFiles/app.dir/app/main.c.o
[100%] Linking C executable app
[100%] Built target app
foo
bar