CMake配置阶段构建fmt与spdlog时链接系统库异常问题咨询

问题背景 #

近几日尝试在CMake配置阶段构建fmt库（10.1.1版本）以及依赖外部fmt的spdlog库（1.12.0版本），编写了相关CMake脚本，但遇到spdlog链接系统libfmt.so.9的问题，仅当将spdlog添加为主程序依赖后重新构建，才能正确链接本地编译的libfmt.so.10，寻求解决方法。

相关CMake脚本及代码 #

BuildFmt.cmake

FetchContent_Declare(
  fmt
  OVERRIDE_FIND_PACKAGE
  URL "file://${PROJECT_SOURCE_DIR}/deps/fmt-10.1.1.tar.gz"
)

FetchContent_GetProperties(fmt)
if(NOT fmt_POPULATED)
  FetchContent_Populate(fmt)
endif()

execute_process(OUTPUT_QUIET
  COMMAND cmake -DBUILD_SHARED_LIBS=ON -DFMT_TEST=OFF ${fmt_SOURCE_DIR}
  WORKING_DIRECTORY "${fmt_BINARY_DIR}"
  RESULT_VARIABLE FMT_RESULT)

execute_process(OUTPUT_QUIET
  COMMAND make
  WORKING_DIRECTORY "${fmt_BINARY_DIR}"
  RESULT_VARIABLE FMT_RESULT)

set(FMT_BUILT ON CACHE BOOL "FMT is built" FORCE)
list(APPEND CMAKE_PREFIX_PATH "${fmt_BINARY_DIR}") 

BuildSpdLog.cmake

FetchContent_Declare(
  spdlog
  OVERRIDE_FIND_PACKAGE
  URL "file://${PROJECT_SOURCE_DIR}/deps/spdlog-1.12.0.tar.gz"
)

FetchContent_GetProperties(spdlog)
if(NOT spdlog_POPULATED)
  FetchContent_Populate(spdlog)
endif()
  
execute_process(
  COMMAND cmake -DSPDLOG_BUILD_SHARED=ON -DSPDLOG_BUILD_PIC=ON -DSPDLOG_BUILD_EXAMPLE=OFF -DSPDLOG_FMT_EXTERNAL=ON ${spdlog_SOURCE_DIR}
  WORKING_DIRECTORY "${spdlog_BINARY_DIR}"
  RESULT_VARIABLE SPDLOG_RESULT)

execute_process(
  COMMAND make
  WORKING_DIRECTORY "${spdlog_BINARY_DIR}"
  RESULT_VARIABLE SPDLOG_RESULT)

set(SPDLOG_BUILT ON CACHE BOOL "SPDLOG is built" FORCE)
list(APPEND CMAKE_PREFIX_PATH "${spdlog_BINARY_DIR}")
add_subdirectory(${spdlog_SOURCE_DIR} ${spdlog_BINARY_DIR})

CMakeLists.txt

cmake_minimum_required(VERSION 3.14.7)

project("test")

add_compile_definitions(SPDLOG_FMT_EXTERNAL)

list(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake)

include(BuildFmt)
include(BuildSpdLog)

find_package(fmt REQUIRED CONFIG)

add_executable(my_importer main.cpp)
target_link_libraries(my_importer fmt::fmt)

main.cpp

#include<fmt/format.h>

int main() {
    return 0;
}

问题现象 #

1. 初始构建无报错，但用ldd命令查看spdlog库时，发现其链接了系统中的libfmt.so.9：

nikola@notebook ~/projects/2m/cmake_test/build $ ldd ./_deps/spdlog-build/libspdlog.so
linux-vdso.so.1 (0x00007fff1a948000)
libfmt.so.9 => /usr/lib64/libfmt.so.9 (0x00007f94489e2000)
libstdc++.so.6 => /usr/lib/gcc/x86_64-pc-linux-gnu/13/libstdc++.so.6 (0x00007f9448782000)
libm.so.6 => /lib64/libm.so.6 (0x00007f94486a2000)
libgcc_s.so.1 => /usr/lib/gcc/x86_64-pc-linux-gnu/13/libgcc_s.so.1 (0x00007f944867e000)
libc.so.6 => /lib64/libc.so.6 (0x00007f94484ab000)
/lib64/ld-linux-x86-64.so.2 (0x00007f9448ab7000)

2. 将spdlog添加为主程序依赖（修改target_link_libraries为target_link_libraries(my_importer fmt::fmt spdlog::spdlog)）后，执行make时spdlog会重新构建，此时能正确链接本地编译的libfmt.so.10：

nikola@notebook ~/projects/cmake_test/build $ make
[ 11%] Building CXX object _deps/spdlog-build/CMakeFiles/spdlog.dir/src/spdlog.cpp.o
[ 22%] Building CXX object _deps/spdlog-build/CMakeFiles/spdlog.dir/src/stdout_sinks.cpp.o
[ 33%] Building CXX object _deps/spdlog-build/CMakeFiles/spdlog.dir/src/color_sinks.cpp.o
[ 44%] Building CXX object _deps/spdlog-build/CMakeFiles/spdlog.dir/src/file_sinks.cpp.o
[ 55%] Building CXX object _deps/spdlog-build/CMakeFiles/spdlog.dir/src/async.cpp.o
[ 66%] Building CXX object _deps/spdlog-build/CMakeFiles/spdlog.dir/src/cfg.cpp.o
[ 77%] Linking CXX shared library libspdlog.so
[ 77%] Built target spdlog
[ 88%] Building CXX object CMakeFiles/2m_importer.dir/main.cpp.o
[100%] Linking CXX executable 2m_importer
[100%] Built target 2m_importer
nikola@notebook ~/projects/2m/cmake_test/build $ ldd ./_deps/spdlog-build/libspdlog.so
    linux-vdso.so.1 (0x00007fffe279d000)
    libfmt.so.10 => /home/nikola/projects/2m/cmake_test/build/_deps/fmt-build/libfmt.so.10 (0x00007f882ee5c000)
    libstdc++.so.6 => /usr/lib/gcc/x86_64-pc-linux-gnu/13/libstdc++.so.6 (0x00007f882ebd7000)
    libm.so.6 => /lib64/libm.so.6 (0x00007f882eaf7000)
    libgcc_s.so.1 => /usr/lib/gcc/x86_64-pc-linux-gnu/13/libgcc_s.so.1 (0x00007f882ead3000)
    libc.so.6 => /lib64/libc.so.6 (0x00007f882e900000)
    /lib64/ld-linux-x86-64.so.2 (0x00007f882eef3000)

求助说明 #

CMake基础薄弱，尝试过ExternalProject但未解决问题，希望找到原因并修正配置，让spdlog在初始构建阶段就能正确链接本地编译的fmt库。

内容的提问来源于stack exchange，提问作者nikoladsp