如何使用 Emscripten-1.38.31 (??) 编译 Boost-1.76.0

Posted 2023-02-21

【中文标题】如何使用 Emscripten-1.38.31 (??) 编译 Boost-1.76.0

【英文标题】：How to compile Boost-1.76.0 with Emscripten-1.38.31 (??)

【发布时间】：2021-02-15 02:18:28

【问题描述】：

我已经搜索了这个答案的高低，我认为它应该在现代环境中得到回答。我看到的大多数东西都是 2013 年或最迟 2015 年的，而 cmets 是 2019 年的。

首先，我使用的是 macOS 11.2 和最新版本的 xcode 12.4。

我从 git 克隆并安装了最新的（截至今天）用于 boost 和 emscripten 的存储库。

由于某些原因，在我的项目中尝试将 enscripten 标志集成到我的 CMakeLists.txt 文件中时，运行时出错

$ cmake .. 然后$ make。

CMakeLists.txt 文件：

cmake_minimum_required(VERSION 3.17)
project(FernQuest) #emscripten version

if ($CMAKE_SYSTEM_NAME MATCHES "Emscripten")
    message(STATUS "using emscripten")
endif ()
if (NOT $CMAKE_SYSTEM_NAME MATCHES "Emscripten")
    message(STATUS "using cmake")
endif ()

#options
option(JS_ONLY "Compiles to native JS (No WASM)" OFF)

set(CMAKE_CXX_STANDARD 14)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY $CMAKE_CURRENT_SOURCE_DIR/out)

include_directories(.)
include_directories(/usr/local/include) #where boost in located

message(STATUS "finding boost!")
find_package(Boost 1.74.0 REQUIRED serialization system filesystem COMPONENTS serialization system filesystem)

if(Boost_FOUND)
    message(STATUS "found boost!")
endif()

include_directories($Boost_INCLUDE_DIR)
link_directories($Boost_LIBRARY_DIR)

if(NOT Boost_FOUND)
    message(FATAL_ERROR "Could not find boost!")
endif()

message(STATUS "setting sources")
SET(FQ_SRCS
    ../src/FernQuest.cpp
    ../src/Item.cpp
    ../src/Item.h
    ../src/Player.cpp
    ../src/Player.h
    ../src/Game.cpp
    ../src/Game.h
    ../src/QuestLog.cpp
    ../src/QuestLog.h)


SET(CMAKE_C_COMPILER emcc)
SET(CMAKE_CPP_COMPILER em++)


add_executable(FernQuest $FQ_SRCS)


if(Boost_FOUND)
  if(JS_ONLY)
    message(STATUS "Setting compilation target to native javascript")
    set(CMAKE_EXECUTABLE_SUFFIX ".js")
    set_target_properties(FernQuest PROPERTIES COMPILE_FLAGS "-s USE_BOOST_HEADERS=1" LINK_FLAGS "-s USE_BOOST_HEADERS=1 -s WASM=0 -s EXPORTED_FUNCTIONS='[_main]'")
  else(JS_ONLY)
    message(STATUS "Setting compilation target to WASM")
    set(CMAKE_EXECUTABLE_SUFFIX ".wasm.js")
    set_target_properties(FernQuest PROPERTIES COMPILE_FLAGS "-s USE_BOOST_HEADERS=1" LINK_FLAGS " -s USE_BOOST_HEADERS=1 -s WASM=1 -s EXPORTED_FUNCTIONS='[_main]'")
  endif(JS_ONLY)
endif()

错误：

-- The C compiler identification is AppleClang 12.0.0.12000032
-- The CXX compiler identification is AppleClang 12.0.0.12000032
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- using cmake
-- finding boost!
-- Found Boost: /usr/local/lib/cmake/Boost-1.76.0/BoostConfig.cmake (found suitable version "1.76.0", minimum required is "1.74.0") found components: serialization system filesystem serialization system filesystem 
-- found boost!
-- setting sources
-- Setting compilation target to WASM
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/codiecottrell/Documents/FernQuest/emscripten/build
Scanning dependencies of target FernQuest
[ 16%] Building CXX object CMakeFiles/FernQuest.dir/Users/codiecottrell/Documents/FernQuest/src/FernQuest.cpp.o
clang: error: no such file or directory: 'USE_BOOST_HEADERS=1'
make[2]: *** [CMakeFiles/FernQuest.dir/Users/codiecottrell/Documents/FernQuest/src/FernQuest.cpp.o] Error 1
make[1]: *** [CMakeFiles/FernQuest.dir/all] Error 2
make: *** [all] Error 2

所以我读了，他们说要解决这个问题，你可以在下面使用它来实际使用 -DCMAKE_TOOLCHAIN_FILE 运行它：

$ emcmake cmake .. 然后$ emmake make

出现此错误：

configure: cmake .. -DCMAKE_TOOLCHAIN_FILE=/Users/codiecottrell/emsdk/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake -DCMAKE_CROSSCOMPILING_EMULATOR="/Users/codiecottrell/emsdk/node/14.15.5_64bit/bin/node"
-- using emscripten
-- finding boost!
CMake Error at /usr/local/Cellar/cmake/3.19.4/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:218 (message):
  Could NOT find Boost (missing: Boost_INCLUDE_DIR serialization system
  filesystem serialization system filesystem) (Required is at least version
  "1.74.0")
Call Stack (most recent call first):
  /usr/local/Cellar/cmake/3.19.4/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:582 (_FPHSA_FAILURE_MESSAGE)
  /usr/local/Cellar/cmake/3.19.4/share/cmake/Modules/FindBoost.cmake:2193 (find_package_handle_standard_args)
  CMakeLists.txt:21 (find_package)


-- Configuring incomplete, errors occurred!
See also "/Users/codiecottrell/Documents/FernQuest/emscripten/build/CMakeFiles/CMakeOutput.log".
make: make
-- using emscripten
-- finding boost!
CMake Error at /usr/local/Cellar/cmake/3.19.4/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:218 (message):
  Could NOT find Boost (missing: Boost_INCLUDE_DIR serialization system
  filesystem serialization system filesystem) (Required is at least version
  "1.74.0")
Call Stack (most recent call first):
  /usr/local/Cellar/cmake/3.19.4/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:582 (_FPHSA_FAILURE_MESSAGE)
  /usr/local/Cellar/cmake/3.19.4/share/cmake/Modules/FindBoost.cmake:2193 (find_package_handle_standard_args)
  CMakeLists.txt:21 (find_package)


-- Configuring incomplete, errors occurred!
See also "/Users/codiecottrell/Documents/FernQuest/emscripten/build/CMakeFiles/CMakeOutput.log".
make: *** [cmake_check_build_system] Error 1

我的问题： 似乎 enscripten 在通过自己的方式运行它时无法找到提升，但是 cmake 可以清楚地找到它。正如我在两个文档中所读到的，还支持通过 emscripten 运行 boost，但是没有明确的方法。这是什么方式，我哪里出错了？我会继续排查问题

编辑

刚试过$ emconfigure ./b2 toolset=gcc --prefix=/usr/local/B2

它并没有改变任何东西

【问题讨论】：

您似乎将-s USE_BOOST_HEADERS=1 传递给C++ 编译器。为什么？

我刚刚看到它在其他几个地方做了这些，我是设置 cmakes 的新手

【参考方案1】：

如果您使用 emscripten 进行构建，那么您 mac 上的库（cmake 正在搜索的地方）将无法工作；您需要静态编译它们。 我建议尝试不使用 CMake 构建您的项目。 如果您的项目只使用 boost 标头（而不是库），那么这样的事情可能会起作用：

$ em++ ../src/*.cpp -o index.html -s USE_BOOST_HEADERS=1

否则，您还需要编译 Boost。一旦你完成了这些并且你有一个libboost.a 文件，你可以像这样编译你的程序：

$ em++ ../src/*.cpp -c -s USE_BOOST_HEADERS=1

然后链接它：

$ em++ *.o /path/to/libboost.a -o index.html

当然，根据您使用的其他库，您需要调整这些命令。但总体思路是将所有依赖项编译成静态归档 (.a) 文件，然后将它们编译在一起以获得生成的 .html（或 .js 或 .wasm）文件。 阅读有关compiling with emcc 的更多信息。