How can vcpkg be integrated with Emscripten to work together?

[bowenxuuu]

How can vcpkg be integrated with Emscripten to work together? I want to compile my project into WASM, but I'm not sure how to go about it. Does vcpkg currently support Emscripten? Are there any relevant operational guidelines?

[dg0yt]

Source Emscripten's emsdk_env to get environment variables.
Then build for triplet wasm32-emscripten.

[bowenxuuu]

Hello, I just tried using the gdcm library. When I used the classic mode, building it as WASM went smoothly; the command I used was: vcpkg install gdcm[core]:wasm32-emscripten

However, when I used the manifest mode, the build failed. I'm not sure where the problem lies. Could you help me?

# vcpkg.json
{
  "dependencies": [
    {
      "name": "gdcm"
    }
  ]
}

# CMakeLists.txt

cmake_minimum_required(VERSION 3.30)

#vcpkg
set(VCPKG_HOST_TRIPLET wasm32-emscripten)
set(VCPKG_TARGET_TRIPLET wasm32-emscripten)
include("C:/CXXThirdParty/vcpkg/scripts/buildsystems/vcpkg.cmake") # include vcpkg toolchainfile
#vcpkg

project(Test001 VERSION 0.1.1 LANGUAGES CXX)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

if(WIN32)
    string(APPEND CMAKE_CXX_FLAGS " /utf-8 /Zc:__cplusplus") # set some msvc args
endif(WIN32)

add_executable(Test001 main.cpp)

find_package(GDCM CONFIG REQUIRED)
target_link_libraries(Test001 PRIVATE gdcmIOD gdcmDICT gdcmDSED gdcmMEXD)

error log:

[proc] Executing command: "C:\Program Files\CMake\bin\cmake.EXE" --version
[proc] Executing command: "C:\Program Files\CMake\bin\cmake.EXE" -E capabilities
[variant] Loaded new set of variants
[kit] Successfully loaded 6 kits from C:\Users\paul\AppData\Local\CMakeTools\cmake-tools-kits.json
[proc] Executing command: chcp
[visual-studio] Patch Windows SDK path from C:\Program Files (x86)\Windows Kits\10\bin\x64 to C:\Program Files (x86)\Windows Kits\10\bin\10.0.22621.0\x64 for C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Auxiliary\Build\vcvarsall.bat
[main] Configuring project: Test001 
[proc] Executing command: "C:\Program Files\CMake\bin\cmake.EXE" -DCMAKE_BUILD_TYPE:STRING=Release -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=TRUE --no-warn-unused-cli -SC:/Workspace/VSCode_Workspace/Test001 -Bc:/Workspace/VSCode_Workspace/Test001/build -G Ninja
[cmake] Not searching for unused variables given on the command line.
[cmake] -- Running vcpkg install
[cmake] Detecting compiler hash for triplet wasm32-emscripten...
[cmake] error: while detecting compiler information:
[cmake] The log file content at "C:\CXXThirdParty\vcpkg\buildtrees\detect_compiler\stdout-wasm32-emscripten.log" is:
[cmake] -- Configuring wasm32-emscripten
[cmake] CMake Error at scripts/cmake/vcpkg_execute_required_process.cmake:127 (message):
[cmake]     Command failed: C:/CXXThirdParty/vcpkg/downloads/tools/ninja/1.10.2-windows/ninja.exe -v
[cmake]     Working Directory: C:/CXXThirdParty/vcpkg/buildtrees/detect_compiler/wasm32-emscripten-rel/vcpkg-parallel-configure
[cmake]     Error code: 1
[cmake]     See logs for more information:
[cmake]       C:\CXXThirdParty\vcpkg\buildtrees\detect_compiler\config-wasm32-emscripten-rel-CMakeCache.txt.log
[cmake]       C:\CXXThirdParty\vcpkg\buildtrees\detect_compiler\config-wasm32-emscripten-out.log
[cmake] 
[cmake] Call Stack (most recent call first):
[cmake]   scripts/cmake/vcpkg_configure_cmake.cmake:314 (vcpkg_execute_required_process)
[cmake]   scripts/detect_compiler/portfile.cmake:18 (vcpkg_configure_cmake)
[cmake]   scripts/ports.cmake:192 (include)
[cmake] 
[cmake] 
[cmake] error: vcpkg was unable to detect the active compiler's information. See above for the CMake failure output.
[cmake] -- Running vcpkg install - failed
[cmake] CMake Error at C:/CXXThirdParty/vcpkg/scripts/buildsystems/vcpkg.cmake:904 (message):
[cmake]   vcpkg install failed.  See logs for more information:
[cmake]   C:\Workspace\VSCode_Workspace\Test001\build\vcpkg-manifest-install.log
[cmake] Call Stack (most recent call first):
[cmake]   CMakeLists.txt:6 (include)
[cmake] -- Configuring incomplete, errors occurred!
[cmake] 
[cmake] 
[proc] The command: "C:\Program Files\CMake\bin\cmake.EXE" -DCMAKE_BUILD_TYPE:STRING=Release -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=TRUE --no-warn-unused-cli -SC:/Workspace/VSCode_Workspace/Test001 -Bc:/Workspace/VSCode_Workspace/Test001/build -G Ninja exited with code: 1
[visual-studio] Patch Windows SDK path from C:\Program Files (x86)\Windows Kits\10\bin\x64 to C:\Program Files (x86)\Windows Kits\10\bin\10.0.22621.0\x64 for C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Auxiliary\Build\vcvarsall.bat

[dg0yt]

However, when I used the manifest mode, the build failed. I'm not sure where the problem lies.

I would guess that your manifest mode build didn't get the environment variables from emsdk_env.

[bowenxuuu]

How can I ensure that vcpkg picks up the environment variables when building WASM in manifest mode?

[carbon-seven]

sorry for the necro but for anyone coming across,

you probably need to specify the CACHE and FORCE option in the set(), so try
set(VCPKG_TARGET_TRIPLET "wasm32-emscripten" CACHE STRING "wasm triplet" FORCE)

i was able to specify my x64-windows-static triplet for static libs linking via CMakePresets.json:

{
  "version": 2,
  "configurePresets": [
    {
      "name": "vcpkg-debug",
      "displayName": "vcpkg Debug",
      "binaryDir": "${sourceDir}/build/debug",
      "generator": "Ninja",
      "cacheVariables": {
        "CMAKE_TOOLCHAIN_FILE": "$env{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake",
        "CMAKE_BUILD_TYPE": "Debug",
        "VCPKG_TARGET_TRIPLET": "x64-windows-static"     <---This
      }
    }
}

[Fighter19]

Your problem isn't manifest mode, but CMakePresets not sourcing EMSDK.
Claude suggested to add this:

"VCPKG_CHAINLOAD_TOOLCHAIN_FILE": "$env{EMSDK}/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake",

to the cacheVariables of your WebAsm config, which seems to make sense, and works for me.

EDIT: Don't forget to clear the build directory, the compiler detection has to re-run.