cross compile error about corrade

[mosra]

Yay, glad to hear that! 🎉

Keeping this open until I add a better error message to the toolchain file as I mentioned above.

[linuxaged]

Yep, cross-building maybe not so friendly to a newcomer like me, but magnum is still a great project especially the architecture, i can hold on. Good job!

Fixed, thanks!

[mosra]

Since mosra/toolchains@c6eaa23 there's an explicit error message when Visual Studio generator is used with Emscripten, explaining what to do instead.

[mosra]

Hi!

This is a common issue on Windows -- CMake uses Visual Studio project files as a default generator on Windows, but Visual Studio projects insist on using MSVC as a compiler (so emcc supplied by the Emscripten toolchain will get ignored). Solution is to specify a different generator (e.g. -G Ninja, if you have Ninja installed). The troubleshooting docs contain more information, including how to use Ninja that's bundled in VS installations.

Since you're not the first person running into this, I'll look if this could be handled with a better error message in the toolchain file itself.

[linuxaged]

Yet, Get another error when generate Ninja project:

C:\workspace\corrade\build-emscripten>cmake .. -G Ninja -DCMAKE_MAKE_PROGRAM="C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\CommonExtensions\Microsoft\CMake\Ninja\ninja.exe" -DCMAKE_TOOLCHAIN_FILE="../toolchains/generic/Emscripten-wasm.cmake"  -DCMAKE_BUILD_TYPE=Release  -DEMSCRIPTEN_PREFIX="C:/workspace/emsdk" -DCMAKE_INSTALL_PREFIX="C:/lib/emscripten/system"
-- The CXX compiler identification is unknown
CMake Error at CMakeLists.txt:50 (project):
  The CMAKE_CXX_COMPILER:

    C:/workspace/emsdk/em++.bat

  is not a full path to an existing compiler tool.

  Tell CMake where to find the compiler by setting either the environment
  variable "CXX" or the CMake cache entry CMAKE_CXX_COMPILER to the full path
  to the compiler, or to the compiler name if it is in the PATH.


-- Configuring incomplete, errors occurred!
See also "C:/workspace/corrade/build-emscripten/CMakeFiles/CMakeOutput.log".
See also "C:/workspace/corrade/build-emscripten/CMakeFiles/CMakeError.log".

[mosra]

Windows is not my primary system and I don't know much about emsdk, so I'm afraid I won't be able to help much... :/

Does C:/workspace/emsdk/em++.bat exist at all? Alternatively, if you have em++.bat in PATH, CMake should be able to pick that up correctly as well.

[linuxaged]

My fault, have assigned wrong value to EMSCRIPTEN_PREFIX, em++.bat is located in emsdk/emscripten/1.38.30.
Ninja project has been generated! Thanks.

[linuxaged]

By the way, got another cmake error when building magnum target WASM,
there're UseCorrade.cmake CorradeLibSuffix.cmake files in my C:\lib\emscripten\system\share\cmake\Corrade folder, how did cmake not find them with find_path?

C:\workspace\magnum\build-emscripten>cmake .. -G Ninja -DCMAKE_MAKE_PROGRAM="C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\CommonExtensions\Microsoft\CMake\Ninja\ninja.exe" -DCMAKE_TOOLCHAIN_FILE="../toolchains/generic/Emscripten-wasm.cmake"  -DCMAKE_BUILD_TYPE=Release  -DEMSCRIPTEN_PREFIX="C:/workspace/emsdk/emscripten/1.38.30" -DCMAKE_PREFIX_PATH="C:/lib/emscripten/system" -DCMAKE_INSTALL_PREFIX="C:/lib/emscripten/system" -DMAGNUM_DEPLOY_PREFIX="C:/http/magnum" -DWITH_SDL2APPLICATION=ON -DCORRADE_INCLUDE_DIR="C:/lib/emscripten/system/include"
CMake Error at modules/FindCorrade.cmake:291 (file):
  file failed to open for reading (No such file or directory):

    C:/workspace/magnum/_CORRADE_CONFIGURE_FILE-NOTFOUND
Call Stack (most recent call first):
  CMakeLists.txt:52 (find_package)


CMake Error at C:/Program Files/CMake/share/cmake-3.15/Modules/FindPackageHandleStandardArgs.cmake:137 (message):
  Could NOT find Corrade (missing: _CORRADE_MODULE_DIR
  _CORRADE_CONFIGURE_FILE Containers Utility)
Call Stack (most recent call first):
  C:/Program Files/CMake/share/cmake-3.15/Modules/FindPackageHandleStandardArgs.cmake:378 (_FPHSA_FAILURE_MESSAGE)
  modules/FindCorrade.cmake:552 (find_package_handle_standard_args)
  CMakeLists.txt:52 (find_package)


-- Configuring incomplete, errors occurred!
See also "C:/workspace/magnum/build-emscripten/CMakeFiles/CMakeOutput.log".
See also "C:/workspace/magnum/build-emscripten/CMakeFiles/CMakeError.log".

[mosra]

Cross-compilation with CMake is painful, right? 🙈

Have a look at this part of the troubleshooting guide -- in particular, adding -DCMAKE_FIND_ROOT_PATH=C:/lib/emscripten/system could help. Hopefully (this is one featurebug of CMake I still don't understand, even after 10 years of using it). And then you shouldn't need to specify -DCORRADE_INCLUDE_DIR.

The "nuclear" solution when everything goes wrong is opening CMake GUI in the directory and pointing all CORRADE_* variables to the dirs/files manually. But that's really the most desperate solution when everything else fails.