Problems attempting to build oboe c++ library using cmake on windows

Question

I am attempting to build 'oboe' on a windows machine using cmake (version 3.25.0) and a visual studio generator. The end goal is to create a c++ audio library that uses oboe as the back end for android, but as a first step simply geting oboe to build is the plan.

I have managed to succesfully generate build and use a static library with a few simple test functions using the method described below, but I run into errors when attempting to build oboe.

I have also managed to get oboe to build by using the method described in the documentation and doing add_subdirectory etc. in the CMakeLists file of android studio. However I am trying to generate/ build using cmake outside of android studio.

The oboe repo is found here: https://github.com/google/oboe

The toolchain file I am using is: 'android.toolchain.cmake' included in the NDK at the location: ndk version/build/cmake/android.toolchain.cmake

I use a batch script to automate generating/ building to several different android ABI's, inspired by a similar shell script included with the oboe repo 'build_all_android.sh'. The .bat script I made is shown below:

@echo OFF
set BUILD_DIR=build
set ANDROID_NDK=C:\Microsoft\AndroidNDK\android-ndk-r23c
set GENERATOR="Visual Studio 17 2022"

set CMAKE_GENERATOR=-G %GENERATOR%
set CMAKE_TOOLCHAIN_FILE=-DCMAKE_TOOLCHAIN_FILE=%ANDROID_NDK%\build\cmake\android.toolchain.cmake
set CMAKE_SYSTEM_NAME=-DCMAKE_SYSTEM_NAME=Android

set EXTRA_CMAKE_ARGS=-DBUILD_SHARED_LIBS=true -DANDROID_TOOLCHAIN=clang -DANDROID_STL=c++_static

CALL :build_android armeabi-v7a ARM 16
CALL :build_android arm64-v8a ARM64 21
CALL :build_android x86_64 x64 21
CALL :build_android x86 x86 16
EXIT /B %ERRORLEVEL% 



:build_android
set ABI_VERSION=%~1
set GENERATOR_PLATFORM=%~2
set MINIMUM_API_LEVEL=%~3
set CMAKE_ANDROID_ARCH_ABI=-DANDROID_ABI=%ABI_VERSION%
set ABI_BUILD_DIR=%BUILD_DIR%\%ABI_VERSION%
set CMAKE_GENERATOR_PLATFORM=-A %GENERATOR_PLATFORM%
set CMAKE_BUILD_DIR=-B %ABI_BUILD_DIR%
set CMAKE_MIN_API=-DANDROID_PLATFORM=android-%MINIMUM_API_LEVEL%

set CMAKE_ARGS=%CMAKE_BUILD_DIR% %CMAKE_ANDROID_ARCH_ABI% %CMAKE_GENERATOR% %CMAKE_GENERATOR_PLATFORM% %CMAKE_SYSTEM_NAME% %CMAKE_TOOLCHAIN_FILE% %CMAKE_MIN_API%

echo building for android ABI: %ABI_VERSION%
echo cmake arguments = %CMAKE_ARGS%
echo:

cmake %CMAKE_ARGS% %EXTRA_CMAKE_ARGS%
echo:

cmake --build %ABI_BUILD_DIR% --target ALL_BUILD

echo:
echo:

EXIT /B 0

When I run this using the ANDROID_NDK variable (line 3) pointing to the root of the up to date ndk that comes with the visual studio 2022 android tools, I get an error:

-- The C compiler identification is unknown
-- The CXX compiler identification is unknown
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - failed
-- Check for working C compiler: C:/Microsoft/AndroidNDK/android-ndk-r23c/toolchains/llvm/prebuilt/windows-x86_64/bin/clang.exe
-- Check for working C compiler: C:/Microsoft/AndroidNDK/android-ndk-r23c/toolchains/llvm/prebuilt/windows-x86_64/bin/clang.exe - broken
CMake Error at C:/Program Files/CMake/share/cmake-3.25/Modules/CMakeTestCCompiler.cmake:70 (message):
  The C compiler

    "C:/Microsoft/AndroidNDK/android-ndk-r23c/toolchains/llvm/prebuilt/windows-x86_64/bin/clang.exe"

  is not able to compile a simple test program.

  It fails with the following output:

    Change Dir: C:/Users/user/Documents/Code Projects/oboe/build/x86/CMakeFiles/CMakeScratch/TryCompile-pp2ibg

    Run Build Command(s):C:/Program Files/Microsoft Visual Studio/2022/Community/MSBuild/Current/Bin/amd64/MSBuild.exe cmTC_c21fb.vcxproj /p:Configuration=Debug /p:Platform=x86 /p:VisualStudioVersion=17.0 /v:m && MSBuild version 17.4.1+9a89d02ff for .NET Framework
      ANDROID_HOME=C:\\Microsoft\AndroidSDK\25
      ANDROID_SDK_ROOT=C:\\Microsoft\AndroidSDK\25
      ANT_HOME=
      JAVA_HOME=C:\Program Files\Android\jdk\jdk-8.0.302.8-hotspot\jdk8u302-b08
      NDK_ROOT=C:\Microsoft\AndroidNDK\android-ndk-r23c
      testCCompiler.c
      In file included from <built-in>:349:
    <command line>(1,9): warning : '__ANDROID_API__' macro redefined [-Wmacro-redefined] [C:\Users\user\Documents\Code Projects\oboe\build\x86\CMakeFiles\CMakeScratch\TryCompile-pp2ibg\cmTC_c21fb.vcxproj]
      #define __ANDROID_API__ 1
              ^
      <built-in>(342,9): note: previous definition is here
      #define __ANDROID_API__ __ANDROID_MIN_SDK_VERSION__
              ^
      1 warning generated.
      ld: error: cannot open crtbegin_so.o: No such file or directory
      ld: error: unable to find library -llog
      ld: error: unable to find library -landroid
      ld: error: cannot open crtend_so.o: No such file or directory
      clang: error: linker command failed with exit code 1 (use -v to see invocation)
    C:\Program Files\Microsoft Visual Studio\2022\Community\MSBuild\Microsoft\VC\v170\Application Type\Android\3.0\Android.Common.targets(125,5): error MSB6006: "clang.exe" exited with code 1. [C:\Users\user\Documents\Code Projects\oboe\build\x86\CMakeFiles\CMakeScratch\TryCompile-pp2ibg\cmTC_c21fb.vcxproj]

  CMake will not be able to correctly generate this project.

and cmake fails to generate the project. I can actually get this to generate correctly, but only if I set the android NDK version within the cross-compilation options of visual studio to use the NDK bundled with my installation of Android studio, and also set the ANDROID_NDK variable of the batch script to point to the same root. In this case, though cmake generates the project the build fails with a similar reason to the warning given above:

  Building Custom Rule C:/Users/user/Documents/Code Projects/oboe/CMakeLists.txt
  AAudioLoader.cpp
  In file included from <built-in>:404:
<command line>(1,9): error : '__ANDROID_API__' macro redefined [-Werror,-Wmacro-redefined] [C:\Users\user\Documents\Co
de Projects\oboe\build\x86\oboe.vcxproj]
  #define __ANDROID_API__ 16
          ^
  <built-in>(394,9): note: previous definition is here
  #define __ANDROID_API__ __ANDROID_MIN_SDK_VERSION__
          ^
  1 error generated.

Thanks in advance for any help, it is much appreciated!

Answer 1

Your build fails because you instruct the compiler to view the warning '__ANDROID_API__' macro redefined as an error. And this warning seems to occur because Visual Studio still sets the macro __ANDROID_API__ instead of setting __ANDROID_MIN_SDK_VERSION__. I think that is a Visual Studio bug that was introduced when they started shipping the NDK 23 instead of 21.

EDIT: This issue is being tracked here.