[BUG] NDK 23.0 with CMake 3.21: "clang++ is not able to compile a simple test program"

[Boris-Rasin]

---

Description

Build error:

    [2/2] Linking CXX executable cmTC_3a497
    FAILED: cmTC_3a497 
    cmd.exe /C "cd . && C:\Users\admin\AppData\Local\Android\Sdk\ndk\23.0.7599858\toolchains\llvm\prebuilt\windows-x86_64\bin\clang++.exe --target=x86_64-none-linux-android16 --sysroot=C:/Users/admin/AppData/Local/Android/Sdk/ndk/23.0.7599858/toolchains/llvm/prebuilt/windows-x86_64/sysroot -DANDROID -fdata-sections -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security -fexceptions -frtti -stdlib=libc++  -O2 -g -DNDEBUG -Wl,--build-id=sha1 -Wl,--no-rosegment -Wl,--fatal-warnings -Qunused-arguments -Wl,--no-undefined  -Wl,--gc-sections CMakeFiles/cmTC_3a497.dir/testCXXCompiler.cxx.o -o cmTC_3a497  -static-libstdc++ -latomic -lm && cd ."
    ld: error: cannot open crtbegin_dynamic.o: No such file or directory
    ld: error: unable to find library -lc++
    ld: error: cannot open crtend_android.o: No such file or directory
    clang++: error: linker command failed with exit code 1 (use -v to see invocation)
    ninja: build stopped: subcommand failed.

Defining ANDROID_USE_LEGACY_TOOLCHAIN_FILE=ON fixes the problem.

Test case:
https://github.com/scapix-com/example1
Open folder ui/android
Remove ANDROID_USE_LEGACY_TOOLCHAIN_FILE=ON to see the error.

Environment Details

• NDK version: 23.0.7599858
• Build system: CMake 3.21.1
• Host OS: Windows, macOS

[DanAlbert]

Reduced test case (CMake must be 3.21+):

$ cat ./foo.cpp
int main(int argc, char** argv) {
  return 0;
}
$ cat ./CMakeLists.txt
cmake_minimum_required(VERSION 3.6.0)

add_executable(foo foo.cpp)
$ cat ./build.sh
#!/bin/sh
if [ $# -lt 1 ]; then
  >&2 echo "usage: ./build.sh NDK_PATH"
  exit 1
fi

set -e

NDK_PATH=$(realpath $1)

cd "$(dirname "$0")"
rm -rf build
mkdir build
cd build
cmake \
  -GNinja \
  -DANDROID_ABI=x86_64 \
  -DANDROID_PLATFORM=android-16 \
  -DCMAKE_TOOLCHAIN_FILE=$NDK_PATH/build/cmake/android.toolchain.cmake \
  ${@:2} ..

ninja -v

The difference is that our toolchain was automatically pulling up android-16 to android-21 for LP64 targets. AGP doesn't do that, nor does CMake. I'm not sure if we can work around that or if AGP just needs to stop asking for configurations that don't exist.

Triaged to r23b to at least figure that out. If it requires an AGP fix we probably need to disable it by default for a year or so while AGP catches up.

[DanAlbert]

It looks like the new toolchain doesn't do any of the API level clamping the old one did. I'm guessing that wasn't intentional.

[DanAlbert]

The fix needed a fix: https://android-review.googlesource.com/c/platform/ndk/+/1826816/. Whoever does the cherry-picks make sure you get both :)

[rprichard]

Fixed in r23b.