Changelog r19

Changelog

Report issues to GitHub.

For Android Studio issues, follow the docs on the Android Studio site.

Announcements

• Developers should begin testing their apps with LLD. AOSP has switched to using LLD by default and the NDK will use it by default in the next release. BFD and Gold will be removed once LLD has been through a release cycle with no major unresolved issues (estimated r21). Test LLD in your app by passing -fuse-ld=lld when linking.

  Note: lld does not currently support compressed symbols on Windows. See Issue 888. Clang also cannot generate compressed symbols on Windows, but this can be a problem when using artifacts built from Darwin or Linux.

• The Play Store will require 64-bit support when uploading an APK beginning in August 2019. Start porting now to avoid surprises when the time comes. For more information, see this blog post.

• Issue 780: Standalone toolchains are now unnecessary. Clang, binutils, the sysroot, and other toolchain pieces are now all installed to $NDK/toolchains/llvm/prebuilt/<host-tag> and Clang will automatically find them. Instead of creating a standalone toolchain for API 26 ARM, instead invoke the compiler directly from the NDK:

  $ $NDK/toolchains/llvm/prebuilt/<host-tag>/bin/armv7a-linux-androideabi26-clang++ src.cpp
  

  For r19 the toolchain is also installed to the old path to give build systems a chance to adapt to the new layout. The old paths will be removed in r20.

  The make_standalone_toolchain.py script will not be removed. It is now unnecessary and will emit a warning with the above information, but the script will remain to preserve existing workflows.

  If you're using ndk-build, CMake, or a standalone toolchain, there should be no change to your workflow. This change is meaningful for maintainers of third-party build systems, who should now be able to delete some Android-specific code. For more information, see the Build System Maintainers guide.

• ndk-depends has been removed. We believe that ReLinker is a better solution to native library loading issues on old Android versions.

• Issue 862: The GCC wrapper scripts which redirected to Clang have been removed, as they are not functional enough to be drop in replacements.

r19c

• Issue 912: Prevent the CMake toolchain file from clobbering a user specified CMAKE_FIND_ROOT_PATH.
• Issue 920: Fix clang wrapper scripts on Windows.

r19b

• Issue 855: ndk-build automatically disables multithreaded linking for LLD on Windows, where it may hang. It is not possible for the NDK to detect this situation for CMake, so CMake users and custom build systems must pass -Wl,--no-threads when linking with LLD on Windows.
• Issue 849: Fixed unused command line argument warning when using standalone toolchains to compile C code.
• Issue 890: Fixed CMAKE_FIND_ROOT_PATH. CMake projects will no longer search the host's sysroot for headers and libraries.
• Issue 906: Explicitly set -march=armv7-a for 32-bit ARM to workaround Clang not setting that flag automatically when using -fno-integrated-as. This fix only affects ndk-build and CMake. Standalone toolchains and custom build systems will need to apply this fix themselves.
• Issue 907: Fixed find_path for NDK headers in CMake.

Changes

• Updated Clang to r339409.

  • C++ compilation now defaults to C++14.

• Issue 780: A complete NDK toolchain is now installed to the Clang directory. See the announcements section for more information.

• ndk-build no longer removes artifacts from NDK_LIBS_OUT for ABIs not present in APP_ABI. This enables workflows like the following:

  for abi in armeabi-v7a arm64-v8a x86 x86_64; do
      ndk-build APP_ABI=$abi
  done

  Prior to this change, the above workflow would remove the previously built ABI's artifacts on each successive build, resulting in only x86_64 being present at the end of the loop.

• ndk-stack has been rewritten in Python.

• Issue 776: To better support LLD, ndk-build and CMake no longer pass -Wl,--fix-cortex-a8 by default.

  • CPUs that require this fix are uncommon in the NDK's supported API range (16+).
  • If you need to continue supporting these devices, add -Wl,--fix-cortex-a8 to your APP_LDFLAGS or CMAKE_C_FLAGS, but note that LLD will not be adding support for this workaround.
  • Alternatively, use the Play Console to blacklist Cortex-A8 CPUs to disallow your app from being installed on those devices.

• Issue 798: The ndk-build and CMake options to disable RelRO and noexecstack are now ignored. All code is built with RelRO and non-executable stacks.

• Issue 294: All code is now built with a subset of compiler-rt to provide a complete set of compiler built-ins for Clang.

Known Issues

• This is not intended to be a comprehensive list of all outstanding bugs.
• Issue 888: lld does not support compressed symbols on Windows. Clang also cannot generate compressed symbols on Windows, but this can be a problem when using artifacts built from Darwin or Linux.
• Issue 360: thread_local variables with non-trivial destructors will cause segfaults if the containing library is dlcloseed on devices running M or newer, or devices before M when using a static STL. The simple workaround is to not call dlclose.
• Issue 70838247: Gold emits broken debug information for AArch64. AArch64 still uses BFD by default.
• Issue 855: LLD may hang on Windows when using multithreaded linking. ndk-build will automatically disable multithreaded linking in this situation, but CMake users and custom build systems should pass -Wl,--no-threads when using LLD on Windows. The other linkers and operating systems are unaffected.
• Issue 884: Third-party build systems must pass -fno-addrsig to Clang for compatibility with binutils. ndk-build, CMake, and standalone toolchains handle this automatically.
• Issue 906: Clang does not pass -march=armv7-a to the assembler when using -fno-integrated-as. This results in the assembler generating ARMv5 instructions. Note that by default Clang uses the integrated assembler which does not have this problem. To workaround this issue, explicitly use -march=armv7-a when building for 32-bit ARM with the non-integrated assembler, or use the integrated assembler. ndk-build and CMake already contain these workarounds.
• This version of the NDK is incompatible with the Android Gradle plugin version 3.0 or older. If you see an error like No toolchains found in the NDK toolchains folder for ABI with prefix: mips64el-linux-android, update your project file to use plugin version 3.1 or newer. You will also need to upgrade to Android Studio 3.1 or newer.