docs/changelogs/Changelog-r28.md

# Changelog

Report issues to [GitHub].

For Android Studio issues, go to https://b.android.com and file a bug using the
Android Studio component, not the NDK component.

If you're a build system maintainer that needs to use the tools in the NDK
directly, see the [build system maintainers guide].

[GitHub]: https://github.com/android/ndk/issues
[build system maintainers guide]:
  https://android.googlesource.com/platform/ndk/+/master/docs/BuildSystemMaintainers.md

## Announcements

- The 16 KiB page size compatibility option that was added in r27 is now on by
  default. If necessary, you can still opt-out (see below).

## Changes

- Updated LLVM to clang-r530567b. See `clang_source_info.md` in the toolchain
  directory for version information.
  - Runtime libraries for non-Android have been removed reduce disk usage.
  - libc++ now includes debug info to aid debugging. This may make
    libc++_shared.so and any binaries that link libc++_static.a much larger
    before they are stripped. The Android Gradle Plugin will strip binaries when
    creating APKs, so this should not affect production apps.
  - [Issue 2046]: libclang and libclang-cpp are now supported.
- `PAGE_SIZE` is no longer defined by default for arm64-v8a or x86_64. To
  re-enable, set `APP_SUPPORT_FLEXIBLE_PAGE_SIZES` (ndk-build) or
  `ANDROID_SUPPORT_FLEXIBLE_PAGE_SIZES` (CMake) to false. See [Support 16 KB
  page sizes] for more information.
- The default alignment of shared libraries for arm64-v86 and x86_64 is now 16k.
  To revert to 4k alignment, set `APP_SUPPORT_FLEXIBLE_PAGE_SIZES` (ndk-build)
  or `ANDROID_SUPPORT_FLEXIBLE_PAGE_SIZES` (CMake) to false. See [Support 16 KB
  page sizes] for more information.
- [Issue 1307]: Removed non-NDK binder headers. A number of binder headers that
  should have been shipped with aidl were mistakenly shipped in the NDK. These
  headers are tightly coupled to the version of aidl used, so this introduced an
  unwanted version restriction between build-tools and the NDK. If you are using
  the NDK aidl backend, you will need to pass the aidl include path when
  building. See the [aidl backend] docs for more information.
- [Issue 2058]: [Weak API references] now work for libc APIs. This was enabled
  by conditionally removing the `#if __ANDROID_API__ >= ...` guards that
  previously wrapped declarations in libc headers when weak API references are
  used. When weak API references are not used (the default behavior), the
  declarations will still be hidden by the preprocessor.

  If your project contains polyfills for any of those APIs **and uses weak API
  references**, this change may break your build due to the conflicting
  declarations. The simplest fix is to rename your polyfill to not collide with
  libc. For example, rename `conflicting_api` to `conflicting_api_fallback` and
  call that instead. Use `#define conflicting_api() conflicting_api_fallback()`
  if you want to avoid rewriting callsites.

  Please open a bug if you run into issues with existing polyfills. We may be
  able to add the polyfill directly to the NDK.

[aidl backend]: https://source.android.com/docs/core/architecture/aidl/aidl-backends#core-build-system
[Issue 1307]: https://github.com/android/ndk/issues/1307
[Issue 2046]: https://github.com/android/ndk/issues/2046
[Issue 2058]: https://github.com/android/ndk/issues/2058
[Weak API references]: https://developer.android.com/ndk/guides/using-newer-apis

[Support 16 KB page sizes]:
  https://developer.android.com/guide/practices/page-sizes