The Bazel team is happy to announce a new version of Bazel, Bazel 0.20.

With this release, we communicate breaking changes following our communication policy.

Breaking changes in 0.20:

• --incompatible_remove_native_http_archive
• --incompatible_remove_native_git_repository
• --incompatible_disable_cc_toolchain_label_from_crosstool_proto
• --incompatible_disable_depset_in_cc_user_flags
• --incompatible_disable_cc_configuration_make_variables
• --incompatible_disallow_conflicting_providers
• --incompatible_range_type

Changes for which 0.20 is a migration window are marked with GitHub label 'migration-0.20'

Breaking changes in the next release (0.21) are marked with GitHub label 'breaking-change-0.21'

General Changes

• (Linux only) Bazel now shuts down when idle for 5 minutes and the system is low on RAM.
• We're deprecating --genrule_strategy=<value> with the intent of removing it in early 2019; please use --strategy=Genrule=<value> instead (see #6760).
• Bazel now queryies remote server Capabilities (per REAPI v2)
• Use different server log files per Bazel server process; java.log is now a symlink to the latest log.
• The code coverage report now includes the actual paths to header files instead of the ugly, Bazel generated, virtual includes path.
• Bazel sorts remote Platform properties for remote execution.

C++

• The --experimental_no_dotd_scanning_with_modules command line argument is not supported anymore.
• The --prune_cpp_modules command line option is not supported anymore.
• The --experimental_prune_cpp_input_discovery command line option is not supported anymore.
• All cc_toolchains depended on from cc_toolchain_suite.toolchains are now analyzed when not using platforms in order to select the right cc_toolchain.
• CROSSTOOL file is now read from the package of cc_toolchain, not from the package of cc_toolchain_suite. This is not expected to break anybody since cc_toolchain_suite and cc_toolchain are commonly in the same package.
• All cc_toolchains dependent on from cc_toolchain_suite.toolchains are now analyzed when not using platforms in order to select the right cc_toolchain.

Java

• The--explicit_jre_deps flag is removed.
• If the --javabase flag is unset, Bazel locates a JDK using the JAVA_HOME environment variable and searching the PATH. If no JDK is found, --javabase is empty and builds targeting Java will not be supported. Previously Bazel would fall back to using the embedded JDK as a --javabase, but this is no longer default behaviour. A JDK should be explicitly installed instead to enable Java development.

Android

• Added support for Android NDK r18.
• Make legacy-test-support (legacy_test-<api-level>) from android_sdk_repository neverlink. The legacy test support libraries shouldn't be built into test binaries. To make them available at runtime, developers should declare them via uses-library.

Starlark

• All overrides of Starlark's ctx.new_file function are now deprecated. Try the --incompatible_new_actions_api flag to ensure your code is forward-compatible.
• The function attr.license is deprecated. It can be disabled now with --incompatible_no_attr_license.
• The 'default' parameter of attr.output and attr.output_list has been removed. This is controlled by --incompatible_no_output_attr_default
• A number of platform-related Starlark APIs which were previously marked "experimental" are now disabled by default, and may be enabled via --experimental_platforms_api

Community

• Jetbrains published a Bazel plugin for the TeamCity CI system.
• Tony Aiuto talked about Bazel in a Google Cloud Platform postcast.
• Martin Probst made a presentation of Bazel at AngularConnect 2018, called “Why you need a build system, and why it should be Bazel”.
• Minko Gechev wrote a blog post about how to build TypeScript projects with Bazel.
• Torgeir Helgevold wrote about Remote Build Execution With Bazel And Svelte.
• Matteo Di Lena started a new rule for building Maya plugins.