Bazel Blog

Bazel 0.19

The Bazel team is happy to announce a new version of Bazel, Bazel 0.19.

This document lists the major changes since Bazel 0.18.

General changes

  • The --incompatible_expand_directories flag automatically expands directories in command lines. See the design document.

  • The --loading_phase_threads flag now defaults to auto instead of 200, which at the moment corresponds to the number of CPUs. This is appropriate for most users. However, if your sources reside on a network file system, increasing this value may yield better analysis-time performance when disk caches are cold.


  • Fixed missing debug symbols when building native code with --compilation_mode=dbg that target Android ARM architectures by adding the -g flag.


  • Added --incompatible_disable_legacy_flags_cc_toolchain_api to deprecate legacy cc_toolchain Starlark API for legacy CROSSTOOL fields. Tracking issue is #6434. See the instructions for migration.

  • Runfiles in cc_test: the C++ runfiles library (@bazel_tools//tools/cpp/runfiles) can now create Runfiles objects for tests. See //tools/cpp/runfiles/runfiles_src.h in the Bazel source tree for documentation.

  • :cc_binary link action no longer hardcodes -static-libgcc for toolchains that support embedded runtimes (guarded by --experimental_dont_emit_static_libgcc temporarily).

  • The flag --experimental_enable_cc_configuration_make_variables is removed, use --incompatible_disable_cc_configuration_make_variables instead.


  • Bazel now requires a JDK to be installed as it no longer falls back to the internal JDK if the --javabase flag is not set. Instead, Bazel now searches for a JDK within the JAVA_HOME and PATH environment variables. If Bazel cannot find a JDK, it will not be able to run Java builds.

Code Coverage

  • LcovMerger was renamed to CoverageOutputGenerator. Please use --coverage_report_generator=@bazel_tools//tools/test/CoverageOutputGenerator/java/com/google/devtools/coverageoutputgenerator:Main

instead of the previous


Other Changes

  • Add --apple_compiler and --apple_grte_top options. These provide the equivalent of --compiler / --grte_top for the toolchain configured in --apple_crosstool_top.

  • There is now a same_pkg_direct_rdeps() query function.

  • Bazel now propagates remote errors to the user even if --verbose_failures=false is set.

  • The number of configured targets is now shown in the analysis phase status output.

  • Bazel will now check stderr instead of stdout to decide if it is outputting to a terminal. --isatty is deprecated, use --is_stderr_atty instead.

Future Changes

We will do incompatible changes in Bazel 0.20. We encourage you to migrate in advance (or report any migration difficulty) with the following flags:

Thank you to our contributors!

This release contains contributions from many people at Google, as well as Andreas Herrmann, Andreas Hippler, Benjamin Peterson, David Ostrovsky, Ed Baunton, George Gensure, Igal Tabachnik, Jason Gavris, Loo Rong Jie, rmalik, and Yannic Bonenberger

Thank you to everyone who contributed to this release!