CODEWITHSUNDEEP
c++bazel
ryancheung
ryancheung

Reputation: 3098

How to set C++ standard version when build with Bazel?

I'm kinda new to C++. I know how to set C++ version with CMake, but don't know how to set C++ version in Bazel.

Maybe set with the copts parameter in cc_libary but I have to set this in every cc_libary?

Upvotes: 30

Views: 36855

Answers (3)

Thomas Deniffel
Thomas Deniffel

Reputation: 173

Add this to your .bazelrc next to your WORKSPACE:

build --action_env=BAZEL_CXXOPTS="-std=c++20"

If you want to set multiple options, separate them with a colon:

build --action_env=BAZEL_CXXOPTS="-std=c++20:-Werror"

It is kind of a workaround as bazel sets an environment variable which bazel then uses. But it works.

BTW: build --cxxopt=-std=c++20 in the .bazelrc did not work form me.

Upvotes: 11

hlopko
hlopko

Reputation: 3270

To set the standard using the default C++ toolchain in Bazel you can set environment variable BAZEL_CXXOPTS, e.g. BAZEL_CXXOPTS="-std=c++14". You can also set it from the command line or from .bazelrc using --repo_env=BAZEL_CXXOPTS. : is the flag separator.

Alternatively you can pass --cxxopt to Bazel, or put it into .bazelrc, e.g. --cxxopt='-std=c++11'.

The robust solution to specifying C++ toolchain in Bazel is to use the CcToolchainConfigInfo. See the documentation at https://docs.bazel.build/versions/master/tutorial/cc-toolchain-config.html and https://docs.bazel.build/versions/master/cc-toolchain-config-reference.html.

Upvotes: 38

ryancheung
ryancheung

Reputation: 3098

bazel build --cxxopt='-std=c++11' main:hello-world This would work, but I wonder if there's way to set this cxxopt globally, like CMAKE_CXX_FLAGS.

Upvotes: 8

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