Bazel.md

Bazel* build support

The main build system of oneTBB is CMake*. Bazel* support is community-based. The Bazel configuration may not include recommended compiler and/or linker flags used in the official CMake configuration.

---

NOTE

Bazel is not recommended for use by oneTBB maintainers. Thus, it is not used internally.

---

The Bazel oneTBB build is currently only intended for a subset of oneTBB that suffices restricted use cases. Pull requests to improve the Bazel build experience are welcome.

The standard Bazel approach to handling third-party libraries is static linking. It is the best practice within the Bazel ecosystem.

Using oneTBB as a dependency

This example demonstrates how to use oneTBB as a dependency within a Bazel project.

The following file structure is assumed:

example
├── .bazelrc
├── BUILD.bazel
├── main.cpp
└── WORKSPACE.bazel

WORKSPACE.bazel:

load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")

git_repository(
    name = "oneTBB",
    branch = "master",
    remote = "https://github.com/oneapi-src/oneTBB/",
)

In the WORKSPACE file, the oneTBB GitHub* repository is fetched.

BUILD.bazel:

cc_binary(
    name = "Demo",
    srcs = ["main.cpp"],
    deps = ["@oneTBB//:tbb"],
)

The BUILD file defines a binary named Demo that has a dependency to oneTBB.

main.cpp:

#include "oneapi/tbb/version.h"

#include <iostream>

int main() {
    std::cout << "Hello from oneTBB "
              << TBB_VERSION_MAJOR << "."
              << TBB_VERSION_MINOR << "."
              << TBB_VERSION_PATCH
              << "!" << std::endl;

    return 0;
}

The expected output of this program is the current version of oneTBB.

Switch to the folder with the files created earlier and run the binary with bazel run //:Demo.

Build oneTBB using Bazel

Run bazel build //... in the oneTBB root directory.

Compiler support

The Bazel build uses the compiler flag -mwaitpkg in non-Windows* builds. This flag is supported by the GNU* Compiler Collection (GCC) version 9.3, Clang* 12, and newer versions of those tools.

---

NOTE

To use the Bazel build with earlier versions of GCC, remove -mwaitpkg flag as it leads to errors during compilation.

---