Building CMake projects

  • Build libraries/binaries with CMake from sources using cmake rule
  • Use cmake targets in cc_library, cc_binary targets as dependency
  • Bazel cc_toolchain parameters are used inside cmake build
  • See full list of cmake arguments below 'example'
  • Works on Ubuntu, Mac OS and Windows (see special notes below in Windows section) operating systems

Example: (Please see full examples in ./examples)

The example for Windows is below, in the section 'Usage on Windows'.

  • In WORKSPACE.bazel, we use a http_archive to download tarballs with the libraries we use.
  • In BUILD.bazel, we instantiate a cmake rule which behaves similarly to a cc_library, which can then be used in a C++ rule (cc_binary in this case).

In WORKSPACE.bazel, put

workspace(name = "rules_foreign_cc_usage_example")

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

# Rule repository, note that it's recommended to use a pinned commit to a released version of the rules
   name = "rules_foreign_cc",
   sha256 = "c2cdcf55ffaf49366725639e45dedd449b8c3fe22b54e31625eb80ce3a240f1e",
   strip_prefix = "rules_foreign_cc-0.1.0",
   url = "",

load("@rules_foreign_cc//foreign_cc:repositories.bzl", "rules_foreign_cc_dependencies")

# This sets up some common toolchains for building targets. For more details, please see

    name = "all_srcs",
    srcs = glob(["**"]),
    visibility = ["//visibility:public"],

# pcre source code repository
    name = "pcre",
    build_file_content = _ALL_CONTENT,
    strip_prefix = "pcre-8.43",
    urls = [
    sha256 = "0b8e7465dc5e98c757cc3650a20a7843ee4c3edf50aaf60bb33fd879690d2c73",

And in the BUILD.bazel file, put:

load("@rules_foreign_cc//foreign_cc:defs.bzl", "cmake")

    name = "pcre",
    cache_entries = {
        "CMAKE_C_FLAGS": "-fPIC",
    lib_source = "@pcre//:all_srcs",
    out_static_libs = ["libpcre.a"],

then build as usual:

bazel build //:pcre

Usage on Windows

When using on Windows, you should start Bazel in MSYS2 shell, as the shell script inside cmake assumes this. Also, you should explicitly specify make commands and option to generate CMake crosstool file.

The default generator for CMake will be detected automatically, or you can specify it explicitly.

The tested generators: Visual Studio 15, Ninja and NMake. The extension .lib is assumed for the static libraries by default.

Example usage (see full example in ./examples/cmake_hello_world_lib): Example assumes that MS Visual Studio and Ninja are installed on the host machine, and Ninja bin directory is added to PATH.

    # expect to find ./lib/hello.lib as the result of the build
    name = "hello",
    # This option can be omitted
    generate_args = [
        "-G \"Visual Studio 16 2019\"",
        "-A Win64",
    lib_source = ":srcs",

    name = "hello_ninja",
    # expect to find ./lib/hello.lib as the result of the build
    lib_name = "hello",
    # explicitly specify the generator
    generate_args = ["-GNinja"],
    lib_source = ":srcs",

    name = "hello_nmake",
    # explicitly specify the generator
    generate_args = ["-G \"NMake Makefiles\""],
    lib_source = ":srcs",
    # expect to find ./lib/hello.lib as the result of the build
    out_static_libs = ["hello.lib"],



Rule for building external library with CMake.


A unique name for this target.


deprecated: Please use the build_data attribute.


deprecated: Please use the build_data attribute.

Optional. if true, link all the object files from the static library, even if they are not used.


Arguments for the CMake build command


Files needed by this rule only during build/compile time. May list file or rule targets. Generally allows any target.


CMake cache entries to initialize (they will be passed with -Dkey=value) Values, defined by the toolchain, will be joined with the values, passed here. (Toolchain values come first)


Optional. Add these options to the compile flags passed to the foreign build system. The flags only take affect for compiling this target, not its dependencies.


Files needed by this rule at runtime. May list file or rule targets. Generally allows any target.


Optional compilation definitions to be passed to the dependencies of this library. They are NOT passed to the compiler, you should duplicate them in the configuration options.


Optional dependencies to be copied into the directory structure. Typically those directly required for the external building of the library/binaries. (i.e. those that the external build system will be looking for and paths to which are provided by the calling rule)


Environment variables to set during the build. $(execpath) macros may be used to point at files which are listed as data, deps, or build_data, but unlike with other rules, these will be replaced with absolute paths to those files, because the build does not run in the exec root. No other macros are supported.Variables containing PATH (e.g. PATH, LD_LIBRARY_PATH, CPATH) entries will be prepended to the existing variable.


Arguments for CMake's generate command. Arguments should be passed as key/value pairs. eg: ["-G Ninja", "--debug-output", "-DFOO=bar"]. Note that unless a generator (-G) argument is provided, the default generators are Unix Makefiles for Linux and MacOS and Ninja for Windows.


When True, CMake crosstool file will be generated from the toolchain values, provided cache-entries and env_vars (some values will still be passed as -Dkey=value and environment variables). If CMAKE_TOOLCHAIN_FILE cache entry is passed, specified crosstool file will be used When using this option to cross-compile, it is required to specify CMAKE_SYSTEM_NAME in the cache_entries


If True, the cmake --install comand will be performed after a build


Arguments for the CMake install command


Library name. Defines the name of the install directory and the name of the static library, if no output files parameters are defined (any of static_libraries, shared_libraries, interface_libraries, binaries_names) Optional. If not defined, defaults to the target's name.


Label with source code to build. Typically a filegroup for the source of remote repository. Mandatory.


Optional link options to be passed up to the dependencies of this library


Optional name of the output subdirectory with the binary files, defaults to 'bin'.


Optional names of the resulting binaries.


Optional names of additional directories created by the build that should be declared as bazel action outputs


Flag variable to indicate that the library produces only headers


Optional name of the output subdirectory with the header files, defaults to 'include'.


Optional names of the resulting interface libraries.


Optional name of the output subdirectory with the library files, defaults to 'lib'.


Optional names of the resulting shared libraries.


Optional names of the resulting static libraries. Note that if out_headers_only, out_static_libs, out_shared_libs, and out_binaries are not set, default lib_name.a/lib_name.lib static library is assumed


Optional part of the shell script to be added after the make commands


A list of targets with in the foreign build system to produce. An empty string ("") will result in a call to the underlying build system with no explicit target set


A prefix for build commands


deprecated: Please use the build_data attribute.


Working directory, with the main CMakeLists.txt (otherwise, the top directory of the lib_source label files is used.)

Macros and Functions


Wrapper macro around the cmake() rule to force usage of the given make variant toolchain.


The target name


The desired make variant toolchain to use, e.g. @rules_foreign_cc//toolchains:preinstalled_nmake_toolchain


Remaining keyword arguments