diff --git a/support/bazel/README.md b/support/bazel/README.md index ae5aded6b6a4..44af620c10ee 100644 --- a/support/bazel/README.md +++ b/support/bazel/README.md @@ -1,85 +1,73 @@ # Bazel support -Bazel is an open-source build tool. -More information about Bazel can be found [here](https://bazel.build/). +To get [Bazel](https://bazel.build/) working with {fmt} you can copy the files `BUILD.bazel`, `WORKSPACE.bazel`, `.bazelrc`, and `.bazelversion` from this folder (`support/bazel`) to the root folder of this project. This way {fmt} gets bazelized and can be used with Bazel (e.g. doing a `bazel build //...` on {fmt}). -## Using the fmt repository with Bazel +## Using {fmt} as a dependency -Even though the {fmt} repository does not contain a `WORKSPACE` file in its root directory, -there is an easy approach to use the {fmt} repository with Bazel out of the box. -This is demonstrated in the following example. +The following minimal example shows how to use {fmt} as a dependency within a Bazel project. -Add to your `WORKSPACE` file: +The following file structure is assumed: -```python -load("@bazel_tools//tools/build_defs/repo:git.bzl", "new_git_repository") - -# Fetch all files from fmt including the BUILD file `support/bazel/BUILD.bazel` -new_git_repository( - name = "fmt_workaround", - branch = "master", - remote = "https://github.com/fmtlib/fmt/", - build_file_content = "# Empty build file on purpose" -) - -# Now the BUILD file `support/bazel/BUILD.bazel` can be used: -new_git_repository( - name = "fmt", - branch = "master", - remote = "https://github.com/fmtlib/fmt/", - build_file = "@fmt_workaround//:support/bazel/BUILD.bazel" -) ``` - -Create a `BUILD.bazel` file and add a dependency to {fmt}: - -```python -cc_binary( # Build a binary - name = "Demo", # Name of the binary - srcs = ["main.cpp"], # List of files - we only have main.cpp - deps = ["@fmt//:fmt"], # Depend on fmt -) +example +├── BUILD.bazel +├── main.cpp +└── WORKSPACE.bazel ``` -Make use of {fmt} in `main.cpp`: +*main.cpp*: -```C++ +```c++ #include "fmt/core.h" int main() { - fmt::print("The answer is {}.\n", 42); + fmt::print("The answer is {}\n", 42); } ``` The expected output of this example is `The answer is 42`. -## Bazelize fmt - -First downloading a build file and then making use of it can be considered as a bit unclean, nevertheless, it works. - -A cleaner Bazel solution would be to move the `WORKSPACE` and `BUILD` files to the root folder of the {fmt} Git repository. - -In favor of keeping the {fmt} project directory clean, those files were not added to the project root directory. - -If you do not like this, you can fork this repository and move the files `BUILD.bazel`, `WORKSPACE.bazel`, `.bazelrc`, and `.bazelversion` from this folder (`support/bazel`) to the root folder of this project. - -This way {fmt} gets bazelized and can be used in your Bazel builds. - -**Example** - -Create a `WORKSPACE.bazel` file with the following content: +*WORKSPACE.bazel*: ```python load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository") -# Fetch bazelized fmt git_repository( name = "fmt", - branch = "bazel-support", # A copy of master where BUILD.bazel, WORKSPACE.bazel, .bazelrc and .bazelversion are moved to root - remote = "https://github.com//fmt", # replace by a valid account + branch = "master", + remote = "https://github.com/fmtlib/fmt", + patch_cmds = [ + "mv support/bazel/.bazelrc .bazelrc", + "mv support/bazel/.bazelversion .bazelversion", + "mv support/bazel/BUILD.bazel BUILD.bazel", + "mv support/bazel/WORKSPACE.bazel WORKSPACE.bazel", + ], + # Windows-related patch commands are only needed in the case MSYS2 is not installed. + # More details about the installation process of MSYS2 on Windows systems can be found here: + # https://docs.bazel.build/versions/main/install-windows.html#installing-compilers-and-language-runtimes + # Even if MSYS2 is installed the Windows related patch commands can still be used. + patch_cmds_win = [ + "Move-Item -Path support/bazel/.bazelrc -Destination .bazelrc", + "Move-Item -Path support/bazel/.bazelversion -Destination .bazelversion", + "Move-Item -Path support/bazel/BUILD.bazel -Destination BUILD.bazel", + "Move-Item -Path support/bazel/WORKSPACE.bazel -Destination WORKSPACE.bazel", + ], ) ``` -Create a `BUILD.bazel` file and add a dependency to {fmt} (same as above). +In the *WORKSPACE* file, the {fmt} GitHub repository is fetched. Using the attribute `patch_cmds` the files `BUILD.bazel`, `WORKSPACE.bazel`, `.bazelrc`, and `.bazelversion` are moved to the root of the {fmt} repository. This way the {fmt} repository is recognized as a bazelized workspace. + +*BUILD.bazel*: + +```python +cc_binary( + name = "Demo", + srcs = ["main.cpp"], + deps = ["@fmt"], +) +``` + +The *BUILD* file defines a binary named `Demo` that has a dependency to {fmt}. + +To execute the binary you can run `bazel run //:Demo`. -Make use of {fmt} in `main.cpp` (same as above).