From d9a731d4862891f274b63cef14bde0e5558a290f Mon Sep 17 00:00:00 2001
From: Vertexwahn <julian.amann@tum.de>
Date: Fri, 24 Sep 2021 22:17:26 +0200
Subject: [PATCH] Add basic support for Bazel (#2505)

---
 support/bazel/.bazelrc        |  1 +
 support/bazel/.bazelversion   |  1 +
 support/bazel/BUILD.bazel     | 29 ++++++++++++
 support/bazel/README.md       | 85 +++++++++++++++++++++++++++++++++++
 support/bazel/WORKSPACE.bazel |  1 +
 5 files changed, 117 insertions(+)
 create mode 100644 support/bazel/.bazelrc
 create mode 100644 support/bazel/.bazelversion
 create mode 100644 support/bazel/BUILD.bazel
 create mode 100644 support/bazel/README.md
 create mode 100644 support/bazel/WORKSPACE.bazel

diff --git a/support/bazel/.bazelrc b/support/bazel/.bazelrc
new file mode 100644
index 00000000..583cbbd2
--- /dev/null
+++ b/support/bazel/.bazelrc
@@ -0,0 +1 @@
+build --symlink_prefix=/ # Out of source build
diff --git a/support/bazel/.bazelversion b/support/bazel/.bazelversion
new file mode 100644
index 00000000..fae6e3d0
--- /dev/null
+++ b/support/bazel/.bazelversion
@@ -0,0 +1 @@
+4.2.1
diff --git a/support/bazel/BUILD.bazel b/support/bazel/BUILD.bazel
new file mode 100644
index 00000000..3380bbca
--- /dev/null
+++ b/support/bazel/BUILD.bazel
@@ -0,0 +1,29 @@
+cc_library(
+    name = "fmt",
+    srcs = [
+        #"src/fmt.cc", # No C++ module support
+        "src/format.cc",
+        "src/os.cc",
+    ],
+    hdrs = [
+        "include/fmt/args.h",
+        "include/fmt/chrono.h",
+        "include/fmt/color.h",
+        "include/fmt/compile.h",
+        "include/fmt/core.h",
+        "include/fmt/format.h",
+        "include/fmt/format-inl.h",
+        "include/fmt/locale.h",
+        "include/fmt/os.h",
+        "include/fmt/ostream.h",
+        "include/fmt/printf.h",
+        "include/fmt/ranges.h",
+        "include/fmt/xchar.h",
+    ],
+    includes = [
+        "include",
+        "src",
+    ],
+    strip_include_prefix = "include",
+    visibility = ["//visibility:public"],
+)
diff --git a/support/bazel/README.md b/support/bazel/README.md
new file mode 100644
index 00000000..ae5aded6
--- /dev/null
+++ b/support/bazel/README.md
@@ -0,0 +1,85 @@
+# Bazel support
+
+Bazel is an open-source build tool.
+More information about Bazel can be found [here](https://bazel.build/).
+
+## Using the fmt repository with Bazel
+
+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.
+
+Add to your `WORKSPACE` file:
+
+```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
+)
+```
+
+Make use of {fmt} in `main.cpp`:
+
+```C++
+#include "fmt/core.h"
+
+int main() {
+  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:
+
+```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/<user_or_organisation>/fmt", # replace <user_or_organisation> by a valid account
+)
+```
+
+Create a `BUILD.bazel` file and add a dependency to {fmt} (same as above).
+
+Make use of {fmt} in `main.cpp` (same as above).
diff --git a/support/bazel/WORKSPACE.bazel b/support/bazel/WORKSPACE.bazel
new file mode 100644
index 00000000..5be77811
--- /dev/null
+++ b/support/bazel/WORKSPACE.bazel
@@ -0,0 +1 @@
+workspace(name = "fmt")