build: add Bazel build files

.github/workflows/bazel.yml

@@ -0,0 +1,33 @@
+name: bazel
+
+permissions:
+  contents: read
+
+on:
+  pull_request:
+    branches:
+      - dev
+  push:
+    branches:
+      - dev
+
+concurrency:
+  group: bazel-ref
+  cancel-in-progress: true
+
+jobs:
+  build:
+    name: bazel build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Bazel
+        uses: bazel-contrib/setup-bazel@0.14.0
+        with:
+          bazelisk-cache: true
+          disk-cache: enabled
+          repository-cache: true
+
+      - name: Build libzstd
+        run: bazel build //lib:zstd

.gitignore

@@ -28,6 +28,8 @@ projects/
 bin/
 .buckd/
 buck-out/
+bazel-*
+MODULE.bazel.lock
 build-*
 *.gcda
 cmakebuild/

MODULE.bazel

@@ -0,0 +1,5 @@
+module(
+    name = "zstd",
+    version = "1.6.0",
+)
+bazel_dep(name = "platforms", version = "0.0.11")

build/bazel/README.md

@@ -0,0 +1,46 @@
+# Bazel build
+
+This directory documents the Bazel build for zstd. Like the CMake and Meson
+builds under `build/`, it is community maintained.
+
+## Building from the repository root
+
+```sh
+bazel build //lib:zstd
+```
+
+This produces a static library (`libzstd.a` on Linux/macOS, `zstd.lib` on
+Windows).
+
+## Layout
+
+- `MODULE.bazel` must stay at the repository root, because Bazel treats the
+  root as the workspace and pre-1.0 modules do not accept it anywhere else.
+  It is the only file Bazel requires at the root.
+- `lib/BUILD.bazel` defines the `zstd` target next to the existing
+  `lib/BUCK`, `Makefile` and `libzstd.mk`.
+- `.github/workflows/bazel.yml` builds `//lib:zstd` on every change to keep
+  the build description from bit-rotting.
+
+## Configuration
+
+`ZSTD_LEGACY_SUPPORT` is disabled and multithreading is off by default,
+matching the static library built by `make lib`. The MSVC C11 flag is applied
+through `select()` in `lib/BUILD.bazel`, so no `.bazelrc` is needed.
+
+## Using zstd from another Bazel workspace
+
+With Bzlmod, depend on the module and use the `zstd` target:
+
+```python
+bazel_dep(name = "zstd", version = "1.6.0")
+```
+
+When zstd is vendored with `local_path_override` or `archive_override`, the
+same `//lib:zstd` target is available.
+
+## Adding languages or features
+
+The target currently builds the C library only. The command line tools in
+`programs/` are not wired into Bazel yet; a follow-up can add them as a
+`cc_binary` if there is demand.

lib/BUILD.bazel

@@ -0,0 +1,31 @@
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+cc_library(
+    name = "zstd",
+    srcs = glob([
+        "common/*.c",
+        "compress/*.c",
+        "decompress/*.c",
+        "deprecated/*.c",
+        "dictBuilder/*.c",
+    ]),
+    hdrs = glob([
+        "*.h",
+        "common/*.h",
+        "compress/*.h",
+        "decompress/*.h",
+        "deprecated/*.h",
+        "dictBuilder/*.h",
+    ]),
+    copts = select({
+        "@platforms//os:windows": ["/std:c11"],
+        "//conditions:default": [],
+    }),
+    includes = ["."],
+    local_defines = [
+        "XXH_NAMESPACE=ZSTD_",
+        "ZSTD_LEGACY_SUPPORT=0",
+    ],
+)