Added rust example (#1354)

I think having this example here vs in `rules_rust` will be more visible
for consumers of `rules_foreign_cc`. `rules_rust` should otherwise try
to demonstrate simple examples or uses of `rules_cc` and leave the
complexity of foreign_cc interactions to this repo.

.bazelci/config.yaml

@@ -167,6 +167,7 @@ tasks:
       - "-//cmake_hello_world_lib/static:libhello_example"
       - "-//cmake_hello_world_lib/static:test_hello"
       - "-//cmake_with_data/..."
+      - "-//rust/..."
     batch_commands:
       - powershell -noexit "& "".\..\.bazelci\windows-update-certs.ps1"""
     build_targets: *windows_targets
@@ -247,7 +248,10 @@ tasks:
     platform: ubuntu1804
     working_directory: examples
     min_supported_targets: &min_supported_targets
+      - "--"
       - "//..."
+      # The min supported version of rules_rust is `>=7`
+      - "-//rust/..."
     build_targets: *min_supported_targets
     test_targets: *min_supported_targets
 

examples/MODULE.bazel

@@ -13,6 +13,7 @@ use_repo(
 )
 
 bazel_dep(name = "platforms", version = "0.0.6")
+bazel_dep(name = "rules_rust", version = "0.56.0")
 bazel_dep(name = "rules_swift", version = "1.6.0", repo_name = "build_bazel_rules_swift")
 bazel_dep(name = "rules_apple", version = "3.4.0", repo_name = "build_bazel_rules_apple")
 bazel_dep(name = "apple_support", version = "1.12.0", repo_name = "build_bazel_apple_support")
@@ -36,6 +37,35 @@ pip.parse(
 )
 use_repo(pip, "pip")
 
+# https://bazelbuild.github.io/rules_rust/crate_universe_bzlmod.html
+rust_example = use_extension("@rules_rust//crate_universe:extensions.bzl", "crate")
+
+inject_repo(rust_example, "rules_foreign_cc")
+
+rust_example.annotation(
+    # Setting build_script_data makes the files available on disk when the rule runs.
+    build_script_data = ["@rules_foreign_cc//toolchains:current_cmake_toolchain"],
+    build_script_env = {
+        # The toolchain supplies a value of $(CMAKE) which is an execroot-relative path, so we need to prefix it with `$${pwd}/`
+        # because build scripts don't typically run in the execroot unlike most bazel rules, for improved compatibility with Cargo.
+        "CMAKE": "$${pwd}/$(CMAKE)",
+    },
+    # Setting build_script_toolchains makes makefile variable substitution work so that we can reference $(CNAME) in attributes.
+    build_script_toolchains = ["@rules_foreign_cc//toolchains:current_cmake_toolchain"],
+    crate = "libz-ng-sys",
+)
+rust_example.spec(
+    package = "libz-ng-sys",
+    version = "=1.1.20",
+)
+rust_example.from_specs(
+    name = "rust_example",
+)
+use_repo(
+    rust_example,
+    "rust_example",
+)
+
 # bazel_dep(name = "rules_android", version = "0.1.1")
 # bazel_dep(name = "rules_jvm_external", version = "5.1")
 #

examples/WORKSPACE.bazel

@@ -124,3 +124,57 @@ load(
 )
 
 apple_support_dependencies()
+
+maybe(
+    http_archive,
+    name = "rules_rust",
+    integrity = "sha256-8TBqrAsli3kN8BrZq8arsN8LZUFsdLTvJ/Sqsph4CmQ=",
+    urls = ["https://github.com/bazelbuild/rules_rust/releases/download/0.56.0/rules_rust-0.56.0.tar.gz"],
+)
+
+load("@rules_rust//rust:repositories.bzl", "rules_rust_dependencies", "rust_register_toolchains")
+
+rules_rust_dependencies()
+
+rust_register_toolchains()
+
+load("@rules_rust//crate_universe:repositories.bzl", "crate_universe_dependencies")
+
+crate_universe_dependencies()
+
+load("@rules_rust//crate_universe:defs.bzl", "crate", "crates_repository", "splicing_config")
+
+crates_repository(
+    name = "rust_example",
+    annotations = {
+        # zlib-ng-sys's build script invokes cmake, so we need to make cmake available.
+        # Fortunately, rules_foreign_cc has a cmake toolchain we can use.
+        "libz-ng-sys": [crate.annotation(
+            # Setting build_script_data makes the files available on disk when the rule runs.
+            build_script_data = ["@rules_foreign_cc//toolchains:current_cmake_toolchain"],
+            build_script_env = {
+                # The toolchain supplies a value of $(CMAKE) which is an execroot-relative path, so we need to prefix it with $${pwd}/ because build scripts don't typically run in the execroot unlike most bazel rules, for improved compatibility with Cargo.
+                "CMAKE": "$${pwd}/$(CMAKE)",
+            },
+            # Setting build_script_toolchains makes makefile variable substitution work so that we can reference $(CNAME) in attributes.
+            build_script_toolchains = ["@rules_foreign_cc//toolchains:current_cmake_toolchain"],
+        )],
+    },
+    cargo_lockfile = "//rust:Cargo.Bazel.lock",
+    lockfile = "//rust:cargo-bazel-lock.json",
+    packages = {
+        "libz-ng-sys": crate.spec(
+            version = "=1.1.20",
+        ),
+    },
+    splicing_config = splicing_config(
+        resolver_version = "2",
+    ),
+)
+
+load(
+    "@rust_example//:defs.bzl",
+    rust_example_crate_repositories = "crate_repositories",
+)
+
+rust_example_crate_repositories()

examples/rust/BUILD.bazel

@@ -0,0 +1,8 @@
+load("@bazel_skylib//rules:build_test.bzl", "build_test")
+
+build_test(
+    name = "build_test",
+    targets = [
+        "@rust_example//:libz-ng-sys",
+    ],
+)

examples/rust/Cargo.Bazel.lock

@@ -0,0 +1,41 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "cc"
+version = "1.0.95"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d32a725bc159af97c3e629873bb9f88fb8cf8a4867175f76dc987815ea07c83b"
+
+[[package]]
+name = "cmake"
+version = "0.1.50"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a31c789563b815f77f4250caee12365734369f942439b7defd71e18a48197130"
+dependencies = [
+ "cc",
+]
+
+[[package]]
+name = "direct-cargo-bazel-deps"
+version = "0.0.1"
+dependencies = [
+ "libz-ng-sys",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.154"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae743338b92ff9146ce83992f766a31066a91a8c84a45e0e9f21e7cf6de6d346"
+
+[[package]]
+name = "libz-ng-sys"
+version = "1.1.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f0f7295a34685977acb2e8cc8b08ee4a8dffd6cf278eeccddbe1ed55ba815d5"
+dependencies = [
+ "cmake",
+ "libc",
+]