wip: rules_rust

.bazelrc

@@ -0,0 +1,5 @@
+# ---- Global C/C++ build options ---------------------------------------------
+
+# Using a custom C++ toolchain to get around an issue with rules_rust on macOS:
+# https://github.com/bazelbuild/rules_rust/issues/226
+build --crosstool_top=@llvm_toolchain//:toolchain

.gitignore

@@ -1 +1,2 @@
 /target
+/bazel-*

WORKSPACE

@@ -0,0 +1,51 @@
+BAZEL_VERSION = "3.1.0"
+
+workspace(name = "io_jez_rs_as_tree")
+
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+http_archive(
+    name = "com_grail_bazel_toolchain",
+    url = "https://github.com/grailbio/bazel-toolchain/archive/0.5.zip",
+    sha256 = "33011cd77021017294d1982b48d0c3a081c777b9aad9a75f3e4eada0e10894d1",
+    strip_prefix = "bazel-toolchain-0.5",
+)
+
+load("@com_grail_bazel_toolchain//toolchain:deps.bzl", "bazel_toolchain_dependencies")
+bazel_toolchain_dependencies()
+
+load("@com_grail_bazel_toolchain//toolchain:rules.bzl", "llvm_toolchain")
+llvm_toolchain(
+    name = "llvm_toolchain",
+    absolute_paths = True,
+    llvm_version = "9.0.0",
+)
+
+load("@llvm_toolchain//:toolchains.bzl", "llvm_register_toolchains")
+llvm_register_toolchains()
+
+# rules_rust (or maybe Bazel itself?)
+http_archive(
+    name = "io_bazel_rules_rust",
+    sha256 = "800ffbce5af3f196448b4844b8ad32f82f6ff1cda192ebf5edd5f5a9d132f348",
+    strip_prefix = "rules_rust-6835a3c8ed1dcd67040cccd603ff3daf611ce41c",
+    urls = [
+        "https://github.com/bazelbuild/rules_rust/archive/6835a3c8ed1dcd67040cccd603ff3daf611ce41c.zip",
+    ],
+)
+
+http_archive(
+    name = "bazel_skylib",
+    sha256 = "9a737999532daca978a158f94e77e9af6a6a169709c0cee274f0a4c3359519bd",
+    strip_prefix = "bazel-skylib-1.0.0",
+    url = "https://github.com/bazelbuild/bazel-skylib/archive/1.0.0.tar.gz",
+)
+
+load("@io_bazel_rules_rust//rust:repositories.bzl", "rust_repositories")
+rust_repositories()
+
+load("@io_bazel_rules_rust//:workspace.bzl", "bazel_version")
+bazel_version(name = "bazel_version")
+
+BAZEL_INSTALLER_VERSION_darwin_SHA = "5cfa97031b43432b3c742c80e2e01c41c0acdca7ba1052fc8cf1e291271bc9cd"
+BAZEL_INSTALLER_VERSION_linux_SHA = "7ba815cbac712d061fe728fef958651512ff394b2708e89f79586ec93d1185ed"

bazel

@@ -0,0 +1,93 @@
+#!/bin/bash
+
+#
+# ./bazel
+#
+# Reads the BAZEL_VERSION variable in the WORKSPACE file and executes the
+# corresponding Bazel version. Downloads and installs it if needed.
+#
+
+set -euo pipefail
+
+if [ "${LOCAL_BAZEL_OVERRIDE:-}" != "" ]; then
+  exec "$LOCAL_BAZEL_OVERRIDE" "$@"
+fi
+
+old_pwd="$PWD"
+cd "$(dirname "${BASH_SOURCE[0]}")"
+
+if ! [ -f WORKSPACE ]; then
+  echo >&2 "Didn't find the workspace"
+  exit 1
+fi
+
+repo_root="$PWD"
+cd "$old_pwd"
+
+workspace_contents=$(< "$repo_root/WORKSPACE")
+
+bazel_version_regex='BAZEL_VERSION = "([^"]+)"'
+if [[ $workspace_contents =~ $bazel_version_regex ]]; then
+  export BAZEL_VERSION="${BASH_REMATCH[1]}"
+else
+  echo >&2 "$0: Failed to extract BAZEL_VERSION from WORKSPACE"
+  exit 1
+fi
+
+XDG_CACHE_HOME="${XDG_CACHE_HOME:-$HOME/.cache}"
+bazel_bin_loc="${bazel_bin_loc:-$XDG_CACHE_HOME/bazel_binaries}"
+bazel_exec_path="$bazel_bin_loc/$BAZEL_VERSION/bin/bazel-real"
+
+if [ -f "$bazel_exec_path" ]; then
+  exec "$bazel_exec_path" "$@"
+fi
+
+# ----- slow path -----
+
+echo >&2 "No cached Bazel v$BAZEL_VERSION found, installing..."
+
+case "$(uname -s)" in
+  Linux)  bazel_launcher_platform_name='linux'  ;;
+  Darwin) bazel_launcher_platform_name='darwin' ;;
+  *) echo >&2 "Your platform $(uname -s) is unsupported, sorry" && exit 1 ;;
+esac
+
+bazel_installer_sha_regex="BAZEL_INSTALLER_VERSION_${bazel_launcher_platform_name}_SHA = \"([^\"]+)\""
+if [[ $workspace_contents =~ $bazel_installer_sha_regex ]]; then
+  export expected_sha="${BASH_REMATCH[1]}"
+else
+  echo >&2 "$0: Failed to extract Bazel version from WORKSPACE"
+  exit 1
+fi
+
+BUILD_DIR="$(mktemp -d)"
+export BUILD_DIR
+mkdir -p "$BUILD_DIR"
+
+(
+  set -euo pipefail
+  cd "$BUILD_DIR"
+  echo "$PWD"
+
+  installer_name="bazel-${BAZEL_VERSION}-installer-${bazel_launcher_platform_name}-x86_64.sh"
+  BAZEL_REMOTE_SOURCE="${BAZEL_REMOTE_SOURCE:-https://github.com/bazelbuild/bazel/releases/download}"
+  BAZEL_INSTALLER_PATH="${BAZEL_INSTALLER_PATH:-$BAZEL_REMOTE_SOURCE/${BAZEL_VERSION}/$installer_name}"
+
+  curl -O -L "$BAZEL_INSTALLER_PATH"
+
+  actual_sha="$(shasum -a 256 "$installer_name" | awk '{print $1}')"
+  if [ "$actual_sha" != "$expected_sha" ]; then
+    echo >&2 "Installer checksum mismatch:"
+    echo >&2 "  Expected: $expected_sha"
+    echo >&2 "  Actual:   $actual_sha"
+    echo >&2 "To accept this mismatch, update the SHA in the WORKSPACE file and re-run."
+    exit 1
+  fi
+
+  chmod +x "$installer_name"
+  mkdir -p "$bazel_bin_loc"
+  "./${installer_name}" --base="${bazel_bin_loc}/${BAZEL_VERSION}" --bin="${bazel_bin_loc}/${BAZEL_VERSION}/bin_t"
+)
+rm -rf "$BUILD_DIR"
+
+exec "$bazel_exec_path" "$@"

src/BUILD

@@ -4,4 +4,5 @@ rust_binary(
     name = "as-tree",
     srcs = ["main.rs"],
     deps = [],
+    visibility = ["//visibility:public"],
 )

tools/bazel

@@ -0,0 +1 @@
+../bazel