Add very minimal support for packaging the toolchain. (#3994)

This takes the installation layout and replicates it using `rules_pkg`
to build either a tarball or a zip file of the toolchain. Correctly
manages file permissions and symlinks, etc.

There are some big remaining things here:

- Figure out how we want to test this. We can add shell tests maybe?
  A bit awkward. Nicer would be to make the `//examples` tree build
  using this rather than the more native-bazel install data, however
  building these is quite slow and it seems bad to pay that cost
  constantly so dedicated testing is probably better. For now, I've
  tested these manually.

- Need to add versions to the toolchain and then thread them through
  here so they install properly as a versioned release.

But my primary goal for now is just to be able to validate that the
install tree is working outside of Bazel and this does enough for that.
The above will be longer-term things.

MODULE.bazel

@@ -22,6 +22,7 @@ http_archive = use_repo_rule(
 )
 
 bazel_dep(name = "bazel_skylib", version = "1.5.0")
+bazel_dep(name = "rules_pkg", version = "0.10.1")
 bazel_dep(name = "abseil-cpp", version = "20240116.1")
 bazel_dep(name = "re2", version = "2024-03-01")
 bazel_dep(name = "googletest", version = "1.14.0.bcr.1")

MODULE.bazel.lock

@@ -1,6 +1,6 @@
 {
   "lockFileVersion": 6,
-  "moduleFileHash": "e8ab8befa6e8b97ea295cf5ec5b694124bd41d0842fc98875746a48ee4108eaf",
+  "moduleFileHash": "439583f1efb19cfa4ef173e2ac4774602be6be5061bc14218f9856f4beb33e07",
   "flags": {
     "cmdRegistries": [
       "https://bcr.bazel.build/"
@@ -55,7 +55,7 @@
               "devDependency": false,
               "location": {
                 "file": "@@//:MODULE.bazel",
-                "line": 65,
+                "line": 66,
                 "column": 13
               }
             },
@@ -80,7 +80,7 @@
               "devDependency": false,
               "location": {
                 "file": "@@//:MODULE.bazel",
-                "line": 112,
+                "line": 113,
                 "column": 13
               }
             }
@@ -94,7 +94,7 @@
           "usingModule": "<root>",
           "location": {
             "file": "@@//:MODULE.bazel",
-            "line": 81,
+            "line": 82,
             "column": 35
           },
           "imports": {
@@ -111,7 +111,7 @@
           "usingModule": "<root>",
           "location": {
             "file": "@@//:MODULE.bazel",
-            "line": 126,
+            "line": 127,
             "column": 29
           },
           "imports": {
@@ -128,7 +128,7 @@
           "usingModule": "<root>",
           "location": {
             "file": "@@//:MODULE.bazel",
-            "line": 138,
+            "line": 139,
             "column": 23
           },
           "imports": {
@@ -144,7 +144,7 @@
               "devDependency": false,
               "location": {
                 "file": "@@//:MODULE.bazel",
-                "line": 139,
+                "line": 140,
                 "column": 17
               }
             }
@@ -155,6 +155,7 @@
       ],
       "deps": {
         "bazel_skylib": "bazel_skylib@1.5.0",
+        "rules_pkg": "rules_pkg@0.10.1",
         "abseil-cpp": "abseil-cpp@20240116.1",
         "re2": "re2@2024-03-01",
         "googletest": "googletest@1.14.0.bcr.1",
@@ -206,6 +207,35 @@
         }
       }
     },
+    "rules_pkg@0.10.1": {
+      "name": "rules_pkg",
+      "version": "0.10.1",
+      "key": "rules_pkg@0.10.1",
+      "repoName": "rules_pkg",
+      "executionPlatformsToRegister": [],
+      "toolchainsToRegister": [],
+      "extensionUsages": [],
+      "deps": {
+        "rules_license": "rules_license@0.0.7",
+        "rules_python": "rules_python@0.31.0",
+        "bazel_skylib": "bazel_skylib@1.5.0",
+        "bazel_tools": "bazel_tools@_",
+        "local_config_platform": "local_config_platform@_"
+      },
+      "repoSpec": {
+        "bzlFile": "@@bazel_tools//tools/build_defs/repo:http.bzl",
+        "ruleClassName": "http_archive",
+        "attributes": {
+          "urls": [
+            "https://github.com/bazelbuild/rules_pkg/releases/download/0.10.1/rules_pkg-0.10.1.tar.gz"
+          ],
+          "integrity": "sha256-0lCSSi7MUXaAj8TCXVz16eeeY0bXnVqxxJPiieci0dA=",
+          "strip_prefix": "",
+          "remote_patches": {},
+          "remote_patch_strip": 0
+        }
+      }
+    },
     "abseil-cpp@20240116.1": {
       "name": "abseil-cpp",
       "version": "20240116.1",
@@ -630,7 +660,7 @@
         "rules_cc": "rules_cc@0.0.9",
         "rules_proto": "rules_proto@6.0.0-rc2",
         "rules_java": "rules_java@7.4.0",
-        "rules_pkg": "rules_pkg@0.7.0",
+        "rules_pkg": "rules_pkg@0.10.1",
         "com_google_abseil": "abseil-cpp@20240116.1",
         "zlib": "zlib@1.3.1.bcr.1",
         "upb": "upb@0.0.0-20220923-a547704",
@@ -1109,6 +1139,32 @@
         "bazel_tools": "bazel_tools@_"
       }
     },
+    "rules_license@0.0.7": {
+      "name": "rules_license",
+      "version": "0.0.7",
+      "key": "rules_license@0.0.7",
+      "repoName": "rules_license",
+      "executionPlatformsToRegister": [],
+      "toolchainsToRegister": [],
+      "extensionUsages": [],
+      "deps": {
+        "bazel_tools": "bazel_tools@_",
+        "local_config_platform": "local_config_platform@_"
+      },
+      "repoSpec": {
+        "bzlFile": "@@bazel_tools//tools/build_defs/repo:http.bzl",
+        "ruleClassName": "http_archive",
+        "attributes": {
+          "urls": [
+            "https://github.com/bazelbuild/rules_license/releases/download/0.0.7/rules_license-0.0.7.tar.gz"
+          ],
+          "integrity": "sha256-RTHezLkTY5ww5cdRKgVNXYdWmNrrddjPkPKEN1/nw2A=",
+          "strip_prefix": "",
+          "remote_patches": {},
+          "remote_patch_strip": 0
+        }
+      }
+    },
     "apple_support@1.14.0": {
       "name": "apple_support",
       "version": "1.14.0",
@@ -1276,32 +1332,6 @@
         }
       }
     },
-    "rules_license@0.0.7": {
-      "name": "rules_license",
-      "version": "0.0.7",
-      "key": "rules_license@0.0.7",
-      "repoName": "rules_license",
-      "executionPlatformsToRegister": [],
-      "toolchainsToRegister": [],
-      "extensionUsages": [],
-      "deps": {
-        "bazel_tools": "bazel_tools@_",
-        "local_config_platform": "local_config_platform@_"
-      },
-      "repoSpec": {
-        "bzlFile": "@@bazel_tools//tools/build_defs/repo:http.bzl",
-        "ruleClassName": "http_archive",
-        "attributes": {
-          "urls": [
-            "https://github.com/bazelbuild/rules_license/releases/download/0.0.7/rules_license-0.0.7.tar.gz"
-          ],
-          "integrity": "sha256-RTHezLkTY5ww5cdRKgVNXYdWmNrrddjPkPKEN1/nw2A=",
-          "strip_prefix": "",
-          "remote_patches": {},
-          "remote_patch_strip": 0
-        }
-      }
-    },
     "bazel_features@1.2.0": {
       "name": "bazel_features",
       "version": "1.2.0",
@@ -1449,37 +1479,6 @@
         }
       }
     },
-    "rules_pkg@0.7.0": {
-      "name": "rules_pkg",
-      "version": "0.7.0",
-      "key": "rules_pkg@0.7.0",
-      "repoName": "rules_pkg",
-      "executionPlatformsToRegister": [],
-      "toolchainsToRegister": [],
-      "extensionUsages": [],
-      "deps": {
-        "rules_python": "rules_python@0.31.0",
-        "bazel_skylib": "bazel_skylib@1.5.0",
-        "rules_license": "rules_license@0.0.7",
-        "bazel_tools": "bazel_tools@_",
-        "local_config_platform": "local_config_platform@_"
-      },
-      "repoSpec": {
-        "bzlFile": "@@bazel_tools//tools/build_defs/repo:http.bzl",
-        "ruleClassName": "http_archive",
-        "attributes": {
-          "urls": [
-            "https://github.com/bazelbuild/rules_pkg/releases/download/0.7.0/rules_pkg-0.7.0.tar.gz"
-          ],
-          "integrity": "sha256-iimOgydi7aGDBZfWT+fbWBeKqEzVkm121bdE1lWJQcI=",
-          "strip_prefix": "",
-          "remote_patches": {
-            "https://bcr.bazel.build/modules/rules_pkg/0.7.0/patches/module_dot_bazel.patch": "sha256-4OaEPZwYF6iC71ZTDg6MJ7LLqX7ZA0/kK4mT+4xKqiE="
-          },
-          "remote_patch_strip": 0
-        }
-      }
-    },
     "upb@0.0.0-20220923-a547704": {
       "name": "upb",
       "version": "0.0.0-20220923-a547704",

toolchain/install/BUILD

@@ -5,6 +5,9 @@
 load("@bazel_skylib//rules:write_file.bzl", "write_file")
 load("@llvm-project//llvm:binary_alias.bzl", "binary_alias")
 load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library", "cc_test")
+load("@rules_pkg//pkg:mappings.bzl", "pkg_attributes", "pkg_filegroup", "pkg_files", "pkg_mklink", "strip_prefix")
+load("@rules_pkg//pkg:tar.bzl", "pkg_tar")
+load("@rules_pkg//pkg:zip.bzl", "pkg_zip")
 load("symlink_filegroup.bzl", "symlink_filegroup")
 
 package(default_visibility = ["//visibility:public"])
@@ -139,3 +142,62 @@ cc_test(
         "@llvm-project//llvm:Support",
     ],
 )
+
+# Build rules to construct packaged versions of the toolchain's install.
+
+pkg_files(
+    name = "packaging_exe_files",
+    # We break out the driver and LLD here because we can't easily use file
+    # groups that contain symlinks, so those are manually handled below. Other
+    # file groups should be directly included.
+    srcs = [
+        "prefix_root/bin/carbon",
+        "prefix_root/lib/carbon/llvm/bin/lld",
+    ],
+    attributes = pkg_attributes(mode = "0755"),
+    strip_prefix = strip_prefix.from_pkg("prefix_root"),
+)
+
+# Currently, `rules_pkg` can't replicate symlinks from the main tree. To an
+# extent, this is reasonable because we want to be much more explicit about the
+# symlink structure in the package where as for the filegroups we're comfortable
+# with whatever "just works" for development and testing.
+[
+    pkg_mklink(
+        name = "packaging_link_lld_alias_" + bin_name,
+        link_name = "lib/carbon/llvm/bin/" + bin_name,
+        target = "lld",
+    )
+    for bin_name in lld_bin_names
+]
+
+pkg_filegroup(
+    name = "packaging_files",
+    srcs = [
+        ":packaging_exe_files",
+    ] + [
+        ":packaging_link_lld_alias_" + bin_name
+        for bin_name in lld_bin_names
+    ],
+)
+
+# TODO: We should add support for injecting a version string into both the
+# output filename and the package directory name.
+pkg_tar(
+    name = "carbon_toolchain.tar.bz2.rule",
+    srcs = [":packaging_files"],
+    out = "carbon_toolchain.tar.bz2",
+    extension = "tar.bz2",
+    package_dir = "carbon_toolchain",
+    tags = ["manual"],  # Slow, exclude from wildcard builds.
+)
+
+# TODO: We should add support for injecting a version string into both the
+# output filename and the package directory name.
+pkg_zip(
+    name = "carbon_toolchain.zip.rule",
+    srcs = [":packaging_files"],
+    out = "carbon_toolchain.zip",
+    package_dir = "carbon_toolchain",
+    tags = ["manual"],  # Slow, exclude from wildcard builds.
+)