fix: don't generate @aspect_bazel_lib_local_config_platform repository as it is a leaky abstraction for rule consumers and not just rule authors (#243)

WORKSPACE

@@ -12,7 +12,7 @@ bazel_lib_internal_deps()
 
 load("//lib:repositories.bzl", "aspect_bazel_lib_dependencies")
 
-aspect_bazel_lib_dependencies()
+aspect_bazel_lib_dependencies(override_local_config_platform = True)
 
 # For running our own unit tests
 load("@bazel_skylib//lib:unittest.bzl", "register_unittest_toolchains")

docs/BUILD.bazel

@@ -98,6 +98,11 @@ stardoc_with_diff_test(
     bzl_library_target = "//lib:host_repo",
 )
 
+stardoc_with_diff_test(
+    name = "platform_utils",
+    bzl_library_target = "//lib:platform_utils",
+)
+
 stardoc_with_diff_test(
     name = "stamping",
     bzl_library_target = "//lib:stamping",

docs/platform_utils.md

@@ -0,0 +1,40 @@
+<!-- Generated with Stardoc: http://skydoc.bazel.build -->
+
+Public API
+
+<a id="platform_utils.host_platform_is_darwin"></a>
+
+## platform_utils.host_platform_is_darwin
+
+<pre>
+platform_utils.host_platform_is_darwin()
+</pre>
+
+
+
+
+
+<a id="platform_utils.host_platform_is_linux"></a>
+
+## platform_utils.host_platform_is_linux
+
+<pre>
+platform_utils.host_platform_is_linux()
+</pre>
+
+
+
+
+
+<a id="platform_utils.host_platform_is_windows"></a>
+
+## platform_utils.host_platform_is_windows
+
+<pre>
+platform_utils.host_platform_is_windows()
+</pre>
+
+
+
+
+

lib/BUILD.bazel

@@ -192,3 +192,9 @@ bzl_library(
     name = "windows_utils",
     srcs = ["windows_utils.bzl"],
 )
+
+bzl_library(
+    name = "platform_utils",
+    srcs = ["platform_utils.bzl"],
+    deps = ["//lib/private:platform_utils"],
+)

lib/platform_utils.bzl

@@ -0,0 +1,5 @@
+"Public API"
+
+load("//lib/private:platform_utils.bzl", _platform_utils = "platform_utils")
+
+platform_utils = _platform_utils

lib/private/BUILD.bazel

@@ -19,7 +19,12 @@ exports_files(
 bzl_library(
     name = "copy_common",
     srcs = ["copy_common.bzl"],
-    deps = ["@aspect_bazel_lib_local_config_platform//:constraints"],
+)
+
+bzl_library(
+    name = "platform_utils",
+    srcs = ["platform_utils.bzl"],
+    deps = ["@local_config_platform//:constraints"],
 )
 
 bzl_library(
@@ -28,13 +33,17 @@ bzl_library(
     deps = [
         ":copy_common",
         ":directory_path",
+        ":platform_utils",
     ],
 )
 
 bzl_library(
     name = "copy_directory",
     srcs = ["copy_directory.bzl"],
-    deps = [":copy_common"],
+    deps = [
+        ":copy_common",
+        ":platform_utils",
+    ],
 )
 
 bzl_library(
@@ -46,6 +55,7 @@ bzl_library(
         ":glob_match",
         ":output_files",
         ":paths",
+        ":platform_utils",
         "@bazel_skylib//lib:paths",
     ],
 )

lib/private/copy_common.bzl

@@ -1,7 +1,5 @@
 "Helpers for copy rules"
 
-load("@aspect_bazel_lib_local_config_platform//:constraints.bzl", "HOST_CONSTRAINTS")
-
 # Hints for Bazel spawn strategy
 COPY_EXECUTION_REQUIREMENTS = {
     # ----------------+-----------------------------------------------------------------------------
@@ -59,6 +57,3 @@ COPY_EXECUTION_REQUIREMENTS = {
     "no-sandbox": "1",
     "local": "1",
 }
-
-def is_windows_host():
-    return "@platforms//os:windows" in HOST_CONSTRAINTS

lib/private/copy_directory.bzl

@@ -4,7 +4,8 @@ This rule copies a directory to another location using Bash (on Linux/macOS) or
 cmd.exe (on Windows).
 """
 
-load(":copy_common.bzl", _COPY_EXECUTION_REQUIREMENTS = "COPY_EXECUTION_REQUIREMENTS", _is_windows_host = "is_windows_host")
+load(":copy_common.bzl", _COPY_EXECUTION_REQUIREMENTS = "COPY_EXECUTION_REQUIREMENTS")
+load(":platform_utils.bzl", _platform_utils = "platform_utils")
 
 def _copy_cmd(ctx, src, dst):
     # Most Windows binaries built with MSVC use a certain argument quoting
@@ -83,7 +84,7 @@ def copy_directory_action(ctx, src, dst, is_windows = None):
     # Because copy actions have "local" execution requirements, we can safely assume
     # the execution is the same as the host platform and generate different actions for Windows
     # and non-Windows host platforms
-    is_windows = _is_windows_host()
+    is_windows = _platform_utils.host_platform_is_windows()
     if is_windows:
         _copy_cmd(ctx, src, dst)
     else:

lib/private/copy_file.bzl

@@ -24,8 +24,9 @@ cmd.exe (on Windows). `_copy_xfile` marks the resulting file executable,
 `_copy_file` does not.
 """
 
-load(":copy_common.bzl", _COPY_EXECUTION_REQUIREMENTS = "COPY_EXECUTION_REQUIREMENTS", _is_windows_host = "is_windows_host")
+load(":copy_common.bzl", _COPY_EXECUTION_REQUIREMENTS = "COPY_EXECUTION_REQUIREMENTS")
 load(":directory_path.bzl", "DirectoryPathInfo")
+load(":platform_utils.bzl", _platform_utils = "platform_utils")
 
 def _copy_cmd(ctx, src, src_path, dst):
     # Most Windows binaries built with MSVC use a certain argument quoting
@@ -113,7 +114,7 @@ def copy_file_action(ctx, src, dst, dir_path = None, is_windows = None):
     # Because copy actions have "local" execution requirements, we can safely assume
     # the execution is the same as the host platform and generate different actions for Windows
     # and non-Windows host platforms
-    is_windows = _is_windows_host()
+    is_windows = _platform_utils.host_platform_is_windows()
     if is_windows:
         _copy_cmd(ctx, src, src_path, dst)
     else:

lib/private/copy_to_directory.bzl

@@ -1,10 +1,11 @@
 "copy_to_directory implementation"
 
 load("@bazel_skylib//lib:paths.bzl", skylib_paths = "paths")
-load(":copy_common.bzl", _COPY_EXECUTION_REQUIREMENTS = "COPY_EXECUTION_REQUIREMENTS", _is_windows_host = "is_windows_host")
+load(":copy_common.bzl", _COPY_EXECUTION_REQUIREMENTS = "COPY_EXECUTION_REQUIREMENTS")
 load(":paths.bzl", "paths")
 load(":directory_path.bzl", "DirectoryPathInfo")
 load(":glob_match.bzl", "glob_match")
+load(":platform_utils.bzl", _platform_utils = "platform_utils")
 
 _filter_transforms_order_docstring = """Filters and transformations are applied in the following order:
 
@@ -764,7 +765,7 @@ def copy_to_directory_action(
     # Because copy actions have "local" execution requirements, we can safely assume
     # the execution is the same as the host platform and generate different actions for Windows
     # and non-Windows host platforms
-    is_windows = _is_windows_host()
+    is_windows = _platform_utils.host_platform_is_windows()
     if is_windows:
         _copy_to_dir_cmd(ctx, copy_paths, dst)
     else:

lib/private/local_config_platform.bzl

@@ -1,27 +1,52 @@
 """local_config_platform repository rule
 """
 
-def _impl(rctx):
-    rctx.file("constraints.bzl", content = rctx.read(rctx.attr._constraints_bzl))
+load(":repo_utils.bzl", "repo_utils")
 
-    rctx.file("BUILD.bazel", content = rctx.read(rctx.attr._build_bazel) + """
+def _impl(rctx):
+    rctx.file("BUILD.bazel", """load(':constraints.bzl', 'HOST_CONSTRAINTS')
 load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
+package(default_visibility = ['//visibility:public'])
+
+platform(name = 'host',
+  # Auto-detected host platform constraints.
+  constraint_values = HOST_CONSTRAINTS,
+)
+
 bzl_library(
     name = "constraints",
     srcs = ["constraints.bzl"],
     visibility = ["//visibility:public"],
 )
+""")
+
+    # TODO: we can detect the host CPU in the future as well if needed;
+    # see the repo_utils.platform(rctx) function for an example of this
+    if repo_utils.is_darwin(rctx):
+        rctx.file("constraints.bzl", content = """HOST_CONSTRAINTS = [
+  '@platforms//cpu:x86_64',
+  '@platforms//os:osx',
+]
+""")
+    elif repo_utils.is_windows(rctx):
+        rctx.file("constraints.bzl", content = """HOST_CONSTRAINTS = [
+  '@platforms//cpu:x86_64',
+  '@platforms//os:windows',
+]
+""")
+    else:
+        rctx.file("constraints.bzl", content = """HOST_CONSTRAINTS = [
+  '@platforms//cpu:x86_64',
+  '@platforms//os:linux',
+]
 """)
 
 local_config_platform = repository_rule(
     implementation = _impl,
-    doc = """Generates a copy of the auto-generated @local_config_platform repository with an added bzl_library.
+    doc = """Generates a repository in the same shape as the auto-generated @local_config_platform repository with an added bzl_library.
     
     This is useful for rules that want to load `HOST_CONSTRAINTS` from `@local_config_platform//:constraints.bzl` and
     also want to use stardoc for generating documentation.
     """,
-    attrs = {
-        "_constraints_bzl": attr.label(default = "@local_config_platform//:constraints.bzl"),
-        "_build_bazel": attr.label(default = "@local_config_platform//:BUILD.bazel"),
-    },
 )

lib/private/platform_utils.bzl

@@ -0,0 +1,18 @@
+"""Utility functions for platforms"""
+
+load("@local_config_platform//:constraints.bzl", "HOST_CONSTRAINTS")
+
+def _host_platform_is_darwin():
+    return "@platforms//os:osx" in HOST_CONSTRAINTS
+
+def _host_platform_is_linux():
+    return "@platforms//os:linux" in HOST_CONSTRAINTS
+
+def _host_platform_is_windows():
+    return "@platforms//os:windows" in HOST_CONSTRAINTS
+
+platform_utils = struct(
+    host_platform_is_darwin = _host_platform_is_darwin,
+    host_platform_is_linux = _host_platform_is_linux,
+    host_platform_is_windows = _host_platform_is_windows,
+)

lib/repositories.bzl

@@ -10,8 +10,15 @@ load("//lib/private:local_config_platform.bzl", "local_config_platform")
 def http_archive(name, **kwargs):
     maybe(_http_archive, name = name, **kwargs)
 
-def aspect_bazel_lib_dependencies():
-    "Load dependencies required by aspect rules"
+def aspect_bazel_lib_dependencies(override_local_config_platform = False):
+    """Load dependencies required by aspect rules
+
+    Args:
+        override_local_config_platform: override the @local_config_platform repository with one that adds stardoc
+            support for loading constraints.bzl.
+
+            Should be set in repositories that load @aspect_bazel_lib copy actions and also generate stardoc.
+    """
     http_archive(
         name = "bazel_skylib",
         sha256 = "f7be3474d42aae265405a592bb7da8e171919d74c16f082a5457840f06054728",
@@ -21,9 +28,10 @@ def aspect_bazel_lib_dependencies():
         ],
     )
 
-    local_config_platform(
-        name = "aspect_bazel_lib_local_config_platform",
-    )
+    if override_local_config_platform:
+        local_config_platform(
+            name = "local_config_platform",
+        )
 
 # Re-export the default versions
 DEFAULT_JQ_VERSION = _DEFAULT_JQ_VERSION