Use the launcher_maker toolchain if available

Author: fmeum

MODULE.bazel

@@ -4,7 +4,7 @@ module(
     compatibility_level = 1,
 )
 
-bazel_dep(name = "bazel_features", version = "1.21.0")
+bazel_dep(name = "bazel_features", version = "1.30.0")
 bazel_dep(name = "bazel_skylib", version = "1.7.1")
 bazel_dep(name = "rules_cc", version = "0.0.16")
 bazel_dep(name = "platforms", version = "0.0.11")

python/private/py_executable.bzl

@@ -13,6 +13,7 @@
 # limitations under the License.
 """Common functionality between test/binary executables."""
 
+load("@bazel_features//:features.bzl", "bazel_features")
 load("@bazel_skylib//lib:dicts.bzl", "dicts")
 load("@bazel_skylib//lib:paths.bzl", "paths")
 load("@bazel_skylib//lib:structs.bzl", "structs")
@@ -70,6 +71,7 @@ _py_builtins = py_internal
 _EXTERNAL_PATH_PREFIX = "external"
 _ZIP_RUNFILES_DIRECTORY_NAME = "runfiles"
 _PYTHON_VERSION_FLAG = str(Label("//python/config_settings:python_version"))
+_LAUNCHER_MAKER_TOOLCHAIN_TYPE = "@bazel_tools//tools/launcher:launcher_maker_toolchain_type"
 
 # Non-Google-specific attributes for executables
 # These attributes are for rules that accept Python sources.
@@ -228,17 +230,19 @@ accepting arbitrary Python versions.
                 "@platforms//os:windows",
             ],
         ),
-        "_windows_launcher_maker": lambda: attrb.Label(
-            default = "@bazel_tools//tools/launcher:launcher_maker",
-            cfg = "exec",
-            executable = True,
-        ),
         "_zipper": lambda: attrb.Label(
             cfg = "exec",
             executable = True,
             default = "@bazel_tools//tools/zip:zipper",
         ),
     },
+    {
+        "_windows_launcher_maker": lambda: attrb.Label(
+            default = "@bazel_tools//tools/launcher:launcher_maker",
+            cfg = "exec",
+            executable = True,
+        ),
+    } if not bazel_features.rules._has_launcher_maker_toolchain else {},
 )
 
 def convert_legacy_create_init_to_int(kwargs):
@@ -842,6 +846,11 @@ def _create_stage1_bootstrap(
         substitutions = subs,
     )
 
+def _find_launcher_maker(ctx):
+    if bazel_features.rules._has_launcher_maker_toolchain:
+        return ctx.toolchains[_LAUNCHER_MAKER_TOOLCHAIN_TYPE].binary
+    return ctx.executable._windows_launcher_maker
+
 def _create_windows_exe_launcher(
         ctx,
         *,
@@ -862,7 +871,7 @@ def _create_windows_exe_launcher(
 
     launcher = ctx.attr._launcher[DefaultInfo].files_to_run.executable
     ctx.actions.run(
-        executable = ctx.executable._windows_launcher_maker,
+        executable = _find_launcher_maker(ctx),
         arguments = [launcher.path, launch_info, output.path],
         inputs = [launcher],
         outputs = [output],
@@ -1910,7 +1919,7 @@ def create_executable_rule_builder(implementation, **kwargs):
             ruleb.ToolchainType(TOOLCHAIN_TYPE),
             ruleb.ToolchainType(EXEC_TOOLS_TOOLCHAIN_TYPE, mandatory = False),
             ruleb.ToolchainType("@bazel_tools//tools/cpp:toolchain_type", mandatory = False),
-        ],
+        ] + ([ruleb.ToolchainType(_LAUNCHER_MAKER_TOOLCHAIN_TYPE)] if bazel_features.rules._has_launcher_maker_toolchain else []),
         cfg = dict(
             implementation = _transition_executable_impl,
             inputs = [_PYTHON_VERSION_FLAG],

tests/base_rules/py_executable_base_tests.bzl

@@ -24,7 +24,7 @@ load("//python/private:util.bzl", "IS_BAZEL_7_OR_HIGHER")  # buildifier: disable
 load("//tests/base_rules:base_tests.bzl", "create_base_tests")
 load("//tests/base_rules:util.bzl", "WINDOWS_ATTR", pt_util = "util")
 load("//tests/support:py_executable_info_subject.bzl", "PyExecutableInfoSubject")
-load("//tests/support:support.bzl", "BOOTSTRAP_IMPL", "CC_TOOLCHAIN", "CROSSTOOL_TOP", "LINUX_X86_64", "WINDOWS_X86_64")
+load("//tests/support:support.bzl", "BOOTSTRAP_IMPL", "CC_TOOLCHAIN", "CROSSTOOL_TOP", "EXOTIC_UNIX", "LINUX_X86_64", "WINDOWS_X86_64")
 
 _tests = []
 
@@ -115,6 +115,28 @@ def _test_basic_zip_impl(env, target):
 
 _tests.append(_test_basic_zip)
 
+def _test_cross_compile_to_unix(name, config):
+    rt_util.helper_target(
+        config.rule,
+        name = name + "_subject",
+        main_module = "dummy",
+    )
+    analysis_test(
+        name = name,
+        impl = _test_cross_compile_to_unix_impl,
+        target = name + "_subject",
+        config_settings = {
+            "//command_line_option:platforms": [EXOTIC_UNIX],
+            "//command_line_option:host_platform": EXOTIC_UNIX,
+        },
+        expect_failure = True,
+    )
+
+def _test_cross_compile_to_unix_impl(env, target):
+    pass
+
+_tests.append(_test_cross_compile_to_unix)
+
 def _test_executable_in_runfiles(name, config):
     rt_util.helper_target(
         config.rule,

tests/support/BUILD.bazel

@@ -87,6 +87,14 @@ platform(
     ],
 )
 
+platform(
+    name = "exotic_unix",
+    constraint_values = [
+        "@platforms//os:linux",
+        "@platforms//cpu:s390x",
+    ],
+)
+
 current_build_settings(
     name = "current_build_settings",
 )

tests/support/support.bzl

@@ -28,6 +28,10 @@ LINUX_X86_64 = Label("//tests/support:linux_x86_64")
 WINDOWS = Label("//tests/support:windows")
 WINDOWS_X86_64 = Label("//tests/support:windows_x86_64")
 
+# Unspecified Unix platform that are unlikely to be the host platform in CI,
+# but still provide a Python toolchain.
+EXOTIC_UNIX = Label("//tests/support:exotic_unix")
+
 PY_TOOLCHAINS = str(Label("//tests/support/py_toolchains:all"))
 CC_TOOLCHAIN = str(Label("//tests/support/cc_toolchains:all"))
 CROSSTOOL_TOP = Label("//tests/support/cc_toolchains:cc_toolchain_suite")