internal: copy Starlark rule implementation from Bazel (#1418)

This is a copy of the Starlark implementation of the Python rules from
Bazel. This code isn't
loaded and won't work as-is. Modifications to make it work will be made
in
subsequent changes. It's almost pristine; changes are made to satisfy
the
buildifier check.

Work towards #1069

Author: rickeylev

python/private/common/attributes.bzl

@@ -0,0 +1,227 @@
+# Copyright 2022 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Attributes for Python rules."""
+
+load(":common/cc/cc_info.bzl", _CcInfo = "CcInfo")
+load(":common/python/common.bzl", "union_attrs")
+load(":common/python/providers.bzl", "PyInfo")
+load(
+    ":common/python/semantics.bzl",
+    "DEPS_ATTR_ALLOW_RULES",
+    "PLATFORMS_LOCATION",
+    "SRCS_ATTR_ALLOW_FILES",
+    "TOOLS_REPO",
+)
+
+PackageSpecificationInfo = _builtins.toplevel.PackageSpecificationInfo
+
+_STAMP_VALUES = [-1, 0, 1]
+
+def create_stamp_attr(**kwargs):
+    return {"stamp": attr.int(values = _STAMP_VALUES, **kwargs)}
+
+def create_srcs_attr(*, mandatory):
+    return {
+        "srcs": attr.label_list(
+            # Google builds change the set of allowed files.
+            allow_files = SRCS_ATTR_ALLOW_FILES,
+            mandatory = mandatory,
+            # Necessary for --compile_one_dependency to work.
+            flags = ["DIRECT_COMPILE_TIME_INPUT"],
+        ),
+    }
+
+SRCS_VERSION_ALL_VALUES = ["PY2", "PY2ONLY", "PY2AND3", "PY3", "PY3ONLY"]
+SRCS_VERSION_NON_CONVERSION_VALUES = ["PY2AND3", "PY2ONLY", "PY3ONLY"]
+
+def create_srcs_version_attr(values):
+    return {
+        "srcs_version": attr.string(
+            default = "PY2AND3",
+            values = values,
+        ),
+    }
+
+def copy_common_binary_kwargs(kwargs):
+    return {
+        key: kwargs[key]
+        for key in BINARY_ATTR_NAMES
+        if key in kwargs
+    }
+
+def copy_common_test_kwargs(kwargs):
+    return {
+        key: kwargs[key]
+        for key in TEST_ATTR_NAMES
+        if key in kwargs
+    }
+
+CC_TOOLCHAIN = {
+    # NOTE: The `cc_helper.find_cpp_toolchain()` function expects the attribute
+    # name to be this name.
+    "_cc_toolchain": attr.label(default = "@" + TOOLS_REPO + "//tools/cpp:current_cc_toolchain"),
+}
+
+# The common "data" attribute definition.
+DATA_ATTRS = {
+    # NOTE: The "flags" attribute is deprecated, but there isn't an alternative
+    # way to specify that constraints should be ignored.
+    "data": attr.label_list(
+        allow_files = True,
+        flags = ["SKIP_CONSTRAINTS_OVERRIDE"],
+    ),
+}
+
+NATIVE_RULES_ALLOWLIST_ATTRS = {
+    "_native_rules_allowlist": attr.label(
+        default = configuration_field(
+            fragment = "py",
+            name = "native_rules_allowlist",
+        ),
+        providers = [PackageSpecificationInfo],
+    ),
+}
+
+# Attributes common to all rules.
+COMMON_ATTRS = union_attrs(
+    DATA_ATTRS,
+    NATIVE_RULES_ALLOWLIST_ATTRS,
+    {
+        # NOTE: This attribute is deprecated and slated for removal.
+        "distribs": attr.string_list(),
+        # TODO(b/148103851): This attribute is deprecated and slated for
+        # removal.
+        # NOTE: The license attribute is missing in some Java integration tests,
+        # so fallback to a regular string_list for that case.
+        # buildifier: disable=attr-license
+        "licenses": attr.license() if hasattr(attr, "license") else attr.string_list(),
+    },
+    allow_none = True,
+)
+
+# Attributes common to rules accepting Python sources and deps.
+PY_SRCS_ATTRS = union_attrs(
+    {
+        "deps": attr.label_list(
+            providers = [[PyInfo], [_CcInfo]],
+            # TODO(b/228692666): Google-specific; remove these allowances once
+            # the depot is cleaned up.
+            allow_rules = DEPS_ATTR_ALLOW_RULES,
+        ),
+        # Required attribute, but details vary by rule.
+        # Use create_srcs_attr to create one.
+        "srcs": None,
+        # NOTE: In Google, this attribute is deprecated, and can only
+        # effectively be PY3 or PY3ONLY. Externally, with Bazel, this attribute
+        # has a separate story.
+        # Required attribute, but the details vary by rule.
+        # Use create_srcs_version_attr to create one.
+        "srcs_version": None,
+    },
+    allow_none = True,
+)
+
+# Attributes specific to Python executable-equivalent rules. Such rules may not
+# accept Python sources (e.g. some packaged-version of a py_test/py_binary), but
+# still accept Python source-agnostic settings.
+AGNOSTIC_EXECUTABLE_ATTRS = union_attrs(
+    DATA_ATTRS,
+    {
+        "env": attr.string_dict(
+            doc = """\
+Dictionary of strings; optional; values are subject to `$(location)` and "Make
+variable" substitution.
+
+Specifies additional environment variables to set when the target is executed by
+`test` or `run`.
+""",
+        ),
+        # The value is required, but varies by rule and/or rule type. Use
+        # create_stamp_attr to create one.
+        "stamp": None,
+    },
+    allow_none = True,
+)
+
+# Attributes specific to Python test-equivalent executable rules. Such rules may
+# not accept Python sources (e.g. some packaged-version of a py_test/py_binary),
+# but still accept Python source-agnostic settings.
+AGNOSTIC_TEST_ATTRS = union_attrs(
+    AGNOSTIC_EXECUTABLE_ATTRS,
+    # Tests have stamping disabled by default.
+    create_stamp_attr(default = 0),
+    {
+        "env_inherit": attr.string_list(
+            doc = """\
+List of strings; optional
+
+Specifies additional environment variables to inherit from the external
+environment when the test is executed by bazel test.
+""",
+        ),
+        # TODO(b/176993122): Remove when Bazel automatically knows to run on darwin.
+        "_apple_constraints": attr.label_list(
+            default = [
+                PLATFORMS_LOCATION + "/os:ios",
+                PLATFORMS_LOCATION + "/os:macos",
+                PLATFORMS_LOCATION + "/os:tvos",
+                PLATFORMS_LOCATION + "/os:visionos",
+                PLATFORMS_LOCATION + "/os:watchos",
+            ],
+        ),
+    },
+)
+
+# Attributes specific to Python binary-equivalent executable rules. Such rules may
+# not accept Python sources (e.g. some packaged-version of a py_test/py_binary),
+# but still accept Python source-agnostic settings.
+AGNOSTIC_BINARY_ATTRS = union_attrs(
+    AGNOSTIC_EXECUTABLE_ATTRS,
+    create_stamp_attr(default = -1),
+)
+
+# Attribute names common to all Python rules
+COMMON_ATTR_NAMES = [
+    "compatible_with",
+    "deprecation",
+    "distribs",  # NOTE: Currently common to all rules, but slated for removal
+    "exec_compatible_with",
+    "exec_properties",
+    "features",
+    "restricted_to",
+    "tags",
+    "target_compatible_with",
+    # NOTE: The testonly attribute requires careful handling: None/unset means
+    # to use the `package(default_testonly`) value, which isn't observable
+    # during the loading phase.
+    "testonly",
+    "toolchains",
+    "visibility",
+] + COMMON_ATTRS.keys()
+
+# Attribute names common to all test=True rules
+TEST_ATTR_NAMES = COMMON_ATTR_NAMES + [
+    "args",
+    "size",
+    "timeout",
+    "flaky",
+    "shard_count",
+    "local",
+] + AGNOSTIC_TEST_ATTRS.keys()
+
+# Attribute names common to all executable=True rules
+BINARY_ATTR_NAMES = COMMON_ATTR_NAMES + [
+    "args",
+    "output_licenses",  # NOTE: Common to all rules, but slated for removal
+] + AGNOSTIC_BINARY_ATTRS.keys()

python/private/common/attributes_bazel.bzl

@@ -0,0 +1,30 @@
+# Copyright 2022 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Attributes specific to the Bazel implementation of the Python rules."""
+
+IMPORTS_ATTRS = {
+    "imports": attr.string_list(
+        doc = """
+List of import directories to be added to the PYTHONPATH.
+
+Subject to "Make variable" substitution. These import directories will be added
+for this rule and all rules that depend on it (note: not the rules this rule
+depends on. Each directory will be added to `PYTHONPATH` by `py_binary` rules
+that depend on this rule. The strings are repo-runfiles-root relative,
+
+Absolute paths (paths that start with `/`) and paths that references a path
+above the execution root are not allowed and will result in an error.
+""",
+    ),
+}