attributes.bzl

# 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("//python/private:reexports.bzl", "BuiltinPyInfo")
load(":common.bzl", "union_attrs")
load(":providers.bzl", "PyInfo")
load(":py_internal.bzl", "py_internal")
load(
    ":semantics.bzl",
    "DEPS_ATTR_ALLOW_RULES",
    "SRCS_ATTR_ALLOW_FILES",
)

# TODO: Load CcInfo from rules_cc
_CcInfo = CcInfo
_PackageSpecificationInfo = getattr(py_internal, "PackageSpecificationInfo", None)

_STAMP_VALUES = [-1, 0, 1]

def create_stamp_attr(**kwargs):
    return {
        "stamp": attr.int(
            values = _STAMP_VALUES,
            doc = """
Whether to encode build information into the binary. Possible values:

* `stamp = 1`: Always stamp the build information into the binary, even in
  `--nostamp` builds. **This setting should be avoided**, since it potentially kills
  remote caching for the binary and any downstream actions that depend on it.
* `stamp = 0`: Always replace build information by constant values. This gives
  good build result caching.
* `stamp = -1`: Embedding of build information is controlled by the
  `--[no]stamp` flag.

Stamped binaries are not rebuilt unless their dependencies change.

WARNING: Stamping can harm build performance by reducing cache hits and should
be avoided if possible.
""",
            **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"],
            doc = """
The list of Python source files that are processed to create the target. This
includes all your checked-in code and may include generated source files.  The
`.py` files belong in `srcs` and library targets belong in `deps`. Other binary
files that may be needed at run time belong in `data`.
""",
        ),
    }

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,
            doc = "Defunct, unused, does nothing.",
        ),
    }

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 = "@bazel_tools//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"],
        doc = """
The list of files need by this library at runtime. See comments about
the [`data` attribute typically defined by rules](https://bazel.build/reference/be/common-definitions#typical-attributes).

There is no `py_embed_data` like there is `cc_embed_data` and `go_embed_data`.
This is because Python has a concept of runtime resources.
""",
    ),
}

def _create_native_rules_allowlist_attrs():
    if py_internal:
        # The fragment and name are validated when configuration_field is called
        default = configuration_field(
            fragment = "py",
            name = "native_rules_allowlist",
        )

        # A None provider isn't allowed
        providers = [_PackageSpecificationInfo]
    else:
        default = None
        providers = []

    return {
        "_native_rules_allowlist": attr.label(
            default = default,
            providers = providers,
        ),
    }

NATIVE_RULES_ALLOWLIST_ATTRS = _create_native_rules_allowlist_attrs()

# Attributes common to all rules.
COMMON_ATTRS = union_attrs(
    DATA_ATTRS,
    NATIVE_RULES_ALLOWLIST_ATTRS,
    # buildifier: disable=attr-licenses
    {
        # 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],
                [BuiltinPyInfo],
            ],
            # TODO(b/228692666): Google-specific; remove these allowances once
            # the depot is cleaned up.
            allow_rules = DEPS_ATTR_ALLOW_RULES,
            doc = """
List of additional libraries to be linked in to the target.
See comments about
the [`deps` attribute typically defined by
rules](https://bazel.build/reference/be/common-definitions#typical-attributes).
These are typically `py_library` rules.

Targets that only provide data files used at runtime belong in the `data`
attribute.
""",
        ),
        # 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//os:ios",
                "@platforms//os:macos",
                "@platforms//os:tvos",
                "@platforms//os:visionos",
                "@platforms//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",
] + list(COMMON_ATTRS)  # Use list() instead .keys() so it's valid Python

# Attribute names common to all test=True rules
TEST_ATTR_NAMES = COMMON_ATTR_NAMES + [
    "args",
    "size",
    "timeout",
    "flaky",
    "shard_count",
    "local",
] + list(AGNOSTIC_TEST_ATTRS)  # Use list() instead .keys() so it's valid Python

# 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
] + list(AGNOSTIC_BINARY_ATTRS)  # Use list() instead .keys() so it's valid Python