build/bazel/platforms/BUILD.bazel

# Copyright 2022 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
#

"""Bazel platform() definitions for the Fuchsia platform build."""

# The Fuchsia build will use transitions that change the --platforms=<label>
# value to modify the current build configuration. As such, each platform
# instance represents:
#
#  - A separate output directory for generated artifacts.
#  - An execution environment for generated binaries.
#
# The `//build/bazel/platforms:common` platform is used for all targets
# that do not generate os- or arch-specific binaries (e.g. Java bytecode,
# auto-generated headers and more). It is set to be the default platforms
# by using --platforms=//build/bazel/platforms:common in the auto-generated
# .bazelrc
#
# In theory, it should be possible to define additionnal platforms that
# correspond to specific Fuchsia product configurations, which will allow
# performing system assembly for several Fuchsia devices in a single
# build invocation (provided the right transitions are used).
#

load("@fuchsia_build_config//:defs.bzl", "build_config")
load("@fuchsia_build_info//:args.bzl", fuchsia_target_cpu = "target_cpu")

package(default_visibility = ["//visibility:public"])

# The `//build/bazel/platforms:common` platform should be used for
# the default build configuration, and will contain all build
# artifacts which do not depend on a specific operating system
# or CPU architecture.
platform(
    name = "common",
    constraint_values = [],
)

# The //build/bazel/platforms:host platform is used to target
# the build configuration matching the current host machine.
alias(
    name = "host",
    actual = ":" + build_config.host_tag_alt,
)

alias(
    name = "default",
    actual = ":fuchsia_" + fuchsia_target_cpu,
)

# The following platforms will be used to generate binaries
# for Fuchsia, Linux and MacOS systems respectively. Other
# parts of Bazel should define C++ and Rust toolchain instances
# and configs that match the same constraint values to be
# selected for them.

# The fuchsia_$cpu platform definitions are used to build
# Fuchsia binaries with our Bazel SDK rules. As a consequence
# they require a working @fuchsia_sdk and @fuchsia_clang
# repository to provide a sysroot and SDK atoms to access
# platform libraries.
platform(
    name = "fuchsia_x64",
    constraint_values = [
        "@platforms//os:fuchsia",
        "@platforms//cpu:x86_64",
        ":fuchsia_artifacts_build_with_sdk_rules",
    ],
)

platform(
    name = "fuchsia_arm64",
    constraint_values = [
        "@platforms//os:fuchsia",
        "@platforms//cpu:arm64",
        ":fuchsia_artifacts_build_with_sdk_rules",
    ],
)

platform(
    name = "fuchsia_riscv64",
    constraint_values = [
        "@platforms//os:fuchsia",
        "@platforms//cpu:riscv64",
        ":fuchsia_artifacts_build_with_sdk_rules",
    ],
)

# The fuchsia_platform_$cpu platform definitions are used to
# build Fuchsia binaries *without* Bazel SDK rules. These artifacts
# are considered part of the Fuchsia platform itself and are used
# to generate the SDK atoms that the fuchsia_$cpu platform targets
# rely on.
platform(
    name = "fuchsia_platform_x64",
    constraint_values = [
        "@platforms//os:fuchsia",
        "@platforms//cpu:x86_64",
        ":fuchsia_artifacts_build_without_sdk_rules",
    ],
)

platform(
    name = "fuchsia_platform_arm64",
    constraint_values = [
        "@platforms//os:fuchsia",
        "@platforms//cpu:arm64",
        ":fuchsia_artifacts_build_without_sdk_rules",
    ],
)

platform(
    name = "fuchsia_platform_riscv64",
    constraint_values = [
        "@platforms//os:fuchsia",
        "@platforms//cpu:riscv64",
        ":fuchsia_artifacts_build_without_sdk_rules",
    ],
)

# Host platform definitions.
platform(
    name = "linux_x64",
    constraint_values = [
        "@platforms//os:linux",
        "@platforms//cpu:x86_64",
    ],
    exec_properties = {
        "container-image": build_config.rbe_container_image,
        "gceMachineType": build_config.rbe_gce_machine_type,
        "OSFamily": "Linux",
    },
)

platform(
    name = "linux_arm64",
    constraint_values = [
        "@platforms//os:linux",
        "@platforms//cpu:arm64",
    ],
)

# Configuration conditions for the platform values above.
config_setting(
    name = "is_fuchsia_x64",
    constraint_values = [
        "@platforms//os:fuchsia",
        "@platforms//cpu:x86_64",
    ],
)

config_setting(
    name = "is_fuchsia_arm64",
    constraint_values = [
        "@platforms//os:fuchsia",
        "@platforms//cpu:arm64",
    ],
)

config_setting(
    name = "is_fuchsia_riscv64",
    constraint_values = [
        "@platforms//os:fuchsia",
        "@platforms//cpu:riscv64",
    ],
)

config_setting(
    name = "is_linux_x64",
    constraint_values = [
        "@platforms//os:linux",
        "@platforms//cpu:x86_64",
    ],
)

config_setting(
    name = "is_linux_arm64",
    constraint_values = [
        "@platforms//os:linux",
        "@platforms//cpu:arm64",
    ],
)

# A constraint dimension which indiciates whether Fuchsia artifacts
# are generated using SDK rules or not. Platform binaries cannot use
# SDK rules.
constraint_setting(
    name = "fuchsia_artifacts_build_mode",
    default_constraint_value = ":fuchsia_artifacts_build_with_sdk_rules",
)

constraint_value(
    name = "fuchsia_artifacts_build_without_sdk_rules",
    constraint_setting = ":fuchsia_artifacts_build_mode",
)

constraint_value(
    name = "fuchsia_artifacts_build_with_sdk_rules",
    constraint_setting = ":fuchsia_artifacts_build_mode",
)