Bazel switch targets by platform

BUILD.bazel

# 3.8+
# https://docs.bazel.build/versions/master/platforms.html#skipping-incompatible-targets
# https://docs.bazel.build/versions/master/be/common-definitions.html#common-attributes

# Pre 3.8:
#
# Bazel Platforms Cookbook:
# https://docs.google.com/document/d/1UZaVcL08wePB41ATZHcxQV4Pu1YfA1RvvWm8FbZHuW8/edit#
# 
# Use this only for simple cases like skipping Windows-only targets on Linux CI.
# Read Description!
# https://github.com/hlopko/bazel_platforms_examples/tree/master/examples/05_select_on_platform

rule_binary(
    name = "my_binary_windows",
    # ...
)

rule_binary(
    name = "my_binary_macos",
    # ...
)

rule_binary(
    name = "my_binary_linux",
    # ...
)

config_setting(
    name = "is_windows",
    constraint_values = [
        "@platforms//os:windows"
    ],
)

config_setting(
    name = "is_macos",
    constraint_values = [
        "@platforms//os:macos"
    ],
)

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

filegroup(
    name = "empty"
)

alias(
    name = "my_binary",
    actual = select({
        ":is_windows": ":my_binary_windows",
        ":is_macos": ":my_binary_macos",
        ":is_linux": ":my_binary_linux",      
        # Skip entirely for other platforms
        "//conditions:default": ":empty",
    }),
)