Add engine/unions.py to consolidate union types into one file (pant…

…sbuild#9580)

Problems with the status quo:

1) `@union` and `UnionRule`/`UnionMembership` are split across two files
2) Unions are an advanced concept. Most rule authors can go by without using them, so they don't belong in `rules.py`.

[ci skip-jvm-tests]

src/python/pants/backend/awslambda/common/BUILD

@@ -13,6 +13,7 @@ python_library(
     'src/python/pants/engine:rules',
     'src/python/pants/engine:selectors',
     'src/python/pants/engine:target',
+    'src/python/pants/engine:unions',
   ],
   tags = {'partially_type_checked'},
 )

src/python/pants/backend/awslambda/common/awslambda_common_rules.py

@@ -14,10 +14,10 @@
 from pants.engine.console import Console
 from pants.engine.fs import Digest, DirectoriesToMerge, DirectoryToMaterialize, Workspace
 from pants.engine.goal import Goal, GoalSubsystem, LineOriented
-from pants.engine.objects import union
-from pants.engine.rules import UnionMembership, goal_rule
+from pants.engine.rules import goal_rule
 from pants.engine.selectors import Get, MultiGet
 from pants.engine.target import Field, RegisteredTargetTypes, Target, Targets
+from pants.engine.unions import UnionMembership, union
 
 
 class AWSLambdaError(Exception):

src/python/pants/backend/awslambda/python/BUILD

@@ -14,6 +14,7 @@ python_library(
     'src/python/pants/engine:rules',
     'src/python/pants/engine:selectors',
     'src/python/pants/engine:target',
+    'src/python/pants/engine:unions',
     'src/python/pants/python',
   ],
   tags = {"type_checked"},

src/python/pants/backend/awslambda/python/awslambda_python_rules.py

@@ -33,8 +33,9 @@
 from pants.engine.addresses import Addresses
 from pants.engine.fs import Digest, DirectoriesToMerge
 from pants.engine.isolated_process import Process, ProcessResult
-from pants.engine.rules import UnionRule, named_rule, subsystem_rule
+from pants.engine.rules import named_rule, subsystem_rule
 from pants.engine.selectors import Get
+from pants.engine.unions import UnionRule
 from pants.python.python_setup import PythonSetup
 
 

src/python/pants/backend/awslambda/python/targets.py

@@ -5,7 +5,7 @@
 from typing import Match, Optional, Tuple, cast
 
 from pants.backend.python.rules.targets import COMMON_PYTHON_FIELDS, PythonSources
-from pants.build_graph.address import Address
+from pants.engine.addresses import Address
 from pants.engine.target import InvalidFieldException, StringField, Target
 
 

src/python/pants/backend/python/lint/BUILD

@@ -8,6 +8,7 @@ python_library(
     'src/python/pants/core/util_rules',
     'src/python/pants/engine/legacy:structs',
     'src/python/pants/engine:rules',
+    'src/python/pants/engine:unions',
   ],
   tags = {"type_checked"},
 )

src/python/pants/backend/python/lint/bandit/BUILD

@@ -13,6 +13,7 @@ python_library(
     'src/python/pants/engine:isolated_process',
     'src/python/pants/engine:rules',
     'src/python/pants/engine:selectors',
+    'src/python/pants/engine:unions',
     'src/python/pants/option',
     'src/python/pants/python',
   ],

src/python/pants/backend/python/lint/bandit/rules.py

@@ -24,8 +24,9 @@
 )
 from pants.engine.fs import Digest, DirectoriesToMerge, PathGlobs, Snapshot
 from pants.engine.isolated_process import FallibleProcessResult, Process
-from pants.engine.rules import UnionRule, named_rule, subsystem_rule
+from pants.engine.rules import named_rule, subsystem_rule
 from pants.engine.selectors import Get
+from pants.engine.unions import UnionRule
 from pants.option.global_options import GlobMatchErrorBehavior
 from pants.python.python_setup import PythonSetup
 

src/python/pants/backend/python/lint/black/BUILD

@@ -13,6 +13,7 @@ python_library(
     'src/python/pants/engine:isolated_process',
     'src/python/pants/engine:rules',
     'src/python/pants/engine:selectors',
+    'src/python/pants/engine:unions',
     'src/python/pants/option',
     'src/python/pants/python',
   ],

src/python/pants/backend/python/lint/black/rules.py

@@ -28,8 +28,9 @@
 )
 from pants.engine.fs import Digest, DirectoriesToMerge, PathGlobs, Snapshot
 from pants.engine.isolated_process import FallibleProcessResult, Process, ProcessResult
-from pants.engine.rules import UnionRule, named_rule, rule, subsystem_rule
+from pants.engine.rules import named_rule, rule, subsystem_rule
 from pants.engine.selectors import Get
+from pants.engine.unions import UnionRule
 from pants.option.global_options import GlobMatchErrorBehavior
 from pants.python.python_setup import PythonSetup
 

src/python/pants/backend/python/lint/docformatter/BUILD

@@ -13,6 +13,7 @@ python_library(
     'src/python/pants/engine:isolated_process',
     'src/python/pants/engine:rules',
     'src/python/pants/engine:selectors',
+    'src/python/pants/engine:unions',
     'src/python/pants/option',
     'src/python/pants/python',
   ],

src/python/pants/backend/python/lint/docformatter/rules.py

@@ -26,8 +26,9 @@
 )
 from pants.engine.fs import Digest, DirectoriesToMerge
 from pants.engine.isolated_process import FallibleProcessResult, Process, ProcessResult
-from pants.engine.rules import UnionRule, named_rule, rule, subsystem_rule
+from pants.engine.rules import named_rule, rule, subsystem_rule
 from pants.engine.selectors import Get
+from pants.engine.unions import UnionRule
 from pants.python.python_setup import PythonSetup
 
 

src/python/pants/backend/python/lint/flake8/BUILD

@@ -31,6 +31,7 @@ python_tests(
     'src/python/pants/engine:fs',
     'src/python/pants/engine:rules',
     'src/python/pants/engine:selectors',
+    'src/python/pants/engine:unions',
     'src/python/pants/engine/legacy:structs',
     'src/python/pants/source',
     'src/python/pants/testutil:interpreter_selection_utils',

src/python/pants/backend/python/lint/flake8/rules.py

@@ -24,8 +24,9 @@
 )
 from pants.engine.fs import Digest, DirectoriesToMerge, PathGlobs, Snapshot
 from pants.engine.isolated_process import FallibleProcessResult, Process
-from pants.engine.rules import UnionRule, named_rule, subsystem_rule
+from pants.engine.rules import named_rule, subsystem_rule
 from pants.engine.selectors import Get
+from pants.engine.unions import UnionRule
 from pants.option.global_options import GlobMatchErrorBehavior
 from pants.python.python_setup import PythonSetup
 

src/python/pants/backend/python/lint/isort/BUILD

@@ -32,6 +32,7 @@ python_tests(
     'src/python/pants/engine:fs',
     'src/python/pants/engine:rules',
     'src/python/pants/engine:selectors',
+    'src/python/pants/engine:unions',
     'src/python/pants/engine/legacy:structs',
     'src/python/pants/source',
     'src/python/pants/testutil:test_base',

src/python/pants/backend/python/lint/isort/rules.py

@@ -26,8 +26,9 @@
 )
 from pants.engine.fs import Digest, DirectoriesToMerge, PathGlobs, Snapshot
 from pants.engine.isolated_process import FallibleProcessResult, Process, ProcessResult
-from pants.engine.rules import UnionRule, named_rule, rule, subsystem_rule
+from pants.engine.rules import named_rule, rule, subsystem_rule
 from pants.engine.selectors import Get
+from pants.engine.unions import UnionRule
 from pants.option.custom_types import GlobExpansionConjunction
 from pants.option.global_options import GlobMatchErrorBehavior
 from pants.python.python_setup import PythonSetup

src/python/pants/backend/python/lint/pylint/BUILD

@@ -13,6 +13,7 @@ python_library(
     'src/python/pants/engine:isolated_process',
     'src/python/pants/engine:rules',
     'src/python/pants/engine:selectors',
+    'src/python/pants/engine:unions',
     'src/python/pants/option',
   ],
   tags = {"partially_type_checked"},

src/python/pants/backend/python/lint/pylint/rules.py

@@ -22,9 +22,10 @@
 from pants.engine.addresses import Addresses
 from pants.engine.fs import Digest, DirectoriesToMerge, PathGlobs, Snapshot
 from pants.engine.isolated_process import FallibleProcessResult, Process
-from pants.engine.rules import UnionRule, named_rule, subsystem_rule
+from pants.engine.rules import named_rule, subsystem_rule
 from pants.engine.selectors import Get
 from pants.engine.target import Dependencies, Targets
+from pants.engine.unions import UnionRule
 from pants.option.global_options import GlobMatchErrorBehavior
 from pants.python.python_setup import PythonSetup
 

src/python/pants/backend/python/lint/python_fmt.py

@@ -13,9 +13,9 @@
 )
 from pants.core.util_rules.determine_source_files import AllSourceFilesRequest, SourceFiles
 from pants.engine.fs import Digest, Snapshot
-from pants.engine.objects import union
-from pants.engine.rules import UnionMembership, UnionRule, rule
+from pants.engine.rules import rule
 from pants.engine.selectors import Get
+from pants.engine.unions import UnionMembership, UnionRule, union
 
 
 @dataclass(frozen=True)

src/python/pants/backend/python/rules/BUILD

@@ -20,6 +20,7 @@ python_library(
     'src/python/pants/engine:rules',
     'src/python/pants/engine:selectors',
     'src/python/pants/engine:target',
+    'src/python/pants/engine:unions',
     'src/python/pants/option',
     'src/python/pants/python',
     'src/python/pants/source:source',

src/python/pants/backend/python/rules/pytest_coverage.py

@@ -40,9 +40,10 @@
     InputFilesContent,
 )
 from pants.engine.isolated_process import Process, ProcessResult
-from pants.engine.rules import RootRule, UnionRule, named_rule, rule, subsystem_rule
+from pants.engine.rules import RootRule, named_rule, rule, subsystem_rule
 from pants.engine.selectors import Get, MultiGet
 from pants.engine.target import Sources, Targets, TransitiveTargets
+from pants.engine.unions import UnionRule
 from pants.python.python_setup import PythonSetup
 from pants.source.source_root import SourceRootConfig
 

src/python/pants/backend/python/rules/pytest_runner.py

@@ -36,9 +36,10 @@
 from pants.engine.fs import Digest, DirectoriesToMerge, InputFilesContent
 from pants.engine.interactive_runner import InteractiveProcessRequest
 from pants.engine.isolated_process import FallibleProcessResult, Process
-from pants.engine.rules import UnionRule, named_rule, rule, subsystem_rule
+from pants.engine.rules import named_rule, rule, subsystem_rule
 from pants.engine.selectors import Get, MultiGet
 from pants.engine.target import Targets, TransitiveTargets
+from pants.engine.unions import UnionRule
 from pants.option.global_options import GlobalOptions
 from pants.python.python_setup import PythonSetup
 

src/python/pants/backend/python/rules/python_create_binary.py

@@ -24,8 +24,9 @@
 from pants.core.goals.binary import BinaryConfiguration, CreatedBinary
 from pants.core.util_rules.determine_source_files import AllSourceFilesRequest, SourceFiles
 from pants.engine.addresses import Addresses
-from pants.engine.rules import UnionRule, rule
+from pants.engine.rules import rule
 from pants.engine.selectors import Get
+from pants.engine.unions import UnionRule
 
 
 @dataclass(frozen=True)

src/python/pants/backend/python/rules/repl.py

@@ -10,8 +10,9 @@
 from pants.backend.python.subsystems.ipython import IPython
 from pants.core.goals.repl import ReplBinary, ReplImplementation
 from pants.engine.addresses import Addresses
-from pants.engine.rules import UnionRule, rule, subsystem_rule
+from pants.engine.rules import rule, subsystem_rule
 from pants.engine.selectors import Get
+from pants.engine.unions import UnionRule
 
 
 class PythonRepl(ReplImplementation):

src/python/pants/bin/BUILD

@@ -26,8 +26,8 @@ python_library(
     'src/python/pants/engine:mapper',
     'src/python/pants/engine:native',
     'src/python/pants/engine:parser',
-    'src/python/pants/engine:rules',
     'src/python/pants/engine:scheduler',
+    'src/python/pants/engine:unions',
     'src/python/pants/goal',
     'src/python/pants/goal:context',
     'src/python/pants/goal:run_tracker',

src/python/pants/bin/daemon_pants_runner.py

@@ -12,7 +12,7 @@
 from pants.base.exception_sink import ExceptionSink
 from pants.base.exiter import PANTS_FAILED_EXIT_CODE, PANTS_SUCCEEDED_EXIT_CODE, ExitCode, Exiter
 from pants.bin.local_pants_runner import LocalPantsRunner
-from pants.engine.rules import UnionMembership
+from pants.engine.unions import UnionMembership
 from pants.help.help_printer import HelpPrinter
 from pants.init.specs_calculator import SpecsCalculator
 from pants.init.util import clean_global_runtime_state

src/python/pants/bin/local_pants_runner.py

@@ -16,7 +16,7 @@
 from pants.bin.goal_runner import GoalRunner
 from pants.build_graph.build_configuration import BuildConfiguration
 from pants.engine.native import Native
-from pants.engine.rules import UnionMembership
+from pants.engine.unions import UnionMembership
 from pants.goal.run_tracker import RunTracker
 from pants.help.help_printer import HelpPrinter
 from pants.init.engine_initializer import EngineInitializer, LegacyGraphSession

src/python/pants/core/goals/BUILD

@@ -19,6 +19,7 @@ python_library(
     'src/python/pants/engine:rules',
     'src/python/pants/engine:selectors',
     'src/python/pants/engine:target',
+    'src/python/pants/engine:unions',
     'src/python/pants/option',
     'src/python/pants/util:contextutil',
   ],
@@ -40,6 +41,7 @@ python_tests(
     'src/python/pants/engine:interactive_runner',
     'src/python/pants/engine:rules',
     'src/python/pants/engine:target',
+    'src/python/pants/engine:unions',
     'src/python/pants/testutil/engine:util',
     'src/python/pants/testutil:test_base',
     'src/python/pants/option',

src/python/pants/core/goals/binary.py

@@ -14,10 +14,10 @@
 from pants.engine.console import Console
 from pants.engine.fs import Digest, DirectoriesToMerge, DirectoryToMaterialize, Workspace
 from pants.engine.goal import Goal, GoalSubsystem, LineOriented
-from pants.engine.objects import union
-from pants.engine.rules import UnionMembership, goal_rule
+from pants.engine.rules import goal_rule
 from pants.engine.selectors import Get, MultiGet
 from pants.engine.target import Field, RegisteredTargetTypes, Target, TargetsWithOrigins
+from pants.engine.unions import UnionMembership, union
 
 
 # TODO: Factor this out once porting fmt.py and lint.py to the Target API.

src/python/pants/core/goals/fmt.py

@@ -19,10 +19,11 @@
 )
 from pants.engine.goal import Goal, GoalSubsystem
 from pants.engine.isolated_process import ProcessResult
-from pants.engine.objects import Collection, union
-from pants.engine.rules import UnionMembership, goal_rule
+from pants.engine.objects import Collection
+from pants.engine.rules import goal_rule
 from pants.engine.selectors import Get, MultiGet
 from pants.engine.target import Field, Target, TargetsWithOrigins, TargetWithOrigin
+from pants.engine.unions import UnionMembership, union
 
 
 @dataclass(frozen=True)

src/python/pants/core/goals/fmt_test.py

@@ -23,8 +23,8 @@
     FileContent,
     Workspace,
 )
-from pants.engine.rules import UnionMembership
 from pants.engine.target import Sources, Target, TargetsWithOrigins, TargetWithOrigin
+from pants.engine.unions import UnionMembership
 from pants.testutil.engine.util import MockConsole, MockGet, create_goal_subsystem, run_rule
 from pants.testutil.test_base import TestBase
 from pants.util.ordered_set import OrderedSet

src/python/pants/core/goals/lint.py

@@ -15,10 +15,11 @@
 from pants.engine.console import Console
 from pants.engine.goal import Goal, GoalSubsystem
 from pants.engine.isolated_process import FallibleProcessResult
-from pants.engine.objects import Collection, union
-from pants.engine.rules import UnionMembership, goal_rule
+from pants.engine.objects import Collection
+from pants.engine.rules import goal_rule
 from pants.engine.selectors import Get, MultiGet
 from pants.engine.target import Field, Sources, Target, TargetsWithOrigins, TargetWithOrigin
+from pants.engine.unions import UnionMembership, union
 
 
 @dataclass(frozen=True)

src/python/pants/core/goals/lint_test.py

@@ -18,8 +18,8 @@
     ConfigurationsWithSourcesRequest,
 )
 from pants.engine.addresses import Address
-from pants.engine.rules import UnionMembership
 from pants.engine.target import Sources, Target, TargetsWithOrigins, TargetWithOrigin
+from pants.engine.unions import UnionMembership
 from pants.testutil.engine.util import MockConsole, MockGet, create_goal_subsystem, run_rule
 from pants.testutil.test_base import TestBase
 from pants.util.ordered_set import OrderedSet

src/python/pants/core/goals/repl.py

@@ -11,10 +11,10 @@
 from pants.engine.fs import Digest, DirectoryToMaterialize, Workspace
 from pants.engine.goal import Goal, GoalSubsystem
 from pants.engine.interactive_runner import InteractiveProcessRequest, InteractiveRunner
-from pants.engine.objects import union
-from pants.engine.rules import UnionMembership, goal_rule
+from pants.engine.rules import goal_rule
 from pants.engine.selectors import Get
 from pants.engine.target import Field, Target, Targets, TransitiveTargets
+from pants.engine.unions import UnionMembership, union
 from pants.option.global_options import GlobalOptions
 from pants.util.contextutil import temporary_dir
 

src/python/pants/core/goals/run.py

@@ -13,9 +13,10 @@
 from pants.engine.fs import DirectoryToMaterialize, Workspace
 from pants.engine.goal import Goal, GoalSubsystem
 from pants.engine.interactive_runner import InteractiveProcessRequest, InteractiveRunner
-from pants.engine.rules import UnionMembership, goal_rule
+from pants.engine.rules import goal_rule
 from pants.engine.selectors import Get
 from pants.engine.target import RegisteredTargetTypes, TargetsWithOrigins
+from pants.engine.unions import UnionMembership
 from pants.option.custom_types import shell_str
 from pants.option.global_options import GlobalOptions
 from pants.util.contextutil import temporary_dir

src/python/pants/core/goals/run_test.py

@@ -10,8 +10,8 @@
 from pants.engine.addresses import Address
 from pants.engine.fs import Digest, FileContent, InputFilesContent, Workspace
 from pants.engine.interactive_runner import InteractiveProcessRequest, InteractiveRunner
-from pants.engine.rules import UnionMembership
 from pants.engine.target import RegisteredTargetTypes, Target, TargetsWithOrigins, TargetWithOrigin
+from pants.engine.unions import UnionMembership
 from pants.option.global_options import GlobalOptions
 from pants.testutil.engine.util import (
     MockConsole,

src/python/pants/core/goals/test.py

@@ -23,8 +23,8 @@
 from pants.engine.goal import Goal, GoalSubsystem
 from pants.engine.interactive_runner import InteractiveProcessRequest, InteractiveRunner
 from pants.engine.isolated_process import FallibleProcessResult
-from pants.engine.objects import Collection, union
-from pants.engine.rules import UnionMembership, goal_rule, rule
+from pants.engine.objects import Collection
+from pants.engine.rules import goal_rule, rule
 from pants.engine.selectors import Get, MultiGet
 from pants.engine.target import (
     Field,
@@ -34,6 +34,7 @@
     TargetsWithOrigins,
     TargetWithOrigin,
 )
+from pants.engine.unions import UnionMembership, union
 
 # TODO(#6004): use proper Logging singleton, rather than static logger.
 logger = logging.getLogger(__name__)