Remove the Scm interface

# Rust tests and lints will be skipped. Delete if not intended.
[ci skip-rust]

# Building wheels and fs_util will be skipped. Delete if not intended.
[ci skip-build-wheels]

src/python/pants/base/build_environment.py

@@ -6,7 +6,7 @@
 from typing import Optional
 
 from pants.base.build_root import BuildRoot
-from pants.scm.scm import Scm
+from pants.vcs.git import Git, GitException
 from pants.version import VERSION
 
 logger = logging.getLogger(__name__)
@@ -52,37 +52,22 @@ def get_default_pants_config_file() -> str:
     return os.path.join(get_buildroot(), "pants.toml")
 
 
-_SCM: Optional[Scm] = None
+_Git: Optional[Git] = None
 
 
-def get_scm() -> Optional[Scm]:
-    """Returns the pants Scm if any.
+def get_git() -> Optional[Git]:
+    """Returns Git, if available."""
+    global _Git
+    if _Git:
+        return _Git
 
-    :API: public
-    """
-    # TODO(John Sirois): Extract a module/class to carry the bootstrap logic.
-    global _SCM
-    if _SCM:
-        return _SCM
-    from pants.scm.git import Git
-
-    # We know about git, so attempt an auto-configure
+    # We know about Git, so attempt an auto-configure
     worktree = Git.detect_worktree()
     if worktree and os.path.isdir(worktree):
         git = Git(worktree=worktree)
         try:
             logger.debug(f"Detected git repository at {worktree} on branch {git.branch_name}")
-            set_scm(git)
-        except git.LocalException as e:
+            _Git = git
+        except GitException as e:
             logger.info(f"Failed to load git repository at {worktree}: {e!r}")
-    return _SCM
-
-
-def set_scm(scm: Optional[Scm]) -> None:
-    """Sets the pants Scm."""
-    if scm is None:
-        return
-    if not isinstance(scm, Scm):
-        raise ValueError(f"The scm must be an instance of Scm, given {scm}")
-    global _SCM
-    _SCM = scm
+    return _Git

src/python/pants/base/run_info.py

@@ -8,7 +8,7 @@
 import time
 from collections import OrderedDict
 
-from pants.base.build_environment import get_buildroot, get_scm
+from pants.base.build_environment import get_buildroot
 from pants.util.dirutil import safe_mkdir_for
 from pants.version import VERSION
 
@@ -92,12 +92,3 @@ def add_basic_info(self, run_id, timestamp):
             ("buildroot", buildroot),
             ("version", VERSION),
         )
-
-    def add_scm_info(self):
-        """Adds SCM-related info."""
-        scm = get_scm()
-        if not scm:
-            return
-        revision = scm.commit_id
-        branch = scm.branch_name or revision
-        self.add_infos(("revision", revision), ("branch", branch))

src/python/pants/init/engine_initializer.py

@@ -31,8 +31,8 @@
 from pants.option.global_options import DEFAULT_EXECUTION_OPTIONS, ExecutionOptions
 from pants.option.options_bootstrapper import OptionsBootstrapper
 from pants.option.subsystem import Subsystem
-from pants.scm.subsystems.changed import rules as changed_rules
 from pants.util.ordered_set import FrozenOrderedSet
+from pants.vcs.changed import rules as changed_rules
 
 logger = logging.getLogger(__name__)
 

src/python/pants/init/global_subsystems.py

@@ -4,7 +4,7 @@
 from pants.goal.run_tracker import RunTracker
 from pants.process.subprocess import Subprocess
 from pants.reporting.reporting import Reporting
-from pants.scm.subsystems.changed import Changed
+from pants.vcs.changed import Changed
 
 
 class GlobalSubsystems:

src/python/pants/init/specs_calculator.py

@@ -4,7 +4,7 @@
 import logging
 from typing import Optional, cast
 
-from pants.base.build_environment import get_buildroot, get_scm
+from pants.base.build_environment import get_buildroot, get_git
 from pants.base.specs import AddressLiteralSpec, AddressSpecs, FilesystemSpecs, Specs
 from pants.base.specs_parser import SpecsParser
 from pants.engine.addresses import AddressInput
@@ -13,7 +13,7 @@
 from pants.engine.rules import QueryRule
 from pants.option.options import Options
 from pants.option.options_bootstrapper import OptionsBootstrapper
-from pants.scm.subsystems.changed import ChangedAddresses, ChangedOptions, ChangedRequest
+from pants.vcs.changed import ChangedAddresses, ChangedOptions, ChangedRequest
 
 logger = logging.getLogger(__name__)
 
@@ -53,13 +53,13 @@ def calculate_specs(
     if not changed_options.provided:
         return specs
 
-    scm = get_scm()
-    if not scm:
+    git = get_git()
+    if not git:
         raise InvalidSpecConstraint(
-            "The `--changed-*` options are not available without a recognized SCM (usually " "Git)."
+            "The `--changed-*` options are only available if Git is used for the repository."
         )
     changed_request = ChangedRequest(
-        sources=tuple(changed_options.changed_files(scm=scm)),
+        sources=tuple(changed_options.changed_files(git)),
         dependees=changed_options.dependees,
     )
     (changed_addresses,) = session.product_request(

src/python/pants/vcs/BUILD

@@ -0,0 +1,22 @@
+# Copyright 2014 Pants project contributors (see CONTRIBUTORS.md).
+# Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+python_library()
+
+python_tests(
+  name="tests",
+  sources=["*_test.py", "!*integration_test.py"],
+)
+
+
+python_integration_tests(
+  name = 'changed_integration',
+  sources = ['changed_integration_test.py'],
+  dependencies = [
+    '//:gitignore',
+    'testprojects/src/python:python_targets_directory',
+    'testprojects/src/python:sources_directory',
+  ],
+  uses_pants_run=True,
+  timeout = 600,
+)

src/python/pants/scm/subsystems/changed.py → src/python/pants/vcs/changed.py

@@ -15,7 +15,7 @@
 from pants.engine.rules import Get, collect_rules, rule
 from pants.option.option_value_container import OptionValueContainer
 from pants.option.subsystem import Subsystem
-from pants.scm.scm import Scm
+from pants.vcs.git import Git
 
 
 class DependeesOption(Enum):
@@ -86,15 +86,15 @@ def from_options(cls, options: OptionValueContainer) -> "ChangedOptions":
     def provided(self) -> bool:
         return bool(self.since) or bool(self.diffspec)
 
-    def changed_files(self, *, scm: Scm) -> List[str]:
+    def changed_files(self, git: Git) -> List[str]:
         """Determines the files changed according to SCM/workspace and options."""
         if self.diffspec:
-            return cast(List[str], scm.changes_in(self.diffspec, relative_to=get_buildroot()))
+            return cast(List[str], git.changes_in(self.diffspec, relative_to=get_buildroot()))
 
-        changes_since = self.since or scm.current_rev_identifier
+        changes_since = self.since or git.current_rev_identifier
         return cast(
             List[str],
-            scm.changed_files(
+            git.changed_files(
                 from_commit=changes_since, include_untracked=True, relative_to=get_buildroot()
             ),
         )

tests/python/pants_test/integration/changed_integration_test.py → src/python/pants/vcs/changed_integration_test.py

@@ -11,11 +11,11 @@
 import pytest
 
 from pants.base.build_environment import get_buildroot
-from pants.scm.git import Git
 from pants.testutil.pants_integration_test import PantsIntegrationTest, ensure_daemon
 from pants.testutil.test_base import AbstractTestGenerator
 from pants.util.contextutil import environment_as, temporary_dir
 from pants.util.dirutil import safe_delete, safe_mkdir, safe_open, touch
+from pants.vcs.git import Git
 
 
 @contextmanager