Remove project tree (#11457)

### Problem

The `ProjectTree` and `FileSystemProjectTree` classes are obsolete, only being used in actual code in a vestigial fashion in one test helper function.

### Solution

Modify the test helper function to no longer use `FileSystemProjectTree`, adding some type annotations along the way. This allows us to completely remove the `ProjectTree` and `FileSystemProjectTree` code.

src/python/pants/engine/internals/scheduler.py

@@ -47,7 +47,6 @@
 from pants.option.global_options import ExecutionOptions
 from pants.util.contextutil import temporary_file_path
 from pants.util.logging import LogLevel
-from pants.util.ordered_set import FrozenOrderedSet
 from pants.util.strutil import pluralize
 
 logger = logging.getLogger(__name__)
@@ -97,7 +96,7 @@ def __init__(
         local_execution_root_dir: str,
         named_caches_dir: str,
         ca_certs_path: Optional[str],
-        rules: FrozenOrderedSet[Rule],
+        rules: Iterable[Rule],
         union_membership: UnionMembership,
         execution_options: ExecutionOptions,
         executor: PyExecutor,

src/python/pants/engine/internals/scheduler_test_base.py

@@ -2,15 +2,12 @@
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
 import os
-import shutil
-from dataclasses import asdict
 
-from pants.base.file_system_project_tree import FileSystemProjectTree
 from pants.engine.internals.native import Native
 from pants.engine.internals.native_engine import PyExecutor
 from pants.engine.internals.scheduler import Scheduler, SchedulerSession
 from pants.engine.unions import UnionMembership
-from pants.option.global_options import DEFAULT_EXECUTION_OPTIONS, ExecutionOptions
+from pants.option.global_options import DEFAULT_EXECUTION_OPTIONS
 from pants.util.contextutil import temporary_file_path
 from pants.util.dirutil import safe_mkdtemp, safe_rmtree
 
@@ -29,53 +26,33 @@ def _create_work_dir(self):
         self.addCleanup(safe_rmtree, work_dir)
         return work_dir
 
-    def mk_fs_tree(self, build_root_src=None, ignore_patterns=None, work_dir=None):
-        """Create a temporary FilesystemProjectTree.
-
-        :param build_root_src: Optional directory to pre-populate from; otherwise, empty.
-        :returns: A FilesystemProjectTree.
-        """
-        work_dir = work_dir or self._create_work_dir()
-        build_root = os.path.join(work_dir, "build_root")
-        if build_root_src is not None:
-            shutil.copytree(build_root_src, build_root, symlinks=True)
-        else:
-            os.makedirs(build_root)
-        return FileSystemProjectTree(build_root, ignore_patterns=ignore_patterns)
-
     def mk_scheduler(
         self,
-        rules=None,
-        project_tree=None,
-        work_dir=None,
-        include_trace_on_error=True,
-        execution_options=None,
-        ca_certs_path=None,
+        rules,
+        include_trace_on_error: bool = True,
     ) -> SchedulerSession:
         """Creates a SchedulerSession for a Scheduler with the given Rules installed."""
-        rules = rules or []
-        work_dir = work_dir or self._create_work_dir()
-        project_tree = project_tree or self.mk_fs_tree(work_dir=work_dir)
+        work_dir = self._create_work_dir()
+
+        build_root = os.path.join(work_dir, "build_root")
+        os.makedirs(build_root)
+
         local_store_dir = os.path.realpath(safe_mkdtemp())
         local_execution_root_dir = os.path.realpath(safe_mkdtemp())
         named_caches_dir = os.path.realpath(safe_mkdtemp())
-        if execution_options is not None:
-            eo = asdict(DEFAULT_EXECUTION_OPTIONS)
-            eo.update(execution_options)
-            execution_options = ExecutionOptions(**eo)
         scheduler = Scheduler(
             native=self._native,
-            ignore_patterns=project_tree.ignore_patterns,
+            ignore_patterns=[],
             use_gitignore=False,
-            build_root=project_tree.build_root,
+            build_root=build_root,
             local_store_dir=local_store_dir,
             local_execution_root_dir=local_execution_root_dir,
             named_caches_dir=named_caches_dir,
-            ca_certs_path=ca_certs_path,
+            ca_certs_path=None,
             rules=rules,
             union_membership=UnionMembership({}),
             executor=self._executor,
-            execution_options=execution_options or DEFAULT_EXECUTION_OPTIONS,
+            execution_options=DEFAULT_EXECUTION_OPTIONS,
             include_trace_on_error=include_trace_on_error,
         )
         return scheduler.new_session(

src/python/pants/engine/rules.py

@@ -468,7 +468,7 @@ class RuleIndex:
     union_rules: FrozenOrderedSet[UnionRule]
 
     @classmethod
-    def create(cls, rule_entries) -> RuleIndex:
+    def create(cls, rule_entries: Iterable[Rule]) -> RuleIndex:
         """Creates a RuleIndex with tasks indexed by their output type."""
         rules: OrderedSet[TaskRule] = OrderedSet()
         queries: OrderedSet[QueryRule] = OrderedSet()