Allow unmatching "changed" globs (#20505)

If `changed` returns globs that match no files, 
because they've all been deleted, that is fine!

The warnings/errors are intended for user-provided
specs that don't match anything, as that is likely
user error. These globs are synthesized by Pants
based on git data, and so whatever they match
or not is an implementation detail, not a user
facing concern.

Fixes #20503

Author: benjyw

src/python/pants/init/specs_calculator.py

@@ -4,6 +4,7 @@
 import logging
 from typing import cast
 
+from pants.base.glob_match_error_behavior import GlobMatchErrorBehavior
 from pants.base.specs import AddressLiteralSpec, FileLiteralSpec, RawSpecs, Specs
 from pants.base.specs_parser import SpecsParser
 from pants.core.util_rules.environments import determine_bootstrap_environment
@@ -96,7 +97,11 @@ def calculate_specs(
             # target-aware vs. target-less goals, e.g. `list` vs `count-loc`.
             address_literals=tuple(address_literal_specs),
             file_literals=file_literal_specs,
-            unmatched_glob_behavior=unmatched_cli_globs,
+            # The globs here are synthesized from VCS data by the `changed` mechanism.
+            # As such it does not make sense to apply user-facing matching errors to them.
+            # In particular, they can legitimately not match anything, if entire git
+            # subtrees were deleted for example.
+            unmatched_glob_behavior=GlobMatchErrorBehavior.ignore,
             filter_by_global_options=True,
             from_change_detection=True,
             description_of_origin="`--changed-since`",

src/python/pants/vcs/git.py

@@ -91,7 +91,7 @@ def changed_files(
             committed_changes = self._git_binary._invoke_unsandboxed(
                 self._create_git_cmdline(committed_cmd)
             )
-            files.update(committed_changes.split())
+            files.update(committed_changes.splitlines())
         if include_untracked:
             untracked_cmd = [
                 "ls-files",
@@ -102,14 +102,14 @@ def changed_files(
             untracked = self._git_binary._invoke_unsandboxed(
                 self._create_git_cmdline(untracked_cmd)
             )
-            files.update(untracked.split())
+            files.update(untracked.splitlines())
         # git will report changed files relative to the worktree: re-relativize to relative_to
         return {self._fix_git_relative_path(f, relative_to) for f in files}
 
     def changes_in(self, diffspec: str, relative_to: PurePath | str | None = None) -> set[str]:
         relative_to = PurePath(relative_to) if relative_to is not None else self.worktree
         cmd = ["diff-tree", "--no-commit-id", "--name-only", "-r", diffspec]
-        files = self._git_binary._invoke_unsandboxed(self._create_git_cmdline(cmd)).split()
+        files = self._git_binary._invoke_unsandboxed(self._create_git_cmdline(cmd)).splitlines()
         return {self._fix_git_relative_path(f.strip(), relative_to) for f in files}
 
     def _create_git_cmdline(self, args: Iterable[str]) -> list[str]:

src/python/pants/vcs/git_test.py

@@ -139,6 +139,9 @@ def test_integration(worktree: Path, readme_file: Path, git: MutatingGitWorktree
     assert {"README"} == git.changed_files()
     assert {"README", "INSTALL"} == git.changed_files(include_untracked=True)
 
+    (worktree / "WITH SPACE").write_text("space in path")
+    assert {"README", "INSTALL", "WITH SPACE"} == git.changed_files(include_untracked=True)
+
     # Confirm that files outside of a given relative_to path are ignored
     assert set() == git.changed_files(relative_to="non-existent")