Refactor: Extract file mtime finding into shared helper function

Create get_latest_file_mtime() helper function in scm_workdir.py to eliminate
code duplication across Git, Mercurial, and hybrid implementations.

Changes:
- Added get_latest_file_mtime() function to scm_workdir.py
- Updated GitWorkdir.get_dirty_tag_date() to use shared helper
- Updated HgWorkdir.get_dirty_tag_date() to use shared helper
- Updated GitWorkdirHgClient.get_dirty_tag_date() to use shared helper
- Removed duplicated mtime calculation logic from all implementations
- Cleaned up unused imports (datetime/timezone in hg_git.py)

This improves maintainability and ensures consistent behavior across
all VCS implementations.

Author: RonnyPfannschmidt

src/setuptools_scm/git.py

@@ -26,6 +26,7 @@
 from ._run_cmd import run as _run
 from .integration import data_from_mime
 from .scm_workdir import Workdir
+from .scm_workdir import get_latest_file_mtime
 from .version import ScmVersion
 from .version import meta
 from .version import tag_to_version
@@ -160,28 +161,11 @@ def get_dirty_tag_date(self) -> date | None:
                 return None
 
             changed_files = changed_files_res.stdout.strip().split("\n")
-            if not changed_files or changed_files == [""]:
-                return None
-
-            latest_mtime = 0.0
-            for filepath in changed_files:
-                full_path = self.path / filepath
-                try:
-                    file_stat = full_path.stat()
-                    latest_mtime = max(latest_mtime, file_stat.st_mtime)
-                except OSError:
-                    # File might not exist or be accessible, skip it
-                    continue
-
-            if latest_mtime > 0:
-                # Convert to UTC date
-                dt = datetime.fromtimestamp(latest_mtime, timezone.utc)
-                return dt.date()
+            return get_latest_file_mtime(changed_files, self.path)
 
         except Exception as e:
             log.debug("Failed to get dirty tag date: %s", e)
-
-        return None
+            return None
 
     def is_shallow(self) -> bool:
         return self.path.joinpath(".git/shallow").is_file()

src/setuptools_scm/hg.py

@@ -11,6 +11,7 @@
 from ._version_cls import Version
 from .integration import data_from_mime
 from .scm_workdir import Workdir
+from .scm_workdir import get_latest_file_mtime
 from .version import ScmVersion
 from .version import meta
 from .version import tag_to_version
@@ -178,25 +179,7 @@ def get_dirty_tag_date(self) -> datetime.date | None:
                     filepath = line[2:]  # Skip status char and space
                     changed_files.append(filepath)
 
-            if not changed_files:
-                return None
-
-            latest_mtime = 0.0
-            for filepath in changed_files:
-                full_path = self.path / filepath
-                try:
-                    file_stat = full_path.stat()
-                    latest_mtime = max(latest_mtime, file_stat.st_mtime)
-                except OSError:
-                    # File might not exist or be accessible, skip it
-                    continue
-
-            if latest_mtime > 0:
-                # Convert to UTC date
-                dt = datetime.datetime.fromtimestamp(
-                    latest_mtime, datetime.timezone.utc
-                )
-                return dt.date()
+            return get_latest_file_mtime(changed_files, self.path)
 
         except Exception as e:
             log.debug("Failed to get dirty tag date: %s", e)

src/setuptools_scm/hg_git.py

@@ -13,6 +13,7 @@
 from .git import GitWorkdir
 from .hg import HG_COMMAND
 from .hg import HgWorkdir
+from .scm_workdir import get_latest_file_mtime
 
 log = logging.getLogger(__name__)
 
@@ -57,9 +58,6 @@ def get_dirty_tag_date(self) -> date | None:
             return None
 
         try:
-            from datetime import datetime
-            from datetime import timezone
-
             # Get list of changed files using hg status
             status_res = _run([HG_COMMAND, "status", "-m", "-a", "-r"], cwd=self.path)
             if status_res.returncode != 0:
@@ -72,29 +70,9 @@ def get_dirty_tag_date(self) -> date | None:
                     filepath = line[2:]  # Skip status char and space
                     changed_files.append(filepath)
 
-            if not changed_files:
-                return None
-
-            latest_mtime = 0.0
-            for filepath in changed_files:
-                full_path = self.path / filepath
-                try:
-                    file_stat = full_path.stat()
-                    latest_mtime = max(latest_mtime, file_stat.st_mtime)
-                except OSError:
-                    # File might not exist or be accessible, skip it
-                    continue
-
-            if latest_mtime > 0:
-                # Convert to UTC date
-                dt = datetime.fromtimestamp(latest_mtime, timezone.utc)
-                return dt.date()
+            return get_latest_file_mtime(changed_files, self.path)
 
         except Exception as e:
-            # Use the parent's log module
-            import logging
-
-            log = logging.getLogger(__name__)
             log.debug("Failed to get dirty tag date: %s", e)
 
         return None

src/setuptools_scm/scm_workdir.py

@@ -1,11 +1,50 @@
 from __future__ import annotations
 
+import logging
+
 from dataclasses import dataclass
+from datetime import date
+from datetime import datetime
+from datetime import timezone
 from pathlib import Path
 
 from ._config import Configuration
 from .version import ScmVersion
 
+log = logging.getLogger(__name__)
+
+
+def get_latest_file_mtime(changed_files: list[str], base_path: Path) -> date | None:
+    """Get the latest modification time of the given files.
+
+    Args:
+        changed_files: List of relative file paths
+        base_path: Base directory path to resolve relative paths
+
+    Returns:
+        The date of the most recently modified file, or None if no valid files found
+    """
+    if not changed_files or changed_files == [""]:
+        return None
+
+    latest_mtime = 0.0
+    for filepath in changed_files:
+        full_path = base_path / filepath
+        try:
+            file_stat = full_path.stat()
+            latest_mtime = max(latest_mtime, file_stat.st_mtime)
+        except OSError:
+            # File might not exist or be accessible, skip it
+            log.debug("Failed to get mtime for %s", full_path)
+            continue
+
+    if latest_mtime > 0:
+        # Convert to UTC date
+        dt = datetime.fromtimestamp(latest_mtime, timezone.utc)
+        return dt.date()
+
+    return None
+
 
 @dataclass()
 class Workdir: