Merging upstream version 2.5.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

pre_commit/commands/run.py

@@ -72,13 +72,7 @@ def filter_by_include_exclude(
 
 
 class Classifier:
-    def __init__(self, filenames: Sequence[str]) -> None:
-        # on windows we normalize all filenames to use forward slashes
-        # this makes it easier to filter using the `files:` regex
-        # this also makes improperly quoted shell-based hooks work better
-        # see #1173
-        if os.altsep == '/' and os.sep == '\\':
-            filenames = [f.replace(os.sep, os.altsep) for f in filenames]
+    def __init__(self, filenames: Collection[str]) -> None:
         self.filenames = [f for f in filenames if os.path.lexists(f)]
 
     @functools.lru_cache(maxsize=None)
@@ -105,6 +99,22 @@ class Classifier:
         names = self.by_types(names, hook.types, hook.exclude_types)
         return tuple(names)
 
+    @classmethod
+    def from_config(
+            cls,
+            filenames: Collection[str],
+            include: str,
+            exclude: str,
+    ) -> 'Classifier':
+        # on windows we normalize all filenames to use forward slashes
+        # this makes it easier to filter using the `files:` regex
+        # this also makes improperly quoted shell-based hooks work better
+        # see #1173
+        if os.altsep == '/' and os.sep == '\\':
+            filenames = [f.replace(os.sep, os.altsep) for f in filenames]
+        filenames = filter_by_include_exclude(filenames, include, exclude)
+        return Classifier(filenames)
+
 
 def _get_skips(environ: EnvironT) -> Set[str]:
     skips = environ.get('SKIP', '')
@@ -221,7 +231,8 @@ def _compute_cols(hooks: Sequence[Hook]) -> int:
 
 
 def _all_filenames(args: argparse.Namespace) -> Collection[str]:
-    if args.hook_stage == 'post-checkout':  # no files for post-checkout
+    # these hooks do not operate on files
+    if args.hook_stage in {'post-checkout', 'post-commit'}:
         return ()
     elif args.hook_stage in {'prepare-commit-msg', 'commit-msg'}:
         return (args.commit_msg_filename,)
@@ -246,10 +257,9 @@ def _run_hooks(
     """Actually run the hooks."""
     skips = _get_skips(environ)
     cols = _compute_cols(hooks)
-    filenames = filter_by_include_exclude(
+    classifier = Classifier.from_config(
         _all_filenames(args), config['files'], config['exclude'],
     )
-    classifier = Classifier(filenames)
     retval = 0
     for hook in hooks:
         retval |= _run_single_hook(
@@ -323,6 +333,12 @@ def run(
             f'`--hook-stage {args.hook_stage}`',
         )
         return 1
+    # prevent recursive post-checkout hooks (#1418)
+    if (
+            args.hook_stage == 'post-checkout' and
+            environ.get('_PRE_COMMIT_SKIP_POST_CHECKOUT')
+    ):
+        return 0
 
     # Expose from-ref / to-ref as environment variables for hooks to consume
     if args.from_ref and args.to_ref:
@@ -340,6 +356,9 @@ def run(
     if args.checkout_type:
         environ['PRE_COMMIT_CHECKOUT_TYPE'] = args.checkout_type
 
+    # Set pre_commit flag
+    environ['PRE_COMMIT'] = '1'
+
     with contextlib.ExitStack() as exit_stack:
         if stash:
             exit_stack.enter_context(staged_files_only(store.directory))