Compare each .gitignore found with an appropiate relative path

CHANGES.md

@@ -18,6 +18,9 @@
 
 <!-- Changes to how Black can be configured -->
 
+- Fix incorrectly applied .gitignore rules by considering the .gitignore location and
+  the relative path to the target file (#3338)
+
 ### Packaging
 
 <!-- Changes to how Black is packaged, such as dependency requirements -->

src/black/__init__.py

@@ -625,6 +625,8 @@ def get_sources(
     sources: Set[Path] = set()
     root = ctx.obj["root"]
 
+    gitignore = None
+
     for s in src:
         if s == "-" and stdin_filename:
             p = Path(stdin_filename)
@@ -660,14 +662,14 @@ def get_sources(
         elif p.is_dir():
             if exclude is None:
                 exclude = re_compile_maybe_verbose(DEFAULT_EXCLUDES)
-                gitignore = get_gitignore(root)
+                root_gitignore = get_gitignore(root)
                 p_gitignore = get_gitignore(p)
                 # No need to use p's gitignore if it is identical to root's gitignore
                 # (i.e. root and p point to the same directory).
-                if gitignore != p_gitignore:
-                    gitignore += p_gitignore
-            else:
-                gitignore = None
+                if root_gitignore == p_gitignore:
+                    gitignore = {root: root_gitignore}
+                else:
+                    gitignore = {root: root_gitignore, root / p: p_gitignore}
             sources.update(
                 gen_python_files(
                     p.iterdir(),

src/black/files.py

@@ -198,7 +198,7 @@ def gen_python_files(
     extend_exclude: Optional[Pattern[str]],
     force_exclude: Optional[Pattern[str]],
     report: Report,
-    gitignore: Optional[PathSpec],
+    gitignore_dict: Optional[Dict[Path, PathSpec]],
     *,
     verbose: bool,
     quiet: bool,
@@ -211,15 +211,27 @@ def gen_python_files(
 
     `report` is where output about exclusions goes.
     """
+
+    def is_ignored(
+        gitignore_dict: Dict[Path, PathSpec], child: Path, report: Report
+    ) -> bool:
+        for _dir, _gitignore in gitignore_dict.items():
+            relative_path = normalize_path_maybe_ignore(child, _dir, report)
+            if relative_path is None:
+                break
+            if _gitignore is not None and _gitignore.match_file(relative_path):
+                report.path_ignored(child, "matches the .gitignore file content")
+                return True
+        return False
+
     assert root.is_absolute(), f"INTERNAL ERROR: `root` must be absolute but is {root}"
     for child in paths:
         normalized_path = normalize_path_maybe_ignore(child, root, report)
         if normalized_path is None:
             continue
 
         # First ignore files matching .gitignore, if passed
-        if gitignore is not None and gitignore.match_file(normalized_path):
-            report.path_ignored(child, "matches the .gitignore file content")
+        if gitignore_dict is not None and is_ignored(gitignore_dict, child, report):
             continue
 
         # Then ignore with `--exclude` `--extend-exclude` and `--force-exclude` options.
@@ -244,6 +256,13 @@ def gen_python_files(
         if child.is_dir():
             # If gitignore is None, gitignore usage is disabled, while a Falsey
             # gitignore is when the directory doesn't have a .gitignore file.
+            if gitignore_dict is not None:
+                new_gitignore_dict = {
+                    **gitignore_dict,
+                    root / child: get_gitignore(child),
+                }
+            else:
+                new_gitignore_dict = None
             yield from gen_python_files(
                 child.iterdir(),
                 root,
@@ -252,7 +271,7 @@ def gen_python_files(
                 extend_exclude,
                 force_exclude,
                 report,
-                gitignore + get_gitignore(child) if gitignore is not None else None,
+                new_gitignore_dict,
                 verbose=verbose,
                 quiet=quiet,
             )

tests/data/ignore_subfolders_gitignore_tests/subdir/.gitignore

@@ -0,0 +1 @@
+*/*

tests/test_black.py

@@ -1989,7 +1989,7 @@ def test_gitignore_exclude(self) -> None:
                 None,
                 None,
                 report,
-                gitignore,
+                {path: gitignore},
                 verbose=False,
                 quiet=False,
             )
@@ -2018,7 +2018,7 @@ def test_nested_gitignore(self) -> None:
                 None,
                 None,
                 report,
-                root_gitignore,
+                {path: root_gitignore},
                 verbose=False,
                 quiet=False,
             )
@@ -2056,6 +2056,32 @@ def test_invalid_nested_gitignore(self) -> None:
         gitignore = path / "a" / ".gitignore"
         assert f"Could not parse {gitignore}" in result.stderr_bytes.decode()
 
+    def test_gitignore_that_ignores_subfolders(self) -> None:
+        # If gitignore with */* is in root
+        root = Path(DATA_DIR / "ignore_subfolders_gitignore_tests" / "subdir")
+        expected = [root / "b.py"]
+        ctx = FakeContext()
+        ctx.obj["root"] = root
+        assert_collected_sources([root], expected, ctx=ctx)
+
+        # If .gitignore with */* is nested
+        root = Path(DATA_DIR / "ignore_subfolders_gitignore_tests")
+        expected = [
+            root / "a.py",
+            root / "subdir" / "b.py",
+        ]
+        ctx = FakeContext()
+        ctx.obj["root"] = root
+        assert_collected_sources([root], expected, ctx=ctx)
+
+        # If command is executed from outer dir
+        root = Path(DATA_DIR / "ignore_subfolders_gitignore_tests")
+        target = root / "subdir"
+        expected = [target / "b.py"]
+        ctx = FakeContext()
+        ctx.obj["root"] = root
+        assert_collected_sources([target], expected, ctx=ctx)
+
     def test_empty_include(self) -> None:
         path = DATA_DIR / "include_exclude_tests"
         src = [path]
@@ -2110,7 +2136,7 @@ def test_symlink_out_of_root_directory(self) -> None:
                     None,
                     None,
                     report,
-                    gitignore,
+                    {path: gitignore},
                     verbose=False,
                     quiet=False,
                 )