Fix matching of absolute paths in --include

CHANGES.md

@@ -19,6 +19,8 @@
 
 - Add support for single line format skip with other comments on the same line (#3959)
 
+- Fix a bug in the matching of absolute path names in `--include` (#3976)
+
 ### Packaging
 
 <!-- Changes to how Black is packaged, such as dependency requirements -->

src/black/files.py

@@ -389,7 +389,7 @@ def gen_python_files(
                 warn=verbose or not quiet
             ):
                 continue
-            include_match = include.search(normalized_path) if include else True
+            include_match = include.search(root_relative_path) if include else True
             if include_match:
                 yield child
 

tests/test_black.py

@@ -2388,6 +2388,27 @@ def test_empty_include(self) -> None:
         # Setting exclude explicitly to an empty string to block .gitignore usage.
         assert_collected_sources(src, expected, include="", exclude="")
 
+    def test_include_absolute_path(self) -> None:
+        path = DATA_DIR / "include_exclude_tests"
+        src = [path]
+        expected = [
+            Path(path / "b/dont_exclude/a.pie"),
+        ]
+        assert_collected_sources(
+            src, expected, root=path, include=r"^/b/dont_exclude/a\.pie$", exclude=""
+        )
+
+    def test_exclude_absolute_path(self) -> None:
+        path = DATA_DIR / "include_exclude_tests"
+        src = [path]
+        expected = [
+            Path(path / "b/dont_exclude/a.py"),
+            Path(path / "b/.definitely_exclude/a.py"),
+        ]
+        assert_collected_sources(
+            src, expected, root=path, include=r"\.py$", exclude=r"^/b/exclude/a\.py$"
+        )
+
     def test_extend_exclude(self) -> None:
         path = DATA_DIR / "include_exclude_tests"
         src = [path]
@@ -2401,27 +2422,51 @@ def test_extend_exclude(self) -> None:
 
     @pytest.mark.incompatible_with_mypyc
     def test_symlinks(self) -> None:
-        path = MagicMock()
         root = THIS_DIR.resolve()
         include = re.compile(black.DEFAULT_INCLUDES)
         exclude = re.compile(black.DEFAULT_EXCLUDES)
         report = black.Report()
         gitignore = PathSpec.from_lines("gitwildmatch", [])
 
         regular = MagicMock()
-        outside_root_symlink = MagicMock()
-        ignored_symlink = MagicMock()
-
-        path.iterdir.return_value = [regular, outside_root_symlink, ignored_symlink]
-
         regular.absolute.return_value = root / "regular.py"
         regular.resolve.return_value = root / "regular.py"
         regular.is_dir.return_value = False
+        regular.is_file.return_value = True
 
+        outside_root_symlink = MagicMock()
         outside_root_symlink.absolute.return_value = root / "symlink.py"
         outside_root_symlink.resolve.return_value = Path("/nowhere")
+        outside_root_symlink.is_dir.return_value = False
+        outside_root_symlink.is_file.return_value = True
 
+        ignored_symlink = MagicMock()
         ignored_symlink.absolute.return_value = root / ".mypy_cache" / "symlink.py"
+        ignored_symlink.is_dir.return_value = False
+        ignored_symlink.is_file.return_value = True
+
+        # A symlink that has an excluded name, but points to an included name
+        symlink_excluded_name = MagicMock()
+        symlink_excluded_name.absolute.return_value = root / "excluded_name"
+        symlink_excluded_name.resolve.return_value = root / "included_name.py"
+        symlink_excluded_name.is_dir.return_value = False
+        symlink_excluded_name.is_file.return_value = True
+
+        # A symlink that has an included name, but points to an excluded name
+        symlink_included_name = MagicMock()
+        symlink_included_name.absolute.return_value = root / "included_name.py"
+        symlink_included_name.resolve.return_value = root / "excluded_name"
+        symlink_included_name.is_dir.return_value = False
+        symlink_included_name.is_file.return_value = True
+
+        path = MagicMock()
+        path.iterdir.return_value = [
+            regular,
+            outside_root_symlink,
+            ignored_symlink,
+            symlink_excluded_name,
+            symlink_included_name,
+        ]
 
         files = list(
             black.gen_python_files(
@@ -2437,7 +2482,7 @@ def test_symlinks(self) -> None:
                 quiet=False,
             )
         )
-        assert files == [regular]
+        assert files == [regular, symlink_included_name]
 
         path.iterdir.assert_called_once()
         outside_root_symlink.resolve.assert_called_once()