Find pyproject.toml only once, and use it in CONFIG_FILES

Author: Felixoid

mypy/config_parser.py

@@ -229,28 +229,6 @@ def split_commas(value: str) -> list[str]:
 )
 
 
-def _find_pyproject() -> list[str]:
-    """Search for file pyproject.toml in the parent directories recursively.
-
-    It resolves symlinks, so if there is any symlink up in the tree, it does not respect them
-    """
-    # We start from the parent dir, since 'pyproject.toml' is already parsed
-    current_dir = os.path.abspath(os.path.join(os.path.curdir, os.path.pardir))
-    is_root = False
-    while not is_root:
-        for pyproject_name in defaults.PYPROJECT_CONFIG_FILES:
-            config_file = os.path.join(current_dir, pyproject_name)
-            if os.path.isfile(config_file):
-                return [os.path.abspath(config_file)]
-        parent = os.path.abspath(os.path.join(current_dir, os.path.pardir))
-        is_root = current_dir == parent or any(
-            os.path.isdir(os.path.join(current_dir, cvs_root)) for cvs_root in (".git", ".hg")
-        )
-        current_dir = parent
-
-    return []
-
-
 def parse_config_file(
     options: Options,
     set_strict_flags: Callable[[], None],
@@ -270,9 +248,7 @@ def parse_config_file(
     if filename is not None:
         config_files: tuple[str, ...] = (filename,)
     else:
-        config_files_iter: Iterable[str] = map(
-            os.path.expanduser, defaults.CONFIG_FILES + _find_pyproject()
-        )
+        config_files_iter: Iterable[str] = map(os.path.expanduser, defaults.CONFIG_FILES)
         config_files = tuple(config_files_iter)
 
     config_parser = configparser.RawConfigParser()

mypy/defaults.py

@@ -12,9 +12,41 @@
 # mypy, at least version PYTHON3_VERSION is needed.
 PYTHON3_VERSION_MIN: Final = (3, 8)  # Keep in sync with typeshed's python support
 
+
+def find_pyproject() -> str:
+    """Search for file pyproject.toml in the parent directories recursively.
+
+    It resolves symlinks, so if there is any symlink up in the tree, it does not respect them
+
+    If the file is not found until the root of FS or repository, PYPROJECT_FILE is used
+    """
+
+    def is_root(current_dir: str) -> bool:
+        parent = os.path.join(current_dir, os.path.pardir)
+        return os.path.samefile(current_dir, parent) or any(
+            os.path.isdir(os.path.join(current_dir, cvs_root)) for cvs_root in (".git", ".hg")
+        )
+
+    # Preserve the original behavior, returning PYPROJECT_FILE if exists
+    if os.path.isfile(PYPROJECT_FILE) or is_root(os.path.curdir):
+        return PYPROJECT_FILE
+
+    # And iterate over the tree
+    current_dir = os.path.pardir
+    while not is_root(current_dir):
+        config_file = os.path.join(current_dir, PYPROJECT_FILE)
+        if os.path.isfile(config_file):
+            return config_file
+        parent = os.path.join(current_dir, os.path.pardir)
+        current_dir = parent
+
+    return PYPROJECT_FILE
+
+
 CACHE_DIR: Final = ".mypy_cache"
 CONFIG_FILE: Final = ["mypy.ini", ".mypy.ini"]
-PYPROJECT_CONFIG_FILES: Final = ["pyproject.toml"]
+PYPROJECT_FILE: Final = "pyproject.toml"
+PYPROJECT_CONFIG_FILES: Final = [find_pyproject()]
 SHARED_CONFIG_FILES: Final = ["setup.cfg"]
 USER_CONFIG_FILES: Final = ["~/.config/mypy/config", "~/.mypy.ini"]
 if os.environ.get("XDG_CONFIG_HOME"):