Add typing to compat.py

src/pip/_internal/utils/compat.py

@@ -11,6 +11,11 @@
 
 from pip._vendor.six import text_type
 
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+
+if MYPY_CHECK_RUNNING:
+    from typing import Tuple, Text  # noqa: F401
+
 try:
     import ipaddress
 except ImportError:
@@ -68,6 +73,7 @@ def backslashreplace_decode_fn(err):
 
 
 def console_to_str(data):
+    # type: (bytes) -> Text
     """Return a string, safe for output, of subprocess output.
 
     We assume the data is in the locale preferred encoding.
@@ -88,13 +94,13 @@ def console_to_str(data):
     # Now try to decode the data - if we fail, warn the user and
     # decode with replacement.
     try:
-        s = data.decode(encoding)
+        decoded_data = data.decode(encoding)
     except UnicodeDecodeError:
         logger.warning(
             "Subprocess output does not appear to be encoded as %s",
             encoding,
         )
-        s = data.decode(encoding, errors=backslashreplace_decode)
+        decoded_data = data.decode(encoding, errors=backslashreplace_decode)
 
     # Make sure we can print the output, by encoding it to the output
     # encoding with replacement of unencodable characters, and then
@@ -112,27 +118,33 @@ def console_to_str(data):
                               "encoding", None)
 
     if output_encoding:
-        s = s.encode(output_encoding, errors="backslashreplace")
-        s = s.decode(output_encoding)
+        output_encoded = decoded_data.encode(
+            output_encoding,
+            errors="backslashreplace"
+        )
+        decoded_data = output_encoded.decode(output_encoding)
 
-    return s
+    return decoded_data
 
 
 if sys.version_info >= (3,):
     def native_str(s, replace=False):
+        # type: (str, bool) -> str
         if isinstance(s, bytes):
             return s.decode('utf-8', 'replace' if replace else 'strict')
         return s
 
 else:
     def native_str(s, replace=False):
+        # type: (str, bool) -> str
         # Replace is ignored -- unicode to UTF-8 can't fail
         if isinstance(s, text_type):
             return s.encode('utf-8')
         return s
 
 
 def get_path_uid(path):
+    # type: (str) -> int
     """
     Return path's uid.
 
@@ -174,6 +186,7 @@ def get_extension_suffixes():
 
 
 def expanduser(path):
+    # type: (str) -> str
     """
     Expand ~ and ~user constructions.
 
@@ -199,6 +212,7 @@ def expanduser(path):
 
 
 def samefile(file1, file2):
+    # type: (str, str) -> bool
     """Provide an alternative for os.path.samefile on Windows/Python2"""
     if hasattr(os.path, 'samefile'):
         return os.path.samefile(file1, file2)
@@ -210,13 +224,15 @@ def samefile(file1, file2):
 
 if hasattr(shutil, 'get_terminal_size'):
     def get_terminal_size():
+        # type: () -> Tuple[int, int]
         """
         Returns a tuple (x, y) representing the width(x) and the height(y)
         in characters of the terminal window.
         """
-        return tuple(shutil.get_terminal_size())
+        return tuple(shutil.get_terminal_size())  # type: ignore
 else:
     def get_terminal_size():
+        # type: () -> Tuple[int, int]
         """
         Returns a tuple (x, y) representing the width(x) and the height(y)
         in characters of the terminal window.