[3.6] bpo-21720: Restore the Python 2.7 logic in handling a fromlist. (GH-4118) (#4128)

BytesWarning no longer emitted when the fromlist argument of
__import__() or the __all__ attribute of the module contain bytes
instances..
(cherry picked from commit 41c56940c6edf3ea169332a6b039b6c8796f0475)

1 files changed, 13 insertions, 7 deletions

diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index 4fc5f02..e2343dd 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -994,7 +994,7 @@ def _gcd_import(name, package=None, level=0):
     return _find_and_load(name, _gcd_import)
 
 
-def _handle_fromlist(module, fromlist, import_):
+def _handle_fromlist(module, fromlist, import_, *, recursive=False):
     """Figure out what __import__ should return.
 
     The import_ parameter is a callable which takes the name of module to
@@ -1005,13 +1005,19 @@ def _handle_fromlist(module, fromlist, import_):
     # The hell that is fromlist ...
     # If a package was imported, try to import stuff from fromlist.
     if hasattr(module, '__path__'):
-        if '*' in fromlist:
-            fromlist = list(fromlist)
-            fromlist.remove('*')
-            if hasattr(module, '__all__'):
-                fromlist.extend(module.__all__)
         for x in fromlist:
-            if not hasattr(module, x):
+            if not isinstance(x, str):
+                if recursive:
+                    where = module.__name__ + '.__all__'
+                else:
+                    where = "``from list''"
+                raise TypeError(f"Item in {where} must be str, "
+                                f"not {type(x).__name__}")
+            elif x == '*':
+                if not recursive and hasattr(module, '__all__'):
+                    _handle_fromlist(module, module.__all__, import_,
+                                     recursive=True)
+            elif not hasattr(module, x):
                 from_name = '{}.{}'.format(module.__name__, x)
                 try:
                     _call_with_frames_removed(import_, from_name)