Issue #15715: Ignore failed imports triggered by the use of fromlist.

When the fromlist argument is specified for __import__() and the
attribute doesn't already exist, an import is attempted. If that fails
(e.g. module doesn't exist), the ImportError will now be silenced (for
backwards-compatibility). This *does not* affect
``from ... import ...`` statements.

Thanks to Eric Snow for the patch and Simon Feltman for reporting the
regression.

2 files changed, 13 insertions, 2 deletions

diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index 8ecc882..471b380 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -1573,8 +1573,13 @@ def _handle_fromlist(module, fromlist, import_):
                 fromlist.extend(module.__all__)
         for x in fromlist:
             if not hasattr(module, x):
-                _call_with_frames_removed(import_,
-                                  '{}.{}'.format(module.__name__, x))
+                try:
+                    _call_with_frames_removed(import_,
+                                      '{}.{}'.format(module.__name__, x))
+                except ImportError:
+                    # Backwards-compatibility dictates we ignore failed
+                    # imports triggered by fromlist.
+                    pass
     return module
 
 
diff --git a/Lib/test/test_import.py b/Lib/test/test_import.py
index 2e58199..7f2fad0 100644
--- a/Lib/test/test_import.py
+++ b/Lib/test/test_import.py
@@ -334,6 +334,12 @@ class ImportTests(unittest.TestCase):
             del sys.path[0]
             remove_files(TESTFN)
 
+    def test_bogus_fromlist(self):
+        try:
+            __import__('http', fromlist=['blah'])
+        except ImportError:
+            self.fail("fromlist must allow bogus names")
+
 
 class PycRewritingTests(unittest.TestCase):
     # Test that the `co_filename` attribute on code objects always points