bpo-30024: Circular imports involving absolute imports with binding (#1264)

a submodule to a name are now supported.

Doc/whatsnew/3.7.rst

@@ -85,6 +85,10 @@ Other Language Changes
 * :exc:`ImportError` now displays module name and module ``__file__`` path when
   ``from ... import ...`` fails. (Contributed by Matthias Bussonnier in :issue:`29546`.)
 
+* Circular imports involving absolute imports with binding a submodule to
+  a name are now supported.
+  (Contributed by Serhiy Storchaka in :issue:`30024`.)
+
 
 New Modules
 ===========

Lib/test/test_import/__init__.py

@@ -1168,6 +1168,12 @@ class CircularImportTests(unittest.TestCase):
         from test.test_import.data.circular_imports.subpkg import util
         self.assertIs(util.util, rebinding.util)
 
+    def test_binding(self):
+        try:
+            import test.test_import.data.circular_imports.binding
+        except ImportError:
+            self.fail('circular import with binding a submodule to a name failed')
+
 
 if __name__ == '__main__':
     # Test needs to be a package, so we can do relative imports.

Lib/test/test_import/data/circular_imports/binding.py

@@ -0,0 +1 @@
+import test.test_import.data.circular_imports.binding2 as binding2

Lib/test/test_import/data/circular_imports/binding2.py

@@ -0,0 +1 @@
+import test.test_import.data.circular_imports.binding as binding

Misc/NEWS

@@ -10,6 +10,9 @@ What's New in Python 3.7.0 alpha 1?
 Core and Builtins
 -----------------
 
+- bpo-30024: Circular imports involving absolute imports with binding
+  a submodule to a name are now supported.
+
 - bpo-12414: sys.getsizeof() on a code object now returns the sizes
   which includes the code struct and sizes of objects which it references.
   Patch by Dong-hee Na.

Python/compile.c

@@ -2546,7 +2546,7 @@ compiler_import_as(struct compiler *c, identifier name, identifier asname)
        merely needs to bind the result to a name.
 
        If there is a dot in name, we need to split it and emit a
-       LOAD_ATTR for each name.
+       IMPORT_FROM for each name.
     */
     Py_ssize_t dot = PyUnicode_FindChar(name, '.', 0,
                                         PyUnicode_GET_LENGTH(name), 1);
@@ -2566,7 +2566,7 @@ compiler_import_as(struct compiler *c, identifier name, identifier asname)
                                        PyUnicode_GET_LENGTH(name));
             if (!attr)
                 return 0;
-            ADDOP_O(c, LOAD_ATTR, attr, names);
+            ADDOP_O(c, IMPORT_FROM, attr, names);
             Py_DECREF(attr);
             pos = dot + 1;
         }