Support from ... import ... with module level __getattr__ (python#3779)

emmatyping · ilevkivskyi · commit 8294f423d706 · 2017-07-30T19:39:49.000+02:00
PEP 484 specifies one can define ``__getattr__`` to specify that
unresolved names should be ``Any`` (or the return type of the
``__getattr__`` method). This change adds support for access to these
attributes via the ``from module import name`` pattern. The ``module.name``
pattern is already supported.
diff --git a/mypy/semanal.py b/mypy/semanal.py
@@ -1377,7 +1377,23 @@ def visit_import_from(self, imp: ImportFrom) -> None:
                     self.add_submodules_to_parent_modules(possible_module_id, True)
                 elif possible_module_id in self.missing_modules:
                     missing = True
-
+            # If it is still not resolved, and the module is a stub
+            # check for a module level __getattr__
+            if module and not node and module.is_stub and '__getattr__' in module.names:
+                getattr_defn = module.names['__getattr__']
+                if isinstance(getattr_defn.node, FuncDef):
+                    if isinstance(getattr_defn.node.type, CallableType):
+                        typ = getattr_defn.node.type.ret_type
+                    else:
+                        typ = AnyType()
+                    if as_id:
+                        name = as_id
+                    else:
+                        name = id
+                    ast_node = Var(name, type=typ)
+                    symbol = SymbolTableNode(GDEF, ast_node, name)
+                    self.add_symbol(name, symbol, imp)
+                    return
             if node and node.kind != UNBOUND_IMPORTED:
                 node = self.normalize_type_alias(node, imp)
                 if not node:
diff --git a/test-data/unit/check-modules.test b/test-data/unit/check-modules.test
@@ -1766,3 +1766,53 @@ main:3: error: Module has no attribute "any_attribute"
 [case testModuleLevelGetattribute]
 
 def __getattribute__(): ...  # E: __getattribute__ is not valid at the module level
+
+[case testModuleLevelGetattrImportFrom]
+from has_attr import name
+reveal_type(name)  # E: Revealed type is 'Any'
+
+[file has_attr.pyi]
+from typing import Any
+def __getattr__(name: str) -> Any: ...
+
+[builtins fixtures/module.pyi]
+
+[case testModuleLevelGetattrImportFromRetType]
+from has_attr import int_attr
+reveal_type(int_attr)  # E: Revealed type is 'builtins.int'
+
+[file has_attr.pyi]
+def __getattr__(name: str) -> int: ...
+
+[builtins fixtures/module.pyi]
+
+[case testModuleLevelGetattrImportFromNotStub]
+from non_stub import name
+reveal_type(name)
+
+[file non_stub.py]
+from typing import Any
+def __getattr__(name: str) -> Any: ...
+
+[out]
+tmp/non_stub.py:2: error: __getattr__ is not valid at the module level outside a stub file
+main:1: error: Module 'non_stub' has no attribute 'name'
+main:2: error: Revealed type is 'Any'
+
+[builtins fixtures/module.pyi]
+
+[case testModuleLevelGetattrImportFromAs]
+from has_attr import name as n
+reveal_type(name)
+reveal_type(n)
+
+[file has_attr.pyi]
+from typing import Any
+def __getattr__(name: str) -> Any: ...
+
+[out]
+main:2: error: Revealed type is 'Any'
+main:2: error: Name 'name' is not defined
+main:3: error: Revealed type is 'Any'
+
+[builtins fixtures/module.pyi]
