semanal: fix module_public in the presence of getattr (#11411)

Author: hauntsaninja

mypy/semanal.py

@@ -1808,6 +1808,12 @@ def visit_import_from(self, imp: ImportFrom) -> None:
             missing_submodule = False
             imported_id = as_id or id
 
+            # Modules imported in a stub file without using 'from Y import X as X' will
+            # not get exported.
+            # When implicit re-exporting is disabled, we have the same behavior as stubs.
+            use_implicit_reexport = not self.is_stub_file and self.options.implicit_reexport
+            module_public = use_implicit_reexport or (as_id is not None and id == as_id)
+
             # If the module does not contain a symbol with the name 'id',
             # try checking if it's a module instead.
             if not node:
@@ -1825,15 +1831,12 @@ def visit_import_from(self, imp: ImportFrom) -> None:
                 fullname = module_id + '.' + id
                 gvar = self.create_getattr_var(module.names['__getattr__'], imported_id, fullname)
                 if gvar:
-                    self.add_symbol(imported_id, gvar, imp)
+                    self.add_symbol(
+                        imported_id, gvar, imp, module_public=module_public,
+                        module_hidden=not module_public
+                    )
                     continue
 
-            # Modules imported in a stub file without using 'from Y import X as X' will
-            # not get exported.
-            # When implicit re-exporting is disabled, we have the same behavior as stubs.
-            use_implicit_reexport = not self.is_stub_file and self.options.implicit_reexport
-            module_public = use_implicit_reexport or (as_id is not None and id == as_id)
-
             if node and not node.module_hidden:
                 self.process_imported_symbol(
                     node, module_id, id, imported_id, fullname, module_public, context=imp

test-data/unit/check-flags.test

@@ -1525,6 +1525,16 @@ __all__ = ('b',)
 [out]
 main:2: error: Module "other_module_2" does not explicitly export attribute "a"; implicit reexport disabled
 
+[case testNoImplicitReexportGetAttr]
+# flags: --no-implicit-reexport --python-version 3.7
+from other_module_2 import a  # E: Module "other_module_2" does not explicitly export attribute "a"; implicit reexport disabled
+[file other_module_1.py]
+from typing import Any
+def __getattr__(name: str) -> Any: ...
+[file other_module_2.py]
+from other_module_1 import a
+[builtins fixtures/tuple.pyi]
+
 [case textNoImplicitReexportSuggestions]
 # flags: --no-implicit-reexport
 from other_module_2 import attr_1

test-data/unit/check-newsemanal.test

@@ -2391,7 +2391,8 @@ import p
 import p
 reveal_type(p.y)
 [file p.pyi]
-from pp import x as y
+from pp import x
+y = x
 [file pp.pyi]
 def __getattr__(attr): ...
 [out2]