Allow importing a submodule ahead of its parent module

mypy/build.py

@@ -774,7 +774,7 @@ def is_meta_fresh(meta: Optional[CacheMeta], id: str, path: str, manager: BuildM
     st = manager.get_stat(path)  # TODO: Errors
     if st.st_mtime != meta.mtime or st.st_size != meta.size:
         manager.log('Metadata abandoned for {}: file {} is modified'.format(id, path))
-        return None
+        return False
 
     # It's a match on (id, path, mtime, size).
     # Check data_json; assume if its mtime matches it's good.
@@ -1650,7 +1650,11 @@ def process_graph(graph: Graph, manager: BuildManager) -> None:
             process_stale_scc(graph, scc)
 
     sccs_left = len(fresh_scc_queue)
-    manager.log("{} fresh SCCs left in queue (and will remain unprocessed)".format(sccs_left))
+    if sccs_left:
+        manager.log("{} fresh SCCs left in queue (and will remain unprocessed)".format(sccs_left))
+        manager.trace(str(fresh_scc_queue))
+    else:
+        manager.log("No fresh SCCs left in queue")
 
 
 def order_ascc(graph: Graph, ascc: AbstractSet[str], pri_max: int = PRI_ALL) -> List[str]:

mypy/semanal.py

@@ -913,11 +913,13 @@ def add_submodules_to_parent_modules(self, id: str, module_public: bool) -> None
         """
         while '.' in id:
             parent, child = id.rsplit('.', 1)
-            modules_loaded = parent in self.modules and id in self.modules
-            if modules_loaded and child not in self.modules[parent].names:
-                sym = SymbolTableNode(MODULE_REF, self.modules[id], parent,
-                        module_public=module_public)
-                self.modules[parent].names[child] = sym
+            parent_mod = self.modules.get(parent)
+            if parent_mod and child not in parent_mod.names:
+                child_mod = self.modules.get(id)
+                if child_mod:
+                    sym = SymbolTableNode(MODULE_REF, child_mod, parent,
+                                          module_public=module_public)
+                    parent_mod.names[child] = sym
             id = parent
 
     def add_module_symbol(self, id: str, as_id: str, module_public: bool,
@@ -931,48 +933,47 @@ def add_module_symbol(self, id: str, as_id: str, module_public: bool,
 
     def visit_import_from(self, imp: ImportFrom) -> None:
         import_id = self.correct_relative_import(imp)
-        if import_id in self.modules:
-            module = self.modules[import_id]
-            self.add_submodules_to_parent_modules(import_id, True)
-            for id, as_id in imp.names:
-                node = module.names.get(id)
-
-                # If the module does not contain a symbol with the name 'id',
-                # try checking if it's a module instead.
-                if id not in module.names or node.kind == UNBOUND_IMPORTED:
-                    possible_module_id = import_id + '.' + id
-                    mod = self.modules.get(possible_module_id)
-                    if mod is not None:
-                        node = SymbolTableNode(MODULE_REF, mod, import_id)
-                        self.add_submodules_to_parent_modules(possible_module_id, True)
-
-                if node and node.kind != UNBOUND_IMPORTED:
-                    node = self.normalize_type_alias(node, imp)
-                    if not node:
-                        return
-                    imported_id = as_id or id
-                    existing_symbol = self.globals.get(imported_id)
-                    if existing_symbol:
-                        # Import can redefine a variable. They get special treatment.
-                        if self.process_import_over_existing_name(
-                                imported_id, existing_symbol, node, imp):
-                            continue
-                    # 'from m import x as x' exports x in a stub file.
-                    module_public = not self.is_stub_file or as_id is not None
-                    symbol = SymbolTableNode(node.kind, node.node,
-                                             self.cur_mod_id,
-                                             node.type_override,
-                                             module_public=module_public)
-                    self.add_symbol(imported_id, symbol, imp)
-                else:
-                    message = "Module '{}' has no attribute '{}'".format(import_id, id)
-                    extra = self.undefined_name_extra_info('{}.{}'.format(import_id, id))
-                    if extra:
-                        message += " {}".format(extra)
-                    self.fail(message, imp)
-        else:
-            # Missing module.
-            for id, as_id in imp.names:
+        self.add_submodules_to_parent_modules(import_id, True)
+        module = self.modules.get(import_id)
+        for id, as_id in imp.names:
+            node = module.names.get(id) if module else None
+
+            # If the module does not contain a symbol with the name 'id',
+            # try checking if it's a module instead.
+            if not node or node.kind == UNBOUND_IMPORTED:
+                possible_module_id = import_id + '.' + id
+                mod = self.modules.get(possible_module_id)
+                if mod is not None:
+                    node = SymbolTableNode(MODULE_REF, mod, import_id)
+                    self.add_submodules_to_parent_modules(possible_module_id, True)
+
+            if node and node.kind != UNBOUND_IMPORTED:
+                node = self.normalize_type_alias(node, imp)
+                if not node:
+                    return
+                imported_id = as_id or id
+                existing_symbol = self.globals.get(imported_id)
+                if existing_symbol:
+                    # Import can redefine a variable. They get special treatment.
+                    if self.process_import_over_existing_name(
+                            imported_id, existing_symbol, node, imp):
+                        continue
+                # 'from m import x as x' exports x in a stub file.
+                module_public = not self.is_stub_file or as_id is not None
+                symbol = SymbolTableNode(node.kind, node.node,
+                                         self.cur_mod_id,
+                                         node.type_override,
+                                         module_public=module_public)
+                self.add_symbol(imported_id, symbol, imp)
+            elif module:
+                # Missing attribute.
+                message = "Module '{}' has no attribute '{}'".format(import_id, id)
+                extra = self.undefined_name_extra_info('{}.{}'.format(import_id, id))
+                if extra:
+                    message += " {}".format(extra)
+                self.fail(message, imp)
+            else:
+                # Missing module.
                 self.add_unknown_symbol(as_id or id, imp, is_import=True)
 
     def process_import_over_existing_name(self,

test-data/unit/check-incremental.test

@@ -1615,3 +1615,22 @@ from funcs import callee
 from classes import Outer
 def caller(a: Outer.Inner) -> int:
     callee(a)
+
+[case testIncrementalLoadsParentAfterChild]
+# cmd: mypy -m r.s
+
+[file r/__init__.py]
+from . import s
+
+[file r/m.py]
+class R: pass
+
+[file r/s.py]
+from . import m
+R = m.R
+a = None  # type: R
+
+[file r/s.py.next]
+from . import m
+R = m.R
+a = None  # type: R