[mypyc] Don't make classes non-extension because of children (python#7988)

msullivan · web-flow · commit 4c77d16b3a7b · 2019-11-20T16:11:51.000-08:00
This is a global behavior that will be solidly busted when doing
separate compilation. Produce an error instead. (We can probably
support it once we support interpreted inheritance.)
diff --git a/mypyc/genops.py b/mypyc/genops.py
@@ -134,14 +134,12 @@ def build_type_map(mapper: 'Mapper',
     for module, cdef in classes:
         class_ir = ClassIR(cdef.name, module.fullname, is_trait(cdef),
                            is_abstract=cdef.info.is_abstract)
+        class_ir.is_ext_class = is_extension_class(cdef)
         # If global optimizations are disabled, turn of tracking of class children
         if not options.global_opts:
             class_ir.children = None
         mapper.type_to_ir[cdef.info] = class_ir
 
-    # Figure out which classes need to be compiled as non-extension classes.
-    mark_non_ext_classes(mapper.type_to_ir)
-
     # Populate structural information in class IR for extension classes.
     for module, cdef in classes:
         with catch_errors(module.path, cdef.line):
@@ -250,39 +248,6 @@ def is_extension_class(cdef: ClassDef) -> bool:
     return True
 
 
-def mark_non_ext_classes(class_map: Dict[TypeInfo, ClassIR]) -> None:
-    """
-    Mark which classes should be compiled as non-extension classes.
-    Classes in the chain of base classes of a non-extension class
-    will all be marked as non-extension because currently
-    non-extension classes cannot inherit from extension classes.
-    """
-    visit_first = list(class_map.keys())
-    visit_second = []  # type: List[TypeInfo]
-    # First pass to gather all non-extension classes without
-    # considering base class chains
-    for typ in visit_first:
-        ir = class_map[typ]
-        ir.is_ext_class = is_extension_class(typ.defn)
-        if not ir.is_ext_class:
-            visit_second.append(typ)
-
-    # FIXME: Just reject these?
-    # Second pass to propagate non-extension markings up the base class
-    # chains of classes marked as non-extension classes during the first pass.
-    for typ in visit_second:
-        todo = [typ]
-        while todo:
-            child = todo.pop()
-            for parent in child.bases:
-                if parent.type in class_map:
-                    parent_ir = class_map[parent.type]
-                    if not parent_ir.is_ext_class:
-                        continue
-                    parent_ir.is_ext_class = False
-                    todo.append(parent.type)
-
-
 def get_func_def(op: Union[FuncDef, Decorator, OverloadedFuncDef]) -> FuncDef:
     if isinstance(op, OverloadedFuncDef):
         assert op.impl
@@ -699,9 +664,15 @@ def prepare_non_ext_class_def(path: str, module_name: str, cdef: ClassDef,
                              path, cdef.line)
             # Handle case for regular function overload
             else:
-                errors.error("Non-extension classes do not support overlaoded functions",
+                errors.error("Non-extension classes do not support overloaded functions",
                              path, cdef.line)
 
+    if any(
+        cls in mapper.type_to_ir and mapper.type_to_ir[cls].is_ext_class for cls in info.mro
+    ):
+        errors.error(
+            "Non-extension classes may not inherit from extension classes", path, cdef.line)
+
 
 def concrete_arg_kind(kind: int) -> int:
     """Find the concrete version of an arg kind that is being passed."""
diff --git a/mypyc/test-data/commandline.test b/mypyc/test-data/commandline.test
@@ -148,6 +148,10 @@ class Concrete2:
 class Trait2(Concrete2):
     pass
 
+@decorator
+class NonExt(Concrete1):  # E: Non-extension classes may not inherit from extension classes
+    pass
+
 class Nope(Trait1, Concrete2):  # E: Non-trait bases must appear first in parent list  # E: Non-trait MRO must be linear
     pass
 
diff --git a/mypyc/test-data/run-classes.test b/mypyc/test-data/run-classes.test
@@ -63,13 +63,15 @@ from typing import Any
 def decorator(cls) -> Any:
     return cls
 
+@decorator
 class C:
     def __init__(self) -> None:
         self.c = 3
 
     def get_c(self) -> int:
         return self.c
 
+@decorator
 class B(C):
     def __init__(self) -> None:
         super().__init__()
