[mypyc] Invoke __init__ functions inherited from non-ext classes (python#7639)

msullivan · web-flow · commit ad90d6259431 · 2019-10-07T08:11:02.000-07:00
Currently if a class inherits from a nonext class or an interpreted
class and doesn't define an __init__, the parent's __init__ is not
invoked. Fix this.
diff --git a/mypyc/emitclass.py b/mypyc/emitclass.py
@@ -427,14 +427,27 @@ def generate_constructor_for_class(cl: ClassIR,
     emitter.emit_line('PyObject *self = {}();'.format(setup_name))
     emitter.emit_line('if (self == NULL)')
     emitter.emit_line('    return NULL;')
+    args = ', '.join(['self'] + [REG_PREFIX + arg.name for arg in fn.sig.args])
     if init_fn is not None:
-        args = ', '.join(['self'] + [REG_PREFIX + arg.name for arg in fn.sig.args])
         emitter.emit_line('char res = {}{}({});'.format(
             NATIVE_PREFIX, init_fn.cname(emitter.names), args))
         emitter.emit_line('if (res == 2) {')
         emitter.emit_line('Py_DECREF(self);')
         emitter.emit_line('return NULL;')
         emitter.emit_line('}')
+
+    # If there is a nontrivial ctor that we didn't define, invoke it via tp_init
+    elif len(fn.sig.args) > 1:
+        emitter.emit_line(
+            'int res = {}->tp_init({});'.format(
+                emitter.type_struct_name(cl),
+                args))
+
+        emitter.emit_line('if (res < 0) {')
+        emitter.emit_line('Py_DECREF(self);')
+        emitter.emit_line('return NULL;')
+        emitter.emit_line('}')
+
     emitter.emit_line('return self;')
     emitter.emit_line('}')
 
diff --git a/mypyc/genops.py b/mypyc/genops.py
@@ -557,6 +557,19 @@ def prepare_class_def(path: str, module_name: str, cdef: ClassDef,
     init_node = cdef.info['__init__'].node
     if not ir.is_trait and not ir.builtin_base and isinstance(init_node, FuncDef):
         init_sig = mapper.fdef_to_sig(init_node)
+
+        defining_ir = mapper.type_to_ir.get(init_node.info)
+        # If there is a nontrivial __init__ that wasn't defined in an
+        # extension class, we need to make the constructor take *args,
+        # **kwargs so it can call tp_init.
+        if ((defining_ir is None or not defining_ir.is_ext_class)
+                and init_node.info.fullname() != 'builtins.object'):
+            init_sig = FuncSignature(
+                [init_sig.args[0],
+                 RuntimeArg("args", tuple_rprimitive, ARG_STAR),
+                 RuntimeArg("kwargs", dict_rprimitive, ARG_STAR2)],
+                init_sig.ret_type)
+
         ctor_sig = FuncSignature(init_sig.args[1:], RInstance(ir))
         ir.ctor = FuncDecl(cdef.name, None, module_name, ctor_sig)
         mapper.func_to_decl[cdef.info] = ir.ctor
diff --git a/mypyc/test-data/run-classes.test b/mypyc/test-data/run-classes.test
@@ -1109,3 +1109,47 @@ e.y = 20
 assert e.__getstate__() == {'y': 20, '__dict__': {'x': 10}}
 e2 = pickle.loads(pickle.dumps(e))
 assert e is not e2 and e.x == e2.x and e.y == e2.y
+
+
+[case testInterpretedParentInit]
+from interp import C
+from typing import TypeVar
+
+T = TypeVar('T')
+
+def dec(x: T) -> T:
+    return x
+
+@dec
+class A:
+    def __init__(self, x: int) -> None:
+        self.x = x
+
+class B(A):
+    s = 'test'
+
+def b(x: int) -> B: return B(x)
+
+class D(C):
+    s = 'test'
+
+def d(x: int) -> D: return D(x)
+
+
+[file interp.py]
+class C:
+    def __init__(self, x: int) -> None:
+        self.x = x
+
+[file driver.py]
+from native import b, d, B, D
+
+def test(f, v):
+    x = f(v)
+    assert x.x == v
+    assert x.s == 'test'
+
+test(b, 20)
+test(d, 30)
+test(B, -1)
+test(D, -2)
