[mypyc] Fix crash when a method overrides a decorated method

mypyc/codegen/emitclass.py

@@ -299,7 +299,8 @@ def generate_class(cl: ClassIR, module: str, emitter: Emitter) -> None:
             fields["tp_traverse"] = f"(traverseproc){name_prefix}_traverse"
             fields["tp_clear"] = f"(inquiry){clear_name}"
     # Populate .tp_finalize and generate a finalize method only if __del__ is defined for this class.
-    del_method = next((e.method for e in cl.vtable_entries if e.name == "__del__"), None)
+    # A decorated __del__ has no vtable entry, so it's looked up in the methods.
+    del_method = cl.get_method("__del__")
     if del_method:
         fields["tp_finalize"] = f"(destructor){finalize_name}"
     if needs_getseters:

mypyc/irbuild/vtable.py

@@ -4,7 +4,6 @@
 
 import itertools
 
-from mypyc.common import UNDECORATED_PREFIX
 from mypyc.ir.class_ir import ClassIR, VTableEntries, VTableMethod
 from mypyc.sametype import is_same_method_signature
 
@@ -40,9 +39,11 @@ def compute_vtable(cls: ClassIR) -> None:
 
     for t in [cls] + [t for t in all_traits if t is not cls]:
         for fn in itertools.chain(t.methods.values()):
-            if fn.name.startswith(UNDECORATED_PREFIX):
-                # The undecorated function of a decorated override is only called by the
-                # decorator at runtime, never natively
+            if fn.name not in t.method_decls:
+                # Decorated methods aren't declared as native methods, since they are only
+                # called through the Python API, so they don't need an entry. This includes
+                # the undecorated function of a decorated override, which only the
+                # decorators call.
                 continue
             # TODO: don't generate a new entry when we overload without changing the type
             if fn == cls.get_method(fn.name, prefer_method=True):

mypyc/test-data/irbuild-glue-methods.test

@@ -509,3 +509,60 @@ L0:
     r0 = ''
     __mypyc_self__._x = r0
     return 1
+
+[case testNoGlueForOverrideOfDecoratedMethod_64bit]
+from typing import TypeVar
+
+T = TypeVar("T")
+
+def dec(f: T) -> T:
+    return f
+
+class Base:
+    @dec
+    def f(self) -> object:
+        return None
+
+class Sub(Base):
+    def f(self) -> int:
+        return 1
+
+def call_base(b: Base) -> object:
+    return b.f()
+
+def call_sub(s: Sub) -> int:
+    return s.f()
+[out]
+def dec(f):
+    f :: object
+L0:
+    return f
+def Base.f(self):
+    self :: __main__.Base
+    r0 :: object
+L0:
+    r0 = box(None, 1)
+    return r0
+def Sub.f(self):
+    self :: __main__.Sub
+L0:
+    return 2
+def call_base(b):
+    b :: __main__.Base
+    r0 :: str
+    r1 :: object[1]
+    r2 :: object_ptr
+    r3 :: object
+L0:
+    r0 = 'f'
+    r1 = [b]
+    r2 = load_address r1
+    r3 = PyObject_VectorcallMethod(r0, r2, 9223372036854775809, 0)
+    keep_alive b
+    return r3
+def call_sub(s):
+    s :: __main__.Sub
+    r0 :: int
+L0:
+    r0 = s.f()
+    return r0