Move abc._Abstract into object by adding a new flag Py_TPFLAGS_IS_ABSTRACT,
which forbids constructing types that have it set. The effect is to speed
./python.exe -m timeit -s 'import abc' -s 'class Foo(object): __metaclass__ = abc.ABCMeta' 'Foo()'
up from 2.5us to 0.201us. This fixes issue 1762.
diff --git a/Include/object.h b/Include/object.h
index 65440a6..8d04935 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -537,6 +537,9 @@
#define Py_TPFLAGS_HAVE_VERSION_TAG (1L<<18)
#define Py_TPFLAGS_VALID_VERSION_TAG (1L<<19)
+/* Type is abstract and cannot be instantiated */
+#define Py_TPFLAGS_IS_ABSTRACT (1L<<20)
+
/* These flags are used to determine if a type is a subclass. */
#define Py_TPFLAGS_INT_SUBCLASS (1L<<23)
#define Py_TPFLAGS_LONG_SUBCLASS (1L<<24)