Make Python builtin types hashable by default

Default hash is the underlying C/C++ pointer.
This matches up with testing for equivalence (Py_EQ in SwigPyObject_richcompare)
which compares the pointers.

Examples/test-suite/python/python_builtin_runme.py

@@ -1,6 +1,17 @@
 from python_builtin import *
 
 if is_python_builtin():
+  # Test 0 for default tp_hash
+  vs = ValueStruct(1234)
+  h = hash(vs)
+  d = dict()
+  d[h] = "hi"
+  if h not in d:
+    raise RuntimeError("h should be in d")
+  h2 = hash(ValueStruct.inout(vs))
+  if h != h2:
+    raise RuntimeError("default tp_hash not working")
+
   # Test 1 for tp_hash
   if hash(SimpleValue(222)) != 222:
     raise RuntimeError("tp_hash not working")

Examples/test-suite/python_builtin.i

@@ -10,6 +10,17 @@ bool is_python_builtin() { return false; }
 #endif
 %}
 
+// Test 0 for default tp_hash
+%inline %{
+struct ValueStruct {
+  int value;
+  ValueStruct(int value) : value(value) {}
+  static ValueStruct *inout(ValueStruct *v) {
+    return v;
+  }
+};
+%}
+
 // Test 1 for tp_hash
 #if defined(SWIGPYTHON_BUILTIN)
 %feature("python:tp_hash") SimpleValue "SimpleValueHashFunction"
@@ -19,9 +30,6 @@ bool is_python_builtin() { return false; }
 struct SimpleValue {
   int value;
   SimpleValue(int value) : value(value) {}
-  static SimpleValue *inout(SimpleValue *sv) {
-    return sv;
-  }
 };
 %}
 

Lib/python/builtin.swg

@@ -187,19 +187,14 @@ wrapper##_closure(PyObject *a) {		\
 }
 
 #define SWIGPY_HASHFUNC_CLOSURE(wrapper)	\
-SWIGINTERN long					\
+SWIGINTERN Py_hash_t				\
 wrapper##_closure(PyObject *a) {		\
     PyObject *pyresult;				\
-    long result;				\
+    Py_hash_t result;				\
     pyresult = wrapper(a, NULL);		\
     if (!pyresult)				\
       return -1;				\
-    if (!PyLong_Check(pyresult))		\
-      PyErr_Format(PyExc_TypeError, "Wrong type for hash function");\
-    else					\
-      result = PyLong_AsLong(pyresult);		\
-    if (PyErr_Occurred())			\
-      result = -1;				\
+    result = SWIG_PyNumber_AsPyHash(pyresult);	\
     Py_DECREF(pyresult);			\
     return result;				\
 }
@@ -227,14 +222,35 @@ SwigPyBuiltin_BadInit(PyObject *self, PyObject *SWIGUNUSEDPARM(args), PyObject *
 }
 
 SWIGINTERN void
-SwigPyBuiltin_BadDealloc(PyObject *pyobj) {
-  SwigPyObject *sobj;
-  sobj = (SwigPyObject *)pyobj;
+SwigPyBuiltin_BadDealloc(PyObject *obj) {
+  SwigPyObject *sobj = (SwigPyObject *)obj;
   if (sobj->own) {
-    PyErr_Format(PyExc_TypeError, "Swig detected a memory leak in type '%.300s': no callable destructor found.", pyobj->ob_type->tp_name);
+    PyErr_Format(PyExc_TypeError, "Swig detected a memory leak in type '%.300s': no callable destructor found.", obj->ob_type->tp_name);
   }
 }
 
+SWIGINTERN Py_hash_t
+SwigPyObject_hash(PyObject *obj) {
+  SwigPyObject *sobj = (SwigPyObject *)obj;
+  void *ptr = sobj->ptr;
+  return (Py_hash_t)ptr;
+}
+
+SWIGINTERN Py_hash_t
+SWIG_PyNumber_AsPyHash(PyObject *obj) {
+  Py_hash_t result = -1;
+#if PY_VERSION_HEX < 0x03020000
+  if (PyLong_Check(obj))
+    result = PyLong_AsLong(obj);
+#else
+  if (PyNumber_Check(obj))
+    result = PyNumber_AsSsize_t(obj, NULL);
+#endif
+  else
+    PyErr_Format(PyExc_TypeError, "Wrong type for hash function");
+  return result;
+}
+
 typedef struct {
   PyCFunction get;
   PyCFunction set;

Lib/python/pyhead.swg

@@ -211,4 +211,5 @@ typedef destructor freefunc;
 #if PY_VERSION_HEX < 0x03020000
 #define PyDescr_TYPE(x) (((PyDescrObject *)(x))->d_type)
 #define PyDescr_NAME(x) (((PyDescrObject *)(x))->d_name)
+#define Py_hash_t long
 #endif

Source/Modules/python.cxx

@@ -4057,6 +4057,7 @@ public:
     static String *tp_basicsize = NewStringf("sizeof(SwigPyObject)");
     static String *tp_dictoffset_default = NewString("offsetof(SwigPyObject, dict)");
     static String *tp_new = NewString("PyType_GenericNew");
+    static String *tp_hash = NewString("SwigPyObject_hash");
     String *tp_as_number = NewStringf("&%s_type.as_number", templ);
     String *tp_as_sequence = NewStringf("&%s_type.as_sequence", templ);
     String *tp_as_mapping = NewStringf("&%s_type.as_mapping", templ);
@@ -4088,7 +4089,7 @@ public:
     printSlot(f, getSlot(n, "feature:python:tp_as_number", tp_as_number), "tp_as_number");
     printSlot(f, getSlot(n, "feature:python:tp_as_sequence", tp_as_sequence), "tp_as_sequence");
     printSlot(f, getSlot(n, "feature:python:tp_as_mapping", tp_as_mapping), "tp_as_mapping");
-    printSlot(f, getSlot(n, "feature:python:tp_hash"), "tp_hash", "hashfunc");
+    printSlot(f, getSlot(n, "feature:python:tp_hash", tp_hash), "tp_hash", "hashfunc");
     printSlot(f, getSlot(n, "feature:python:tp_call"), "tp_call", "ternaryfunc");
     printSlot(f, getSlot(n, "feature:python:tp_str"), "tp_str", "reprfunc");
     printSlot(f, getSlot(n, "feature:python:tp_getattro"), "tp_getattro", "getattrofunc");