5 files changed, 32 insertions, 35 deletions

diff --git a/numpy/core/src/multiarray/convert_datatype.c b/numpy/core/src/multiarray/convert_datatype.c
index c22e6a0b7..6cd4e7a79 100644
--- a/numpy/core/src/multiarray/convert_datatype.c
+++ b/numpy/core/src/multiarray/convert_datatype.c
@@ -22,6 +22,9 @@
  *
  * Cast an array using typecode structure.
  * steals reference to at --- cannot be NULL
+ *
+ * This function always makes a copy of mp, even if the dtype
+ * doesn't change.
  */
 NPY_NO_EXPORT PyObject *
 PyArray_CastToType(PyArrayObject *mp, PyArray_Descr *at, int fortran)
@@ -32,16 +35,6 @@ PyArray_CastToType(PyArrayObject *mp, PyArray_Descr *at, int fortran)
 
     mpd = mp->descr;
 
-    if (((mpd == at) ||
-                ((mpd->type_num == at->type_num) &&
-                 PyArray_EquivByteorders(mpd->byteorder, at->byteorder) &&
-                 ((mpd->elsize == at->elsize) || (at->elsize==0)))) &&
-                 PyArray_ISBEHAVED_RO(mp)) {
-        Py_DECREF(at);
-        Py_INCREF(mp);
-        return (PyObject *)mp;
-    }
-
     if (at->elsize == 0) {
         PyArray_DESCR_REPLACE(at);
         if (at == NULL) {
diff --git a/numpy/core/src/multiarray/getset.c b/numpy/core/src/multiarray/getset.c
index a636383a6..8367329d1 100644
--- a/numpy/core/src/multiarray/getset.c
+++ b/numpy/core/src/multiarray/getset.c
@@ -418,10 +418,21 @@ array_descr_set(PyArrayObject *self, PyObject *arg)
     }
 
     if (newtype->elsize == 0) {
-        PyErr_SetString(PyExc_TypeError,
-                        "data-type must not be 0-sized");
-        Py_DECREF(newtype);
-        return -1;
+        /* Allow a void view */
+        if (newtype->type_num == NPY_VOID) {
+            PyArray_DESCR_REPLACE(newtype);
+            if (newtype == NULL) {
+                return -1;
+            }
+            newtype->elsize = self->descr->elsize;
+        }
+        /* But no other flexible types */
+        else {
+            PyErr_SetString(PyExc_TypeError,
+                            "data-type must not be 0-sized");
+            Py_DECREF(newtype);
+            return -1;
+        }
     }
 
 
diff --git a/numpy/core/src/multiarray/methods.c b/numpy/core/src/multiarray/methods.c
index e2ccb3f80..28b57c8ce 100644
--- a/numpy/core/src/multiarray/methods.c
+++ b/numpy/core/src/multiarray/methods.c
@@ -770,7 +770,7 @@ array_setasflat(PyArrayObject *self, PyObject *args)
 }
 
 static PyObject *
-array_cast(PyArrayObject *self, PyObject *args)
+array_astype(PyArrayObject *self, PyObject *args)
 {
     PyArray_Descr *descr = NULL;
     PyObject *obj;
@@ -781,19 +781,6 @@ array_cast(PyArrayObject *self, PyObject *args)
         return NULL;
     }
 
-    if (PyArray_EquivTypes(descr, self->descr)) {
-        obj = _ARET(PyArray_NewCopy(self,NPY_ANYORDER));
-        Py_XDECREF(descr);
-        return obj;
-    }
-    if (descr->names != NULL) {
-        int flags;
-        flags = NPY_FORCECAST;
-        if (PyArray_ISFORTRAN(self)) {
-            flags |= NPY_FORTRAN;
-        }
-        return PyArray_FromArray(self, descr, flags);
-    }
     return PyArray_CastToType(self, descr, PyArray_ISFORTRAN(self));
 }
 
@@ -2205,7 +2192,7 @@ NPY_NO_EXPORT PyMethodDef array_methods[] = {
         (PyCFunction)array_argsort,
         METH_VARARGS | METH_KEYWORDS, NULL},
     {"astype",
-        (PyCFunction)array_cast,
+        (PyCFunction)array_astype,
         METH_VARARGS, NULL},
     {"byteswap",
         (PyCFunction)array_byteswap,
diff --git a/numpy/core/src/multiarray/multiarraymodule.c b/numpy/core/src/multiarray/multiarraymodule.c
index 2d1a75423..96118acaf 100644
--- a/numpy/core/src/multiarray/multiarraymodule.c
+++ b/numpy/core/src/multiarray/multiarraymodule.c
@@ -1410,10 +1410,16 @@ _equivalent_subarrays(PyArray_ArrayDescr *sub1, PyArray_ArrayDescr *sub2)
 NPY_NO_EXPORT unsigned char
 PyArray_EquivTypes(PyArray_Descr *typ1, PyArray_Descr *typ2)
 {
-    int typenum1 = typ1->type_num;
-    int typenum2 = typ2->type_num;
-    int size1 = typ1->elsize;
-    int size2 = typ2->elsize;
+    int typenum1, typenum2, size1, size2;
+
+    if (typ1 == typ2) {
+        return TRUE;
+    }
+
+    typenum1 = typ1->type_num;
+    typenum2 = typ2->type_num;
+    size1 = typ1->elsize;
+    size2 = typ2->elsize;
 
     if (size1 != size2) {
         return FALSE;
diff --git a/numpy/ma/core.py b/numpy/ma/core.py
index 6873bef6c..98100621e 100644
--- a/numpy/ma/core.py
+++ b/numpy/ma/core.py
@@ -5552,8 +5552,8 @@ class mvoid(MaskedArray):
 
     def __getitem__(self, indx):
         "Get the index..."
-        _mask = self._mask.astype(np.void)
-        if _mask is not nomask and _mask[indx]:
+        m = self._mask
+        if m is not nomask and m[indx]:
             return masked
         return self._data[indx]