Merge pull request #6053 from ahaldane/multifield_structassign

MAINT: struct assignment "by field position", multi-field indices return views

16 files changed, 444 insertions, 602 deletions

diff --git a/numpy/core/src/multiarray/array_assign_array.c b/numpy/core/src/multiarray/array_assign_array.c
index 28cc7031a..d1bce8c3b 100644
--- a/numpy/core/src/multiarray/array_assign_array.c
+++ b/numpy/core/src/multiarray/array_assign_array.c
@@ -293,7 +293,8 @@ PyArray_AssignArray(PyArrayObject *dst, PyArrayObject *src,
     if (((PyArray_NDIM(dst) == 1 && PyArray_NDIM(src) >= 1 &&
                     PyArray_STRIDES(dst)[0] *
                             PyArray_STRIDES(src)[PyArray_NDIM(src) - 1] < 0) ||
-                    PyArray_NDIM(dst) > 1) && arrays_overlap(src, dst)) {
+                    PyArray_NDIM(dst) > 1 || PyArray_HASFIELDS(dst)) &&
+                    arrays_overlap(src, dst)) {
         PyArrayObject *tmp;
 
         /*
diff --git a/numpy/core/src/multiarray/arraytypes.c.src b/numpy/core/src/multiarray/arraytypes.c.src
index 921fbbe50..43dd101c5 100644
--- a/numpy/core/src/multiarray/arraytypes.c.src
+++ b/numpy/core/src/multiarray/arraytypes.c.src
@@ -774,66 +774,173 @@ VOID_getitem(void *input, void *vap)
 
 NPY_NO_EXPORT int PyArray_CopyObject(PyArrayObject *, PyObject *);
 
+/* Given a structured PyArrayObject arr, index i and structured datatype descr,
+ * modify the dtype of arr to contain a single field corresponding to the ith
+ * field of descr, recompute the alignment flag, and return the offset of the
+ * field (in offset_p). This is useful in preparation for calling copyswap on
+ * individual fields of a numpy structure, in VOID_setitem.  Compare to inner
+ * loops in VOID_getitem and VOID_nonzero.
+ *
+ * WARNING: Clobbers arr's dtype and alignment flag.
+ */
+NPY_NO_EXPORT int
+_setup_field(int i, PyArray_Descr *descr, PyArrayObject *arr,
+            npy_intp *offset_p)
+{
+    PyObject *key;
+    PyObject *tup;
+    PyArray_Descr *new;
+    npy_intp offset;
+
+    key = PyTuple_GET_ITEM(descr->names, i);
+    tup = PyDict_GetItem(descr->fields, key);
+    if (_unpack_field(tup, &new, &offset) < 0) {
+        return -1;
+    }
+
+    ((PyArrayObject_fields *)(arr))->descr = new;
+    if ((new->alignment > 1) && ((offset % new->alignment) != 0)) {
+        PyArray_CLEARFLAGS(arr, NPY_ARRAY_ALIGNED);
+    }
+    else {
+        PyArray_ENABLEFLAGS(arr, NPY_ARRAY_ALIGNED);
+    }
+
+    *offset_p = offset;
+    return 0;
+}
+
+/* Helper function for VOID_setitem, which uses the copyswap or casting code to
+ * copy structured datatypes between numpy arrays or scalars.
+ */
+static int
+_copy_and_return_void_setitem(PyArray_Descr *dstdescr, char *dstdata,
+                              PyArray_Descr *srcdescr, char *srcdata){
+    PyArrayObject_fields dummy_struct;
+    PyArrayObject *dummy = (PyArrayObject *)&dummy_struct;
+    npy_int names_size = PyTuple_GET_SIZE(dstdescr->names);
+    npy_intp offset;
+    npy_int i;
+    int ret;
+
+    /* Fast path if dtypes are equal */
+    if (PyArray_EquivTypes(srcdescr, dstdescr)) {
+        for (i = 0; i < names_size; i++) {
+            /* neither line can ever fail, in principle */
+            if (_setup_field(i, dstdescr, dummy, &offset)) {
+                return -1;
+            }
+            PyArray_DESCR(dummy)->f->copyswap(dstdata + offset,
+                                              srcdata + offset, 0, dummy);
+        }
+        return 0;
+    }
+
+    /* Slow path */
+    ret = PyArray_CastRawArrays(1, srcdata, dstdata, 0, 0,
+                                srcdescr, dstdescr, 0);
+    if (ret != NPY_SUCCEED) {
+        return -1;
+    }
+    return 0;
+}
+
 static int
 VOID_setitem(PyObject *op, void *input, void *vap)
 {
     char *ip = input;
     PyArrayObject *ap = vap;
     PyArray_Descr *descr;
+    int flags;
     int itemsize=PyArray_DESCR(ap)->elsize;
     int res;
 
     descr = PyArray_DESCR(ap);
-    if (descr->names && PyTuple_Check(op)) {
-        PyObject *key;
-        PyObject *names;
-        int i, n;
-        PyObject *tup;
-        int savedflags;
-
-        res = 0;
-        /* get the names from the fields dictionary*/
-        names = descr->names;
-        n = PyTuple_GET_SIZE(names);
-        if (PyTuple_GET_SIZE(op) != n) {
-            PyErr_SetString(PyExc_ValueError,
-                    "size of tuple must match number of fields.");
-            return -1;
-        }
-        savedflags = PyArray_FLAGS(ap);
-        for (i = 0; i < n; i++) {
-            PyArray_Descr *new;
-            npy_intp offset;
-            key = PyTuple_GET_ITEM(names, i);
-            tup = PyDict_GetItem(descr->fields, key);
-            if (_unpack_field(tup, &new, &offset) < 0) {
-                ((PyArrayObject_fields *)ap)->descr = descr;
+    flags = PyArray_FLAGS(ap);
+    if (PyDataType_HASFIELDS(descr)) {
+        PyObject *errmsg;
+        npy_int i;
+        npy_intp offset;
+        int failed = 0;
+
+        /* If op is 0d-ndarray or numpy scalar, directly get dtype & data ptr */
+        if (PyArray_Check(op)) {
+            PyArrayObject *oparr = (PyArrayObject *)op;
+            if (PyArray_SIZE(oparr) != 1) {
+                PyErr_SetString(PyExc_ValueError,
+                        "setting an array element with a sequence.");
                 return -1;
             }
-            /*
-             * TODO: temporarily modifying the array like this
-             *       is bad coding style, should be changed.
-             */
-            ((PyArrayObject_fields *)ap)->descr = new;
-            /* remember to update alignment flags */
-            if ((new->alignment > 1)
-                    && ((((npy_intp)(ip+offset)) % new->alignment) != 0)) {
-                PyArray_CLEARFLAGS(ap, NPY_ARRAY_ALIGNED);
+            return _copy_and_return_void_setitem(descr, ip,
+                                    PyArray_DESCR(oparr), PyArray_DATA(oparr));
+        }
+        else if (PyArray_IsScalar(op, Void)) {
+            PyArray_Descr *srcdescr = ((PyVoidScalarObject *)op)->descr;
+            char *srcdata = ((PyVoidScalarObject *)op)->obval;
+            return _copy_and_return_void_setitem(descr, ip, srcdescr, srcdata);
+        }
+        else if (PyTuple_Check(op)) {
+            /* if it's a tuple, copy field-by-field to ap, */
+            npy_intp names_size = PyTuple_GET_SIZE(descr->names);
+
+            if (names_size != PyTuple_Size(op)) {
+                errmsg = PyUString_FromFormat(
+                        "could not assign tuple of length %zd to structure "
+                        "with %" NPY_INTP_FMT " fields.", 
+                        PyTuple_Size(op), names_size);
+                PyErr_SetObject(PyExc_ValueError, errmsg);
+                Py_DECREF(errmsg);
+                return -1;
             }
-            else {
-                PyArray_ENABLEFLAGS(ap, NPY_ARRAY_ALIGNED);
+
+            for (i = 0; i < names_size; i++) {
+                PyObject *item;
+
+                /* temporarily make ap have only this field */
+                if (_setup_field(i, descr, ap, &offset) == -1) {
+                    failed = 1;
+                    break;
+                }
+                item = PyTuple_GetItem(op, i);
+                if (item == NULL) {
+                    failed = 1;
+                    break;
+                }
+                /* use setitem to set this field */
+                if (PyArray_DESCR(ap)->f->setitem(item, ip + offset, ap) < 0) {
+                    failed = 1;
+                    break;
+                }
             }
-            res = new->f->setitem(PyTuple_GET_ITEM(op, i), ip+offset, ap);
-            ((PyArrayObject_fields *)ap)->flags = savedflags;
-            if (res < 0) {
-                break;
+        }
+        else {
+            /* Otherwise must be non-void scalar. Try to assign to each field */
+            npy_intp names_size = PyTuple_GET_SIZE(descr->names);
+
+            for (i = 0; i < names_size; i++) {
+                /* temporarily make ap have only this field */
+                if (_setup_field(i, descr, ap, &offset) == -1) {
+                    failed = 1;
+                    break;
+                }
+                /* use setitem to set this field */
+                if (PyArray_DESCR(ap)->f->setitem(op, ip + offset, ap) < 0) {
+                    failed = 1;
+                    break;
+                }
             }
         }
-        ((PyArrayObject_fields *)ap)->descr = descr;
-        return res;
-    }
 
-    if (descr->subarray) {
+        /* reset clobbered attributes */
+        ((PyArrayObject_fields *)(ap))->descr = descr;
+        ((PyArrayObject_fields *)(ap))->flags = flags;
+
+        if (failed) {
+            return -1;
+        }
+        return 0;
+    }
+    else if (PyDataType_HASSUBARRAY(descr)) {
         /* copy into an array of the same basic type */
         PyArray_Dims shape = {NULL, -1};
         PyArrayObject *ret;
@@ -862,19 +969,17 @@ VOID_setitem(PyObject *op, void *input, void *vap)
         return res;
     }
 
-    /* Default is to use buffer interface to set item */
+    /*
+     * Fall through case - non-structured void datatype. This is a very
+     * undiscerning case: It interprets any object as a buffer
+     * and reads as many bytes as possible, padding with 0.
+     */
     {
         const void *buffer;
         Py_ssize_t buflen;
-        if (PyDataType_FLAGCHK(descr, NPY_ITEM_HASOBJECT)
-                || PyDataType_FLAGCHK(descr, NPY_ITEM_IS_POINTER)) {
-            PyErr_SetString(PyExc_ValueError,
-                    "Setting void-array with object members using buffer.");
-            return -1;
-        }
         res = PyObject_AsReadBuffer(op, &buffer, &buflen);
         if (res == -1) {
-            goto fail;
+            return -1;
         }
         memcpy(ip, buffer, PyArray_MIN(buflen, itemsize));
         if (itemsize > buflen) {
@@ -882,9 +987,6 @@ VOID_setitem(PyObject *op, void *input, void *vap)
         }
     }
     return 0;
-
-fail:
-    return -1;
 }
 
 static PyObject *
diff --git a/numpy/core/src/multiarray/descriptor.c b/numpy/core/src/multiarray/descriptor.c
index 8e6aa6789..32b926ae8 100644
--- a/numpy/core/src/multiarray/descriptor.c
+++ b/numpy/core/src/multiarray/descriptor.c
@@ -3119,7 +3119,7 @@ static PyMethodDef arraydescr_methods[] = {
  *
  * Returns 1 if it has a simple layout, 0 otherwise.
  */
-static int
+NPY_NO_EXPORT int
 is_dtype_struct_simple_unaligned_layout(PyArray_Descr *dtype)
 {
     PyObject *names, *fields, *key, *tup, *title;
diff --git a/numpy/core/src/multiarray/descriptor.h b/numpy/core/src/multiarray/descriptor.h
index ff1fc980a..f95041195 100644
--- a/numpy/core/src/multiarray/descriptor.h
+++ b/numpy/core/src/multiarray/descriptor.h
@@ -10,6 +10,10 @@ array_set_typeDict(PyObject *NPY_UNUSED(ignored), PyObject *args);
 NPY_NO_EXPORT PyArray_Descr *
 _arraydescr_fromobj(PyObject *obj);
 
+
+NPY_NO_EXPORT int
+is_dtype_struct_simple_unaligned_layout(PyArray_Descr *dtype);
+
 /*
  * Creates a string repr of the dtype, excluding the 'dtype()' part
  * surrounding the object. This object may be a string, a list, or
diff --git a/numpy/core/src/multiarray/dtype_transfer.c b/numpy/core/src/multiarray/dtype_transfer.c
index dfe95d65c..9c27255aa 100644
--- a/numpy/core/src/multiarray/dtype_transfer.c
+++ b/numpy/core/src/multiarray/dtype_transfer.c
@@ -25,6 +25,7 @@
 #include "ctors.h"
 #include "_datetime.h"
 #include "datetime_strings.h"
+#include "descriptor.h"
 
 #include "shape.h"
 #include "lowlevel_strided_loops.h"
@@ -2521,7 +2522,7 @@ _strided_to_strided_field_transfer(char *dst, npy_intp dst_stride,
 
 /*
  * Handles fields transfer.  To call this, at least one of the dtypes
- * must have fields
+ * must have fields. Does not take care of object<->structure conversion
  */
 static int
 get_fields_transfer_function(int aligned,
@@ -2532,22 +2533,26 @@ get_fields_transfer_function(int aligned,
                             NpyAuxData **out_transferdata,
                             int *out_needs_api)
 {
-    PyObject *names, *key, *tup, *title;
+    PyObject *key, *tup, *title;
     PyArray_Descr *src_fld_dtype, *dst_fld_dtype;
-    npy_int i, names_size, field_count, structsize;
+    npy_int i, field_count, structsize;
     int src_offset, dst_offset;
     _field_transfer_data *data;
     _single_field_transfer *fields;
+    int failed = 0;
+
+    /*
+     * There are three cases to take care of: 1. src is non-structured,
+     * 2. dst is non-structured, or 3. both are structured.
+     */
 
-    /* Copy the src value to all the fields of dst */
+    /* 1. src is non-structured. Copy the src value to all the fields of dst */
     if (!PyDataType_HASFIELDS(src_dtype)) {
-        names = dst_dtype->names;
-        names_size = PyTuple_GET_SIZE(dst_dtype->names);
+        field_count = PyTuple_GET_SIZE(dst_dtype->names);
 
-        field_count = names_size;
+        /* Allocate the field-data structure and populate it */
         structsize = sizeof(_field_transfer_data) +
                         (field_count + 1) * sizeof(_single_field_transfer);
-        /* Allocate the data and populate it */
         data = (_field_transfer_data *)PyArray_malloc(structsize);
         if (data == NULL) {
             PyErr_NoMemory();
@@ -2557,8 +2562,8 @@ get_fields_transfer_function(int aligned,
         data->base.clone = &_field_transfer_data_clone;
         fields = &data->fields;
 
-        for (i = 0; i < names_size; ++i) {
-            key = PyTuple_GET_ITEM(names, i);
+        for (i = 0; i < field_count; ++i) {
+            key = PyTuple_GET_ITEM(dst_dtype->names, i);
             tup = PyDict_GetItem(dst_dtype->fields, key);
             if (!PyArg_ParseTuple(tup, "Oi|O", &dst_fld_dtype,
                                                     &dst_offset, &title)) {
@@ -2584,7 +2589,7 @@ get_fields_transfer_function(int aligned,
         }
 
         /*
-         * If the references should be removed from src, add
+         * If references should be decrefd in src, add
          * another transfer function to do that.
          */
         if (move_references && PyDataType_REFCHK(src_dtype)) {
@@ -2612,24 +2617,19 @@ get_fields_transfer_function(int aligned,
 
         return NPY_SUCCEED;
     }
-    /* Copy the value of the first field to dst */
-    else if (!PyDataType_HASFIELDS(dst_dtype)) {
-        names = src_dtype->names;
-        names_size = PyTuple_GET_SIZE(src_dtype->names);
 
-        /*
-         * If DECREF is needed on source fields, may need
-         * to process all the fields
-         */
-        if (move_references && PyDataType_REFCHK(src_dtype)) {
-            field_count = names_size + 1;
-        }
-        else {
-            field_count = 1;
+    /* 2. dst is non-structured. Allow transfer from single-field src to dst */
+    if (!PyDataType_HASFIELDS(dst_dtype)) {
+        if (PyTuple_GET_SIZE(src_dtype->names) != 1) {
+            PyErr_SetString(PyExc_ValueError,
+                    "Can't cast from structure to non-structure, except if the "
+                    "structure only has a single field.");
+            return NPY_FAIL;
         }
+
+        /* Allocate the field-data structure and populate it */
         structsize = sizeof(_field_transfer_data) +
-                        field_count * sizeof(_single_field_transfer);
-        /* Allocate the data and populate it */
+                        1 * sizeof(_single_field_transfer);
         data = (_field_transfer_data *)PyArray_malloc(structsize);
         if (data == NULL) {
             PyErr_NoMemory();
@@ -2639,286 +2639,102 @@ get_fields_transfer_function(int aligned,
         data->base.clone = &_field_transfer_data_clone;
         fields = &data->fields;
 
-        key = PyTuple_GET_ITEM(names, 0);
+        key = PyTuple_GET_ITEM(src_dtype->names, 0);
         tup = PyDict_GetItem(src_dtype->fields, key);
-        if (!PyArg_ParseTuple(tup, "Oi|O", &src_fld_dtype,
-                                                &src_offset, &title)) {
-            PyArray_free(data);
+        if (!PyArg_ParseTuple(tup, "Oi|O",
+                              &src_fld_dtype, &src_offset, &title)) {
             return NPY_FAIL;
         }
-        field_count = 0;
-        /*
-         * Special case bool type, the existence of fields implies True
-         *
-         * TODO: Perhaps a better behavior would be to combine all the
-         *       input fields with an OR?  The same would apply to subarrays.
-         */
-        if (dst_dtype->type_num == NPY_BOOL) {
-            if (get_bool_setdstone_transfer_function(dst_stride,
-                                    &fields[field_count].stransfer,
-                                    &fields[field_count].data,
-                                    out_needs_api) != NPY_SUCCEED) {
-                PyArray_free(data);
-                return NPY_FAIL;
-            }
-            fields[field_count].src_offset = 0;
-            fields[field_count].dst_offset = 0;
-            fields[field_count].src_itemsize = 0;
-            field_count++;
-
-            /* If the src field has references, may need to clear them */
-            if (move_references && PyDataType_REFCHK(src_fld_dtype)) {
-                if (get_decsrcref_transfer_function(0,
-                            src_stride,
-                            src_fld_dtype,
-                            &fields[field_count].stransfer,
-                            &fields[field_count].data,
-                            out_needs_api) != NPY_SUCCEED) {
-                    NPY_AUXDATA_FREE(fields[0].data);
-                    PyArray_free(data);
-                    return NPY_FAIL;
-                }
-                fields[field_count].src_offset = src_offset;
-                fields[field_count].dst_offset = 0;
-                fields[field_count].src_itemsize = src_fld_dtype->elsize;
-                field_count++;
-            }
-        }
-        /* Transfer the first field to the output */
-        else {
-            if (PyArray_GetDTypeTransferFunction(0,
-                                    src_stride, dst_stride,
-                                    src_fld_dtype, dst_dtype,
-                                    move_references,
-                                    &fields[field_count].stransfer,
-                                    &fields[field_count].data,
-                                    out_needs_api) != NPY_SUCCEED) {
-                PyArray_free(data);
-                return NPY_FAIL;
-            }
-            fields[field_count].src_offset = src_offset;
-            fields[field_count].dst_offset = 0;
-            fields[field_count].src_itemsize = src_fld_dtype->elsize;
-            field_count++;
-        }
 
-        /*
-         * If the references should be removed from src, add
-         * more transfer functions to decrement the references
-         * for all the other fields.
-         */
-        if (move_references && PyDataType_REFCHK(src_dtype)) {
-            for (i = 1; i < names_size; ++i) {
-                key = PyTuple_GET_ITEM(names, i);
-                tup = PyDict_GetItem(src_dtype->fields, key);
-                if (!PyArg_ParseTuple(tup, "Oi|O", &src_fld_dtype,
-                                                    &src_offset, &title)) {
-                    return NPY_FAIL;
-                }
-                if (PyDataType_REFCHK(src_fld_dtype)) {
-                    if (get_decsrcref_transfer_function(0,
-                                src_stride,
-                                src_fld_dtype,
-                                &fields[field_count].stransfer,
-                                &fields[field_count].data,
-                                out_needs_api) != NPY_SUCCEED) {
-                        for (i = field_count-1; i >= 0; --i) {
-                            NPY_AUXDATA_FREE(fields[i].data);
-                        }
-                        PyArray_free(data);
-                        return NPY_FAIL;
-                    }
-                    fields[field_count].src_offset = src_offset;
-                    fields[field_count].dst_offset = 0;
-                    fields[field_count].src_itemsize = src_fld_dtype->elsize;
-                    field_count++;
-                }
-            }
+        if (PyArray_GetDTypeTransferFunction(0,
+                                             src_stride, dst_stride,
+                                             src_fld_dtype, dst_dtype,
+                                             move_references,
+                                             &fields[0].stransfer,
+                                             &fields[0].data,
+                                             out_needs_api) != NPY_SUCCEED) {
+            PyArray_free(data);
+            return NPY_FAIL;
         }
+        fields[0].src_offset = src_offset;
+        fields[0].dst_offset = 0;
+        fields[0].src_itemsize = src_fld_dtype->elsize;
 
-        data->field_count = field_count;
+        data->field_count = 1;
 
         *out_stransfer = &_strided_to_strided_field_transfer;
         *out_transferdata = (NpyAuxData *)data;
 
         return NPY_SUCCEED;
     }
-    /* Match up the fields to copy */
-    else {
-        /* Keeps track of the names we already used */
-        PyObject *used_names_dict = NULL;
-        int cmpval;
-
-        const char *msg =
-            "Assignment between structured arrays with different field names "
-            "will change in numpy 1.14.\n\n"
-            "Previously fields in the dst would be set to the value of the "
-            "identically-named field in the src. In numpy 1.14 fields will "
-            "instead be assigned 'by position': The Nth field of the dst "
-            "will be set to the Nth field of the src array.\n\n"
-            "See the release notes for details";
-        /*
-         * 2016-09-19, 1.12
-         * Warn if the field names of the dst and src are not
-         * identical, since then behavior will change in 1.13.
-         */
-        cmpval = PyObject_RichCompareBool(src_dtype->names,
-                                          dst_dtype->names, Py_EQ);
-        if (PyErr_Occurred()) {
-            return NPY_FAIL;
-        }
-        if (cmpval != 1) {
-            if (DEPRECATE_FUTUREWARNING(msg) < 0) {
-                return NPY_FAIL;
-            }
-        }
 
-        names = dst_dtype->names;
-        names_size = PyTuple_GET_SIZE(dst_dtype->names);
+    /* 3. Otherwise both src and dst are structured arrays */
+    field_count = PyTuple_GET_SIZE(dst_dtype->names);
 
-        /*
-         * If DECREF is needed on source fields, will need
-         * to also go through its fields.
-         */
-        if (move_references && PyDataType_REFCHK(src_dtype)) {
-            field_count = names_size + PyTuple_GET_SIZE(src_dtype->names);
-            used_names_dict = PyDict_New();
-            if (used_names_dict == NULL) {
-                return NPY_FAIL;
-            }
-        }
-        else {
-            field_count = names_size;
-        }
-        structsize = sizeof(_field_transfer_data) +
-                        field_count * sizeof(_single_field_transfer);
-        /* Allocate the data and populate it */
-        data = (_field_transfer_data *)PyArray_malloc(structsize);
-        if (data == NULL) {
-            PyErr_NoMemory();
-            Py_XDECREF(used_names_dict);
-            return NPY_FAIL;
-        }
-        data->base.free = &_field_transfer_data_free;
-        data->base.clone = &_field_transfer_data_clone;
-        fields = &data->fields;
+    /* Match up the fields to copy (field-by-field transfer) */
+    if (PyTuple_GET_SIZE(src_dtype->names) != field_count) {
+        PyErr_SetString(PyExc_ValueError, "structures must have the same size");
+        return NPY_FAIL;
+    }
 
-        for (i = 0; i < names_size; ++i) {
-            key = PyTuple_GET_ITEM(names, i);
-            tup = PyDict_GetItem(dst_dtype->fields, key);
-            if (!PyArg_ParseTuple(tup, "Oi|O", &dst_fld_dtype,
-                                                    &dst_offset, &title)) {
-                for (i = i-1; i >= 0; --i) {
-                    NPY_AUXDATA_FREE(fields[i].data);
-                }
-                PyArray_free(data);
-                Py_XDECREF(used_names_dict);
-                return NPY_FAIL;
-            }
-            tup = PyDict_GetItem(src_dtype->fields, key);
-            if (tup != NULL) {
-                if (!PyArg_ParseTuple(tup, "Oi|O", &src_fld_dtype,
-                                                        &src_offset, &title)) {
-                    for (i = i-1; i >= 0; --i) {
-                        NPY_AUXDATA_FREE(fields[i].data);
-                    }
-                    PyArray_free(data);
-                    Py_XDECREF(used_names_dict);
-                    return NPY_FAIL;
-                }
-                if (PyArray_GetDTypeTransferFunction(0,
-                                        src_stride, dst_stride,
-                                        src_fld_dtype, dst_fld_dtype,
-                                        move_references,
-                                        &fields[i].stransfer,
-                                        &fields[i].data,
-                                        out_needs_api) != NPY_SUCCEED) {
-                    for (i = i-1; i >= 0; --i) {
-                        NPY_AUXDATA_FREE(fields[i].data);
-                    }
-                    PyArray_free(data);
-                    Py_XDECREF(used_names_dict);
-                    return NPY_FAIL;
-                }
-                fields[i].src_offset = src_offset;
-                fields[i].dst_offset = dst_offset;
-                fields[i].src_itemsize = src_fld_dtype->elsize;
+    /* Allocate the field-data structure and populate it */
+    structsize = sizeof(_field_transfer_data) +
+                    field_count * sizeof(_single_field_transfer);
+    data = (_field_transfer_data *)PyArray_malloc(structsize);
+    if (data == NULL) {
+        PyErr_NoMemory();
+        return NPY_FAIL;
+    }
+    data->base.free = &_field_transfer_data_free;
+    data->base.clone = &_field_transfer_data_clone;
+    fields = &data->fields;
 
-                if (used_names_dict != NULL) {
-                    PyDict_SetItem(used_names_dict, key, Py_True);
-                }
-            }
-            else {
-                if (get_setdstzero_transfer_function(0,
-                                            dst_stride,
-                                            dst_fld_dtype,
-                                            &fields[i].stransfer,
-                                            &fields[i].data,
-                                            out_needs_api) != NPY_SUCCEED) {
-                    for (i = i-1; i >= 0; --i) {
-                        NPY_AUXDATA_FREE(fields[i].data);
-                    }
-                    PyArray_free(data);
-                    Py_XDECREF(used_names_dict);
-                    return NPY_FAIL;
-                }
-                fields[i].src_offset = 0;
-                fields[i].dst_offset = dst_offset;
-                fields[i].src_itemsize = 0;
-            }
+    /* set up the transfer function for each field */
+    for (i = 0; i < field_count; ++i) {
+        key = PyTuple_GET_ITEM(dst_dtype->names, i);
+        tup = PyDict_GetItem(dst_dtype->fields, key);
+        if (!PyArg_ParseTuple(tup, "Oi|O", &dst_fld_dtype,
+                                                &dst_offset, &title)) {
+            failed = 1;
+            break;
+        }
+        key = PyTuple_GET_ITEM(src_dtype->names, i);
+        tup = PyDict_GetItem(src_dtype->fields, key);
+        if (!PyArg_ParseTuple(tup, "Oi|O", &src_fld_dtype,
+                                                &src_offset, &title)) {
+            failed = 1;
+            break;
         }
 
-        if (move_references && PyDataType_REFCHK(src_dtype)) {
-            /* Use field_count to track additional functions added */
-            field_count = names_size;
-
-            names = src_dtype->names;
-            names_size = PyTuple_GET_SIZE(src_dtype->names);
-            for (i = 0; i < names_size; ++i) {
-                key = PyTuple_GET_ITEM(names, i);
-                if (PyDict_GetItem(used_names_dict, key) == NULL) {
-                    tup = PyDict_GetItem(src_dtype->fields, key);
-                    if (!PyArg_ParseTuple(tup, "Oi|O", &src_fld_dtype,
-                                                    &src_offset, &title)) {
-                        for (i = field_count-1; i >= 0; --i) {
-                            NPY_AUXDATA_FREE(fields[i].data);
-                        }
-                        PyArray_free(data);
-                        Py_XDECREF(used_names_dict);
-                        return NPY_FAIL;
-                    }
-                    if (PyDataType_REFCHK(src_fld_dtype)) {
-                        if (get_decsrcref_transfer_function(0,
-                                    src_stride,
-                                    src_fld_dtype,
-                                    &fields[field_count].stransfer,
-                                    &fields[field_count].data,
-                                    out_needs_api) != NPY_SUCCEED) {
-                            for (i = field_count-1; i >= 0; --i) {
-                                NPY_AUXDATA_FREE(fields[i].data);
-                            }
-                            PyArray_free(data);
-                            return NPY_FAIL;
-                        }
-                        fields[field_count].src_offset = src_offset;
-                        fields[field_count].dst_offset = 0;
-                        fields[field_count].src_itemsize =
-                                                src_fld_dtype->elsize;
-                        field_count++;
-                    }
-                }
-            }
+        if (PyArray_GetDTypeTransferFunction(0,
+                                             src_stride, dst_stride,
+                                             src_fld_dtype, dst_fld_dtype,
+                                             move_references,
+                                             &fields[i].stransfer,
+                                             &fields[i].data,
+                                             out_needs_api) != NPY_SUCCEED) {
+            failed = 1;
+            break;
         }
+        fields[i].src_offset = src_offset;
+        fields[i].dst_offset = dst_offset;
+        fields[i].src_itemsize = src_fld_dtype->elsize;
+    }
 
-        Py_XDECREF(used_names_dict);
+    if (failed) {
+        for (i = i-1; i >= 0; --i) {
+            NPY_AUXDATA_FREE(fields[i].data);
+        }
+        PyArray_free(data);
+        return NPY_FAIL;
+    }
 
-        data->field_count = field_count;
+    data->field_count = field_count;
 
-        *out_stransfer = &_strided_to_strided_field_transfer;
-        *out_transferdata = (NpyAuxData *)data;
+    *out_stransfer = &_strided_to_strided_field_transfer;
+    *out_transferdata = (NpyAuxData *)data;
 
-        return NPY_SUCCEED;
-    }
+    return NPY_SUCCEED;
 }
 
 static int
@@ -3649,8 +3465,10 @@ PyArray_GetDTypeTransferFunction(int aligned,
      * If there are no references and the data types are equivalent,
      * return a simple copy
      */
-    if (!PyDataType_REFCHK(src_dtype) && !PyDataType_REFCHK(dst_dtype) &&
-                            PyArray_EquivTypes(src_dtype, dst_dtype)) {
+    if (PyArray_EquivTypes(src_dtype, dst_dtype) &&
+            !PyDataType_REFCHK(src_dtype) && !PyDataType_REFCHK(dst_dtype) &&
+            ( !PyDataType_HASFIELDS(dst_dtype) ||
+              is_dtype_struct_simple_unaligned_layout(dst_dtype)) ) {
         /*
          * We can't pass through the aligned flag because it's not
          * appropriate. Consider a size-8 string, it will say it's
diff --git a/numpy/core/src/multiarray/mapping.c b/numpy/core/src/multiarray/mapping.c
index 4833b5069..1a92365c8 100644
--- a/numpy/core/src/multiarray/mapping.c
+++ b/numpy/core/src/multiarray/mapping.c
@@ -1446,10 +1446,6 @@ _get_field_view(PyArrayObject *arr, PyObject *ind, PyArrayObject **view)
         PyObject *fields, *names;
         PyArray_Descr *view_dtype;
 
-        /* variables needed to make a copy, to remove in the future */
-        static PyObject *copyfunc = NULL;
-        PyObject *viewcopy;
-
         seqlen = PySequence_Size(ind);
 
         /* quit if have a 0-d array (seqlen==-1) or a 0-len array */
@@ -1502,6 +1498,35 @@ _get_field_view(PyArrayObject *arr, PyObject *ind, PyArrayObject **view)
                 Py_DECREF(names);
                 return 0;
             }
+            // disallow use of titles as index
+            if (PyTuple_Size(tup) == 3) {
+                PyObject *title = PyTuple_GET_ITEM(tup, 2);
+                int titlecmp = PyObject_RichCompareBool(title, name, Py_EQ);
+                if (titlecmp == 1) {
+                    // if title == name, we were given a title, not a field name
+                    PyErr_SetString(PyExc_KeyError,
+                                "cannot use field titles in multi-field index");
+                }
+                if (titlecmp != 0 || PyDict_SetItem(fields, title, tup) < 0) {
+                    Py_DECREF(title);
+                    Py_DECREF(name);
+                    Py_DECREF(fields);
+                    Py_DECREF(names);
+                    return 0;
+                }
+                Py_DECREF(title);
+            }
+            // disallow duplicate field indices
+            if (PyDict_Contains(fields, name)) {
+                PyObject *errmsg = PyUString_FromString(
+                                       "duplicate field of name ");
+                PyUString_ConcatAndDel(&errmsg, name);
+                PyErr_SetObject(PyExc_KeyError, errmsg);
+                Py_DECREF(errmsg);
+                Py_DECREF(fields);
+                Py_DECREF(names);
+                return 0;
+            }
             if (PyDict_SetItem(fields, name, tup) < 0) {
                 Py_DECREF(name);
                 Py_DECREF(fields);
@@ -1545,29 +1570,6 @@ _get_field_view(PyArrayObject *arr, PyObject *ind, PyArrayObject **view)
             return 0;
         }
 
-        /*
-         * Return copy for now (future plan to return the view above). All the
-         * following code in this block can then be replaced by "return 0;"
-         */
-        npy_cache_import("numpy.core._internal", "_copy_fields", &copyfunc);
-        if (copyfunc == NULL) {
-            Py_DECREF(*view);
-            *view = NULL;
-            return 0;
-        }
-
-        PyArray_CLEARFLAGS(*view, NPY_ARRAY_WARN_ON_WRITE);
-        viewcopy = PyObject_CallFunction(copyfunc, "O", *view);
-        if (viewcopy == NULL) {
-            Py_DECREF(*view);
-            *view = NULL;
-            return 0;
-        }
-        Py_DECREF(*view);
-        *view = (PyArrayObject*)viewcopy;
-
-        /* warn when writing to the copy */
-        PyArray_ENABLEFLAGS(*view, NPY_ARRAY_WARN_ON_WRITE);
         return 0;
     }
     return -1;
@@ -1601,11 +1603,6 @@ array_subscript(PyArrayObject *self, PyObject *op)
             if (view == NULL) {
                 return NULL;
             }
-
-            /* warn if writing to a copy. copies will have no base */
-            if (PyArray_BASE(view) == NULL) {
-                PyArray_ENABLEFLAGS(view, NPY_ARRAY_WARN_ON_WRITE);
-            }
             return (PyObject*)view;
         }
     }
@@ -1892,17 +1889,6 @@ array_assign_subscript(PyArrayObject *self, PyObject *ind, PyObject *op)
         PyArrayObject *view;
         int ret = _get_field_view(self, ind, &view);
         if (ret == 0){
-
-#if defined(NPY_PY3K)
-            if (!PyUnicode_Check(ind)) {
-#else
-            if (!PyString_Check(ind) && !PyUnicode_Check(ind)) {
-#endif
-                PyErr_SetString(PyExc_ValueError,
-                                "multi-field assignment is not supported");
-                return -1;
-            }
-
             if (view == NULL) {
                 return -1;
             }
diff --git a/numpy/core/src/multiarray/multiarraymodule.c b/numpy/core/src/multiarray/multiarraymodule.c
index 72515a3aa..3bf42d72c 100644
--- a/numpy/core/src/multiarray/multiarraymodule.c
+++ b/numpy/core/src/multiarray/multiarraymodule.c
@@ -1418,29 +1418,34 @@ array_putmask(PyObject *NPY_UNUSED(module), PyObject *args, PyObject *kwds)
 /*
  * Compare the field dictionaries for two types.
  *
- * Return 1 if the contents are the same, 0 if not.
+ * Return 1 if the field types and field names of the two descrs are equal and
+ * in the same order, 0 if not.
  */
 static int
-_equivalent_fields(PyObject *field1, PyObject *field2) {
+_equivalent_fields(PyArray_Descr *type1, PyArray_Descr *type2) {
 
-    int same, val;
+    int val;
 
-    if (field1 == field2) {
+    if (type1->fields == type2->fields && type1->names == type2->names) {
         return 1;
     }
-    if (field1 == NULL || field2 == NULL) {
+    if (type1->fields == NULL || type2->fields == NULL) {
         return 0;
     }
 
-    val = PyObject_RichCompareBool(field1, field2, Py_EQ);
+    val = PyObject_RichCompareBool(type1->fields, type2->fields, Py_EQ);
     if (val != 1 || PyErr_Occurred()) {
-        same = 0;
+        PyErr_Clear();
+        return 0;
     }
-    else {
-        same = 1;
+
+    val = PyObject_RichCompareBool(type1->names, type2->names, Py_EQ);
+    if (val != 1 || PyErr_Occurred()) {
+        PyErr_Clear();
+        return 0;
     }
-    PyErr_Clear();
-    return same;
+
+    return 1;
 }
 
 /*
@@ -1499,10 +1504,8 @@ PyArray_EquivTypes(PyArray_Descr *type1, PyArray_Descr *type2)
         return ((type_num1 == type_num2)
                 && _equivalent_subarrays(type1->subarray, type2->subarray));
     }
-    if (type_num1 == NPY_VOID
-        || type_num2 == NPY_VOID) {
-        return ((type_num1 == type_num2)
-                && _equivalent_fields(type1->fields, type2->fields));
+    if (type_num1 == NPY_VOID || type_num2 == NPY_VOID) {
+        return ((type_num1 == type_num2) && _equivalent_fields(type1, type2));
     }
     if (type_num1 == NPY_DATETIME
             || type_num1 == NPY_TIMEDELTA
diff --git a/numpy/core/src/multiarray/scalartypes.c.src b/numpy/core/src/multiarray/scalartypes.c.src
index 3b2aa8a43..7a6ed6a86 100644
--- a/numpy/core/src/multiarray/scalartypes.c.src
+++ b/numpy/core/src/multiarray/scalartypes.c.src
@@ -2179,35 +2179,31 @@ static PyObject *
 voidtype_subscript(PyVoidScalarObject *self, PyObject *ind)
 {
     npy_intp n;
-    PyObject *ret, *args;
+    PyObject *ret, *res;
 
-    if (!(PyDataType_HASFIELDS(self->descr))) {
-        PyErr_SetString(PyExc_IndexError,
-                "can't index void scalar without fields");
-        return NULL;
+    /* structured voids will accept an integer index */
+    if (PyDataType_HASFIELDS(self->descr)) {
+        n = PyArray_PyIntAsIntp(ind);
+        if (!error_converting(n)) {
+            return voidtype_item(self, (Py_ssize_t)n);
+        }
+        PyErr_Clear();
     }
 
-#if defined(NPY_PY3K)
-    if (PyUString_Check(ind)) {
-#else
-    if (PyBytes_Check(ind) || PyUnicode_Check(ind)) {
-#endif
-        args = Py_BuildValue("(O)", ind);
-        ret = gentype_generic_method((PyObject *)self, args, NULL, "__getitem__");
-        Py_DECREF(args);
-        return ret;
-    }
+    res = PyArray_FromScalar((PyObject*)self, NULL);
 
-    /* try to convert it to a number */
-    n = PyArray_PyIntAsIntp(ind);
-    if (error_converting(n)) {
-        goto fail;
+    /* ellipsis should return 0d array */
+    if(ind == Py_Ellipsis){
+        return res;
     }
-    return voidtype_item(self, (Py_ssize_t)n);
 
-fail:
-    PyErr_SetString(PyExc_IndexError, "invalid index");
-    return NULL;
+    /*
+     * other cases (field names, empty tuple) will return either
+     * scalar or non-0d array. Compute this using ndarray subscript.
+     */
+    ret = array_subscript((PyArrayObject *)res, ind);
+    Py_DECREF(res);
+    return PyArray_Return((PyArrayObject*)ret);
 }
 
 static int
diff --git a/numpy/core/tests/test_dtype.py b/numpy/core/tests/test_dtype.py
index 6f6654d42..9cefb2ad1 100644
--- a/numpy/core/tests/test_dtype.py
+++ b/numpy/core/tests/test_dtype.py
@@ -104,6 +104,15 @@ class TestBuiltin(object):
                          'formats':['i1', 'f4'],
                          'offsets':[0, 2]}, align=True)
 
+    def test_field_order_equality(self):
+        x = np.dtype({'names': ['A', 'B'], 
+                      'formats': ['i4', 'f4'], 
+                      'offsets': [0, 4]})
+        y = np.dtype({'names': ['B', 'A'], 
+                      'formats': ['f4', 'i4'], 
+                      'offsets': [4, 0]})
+        assert_equal(x == y, False)
+
 class TestRecord(object):
     def test_equivalent_record(self):
         """Test whether equivalent record dtypes hash the same."""
@@ -211,11 +220,12 @@ class TestRecord(object):
         dt = np.dtype({'names':['f0', 'f1', 'f2'], 'formats':['<u4', '<u2', '<u2'],
                         'offsets':[4, 0, 2]}, align=True)
         assert_equal(dt.itemsize, 8)
+        # field name should not matter: assignment is by position
         dt2 = np.dtype({'names':['f2', 'f0', 'f1'],
-                        'formats':['<u2', '<u4', '<u2'],
-                        'offsets':[2, 4, 0]}, align=True)
+                        'formats':['<u4', '<u2', '<u2'],
+                        'offsets':[4, 0, 2]}, align=True)
         vals = [(0, 1, 2), (3, -1, 4)]
-        vals2 = [(2, 0, 1), (4, 3, -1)]
+        vals2 = [(0, 1, 2), (3, -1, 4)]
         a = np.array(vals, dt)
         b = np.array(vals2, dt2)
         assert_equal(a.astype(dt2), b)
diff --git a/numpy/core/tests/test_indexing.py b/numpy/core/tests/test_indexing.py
index 43965d994..4c3bac529 100644
--- a/numpy/core/tests/test_indexing.py
+++ b/numpy/core/tests/test_indexing.py
@@ -106,6 +106,12 @@ class TestIndexing(object):
         a = np.array(0)
         assert_(isinstance(a[()], np.int_))
 
+    def test_void_scalar_empty_tuple(self):
+        s = np.zeros((), dtype='V4')
+        assert_equal(s[()].dtype, s.dtype)
+        assert_equal(s[()], s)
+        assert_equal(type(s[...]), np.ndarray)
+
     def test_same_kind_index_casting(self):
         # Indexes should be cast with same-kind and not safe, even if that
         # is somewhat unsafe. So test various different code paths.
diff --git a/numpy/core/tests/test_multiarray.py b/numpy/core/tests/test_multiarray.py
index 0ec05eed5..e19087540 100644
--- a/numpy/core/tests/test_multiarray.py
+++ b/numpy/core/tests/test_multiarray.py
@@ -952,16 +952,13 @@ class TestStructured(object):
         # Check that equality comparison works on structured arrays if
         # they are 'equiv'-castable
         a = np.array([(5, 42), (10, 1)], dtype=[('a', '>i4'), ('b', '<f8')])
-        b = np.array([(42, 5), (1, 10)], dtype=[('b', '>f8'), ('a', '<i4')])
+        b = np.array([(5, 42), (10, 1)], dtype=[('a', '<i4'), ('b', '>f8')])
         assert_(np.can_cast(a.dtype, b.dtype, casting='equiv'))
         assert_equal(a == b, [True, True])
 
-        # Check that 'equiv' casting can reorder fields and change byte
-        # order
-        # New in 1.12: This behavior changes in 1.13, test for dep warning
+        # Check that 'equiv' casting can change byte order
         assert_(np.can_cast(a.dtype, b.dtype, casting='equiv'))
-        with assert_warns(FutureWarning):
-            c = a.astype(b.dtype, casting='equiv')
+        c = a.astype(b.dtype, casting='equiv')
         assert_equal(a == c, [True, True])
 
         # Check that 'safe' casting can change byte order and up-cast
@@ -1096,6 +1093,54 @@ class TestStructured(object):
         b = a[0]
         assert_(b.base is a)
 
+    def test_assignment(self):
+        def testassign(arr, v):
+            c = arr.copy()
+            c[0] = v  # assign using setitem
+            c[1:] = v # assign using "dtype_transfer" code paths
+            return c
+
+        dt = np.dtype([('foo', 'i8'), ('bar', 'i8')])
+        arr = np.ones(2, dt)
+        v1 = np.array([(2,3)], dtype=[('foo', 'i8'), ('bar', 'i8')])
+        v2 = np.array([(2,3)], dtype=[('bar', 'i8'), ('foo', 'i8')])
+        v3 = np.array([(2,3)], dtype=[('bar', 'i8'), ('baz', 'i8')])
+        v4 = np.array([(2,)],  dtype=[('bar', 'i8')])
+        v5 = np.array([(2,3)], dtype=[('foo', 'f8'), ('bar', 'f8')])
+        w = arr.view({'names': ['bar'], 'formats': ['i8'], 'offsets': [8]})
+
+        ans = np.array([(2,3),(2,3)], dtype=dt)
+        assert_equal(testassign(arr, v1), ans)
+        assert_equal(testassign(arr, v2), ans)
+        assert_equal(testassign(arr, v3), ans)
+        assert_raises(ValueError, lambda: testassign(arr, v4))
+        assert_equal(testassign(arr, v5), ans)
+        w[:] = 4
+        assert_equal(arr, np.array([(1,4),(1,4)], dtype=dt))
+
+        # test field-reordering, assignment by position, and self-assignment
+        a = np.array([(1,2,3)],
+                     dtype=[('foo', 'i8'), ('bar', 'i8'), ('baz', 'f4')])
+        a[['foo', 'bar']] = a[['bar', 'foo']]
+        assert_equal(a[0].item(), (2,1,3))
+
+        # test that this works even for 'simple_unaligned' structs
+        # (ie, that PyArray_EquivTypes cares about field order too)
+        a = np.array([(1,2)], dtype=[('a', 'i4'), ('b', 'i4')])
+        a[['a', 'b']] = a[['b', 'a']]
+        assert_equal(a[0].item(), (2,1))
+
+    def test_structuredscalar_indexing(self):
+        # test gh-7262
+        x = np.empty(shape=1, dtype="(2)3S,(2)3U")
+        assert_equal(x[["f0","f1"]][0], x[0][["f0","f1"]])
+        assert_equal(x[0], x[0][()])
+
+    def test_multiindex_titles(self):
+        a = np.zeros(4, dtype=[(('a', 'b'), 'i'), ('c', 'i'), ('d', 'i')])
+        assert_raises(KeyError, lambda : a[['a','c']])
+        assert_raises(KeyError, lambda : a[['b','b']])
+        a[['b','c']]  # no exception
 
 class TestBool(object):
     def test_test_interning(self):
@@ -4498,23 +4543,11 @@ class TestRecord(object):
             # multiple subfields
             fn2 = func('f2')
             b[fn2] = 3
-            with suppress_warnings() as sup:
-                sup.filter(FutureWarning,
-                           "Assignment between structured arrays.*")
-                sup.filter(FutureWarning,
-                           "Numpy has detected that you .*")
-
-                assert_equal(b[['f1', 'f2']][0].tolist(), (2, 3))
-                assert_equal(b[['f2', 'f1']][0].tolist(), (3, 2))
-                assert_equal(b[['f1', 'f3']][0].tolist(), (2, (1,)))
-                # view of subfield view/copy
-                assert_equal(b[['f1', 'f2']][0].view(('i4', 2)).tolist(),
-                             (2, 3))
-                assert_equal(b[['f2', 'f1']][0].view(('i4', 2)).tolist(),
-                             (3, 2))
-                view_dtype = [('f1', 'i4'), ('f3', [('', 'i4')])]
-                assert_equal(b[['f1', 'f3']][0].view(view_dtype).tolist(),
-                             (2, (1,)))
+
+            assert_equal(b[['f1', 'f2']][0].tolist(), (2, 3))
+            assert_equal(b[['f2', 'f1']][0].tolist(), (3, 2))
+            assert_equal(b[['f1', 'f3']][0].tolist(), (2, (1,)))
+
         # non-ascii unicode field indexing is well behaved
         if not is_py3:
             raise SkipTest('non ascii unicode field indexing skipped; '
@@ -4523,54 +4556,6 @@ class TestRecord(object):
             assert_raises(ValueError, a.__setitem__, u'\u03e0', 1)
             assert_raises(ValueError, a.__getitem__, u'\u03e0')
 
-    def test_field_names_deprecation(self):
-
-        def collect_warnings(f, *args, **kwargs):
-            with warnings.catch_warnings(record=True) as log:
-                warnings.simplefilter("always")
-                f(*args, **kwargs)
-            return [w.category for w in log]
-
-        a = np.zeros((1,), dtype=[('f1', 'i4'),
-                                  ('f2', 'i4'),
-                                  ('f3', [('sf1', 'i4')])])
-        a['f1'][0] = 1
-        a['f2'][0] = 2
-        a['f3'][0] = (3,)
-        b = np.zeros((1,), dtype=[('f1', 'i4'),
-                                  ('f2', 'i4'),
-                                  ('f3', [('sf1', 'i4')])])
-        b['f1'][0] = 1
-        b['f2'][0] = 2
-        b['f3'][0] = (3,)
-
-        # All the different functions raise a warning, but not an error
-        assert_equal(collect_warnings(a[['f1', 'f2']].__setitem__, 0, (10, 20)),
-                     [FutureWarning])
-        # For <=1.12 a is not modified, but it will be in 1.13
-        assert_equal(a, b)
-
-        # Views also warn
-        subset = a[['f1', 'f2']]
-        subset_view = subset.view()
-        assert_equal(collect_warnings(subset_view['f1'].__setitem__, 0, 10),
-                     [FutureWarning])
-        # But the write goes through:
-        assert_equal(subset['f1'][0], 10)
-        # Only one warning per multiple field indexing, though (even if there
-        # are multiple views involved):
-        assert_equal(collect_warnings(subset['f1'].__setitem__, 0, 10), [])
-
-        # make sure views of a multi-field index warn too
-        c = np.zeros(3, dtype='i8,i8,i8')
-        assert_equal(collect_warnings(c[['f0', 'f2']].view, 'i8,i8'),
-                     [FutureWarning])
-
-        # make sure assignment using a different dtype warns
-        a = np.zeros(2, dtype=[('a', 'i4'), ('b', 'i4')])
-        b = np.zeros(2, dtype=[('b', 'i4'), ('a', 'i4')])
-        assert_equal(collect_warnings(a.__setitem__, (), b), [FutureWarning])
-
     def test_record_hash(self):
         a = np.array([(1, 2), (1, 2)], dtype='i1,i2')
         a.flags.writeable = False
diff --git a/numpy/core/tests/test_nditer.py b/numpy/core/tests/test_nditer.py
index 885dcb56f..59e11f22e 100644
--- a/numpy/core/tests/test_nditer.py
+++ b/numpy/core/tests/test_nditer.py
@@ -1816,100 +1816,45 @@ def test_iter_buffered_cast_structured_type():
     if HAS_REFCOUNT:
         assert_equal(sys.getrefcount(a[0]), rc)
 
-    # struct type -> simple (takes the first value)
-    sdt = [('a', 'f4'), ('b', 'i8'), ('d', 'O')]
-    a = np.array([(5.5, 7, 'test'), (8, 10, 11)], dtype=sdt)
+    # single-field struct type -> simple
+    sdt = [('a', 'f4')]
+    a = np.array([(5.5,), (8,)], dtype=sdt)
     i = nditer(a, ['buffered', 'refs_ok'], ['readonly'],
                     casting='unsafe',
                     op_dtypes='i4')
     assert_equal([x_[()] for x_ in i], [5, 8])
 
+    # make sure multi-field struct type -> simple doesn't work
+    sdt = [('a', 'f4'), ('b', 'i8'), ('d', 'O')]
+    a = np.array([(5.5, 7, 'test'), (8, 10, 11)], dtype=sdt)
+    assert_raises(ValueError, lambda: (
+        nditer(a, ['buffered', 'refs_ok'], ['readonly'],
+               casting='unsafe',
+               op_dtypes='i4')))
+
     # struct type -> struct type (field-wise copy)
     sdt1 = [('a', 'f4'), ('b', 'i8'), ('d', 'O')]
     sdt2 = [('d', 'u2'), ('a', 'O'), ('b', 'f8')]
     a = np.array([(1, 2, 3), (4, 5, 6)], dtype=sdt1)
-    # New in 1.12: This behavior changes in 1.13, test for dep warning
-    with assert_warns(FutureWarning):
-        i = nditer(a, ['buffered', 'refs_ok'], ['readonly'],
-                        casting='unsafe',
-                        op_dtypes=sdt2)
+    i = nditer(a, ['buffered', 'refs_ok'], ['readonly'],
+                    casting='unsafe',
+                    op_dtypes=sdt2)
     assert_equal(i[0].dtype, np.dtype(sdt2))
     assert_equal([np.array(x_) for x_ in i],
-                 [np.array((3, 1, 2), dtype=sdt2),
-                  np.array((6, 4, 5), dtype=sdt2)])
+                 [np.array((1, 2, 3), dtype=sdt2),
+                  np.array((4, 5, 6), dtype=sdt2)])
 
-    # struct type -> struct type (field gets discarded)
+    # make sure struct type -> struct type with different
+    # number of fields fails
     sdt1 = [('a', 'f4'), ('b', 'i8'), ('d', 'O')]
     sdt2 = [('b', 'O'), ('a', 'f8')]
     a = np.array([(1, 2, 3), (4, 5, 6)], dtype=sdt1)
-    # New in 1.12: This behavior changes in 1.13, test for dep warning
-    with assert_warns(FutureWarning):
-        i = nditer(a, ['buffered', 'refs_ok'], ['readwrite'],
-                        casting='unsafe',
-                        op_dtypes=sdt2)
-    assert_equal(i[0].dtype, np.dtype(sdt2))
-    vals = []
-    for x in i:
-        vals.append(np.array(x))
-        x['a'] = x['b']+3
-    assert_equal(vals, [np.array((2, 1), dtype=sdt2),
-                     np.array((5, 4), dtype=sdt2)])
-    assert_equal(a, np.array([(5, 2, None), (8, 5, None)], dtype=sdt1))
-
-    # struct type -> struct type (structured field gets discarded)
-    sdt1 = [('a', 'f4'), ('b', 'i8'), ('d', [('a', 'i2'), ('b', 'i4')])]
-    sdt2 = [('b', 'O'), ('a', 'f8')]
-    a = np.array([(1, 2, (0, 9)), (4, 5, (20, 21))], dtype=sdt1)
-    # New in 1.12: This behavior changes in 1.13, test for dep warning
-    with assert_warns(FutureWarning):
-        i = nditer(a, ['buffered', 'refs_ok'], ['readwrite'],
-                        casting='unsafe',
-                        op_dtypes=sdt2)
-    assert_equal(i[0].dtype, np.dtype(sdt2))
-    vals = []
-    for x in i:
-        vals.append(np.array(x))
-        x['a'] = x['b']+3
-    assert_equal(vals, [np.array((2, 1), dtype=sdt2),
-                     np.array((5, 4), dtype=sdt2)])
-    assert_equal(a, np.array([(5, 2, (0, 0)), (8, 5, (0, 0))], dtype=sdt1))
-
-    # struct type -> struct type (structured field w/ ref gets discarded)
-    sdt1 = [('a', 'f4'), ('b', 'i8'), ('d', [('a', 'i2'), ('b', 'O')])]
-    sdt2 = [('b', 'O'), ('a', 'f8')]
-    a = np.array([(1, 2, (0, 9)), (4, 5, (20, 21))], dtype=sdt1)
-    # New in 1.12: This behavior changes in 1.13, test for dep warning
-    with assert_warns(FutureWarning):
-        i = nditer(a, ['buffered', 'refs_ok'], ['readwrite'],
-                        casting='unsafe',
-                        op_dtypes=sdt2)
-    assert_equal(i[0].dtype, np.dtype(sdt2))
-    vals = []
-    for x in i:
-        vals.append(np.array(x))
-        x['a'] = x['b']+3
-    assert_equal(vals, [np.array((2, 1), dtype=sdt2),
-                     np.array((5, 4), dtype=sdt2)])
-    assert_equal(a, np.array([(5, 2, (0, None)), (8, 5, (0, None))], dtype=sdt1))
-
-    # struct type -> struct type back (structured field w/ ref gets discarded)
-    sdt1 = [('b', 'O'), ('a', 'f8')]
-    sdt2 = [('a', 'f4'), ('b', 'i8'), ('d', [('a', 'i2'), ('b', 'O')])]
-    a = np.array([(1, 2), (4, 5)], dtype=sdt1)
-    # New in 1.12: This behavior changes in 1.13, test for dep warning
-    with assert_warns(FutureWarning):
-        i = nditer(a, ['buffered', 'refs_ok'], ['readwrite'],
-                        casting='unsafe',
-                        op_dtypes=sdt2)
-    assert_equal(i[0].dtype, np.dtype(sdt2))
-    vals = []
-    for x in i:
-        vals.append(np.array(x))
-        assert_equal(x['d'], np.array((0, None), dtype=[('a', 'i2'), ('b', 'O')]))
-        x['a'] = x['b']+3
-    assert_equal(vals, [np.array((2, 1, (0, None)), dtype=sdt2),
-                     np.array((5, 4, (0, None)), dtype=sdt2)])
-    assert_equal(a, np.array([(1, 4), (4, 7)], dtype=sdt1))
+
+    assert_raises(ValueError, lambda : (
+        nditer(a, ['buffered', 'refs_ok'], ['readwrite'],
+               casting='unsafe',
+               op_dtypes=sdt2)))
+
 
 def test_iter_buffered_cast_subarray():
     # Tests buffering of subarrays
diff --git a/numpy/core/tests/test_records.py b/numpy/core/tests/test_records.py
index d7714132b..27d35fa65 100644
--- a/numpy/core/tests/test_records.py
+++ b/numpy/core/tests/test_records.py
@@ -153,11 +153,6 @@ class TestFromrecords(object):
         assert_equal(r['c'].dtype.type, np.record)
         assert_equal(type(r['c']), np.recarray)
 
-        # suppress deprecation warning in 1.12 (remove in 1.13)
-        with assert_warns(FutureWarning):
-            assert_equal(r[['a', 'b']].dtype.type, np.record)
-            assert_equal(type(r[['a', 'b']]), np.recarray)
-
         #and that it preserves subclasses (gh-6949)
         class C(np.recarray):
             pass
@@ -334,15 +329,6 @@ class TestRecord(object):
         with assert_raises(ValueError):
             r.setfield([2,3], *r.dtype.fields['f'])
 
-    def test_out_of_order_fields(self):
-        """Ticket #1431."""
-        # this test will be invalid in 1.13
-        # suppress deprecation warning in 1.12 (remove in 1.13)
-        with assert_warns(FutureWarning):
-            x = self.data[['col1', 'col2']]
-            y = self.data[['col2', 'col1']]
-        assert_equal(x[0][0], y[0][1])
-
     def test_pickle_1(self):
         # Issue #1529
         a = np.array([(1, [])], dtype=[('a', np.int32), ('b', np.int32, 0)])
@@ -371,8 +357,7 @@ class TestRecord(object):
 
         # https://github.com/numpy/numpy/issues/3256
         ra = np.recarray((2,), dtype=[('x', object), ('y', float), ('z', int)])
-        with assert_warns(FutureWarning):
-            ra[['x','y']]  # TypeError?
+        ra[['x','y']]  # TypeError?
 
     def test_record_scalar_setitem(self):
         # https://github.com/numpy/numpy/issues/3561
diff --git a/numpy/lib/tests/test_io.py b/numpy/lib/tests/test_io.py
index f2fd37230..e6b1eac7a 100644
--- a/numpy/lib/tests/test_io.py
+++ b/numpy/lib/tests/test_io.py
@@ -1178,12 +1178,12 @@ M   33  21.99
         conv = {0: int, 1: int, 2: int, 3: lambda r: dmap[r.decode()]}
         test = np.recfromcsv(TextIO(dstr,), dtype=dtyp, delimiter=',',
                              names=None, converters=conv)
-        control = np.rec.array([[1,5,-1,0], [2,8,-1,1], [3,3,-2,3]], dtype=dtyp)
+        control = np.rec.array([(1,5,-1,0), (2,8,-1,1), (3,3,-2,3)], dtype=dtyp)
         assert_equal(test, control)
         dtyp = [('e1','i4'),('e2','i4'),('n', 'i1')]
         test = np.recfromcsv(TextIO(dstr,), dtype=dtyp, delimiter=',',
                              usecols=(0,1,3), names=None, converters=conv)
-        control = np.rec.array([[1,5,0], [2,8,1], [3,3,3]], dtype=dtyp)
+        control = np.rec.array([(1,5,0), (2,8,1), (3,3,3)], dtype=dtyp)
         assert_equal(test, control)
 
     def test_dtype_with_object(self):
diff --git a/numpy/ma/core.py b/numpy/ma/core.py
index 8efe45eed..78e7b27a7 100644
--- a/numpy/ma/core.py
+++ b/numpy/ma/core.py
@@ -1613,6 +1613,11 @@ def make_mask(m, copy=False, shrink=True, dtype=MaskType):
 
     # Make sure the input dtype is valid.
     dtype = make_mask_descr(dtype)
+    
+    # legacy boolean special case: "existence of fields implies true"
+    if isinstance(m, ndarray) and m.dtype.fields and dtype == np.bool_:
+        return np.ones(m.shape, dtype=dtype)
+
     # Fill the mask in case there are missing data; turn it into an ndarray.
     result = np.array(filled(m, True), copy=copy, dtype=dtype, subok=True)
     # Bas les masques !
diff --git a/numpy/ma/tests/test_core.py b/numpy/ma/tests/test_core.py
index 5da19f9ca..fa9f97233 100644
--- a/numpy/ma/tests/test_core.py
+++ b/numpy/ma/tests/test_core.py
@@ -1760,15 +1760,11 @@ class TestFillingValues(object):
         assert_equal(fval.item(), [-999, -12345678.9, b"???"])
 
         #.....Using a flexible type w/ a different type shouldn't matter
-        # BEHAVIOR in 1.5 and earlier: match structured types by position
-        #fill_val = np.array((-999, -12345678.9, "???"),
-        #                    dtype=[("A", int), ("B", float), ("C", "|S3")])
-        # BEHAVIOR in 1.6 and later: match structured types by name
-        fill_val = np.array(("???", -999, -12345678.9),
-                            dtype=[("c", "|S3"), ("a", int), ("b", float), ])
-        # suppress deprecation warning in 1.12 (remove in 1.13)
-        with assert_warns(FutureWarning):
-            fval = _check_fill_value(fill_val, ndtype)
+        # BEHAVIOR in 1.5 and earlier, and 1.13 and later: match structured
+        # types by position
+        fill_val = np.array((-999, -12345678.9, "???"),
+                            dtype=[("A", int), ("B", float), ("C", "|S3")])
+        fval = _check_fill_value(fill_val, ndtype)
         assert_(isinstance(fval, ndarray))
         assert_equal(fval.item(), [-999, -12345678.9, b"???"])