DEP: Stricter arg checking for array ordering

The bug traces to the PyArray_OrderConverter
method in conversion_utils.c, where no errors
are thrown if the ORDER parameter passed in
is not of the string data-type or has a string
value of length greater than one. This commit
causes a DeprecationWarning to be raised, which
will later be turned into a TypeError or another
type of error in a future release.

Closes gh-6598.

5 files changed, 73 insertions, 14 deletions

diff --git a/numpy/add_newdocs.py b/numpy/add_newdocs.py
index c14036089..01ef24a5b 100644
--- a/numpy/add_newdocs.py
+++ b/numpy/add_newdocs.py
@@ -3567,10 +3567,14 @@ add_newdoc('numpy.core.multiarray', 'ndarray', ('flatten',
 
     Parameters
     ----------
-    order : {'C', 'F', 'A'}, optional
-        Whether to flatten in row-major (C-style) or
-        column-major (Fortran-style) order or preserve the
-        C/Fortran ordering from `a`.  The default is 'C'.
+    order : {'C', 'F', 'A', 'K'}, optional
+        'C' means to flatten in row-major (C-style) order.
+        'F' means to flatten in column-major (Fortran-
+        style) order. 'A' means to flatten in column-major
+        order if `a` is Fortran *contiguous* in memory,
+        row-major order otherwise. 'K' means to flatten
+        `a` in the order the elements occur in memory.
+        The default is 'C'.
 
     Returns
     -------
diff --git a/numpy/core/src/multiarray/conversion_utils.c b/numpy/core/src/multiarray/conversion_utils.c
index 88064c1d6..d7a617875 100644
--- a/numpy/core/src/multiarray/conversion_utils.c
+++ b/numpy/core/src/multiarray/conversion_utils.c
@@ -540,6 +540,15 @@ PyArray_OrderConverter(PyObject *object, NPY_ORDER *val)
         return ret;
     }
     else if (!PyBytes_Check(object) || PyBytes_GET_SIZE(object) < 1) {
+        /* 2015-12-14, 1.11 */
+        int ret = DEPRECATE("Non-string object detected for "
+                            "the array ordering. Please pass "
+                            "in 'C', 'F', 'A', or 'K' instead");
+
+        if (ret < 0) {
+            return -1;
+        }
+
         if (PyObject_IsTrue(object)) {
             *val = NPY_FORTRANORDER;
         }
@@ -553,6 +562,18 @@ PyArray_OrderConverter(PyObject *object, NPY_ORDER *val)
     }
     else {
         str = PyBytes_AS_STRING(object);
+        if (strlen(str) != 1) {
+            /* 2015-12-14, 1.11 */
+            int ret = DEPRECATE("Non length-one string passed "
+                                "in for the array ordering. "
+                                "Please pass in 'C', 'F', 'A', "
+                                "or 'K' instead");
+
+            if (ret < 0) {
+                return -1;
+            }
+        }
+
         if (str[0] == 'C' || str[0] == 'c') {
             *val = NPY_CORDER;
         }
diff --git a/numpy/core/tests/test_deprecations.py b/numpy/core/tests/test_deprecations.py
index f6dc3d842..65ddc1e77 100644
--- a/numpy/core/tests/test_deprecations.py
+++ b/numpy/core/tests/test_deprecations.py
@@ -400,6 +400,36 @@ class TestNonCContiguousViewDeprecation(_DeprecationTestCase):
         self.assert_deprecated(np.ones((2,2)).T.view, args=(np.int8,))
 
 
+class TestInvalidOrderParameterInputForFlattenArrayDeprecation(_DeprecationTestCase):
+    """Invalid arguments to the ORDER parameter in array.flatten() should not be
+    allowed and should raise an error.  However, in the interests of not breaking
+    code that may inadvertently pass invalid arguments to this parameter, a
+    DeprecationWarning will be issued instead for the time being to give developers
+    time to refactor relevant code.
+    """
+
+    def test_flatten_array_non_string_arg(self):
+        x = np.zeros((3, 5))
+        self.message = ("Non-string object detected for "
+                        "the array ordering. Please pass "
+                        "in 'C', 'F', 'A', or 'K' instead")
+        self.assert_deprecated(x.flatten, args=(np.pi,))
+
+    def test_flatten_array_invalid_string_arg(self):
+        # Tests that a DeprecationWarning is raised
+        # when a string of length greater than one
+        # starting with "C", "F", "A", or "K" (case-
+        # and unicode-insensitive) is passed in for
+        # the ORDER parameter. Otherwise, a TypeError
+        # will be raised!
+
+        x = np.zeros((3, 5))
+        self.message = ("Non length-one string passed "
+                        "in for the array ordering. Please "
+                        "pass in 'C', 'F', 'A', or 'K' instead")
+        self.assert_deprecated(x.flatten, args=("FACK",))
+
+
 class TestTestDeprecated(object):
     def test_assert_deprecated(self):
         test_case_instance = _DeprecationTestCase()
diff --git a/numpy/lib/function_base.py b/numpy/lib/function_base.py
index 3298789ee..541ad079c 100644
--- a/numpy/lib/function_base.py
+++ b/numpy/lib/function_base.py
@@ -3966,6 +3966,7 @@ def delete(arr, obj, axis=None):
 
     arr = asarray(arr)
     ndim = arr.ndim
+    arrorder = 'F' if arr.flags.fnc else 'C'
     if axis is None:
         if ndim != 1:
             arr = arr.ravel()
@@ -4003,7 +4004,7 @@ def delete(arr, obj, axis=None):
             stop = xr[0] + 1
 
         newshape[axis] -= numtodel
-        new = empty(newshape, arr.dtype, arr.flags.fnc)
+        new = empty(newshape, arr.dtype, arrorder)
         # copy initial chunk
         if start == 0:
             pass
@@ -4054,7 +4055,7 @@ def delete(arr, obj, axis=None):
         if (obj < 0):
             obj += N
         newshape[axis] -= 1
-        new = empty(newshape, arr.dtype, arr.flags.fnc)
+        new = empty(newshape, arr.dtype, arrorder)
         slobj[axis] = slice(None, obj)
         new[slobj] = arr[slobj]
         slobj[axis] = slice(obj, None)
@@ -4197,6 +4198,7 @@ def insert(arr, obj, values, axis=None):
 
     arr = asarray(arr)
     ndim = arr.ndim
+    arrorder = 'F' if arr.flags.fnc else 'C'
     if axis is None:
         if ndim != 1:
             arr = arr.ravel()
@@ -4265,7 +4267,7 @@ def insert(arr, obj, values, axis=None):
             values = np.rollaxis(values, 0, (axis % values.ndim) + 1)
         numnew = values.shape[axis]
         newshape[axis] += numnew
-        new = empty(newshape, arr.dtype, arr.flags.fnc)
+        new = empty(newshape, arr.dtype, arrorder)
         slobj[axis] = slice(None, index)
         new[slobj] = arr[slobj]
         slobj[axis] = slice(index, index+numnew)
@@ -4298,7 +4300,7 @@ def insert(arr, obj, values, axis=None):
     old_mask = ones(newshape[axis], dtype=bool)
     old_mask[indices] = False
 
-    new = empty(newshape, arr.dtype, arr.flags.fnc)
+    new = empty(newshape, arr.dtype, arrorder)
     slobj2 = [slice(None)]*ndim
     slobj[axis] = indices
     slobj2[axis] = old_mask
diff --git a/numpy/matrixlib/defmatrix.py b/numpy/matrixlib/defmatrix.py
index ffd4578ba..170db87c8 100644
--- a/numpy/matrixlib/defmatrix.py
+++ b/numpy/matrixlib/defmatrix.py
@@ -277,9 +277,9 @@ class matrix(N.ndarray):
         elif ndim == 1:
             shape = (1, shape[0])
 
-        order = False
+        order = 'C'
         if (ndim == 2) and arr.flags.fortran:
-            order = True
+            order = 'F'
 
         if not (order or arr.flags.contiguous):
             arr = arr.copy()
@@ -519,10 +519,12 @@ class matrix(N.ndarray):
 
         Parameters
         ----------
-        order : {'C', 'F', 'A'}, optional
-            Whether to flatten in C (row-major), Fortran (column-major) order,
-            or preserve the C/Fortran ordering from `m`.
-            The default is 'C'.
+        order : {'C', 'F', 'A', 'K'}, optional
+            'C' means to flatten in row-major (C-style) order. 'F' means to
+            flatten in column-major (Fortran-style) order. 'A' means to
+            flatten in column-major order if `m` is Fortran *contiguous* in
+            memory, row-major order otherwise. 'K' means to flatten `m` in
+            the order the elements occur in memory. The default is 'C'.
 
         Returns
         -------