BUG: fix array too big error for wide dtypes.

The error was not being raised when arr.size * arr.dtype.itemsize
was too large, but only when arr.size was too large alone.

Closes gh-7451

2 files changed, 21 insertions, 4 deletions

diff --git a/numpy/core/src/multiarray/ctors.c b/numpy/core/src/multiarray/ctors.c
index 79c2b16b1..5671f2251 100644
--- a/numpy/core/src/multiarray/ctors.c
+++ b/numpy/core/src/multiarray/ctors.c
@@ -929,8 +929,7 @@ PyArray_NewFromDescr_int(PyTypeObject *subtype, PyArray_Descr *descr, int nd,
         return NULL;
     }
 
-    /* Check dimensions */
-    size = 1;
+    /* Check datatype element size */
     sd = (size_t) descr->elsize;
     if (sd == 0) {
         if (!PyDataType_ISSTRING(descr)) {
@@ -950,6 +949,8 @@ PyArray_NewFromDescr_int(PyTypeObject *subtype, PyArray_Descr *descr, int nd,
         }
     }
 
+    /* Check dimensions */
+    size = sd;
     for (i = 0; i < nd; i++) {
         npy_intp dim = dims[i];
 
@@ -976,7 +977,8 @@ PyArray_NewFromDescr_int(PyTypeObject *subtype, PyArray_Descr *descr, int nd,
          */
         if (npy_mul_with_overflow_intp(&size, size, dim)) {
             PyErr_SetString(PyExc_ValueError,
-                            "array is too big.");
+                "array is too big; `arr.size * arr.dtype.itemsize` "
+                "is larger than the maximum possible size.");
             Py_DECREF(descr);
             return NULL;
         }
@@ -1025,7 +1027,7 @@ PyArray_NewFromDescr_int(PyTypeObject *subtype, PyArray_Descr *descr, int nd,
              * the memory, but be careful with this...
              */
             memcpy(fa->strides, strides, sizeof(npy_intp)*nd);
-            sd *= size;
+            sd = size;
         }
     }
     else {
diff --git a/numpy/core/tests/test_multiarray.py b/numpy/core/tests/test_multiarray.py
index 14a902b9c..94731f20c 100644
--- a/numpy/core/tests/test_multiarray.py
+++ b/numpy/core/tests/test_multiarray.py
@@ -730,6 +730,21 @@ class TestCreation(TestCase):
         d = A([1,2,3])
         assert_equal(len(np.array(d)), 3)
 
+    def test_array_too_big(self):
+        # Test that array creation succeeds for arrays addressable by intp
+        # on the byte level and fails for too large arrays.
+        buf = np.zeros(100)
+
+        max_bytes = np.iinfo(np.intp).max
+        for dtype in ["intp", "S20", "b"]:
+            dtype = np.dtype(dtype)
+            itemsize = dtype.itemsize
+
+            np.ndarray(buffer=buf, strides=(0,),
+                       shape=(max_bytes//itemsize,), dtype=dtype)
+            assert_raises(ValueError, np.ndarray, buffer=buf, strides=(0,),
+                          shape=(max_bytes//itemsize + 1,), dtype=dtype)
+
 
 class TestStructured(TestCase):
     def test_subarray_field_access(self):