Fix ravel for strides 0

cupy/_core/_routines_manipulation.pxd

@@ -29,7 +29,8 @@ cpdef ndarray _move_single_axis(ndarray a, Py_ssize_t source,
                                 Py_ssize_t destination)
 cpdef ndarray rollaxis(ndarray a, Py_ssize_t axis, Py_ssize_t start=*)
 cpdef ndarray broadcast_to(ndarray array, shape)
-cpdef ndarray _reshape(ndarray self, const shape_t &shape_spec)
+cpdef ndarray _reshape(ndarray self, const shape_t &shape_spec,
+                       bint enforce_copy=*)
 cpdef ndarray _T(ndarray self)
 cpdef ndarray _transpose(ndarray self, const vector.vector[Py_ssize_t] &axes)
 cpdef ndarray _concatenate(

cupy/_core/_routines_manipulation.pyx

@@ -133,15 +133,16 @@ cdef ndarray _ndarray_ravel(ndarray self, order):
     shape.push_back(self.size)
 
     order_char = internal._normalize_order(order, True)
+    enforce_copy = not self._f_contiguous and not self._c_contiguous
     if order_char == b'A':
         if self._f_contiguous and not self._c_contiguous:
             order_char = b'F'
         else:
             order_char = b'C'
     if order_char == b'C':
-        return _reshape(self, shape)
+        return _reshape(self, shape, enforce_copy)
     elif order_char == b'F':
-        return _reshape(_T(self), shape)
+        return _reshape(_T(self), shape, enforce_copy)
     elif order_char == b'K':
         raise NotImplementedError(
             'ravel with order=\'K\' not yet implemented.')
@@ -294,17 +295,20 @@ cpdef ndarray rollaxis(ndarray a, Py_ssize_t axis, Py_ssize_t start=0):
     return _transpose(a, axes)
 
 
-cpdef ndarray _reshape(ndarray self, const shape_t &shape_spec):
+cpdef ndarray _reshape(
+        ndarray self, const shape_t &shape_spec, bint enforce_copy=0):
     cdef shape_t shape
     cdef strides_t strides
     cdef ndarray newarray
     shape = internal.infer_unknown_dimension(shape_spec, self.size)
-    if internal.vector_equal(shape, self._shape):
-        return self.view()
+    if not enforce_copy:
+        if internal.vector_equal(shape, self._shape):
+            return self.view()
+
+        _get_strides_for_nocopy_reshape(self, shape, strides)
+        if strides.size() == shape.size():
+            return self._view(shape, strides, False, True)
 
-    _get_strides_for_nocopy_reshape(self, shape, strides)
-    if strides.size() == shape.size():
-        return self._view(shape, strides, False, True)
     newarray = self.copy()
     _get_strides_for_nocopy_reshape(newarray, shape, strides)
 

tests/cupy_tests/manipulation_tests/test_shape.py

@@ -176,6 +176,20 @@ def test_external_ravel(self, xp):
         a = a.transpose(2, 0, 1)
         return xp.ravel(a)
 
+    @testing.for_orders('CFA')
+    @testing.numpy_cupy_array_equal()
+    def test_ravel_non_contiguous(self, xp, order):
+        a = xp.array([1])
+        b = xp.broadcast_to(a, (10,))
+        assert not b.flags.c_contiguous and not b.flags.f_contiguous
+        b = b.ravel(order)
+        if order == 'C':
+            assert  b.flags.c_contiguous
+        else:
+            assert  b.flags.f_contiguous
+        return b
+
+
 
 @testing.parameterize(*testing.product({
     'order_init': ['C', 'F'],