Fix view scalar bug segfault (#1603)

* fix view scalar bug

* fix view scalar bug

* one more fix

Author: awni

mlx/backend/common/primitives.cpp

@@ -606,7 +606,7 @@ void View::eval_cpu(const std::vector<array>& inputs, array& out) {
   if (ibytes == obytes || obytes < ibytes && in.strides().back() == 1 ||
       in.flags().row_contiguous) {
     auto strides = in.strides();
-    for (int i = 0; i < strides.size() - 1; ++i) {
+    for (int i = 0; i < static_cast<int>(strides.size()) - 1; ++i) {
       strides[i] *= ibytes;
       strides[i] /= obytes;
     }

mlx/backend/metal/primitives.cpp

@@ -417,7 +417,7 @@ void View::eval_gpu(const std::vector<array>& inputs, array& out) {
   if (ibytes == obytes || obytes < ibytes && in.strides().back() == 1 ||
       in.flags().row_contiguous) {
     auto strides = in.strides();
-    for (int i = 0; i < strides.size() - 1; ++i) {
+    for (int i = 0; i < static_cast<int>(strides.size()) - 1; ++i) {
       strides[i] *= ibytes;
       strides[i] /= obytes;
     }

mlx/ops.cpp

@@ -4587,7 +4587,7 @@ array view(const array& a, const Dtype& dtype, StreamOrDevice s /* = {} */) {
             " axis must be a multiple of the requested type size.");
       }
       out_shape.back() /= (obytes / ibytes);
-    } else {
+    } else if (ibytes > obytes) {
       // Type size ratios are always integers
       out_shape.back() *= (ibytes / obytes);
     }

python/tests/test_ops.py

@@ -2532,6 +2532,10 @@ def test_conjugate(self):
         self.assertTrue(np.array_equal(np.array(out_mlx), out_np))
 
     def test_view(self):
+        # Check scalar
+        out = mx.array(1, mx.int8).view(mx.uint8).item()
+        self.assertEqual(out, 1)
+
         a = mx.random.randint(shape=(4, 2, 4), low=-100, high=100)
         a_np = np.array(a)