Add failing tests for #46 (#165)

These passed before 02cd324.

tests/ui/lang/issue-46.rs

@@ -0,0 +1,15 @@
+// build-fail
+
+use spirv_std::spirv;
+
+#[derive(Default)]
+struct Foo {
+    bar: bool,
+    baz: [[u32; 2]; 1],
+}
+
+#[spirv(fragment)]
+pub fn main() {
+    let x = [[1; 2]; 1];
+    let y = [Foo::default(); 1];
+}

tests/ui/lang/issue-46.stderr

@@ -0,0 +1,40 @@
+error: cannot cast between pointer types
+       from `*i32`
+         to `*[i32; 2]`
+  --> $DIR/issue-46.rs:13:13
+   |
+13 |     let x = [[1; 2]; 1];
+   |             ^^^^^^^^^^^
+   |
+note: used from within `issue_46::main`
+  --> $DIR/issue-46.rs:13:13
+   |
+13 |     let x = [[1; 2]; 1];
+   |             ^^^^^^^^^^^
+note: called by `main`
+  --> $DIR/issue-46.rs:12:8
+   |
+12 | pub fn main() {
+   |        ^^^^
+
+error: cannot cast between pointer types
+       from `*[[u32; 2]; 1]`
+         to `*struct Foo { baz: [[u32; 2]; 1], bar: bool }`
+  --> $DIR/issue-46.rs:14:13
+   |
+14 |     let y = [Foo::default(); 1];
+   |             ^^^^^^^^^^^^^^^^^^^
+   |
+note: used from within `issue_46::main`
+  --> $DIR/issue-46.rs:14:13
+   |
+14 |     let y = [Foo::default(); 1];
+   |             ^^^^^^^^^^^^^^^^^^^
+note: called by `main`
+  --> $DIR/issue-46.rs:12:8
+   |
+12 | pub fn main() {
+   |        ^^^^
+
+error: aborting due to 2 previous errors
+