Remove bad cast in test, cover more cases

Author: ranweiler

tests/ui/zero_offset.rs

@@ -1,12 +1,18 @@
 fn main() {
     unsafe {
-        let x = &() as *const ();
-        x.offset(0);
-        x.wrapping_add(0);
-        x.sub(0);
-        x.wrapping_sub(0);
+        let m = &mut () as *mut ();
+        m.offset(0);
+        m.wrapping_add(0);
+        m.sub(0);
+        m.wrapping_sub(0);
 
-        let y = &1 as *const u8;
+        let c = &() as *const ();
+        c.offset(0);
+        c.wrapping_add(0);
+        c.sub(0);
+        c.wrapping_sub(0);
+
+        let y = &1 as *const i32;
         y.offset(0);
     }
 }

tests/ui/zero_offset.stderr

@@ -1,9 +1,52 @@
-error[E0606]: casting `&i32` as `*const u8` is invalid
-  --> $DIR/zero_offset.rs:9:17
+error: offset calculation on zero-sized value
+  --> $DIR/zero_offset.rs:4:9
    |
-LL |         let y = &1 as *const u8;
-   |                 ^^^^^^^^^^^^^^^
+LL |         m.offset(0);
+   |         ^^^^^^^^^^^
+   |
+   = note: `#[deny(clippy::zst_offset)]` on by default
+
+error: offset calculation on zero-sized value
+  --> $DIR/zero_offset.rs:5:9
+   |
+LL |         m.wrapping_add(0);
+   |         ^^^^^^^^^^^^^^^^^
+
+error: offset calculation on zero-sized value
+  --> $DIR/zero_offset.rs:6:9
+   |
+LL |         m.sub(0);
+   |         ^^^^^^^^
+
+error: offset calculation on zero-sized value
+  --> $DIR/zero_offset.rs:7:9
+   |
+LL |         m.wrapping_sub(0);
+   |         ^^^^^^^^^^^^^^^^^
+
+error: offset calculation on zero-sized value
+  --> $DIR/zero_offset.rs:10:9
+   |
+LL |         c.offset(0);
+   |         ^^^^^^^^^^^
+
+error: offset calculation on zero-sized value
+  --> $DIR/zero_offset.rs:11:9
+   |
+LL |         c.wrapping_add(0);
+   |         ^^^^^^^^^^^^^^^^^
+
+error: offset calculation on zero-sized value
+  --> $DIR/zero_offset.rs:12:9
+   |
+LL |         c.sub(0);
+   |         ^^^^^^^^
+
+error: offset calculation on zero-sized value
+  --> $DIR/zero_offset.rs:13:9
+   |
+LL |         c.wrapping_sub(0);
+   |         ^^^^^^^^^^^^^^^^^
 
-error: aborting due to previous error
+error: aborting due to 8 previous errors
 
-For more information about this error, try `rustc --explain E0606`.