Start regression tests for types.rs

Author: Darren Tsung

tests/ui/types.rs

@@ -0,0 +1,10 @@
+// should not warn on lossy casting in constant types
+// because not supported yet
+const C : i32 = 42;
+const C_I64 : i64 = C as i64;
+
+fn main() {
+    // should suggest i64::from(c)
+    let c : i32 = 42;
+    let c_i64 : i64 = c as i64;
+}

tests/ui/types.stderr

@@ -0,0 +1,8 @@
+error: casting i32 to i64 may become silently lossy if types change
+ --> $DIR/types.rs:9:23
+  |
+9 |     let c_i64 : i64 = c as i64;
+  |                       ^^^^^^^^ help: try: `i64::from(c)`
+  |
+  = note: `-D cast-lossless` implied by `-D warnings`
+