Add regression test for negative unsigned literals in patterns

Author: oli-obk

tests/ui/type/pattern_types/signed_ranges.rs

@@ -0,0 +1,22 @@
+#![feature(pattern_types)]
+#![feature(pattern_type_macro)]
+
+//@ check-pass
+
+use std::pat::pattern_type;
+
+type Sign = pattern_type!(u32 is -10..);
+
+type SignedChar = pattern_type!(char is -'A'..);
+
+fn main() {
+    match 42_u8 {
+        -10..253 => {}
+        _ => {}
+    }
+
+    match 'A' {
+        -'\0'..'a' => {}
+        _ => {}
+    }
+}