Add regression test for negative unsigned literals in patterns

tests/ui/type/pattern_types/signed_ranges.rs

@@ -0,0 +1,22 @@
+#![feature(pattern_types)]
+#![feature(pattern_type_macro)]
+
+use std::pat::pattern_type;
+
+type Sign = pattern_type!(u32 is -10..);
+//~^ ERROR: cannot apply unary operator `-`
+
+type SignedChar = pattern_type!(char is -'A'..);
+//~^ ERROR: cannot apply unary operator `-`
+
+fn main() {
+    match 42_u8 {
+        -10..253 => {}
+        _ => {}
+    }
+
+    match 'A' {
+        -'\0'..'a' => {}
+        _ => {}
+    }
+}

tests/ui/type/pattern_types/signed_ranges.stderr

@@ -0,0 +1,17 @@
+error[E0600]: cannot apply unary operator `-` to type `u32`
+  --> $DIR/signed_ranges.rs:6:34
+   |
+LL | type Sign = pattern_type!(u32 is -10..);
+   |                                  ^^^ cannot apply unary operator `-`
+   |
+   = note: unsigned values cannot be negated
+
+error[E0600]: cannot apply unary operator `-` to type `char`
+  --> $DIR/signed_ranges.rs:9:41
+   |
+LL | type SignedChar = pattern_type!(char is -'A'..);
+   |                                         ^^^^ cannot apply unary operator `-`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0600`.