Add guarded arms to tests

Author: varkor

src/test/ui/exhaustive_integer_patterns.rs

@@ -120,4 +120,16 @@ fn main() {
     match 0i128 {
         i128::MIN ..= i128::MAX => {} // ok
     }
+
+    // Make sure that guards don't factor into the exhaustiveness checks.
+    match 0u8 { //~ ERROR non-exhaustive patterns
+        0 .. 128 => {}
+        128 ..= 255 if true => {}
+    }
+
+    match 0u8 {
+        0 .. 128 => {}
+        128 ..= 255 if false => {}
+        128 ..= 255 => {} // ok, because previous arm was guarded
+    }
 }

src/test/ui/exhaustive_integer_patterns.stderr

@@ -46,6 +46,12 @@ error[E0004]: non-exhaustive patterns: `0i16` not covered
 LL |     match 0i16 { //~ ERROR non-exhaustive patterns
    |           ^^^^ pattern `0i16` not covered
 
-error: aborting due to 7 previous errors
+error[E0004]: non-exhaustive patterns: `128u8..=255u8` not covered
+  --> $DIR/exhaustive_integer_patterns.rs:125:11
+   |
+LL |     match 0u8 { //~ ERROR non-exhaustive patterns
+   |           ^^^ pattern `128u8..=255u8` not covered
+
+error: aborting due to 8 previous errors
 
 For more information about this error, try `rustc --explain E0004`.