Tests only: more tests with constraints and loops

src/test/compile-fail/do-while-pred-constraints.rs

@@ -0,0 +1,26 @@
+// xfail-stage0
+// error-pattern: Unsatisfied precondition constraint (for example, even(y
+
+fn print_even(int y) : even(y) {
+  log y;
+}
+
+pred even(int y) -> bool {
+  true
+}
+
+fn main() {
+
+  let int y = 42;
+  check even(y);
+  do {
+    print_even(y);
+    do {
+      do {
+	do {
+	  y += 1;
+	} while (true);
+      } while (true);
+    } while (true);
+  } while (true);
+}

src/test/compile-fail/while-loop-pred-constraints.rs

@@ -0,0 +1,27 @@
+// xfail-stage0
+// error-pattern: Unsatisfied precondition constraint (for example, even(y
+
+fn print_even(int y) : even(y) {
+  log y;
+}
+
+pred even(int y) -> bool {
+  true
+}
+
+fn main() {
+
+  let int y = 42;
+  let int x = 1;
+  check even(y);
+  while (true) {
+    print_even(y);
+    while (true) {
+      while (true) {
+	while (true) {
+	  y += x;
+	}
+      }
+    }
+  }
+}