Add test to reproduce issue Manishearth#48

Author: fpoli

test-project/tests/compile-fail/macro.rs

@@ -0,0 +1,9 @@
+macro_rules! macro_with_error {
+    ( ) => {
+        let x: u64 = true;
+    };
+}
+
+fn main() {
+    macro_with_error!();  //~ ERROR mismatched types
+}