lib/scanner: fix macro propagation to submodules

src/scanner/mod.rs

@@ -1,7 +1,11 @@
-mod error;
+// Note that this module must come before all others, as
+// they depend on the macros which expand into this scope
 #[macro_use]
 mod macros;
 
+mod error;
+mod scalar;
+
 use atoi::atoi;
 
 use self::error::{ScanError, ScanResult as Result};