Reduce size of Stmt.

src/api/compile.rs

@@ -99,12 +99,15 @@ impl Engine {
         ) {
             ast.walk(&mut |path| match path.last().unwrap() {
                 // Collect all `import` statements with a string constant path
-                ASTNode::Stmt(Stmt::Import(Expr::StringConstant(s, ..), ..))
-                    if !resolver.contains_path(s) && !imports.contains(s.as_str()) =>
-                {
-                    imports.insert(s.clone().into());
-                    true
-                }
+                ASTNode::Stmt(Stmt::Import(x, ..)) => match x.0 {
+                    Expr::StringConstant(ref s, ..)
+                        if !resolver.contains_path(s) && !imports.contains(s.as_str()) =>
+                    {
+                        imports.insert(s.clone().into());
+                        true
+                    }
+                    _ => true,
+                },
                 _ => true,
             });
         }