fix 'Ident of macro+ident gets duplicated' error

src/macros.rs

@@ -432,7 +432,8 @@ pub fn rewrite_macro_inner(
             // the `macro_name!` and `{ /* macro_body */ }` but skip modifying
             // anything in between the braces (for now).
             let snippet = context.snippet(mac.span);
-            let macro_raw = snippet.split_at(snippet.find('!')? + 1).1.trim_start();
+            // to remove unnecessary space after macro name
+            let macro_raw = snippet.trim_start_matches(&macro_name).trim_start();
             match trim_left_preserve_layout(macro_raw, shape.indent, &context.config) {
                 Some(macro_body) => Some(format!("{} {}", macro_name, macro_body)),
                 None => Some(format!("{} {}", macro_name, macro_raw)),

tests/target/issue-3439.rs

@@ -0,0 +1,6 @@
+use repro::my_macro;
+
+#[my_macro]
+xyz! abc {
+    let a = 1;
+}