`binds` can only appear once in the argument list

1 files changed, 7 insertions, 0 deletions

diff --git a/macros/src/syntax.rs b/macros/src/syntax.rs
index ee03b2f..23981d9 100644
--- a/macros/src/syntax.rs
+++ b/macros/src/syntax.rs
@@ -973,6 +973,13 @@ fn parse_args(
         let ident_s = ident.to_string();
         match &*ident_s {
             "binds" if accepts_binds => {
+                if binds.is_some() {
+                    return Err(parse::Error::new(
+                        ident.span(),
+                        "argument appears more than once",
+                    ));
+                }
+
                 // #ident
                 let ident = content.parse()?;