Simplify search for packed repr attr

serde_derive/Cargo.toml

@@ -22,7 +22,7 @@ proc-macro = true
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = { version = "1.0", features = ["visit"] }
+syn = { version = "1.0.33", features = ["visit"] }
 
 [dev-dependencies]
 serde = { version = "1.0", path = "../serde" }

serde_derive/src/internals/attr.rs

@@ -597,19 +597,12 @@ impl Container {
         for attr in &item.attrs {
             if attr.path.is_ident("repr") {
                 let _ = attr.parse_args_with(|input: ParseStream| {
-                    input.step(|cursor| {
+                    while let Some(token) = input.parse()? {
-                        let mut rest = *cursor;
+                        if let TokenTree::Ident(ident) = token {
-                        while let Some((tt, next)) = rest.token_tree() {
+                            is_packed |= ident == "packed";
-                            match &tt {
-                                TokenTree::Ident(ident) if ident == "packed" => {
-                                    is_packed |= true;
-                                    return Ok(((), next));
-                                }
-                                _ => rest = next,
                         }
                     }
-                        Err(cursor.error("no `packed` was found in the reprs"))
+                    Ok(())
-                    })
                 });
             }
         }

serde_derive_internals/Cargo.toml

@@ -16,7 +16,7 @@ path = "lib.rs"
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = { version = "1.0", default-features = false, features = ["derive", "parsing", "printing", "clone-impls"] }
+syn = { version = "1.0.33", default-features = false, features = ["derive", "parsing", "printing", "clone-impls"] }
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]