Check for None-delimited group in attribute value

serde_derive/Cargo.toml

@@ -24,7 +24,7 @@ proc-macro = true
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = "2.0"
+syn = "2.0.3"
 
 [dev-dependencies]
 serde = { version = "1.0", path = "../serde" }

serde_derive/src/internals/attr.rs

@@ -1381,12 +1381,18 @@ fn get_lit_str2(
     meta_item_name: Symbol,
     meta: &ParseNestedMeta,
 ) -> syn::Result<Option<syn::LitStr>> {
-    match meta.value()?.parse()? {
-        syn::Expr::Lit(syn::ExprLit {
+    let expr: syn::Expr = meta.value()?.parse()?;
+    let mut value = &expr;
+    while let syn::Expr::Group(e) = value {
+        value = &e.expr;
+    }
+    if let syn::Expr::Lit(syn::ExprLit {
         lit: syn::Lit::Str(lit),
         ..
-        }) => Ok(Some(lit)),
-        expr => {
+    }) = value
+    {
+        Ok(Some(lit.clone()))
+    } else {
         cx.error_spanned_by(
             expr,
             format!(
@@ -1397,7 +1403,6 @@ fn get_lit_str2(
         Ok(None)
     }
 }
-}
 
 fn parse_lit_into_path(
     cx: &Ctxt,