swc-project/swc · error · Error

Expected at least one name

Error message

Expected at least one name

What it means

Fired during @layer prelude canonicalization: the layer name list was empty even though the at-rule form requires at least one layer name (or a block-only '@layer { }' which is handled separately). The parser cannot attribute the rule to any layer and reports this error.

Source

Thrown at crates/swc_css_parser/src/parser/util.rs:113

        at_rule.prelude = match self
            .parse_according_to_grammar(&list_of_component_values, |parser| {
                parser.parse_at_rule_prelude(&normalized_at_rule_name)
            }) {
            Ok(at_rule_prelude) => match at_rule_prelude {
                Some(AtRulePrelude::LayerPrelude(LayerPrelude::NameList(name_list)))
                    if name_list.name_list.len() > 1 && at_rule.block.is_some() =>
                {
                    self.errors.push(Error::new(
                        name_list.span,
                        ErrorKind::Expected("only one name"),
                    ));

                    Some(Box::new(AtRulePrelude::ListOfComponentValues(
                        list_of_component_values,
                    )))
                }
                None if normalized_at_rule_name == "layer" && at_rule.block.is_none() => {
                    self.errors.push(Error::new(
                        at_rule.span,
                        ErrorKind::Expected("at least one name"),
                    ));

                    Some(Box::new(AtRulePrelude::ListOfComponentValues(
                        list_of_component_values,
                    )))
                }
                _ => at_rule_prelude.map(Box::new),
            },
            Err(err) => {
                if *err.kind() != ErrorKind::Ignore {
                    self.errors.push(err);
                }

                if !list_of_component_values.children.is_empty() {
                    Some(Box::new(AtRulePrelude::ListOfComponentValues(
                        list_of_component_values,

View on GitHub (pinned to 5176682b65)

Solutions

1. Provide at least one layer name: '@layer name;' or '@layer name { ... }'
2. If an anonymous layer is intended, drop the prelude entirely: '@layer { ... }'

When it happens

Trigger: Thrown at crates/swc_css_parser/src/parser/util.rs:113 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of swc-project/swc@5176682b65 (2026-08-17). Data as JSON: /api/errors/8a3e1afc9c5db01b. Report an issue: GitHub.