oxc-project/oxc · error · OxcDiagnostic

Missing braces in case clause.

Error message

Missing braces in case clause.

What it means

Emitted by the unicorn/switch-case-braces rule when a `case` clause contains lexical declarations (`let`/`const`/`class`) but has no surrounding braces. Braces are required there so the declarations get their own block scope and cannot leak into the shared switch-block scope.

Source

Thrown at crates/oxc_linter/src/rules/unicorn/switch_case_braces.rs:22

use oxc_span::{GetSpan, Span};
use schemars::JsonSchema;
use serde::{Deserialize, Serialize};

use crate::{
    AstNode,
    ast_util::get_preceding_indent_str,
    context::LintContext,
    rule::{DefaultRuleConfig, Rule},
};

fn switch_case_braces_diagnostic_empty_clause(span: Span) -> OxcDiagnostic {
    OxcDiagnostic::warn("Unexpected braces in empty case clause.")
        .with_help("Remove braces in empty case clause.")
        .with_label(span)
}

fn switch_case_braces_diagnostic_missing_braces(span: Span) -> OxcDiagnostic {
    OxcDiagnostic::warn("Missing braces in case clause.")
        .with_help("Add Braces for case clause.")
        .with_label(span)
}

fn switch_case_braces_diagnostic_unnecessary_braces(span: Span) -> OxcDiagnostic {
    OxcDiagnostic::warn("Unnecessary braces in case clause.")
        .with_help("Remove Braces for case clause.")
        .with_label(span)
}

#[derive(Debug, Clone, Deserialize)]
pub struct SwitchCaseBraces(Box<SwitchCaseBracesConfig>);

impl Default for SwitchCaseBraces {
    fn default() -> Self {
        Self(Box::new(SwitchCaseBracesConfig::Always))
    }
}

View on GitHub (pinned to e1e7af627c)

Solutions

1. Wrap the case clause body in braces: `case 'a': { ... break; }`

When it happens

Trigger: Thrown at crates/oxc_linter/src/rules/unicorn/switch_case_braces.rs:22 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of oxc-project/oxc@e1e7af627c (2026-08-20). Data as JSON: /api/errors/426ddd3e313d1a31. Report an issue: GitHub.