use syn::{Expr, ExprLit, Lit}; pub(crate) trait RequireStrLit { fn require_str_lit(&self) -> syn::Result; } impl RequireStrLit for Expr { fn require_str_lit(&self) -> syn::Result { match self { Expr::Lit(ExprLit { lit: Lit::Str(str), .. }) => Ok(str.value()), _ => Err(syn::Error::new_spanned(self, "expected a string literal")), } } }