Function syntax::ext::base::expr_to_str[src]
pub fn expr_to_str(cx: &mut ExtCtxt, expr: Gc<Expr>, err_msg: &str) -> Option<(InternedString, StrStyle)>
Extract a string literal from the macro expanded version of expr,
emitting err_msg if expr is not a string literal. This does not stop
compilation on error, merely emits a non-fatal error and returns None.