style nit

Author: J-ZhengLi

clippy_lints/src/casts/cast_possible_truncation.rs

@@ -86,7 +86,6 @@ pub(super) fn check(
     cast_to: Ty<'_>,
     cast_to_span: Span,
 ) {
-    let help = "if this is intentional allow the lint with `#[allow(clippy::cast_possible_truncation)]` ...";
     let msg = match (cast_from.kind(), cast_to.is_integral()) {
         (ty::Int(_) | ty::Uint(_), true) => {
             let from_nbits = apply_reductions(
@@ -166,7 +165,7 @@ pub(super) fn check(
     };
 
     span_lint_and_then(cx, CAST_POSSIBLE_TRUNCATION, expr.span, &msg, |diag| {
-        diag.help(help);
+        diag.help("if this is intentional allow the lint with `#[allow(clippy::cast_possible_truncation)]` ...");
         if !cast_from.is_floating_point() {
             offer_suggestion(cx, expr, cast_expr, cast_to_span, diag);
         }