Prefer format!

Author: tesuji

clippy_lints/src/misc.rs

@@ -632,14 +632,14 @@ fn check_cast(cx: &LateContext<'_, '_>, span: Span, e: &Expr, ty: &Ty) {
             };
 
             if let TyKind::Infer = mut_ty.ty.kind {
-                let sugg = String::from(sugg_fn) + "()";
+                let sugg = format!("{}()", sugg_fn);
                 span_lint_and_sugg(cx, ZERO_PTR, span, msg, "try", sugg, Applicability::MachineApplicable);
             } else if let Some(mut_ty_snip) = snippet_opt(cx, mut_ty.ty.span) {
                 let sugg = format!("{}::<{}>()", sugg_fn, mut_ty_snip);
                 span_lint_and_sugg(cx, ZERO_PTR, span, msg, "try", sugg, Applicability::MachineApplicable);
             } else {
                 // `MaybeIncorrect` as type inference may not work with the suggested code
-                let sugg = String::from(sugg_fn) + "()";
+                let sugg = format!("{}()", sugg_fn);
                 span_lint_and_sugg(cx, ZERO_PTR, span, msg, "try", sugg, Applicability::MaybeIncorrect);
             }
         }