Address PR's comments

Author: mcarton

clippy_lints/src/needless_bool.rs

@@ -59,7 +59,7 @@ impl LateLintPass for NeedlessBool {
                 };
 
                 let hint = if ret {
-                    format!("return {};", snip)
+                    format!("return {}", snip)
                 } else {
                     snip.to_string()
                 };

clippy_lints/src/transmute.rs

@@ -95,9 +95,9 @@ impl LateLintPass for Transmute {
                             |db| {
                                 if let Some(arg) = sugg::Sugg::hir_opt(cx, &*args[0]) {
                                     let sugg = if ptr_ty == rty {
-                                        arg.as_ty(&to_ty.to_string())
+                                        arg.as_ty(to_ty)
                                     } else {
-                                        arg.as_ty(&format!("{} as {}", cx.tcx.mk_ptr(rty), to_ty))
+                                        arg.as_ty(cx.tcx.mk_ptr(rty)).as_ty(to_ty)
                                     };
 
                                     db.span_suggestion(e.span, "try", sugg.to_string());

clippy_lints/src/utils/sugg.rs

@@ -126,8 +126,8 @@ impl<'a> Sugg<'a> {
     }
 
     /// Convenience method to create the `<lhs> as <rhs>` suggestion.
-    pub fn as_ty(self, rhs: &str) -> Sugg<'static> {
-        make_assoc(AssocOp::As, &self, &Sugg::NonParen(rhs.into()))
+    pub fn as_ty<R: std::fmt::Display>(self, rhs: R) -> Sugg<'static> {
+        make_assoc(AssocOp::As, &self, &Sugg::NonParen(rhs.to_string().into()))
     }
 
     /// Convenience method to create the `&<expr>` suggestion.