are scope guards (scope(exit, success, failure)) zero-cost abstractions?

[Timothee Cour]

likewise, will scope(exit) add any overhead over naive code in the
case where no exception is thrown?

```
void fun(){
  ...
  scope(success) {bar;}
  ...
}

vs

void fun(){
 ...
  if(foo1){
    bar;  // add this before each return
    return;
  }
  ...
  bar;
  return;
}
```


On Thu, Feb 8, 2018 at 2:09 AM, Timothee Cour <thelastmammoth at gmail.com> wrote:
> I'm curious whether scope guards add any cost over the naive way, eg:
>
> ```
> void fun(){
>   ...
>   scope(success) {bar;}
>   ...
> }
> ```
>
> vs:
>
> ```
> void fun(){
>   ...
>   if(foo1){
>     bar;  // add this before each return
>     return;
>   }
>   ...
>   bar;
>   return;
> }
> ```
>
> For scope(success) and scope(failure), the naive way would anyway
> involve try/catch statements but what about scope(exit)? Does the
> zero-cost exception model (zero cost being for non-thrown exceptions)
> guarantee us that scope(success) has 0 overhead over naive way?