incorrect data when returning static array in place of dynamic

[sigod via Digitalmars-d-learn]

On Monday, 6 July 2015 at 05:30:46 UTC, thedeemon wrote:
> On Sunday, 5 July 2015 at 18:57:46 UTC, sigod wrote:
>> Why does function return incorrect data? Using `.dup` in 
>> return expression or using `ubyte[20]` as return type fixes 
>> problem, but why?
>
> Because sha1Of() returns ubyte[20], this is a stack-allocated 
> array, a value type. If you put correct return type there, it 
> will be returned by value and everything's fine. If your return 
> type is ubyte[] (a reference type), a slice of stack-allocated 
> array is returned which creates a reference to stack data that 
> doesn't exist anymore.

Aren't compiler smart enough to prevent it?

```
ubyte[] test1()
{
	auto b = sha1Of("");

	return b; // Error: escaping reference to local b
}

ubyte[] test2()
{
	return sha1Of(""); // works, but returns incorrect data
}
```

Looks more like a bug to me.