Confirm: D escapes auto ref similar to Go language

[Steven Schveighoffer]

On Sunday, 24 August 2025 at 15:03:12 UTC, Brother Bill wrote:
> On page 549 of Programming in D, it appears that D supports 
> 'escaping' local variables to the heap, when returning their 
> address.
>
> This is similar to Go.
> Is this what is actually going on?
> Is this 'safe' to do?
>
> ```
> &result: AC067AF730
> &result: AC067AF730
> ptrSum : AC067AF7B0 (2 + 3)
> sum    : (4 * 5)
> ```
>
> source/app.d
> ```
> import std.stdio;
>
> void main() {
>     string * ptrSum = &parenthesized("2 + 3");
> 	string sum = parenthesized("4 * 5");
>
>     writefln("ptrSum : %s %s", ptrSum, *ptrSum);
>     writefln("sum    : %s", sum);
> }
>
> auto ref string parenthesized(string phrase) {
>     string result = '(' ~ phrase ~ ')';
> 	writeln("&result: ", &result);
>     return result;      // ← compilation ERROR
> }
> ```

I don't know what's happening here, but it seems like a bug. This 
should not compile (it does for me, despite the comment above).

If you change `auto ref` to just `ref`, it fails, and if you 
change it to just returning `string` it fails.

If you change it to returning `auto ref` without `string`, it 
also fails.

It appears that the address taken is one of a local stack 
temporary.

-Steve