[Issue 24724] Error when @trusted function returns reference to parameter

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24724

--- Comment #5 from elpenguino+D at gmail.com ---
(In reply to Nick Treleaven from comment #3)
> > this is not enforced by restrictions on the function body
> 
> Why not enforce it at the interface level?

We do. With `@safe`. `@trusted` is specifically for manual enforcement.

(In reply to Nick Treleaven from comment #4)
> In what scenario is allowing @trusted to have an unsafe interface useful? A
> single example will suffice, please provide one (that can't be @system).

The compiler can't prove all memory-safe code is memory-safe, only a subset. It
is occasionally useful to call manually-verified code from `@safe` functions,
which `@trusted` enables. There is no other value to it. Adding enforcement to
it removes that value, and reduces it to just a carbon copy of `@safe`.

I'd rather see `@trusted` removed entirely than go down that path.

--