void process()(void delegate() userData) {}

...a @nogc delegate.  But if the caller is GC allocating, then an allocating delegate is...

If a function takes a delegate, there is no way (outside of changing the type...

...delegate context parameter should require `shared` (which would allow `immutable` too). Unfortunately the opApply delegate...

https://issues.dlang.org/show_bug.cgi?id=23626

--- Comment #9 from Dlang Bot <dlang...

...com

Basically, permit this:

```
void foo(void delegate() dg) pure {
        dg();
}
```

Similarly to how you...

...deduction with auto const ref Args...
and delegate

https://github.com/dlang/dmd/pull/14823

--

...deduction with auto const ref Args... and delegate" was merged into stable:

- ca530908ce1ce07d52f0c90aaa5f3824cbc7816e by Iain...

...delegate, so it should be easy to just lower to the right kind of delegate...

...Removed                     |Added
----------------------------------------------------------------------------
            Summary|`@safe` prohibits capture   |`@safe` prohibits capture
                   |if lazy delegate            |of lazy delegate

--