[Issue 24265] New: ref delegate no longer implicitly converts to unannotated type

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24265

          Issue ID: 24265
           Summary: ref delegate no longer implicitly converts to
                    unannotated type
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: regression
          Priority: P3
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: destructionator at gmail.com

This worked fine on dmd 2.098 (my mainline LTS version) but ceased working some
time between that and 2.105 (I don't feel like doing a bisect tonight):

```
void main() {
        ref int alol();
        typeof(&alol) dg;
        int a;
        dg = delegate ref() { return a; };
        dg() = 5;
        assert(a == 5);
}
```

me at arsd:~/test$ dmd-2098 refdg
me at arsd:~/test$ ./refdg # compiles and passes assert


me at arsd:~/test$ dmd-master refdg
refdg.d(5): Error: cannot implicitly convert expression `__dgliteral4` of type
int delegate() pure nothrow @nogc ref @safe` to `int delegate() ref`
refdg.d(5): Error: cannot implicitly convert expression `__dgliteral4` of type
int delegate() pure nothrow @nogc ref @safe` to `int delegate() ref`



Fails on the new dmd. If you write out all the attributes on the dg type:

```
void main() {
        ref int alol() @safe @nogc nothrow pure;
        typeof(&alol) dg;
        int a;
        dg = delegate ref() { return a; };
        dg() = 5;
        assert(a == 5);
}
```

Compiles and runs successfully on both old and new dmd.

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