[Issue 24396] New: Error on forward reference in enum member UDA

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24396

          Issue ID: 24396
           Summary: Error on forward reference in enum member UDA
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: snarwin+bugzilla at gmail.com

As of DMD 2.107.0, the following program fails to compile:

---
struct S { E e; }

enum E
{
    @S(e2) e1,
    @S(e1) e2
}
---

The error message is:

---
bug.d(5): Error: enum member `bug.E.e1` circular reference to `enum` member
---

According to run.dlang.io, this is a regression introduced in DMD 2.101:

---
2.082.1 to 2.101.2: Success and no output
Since      2.102.2: Failure with output: onlineapp.d(5): Error: enum member
`onlineapp.E.e1` circular reference to `enum` member
---

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