[Issue 24346] New: Lambda as UDA is valid but spec requires brackets

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24346

          Issue ID: 24346
           Summary: Lambda as UDA is valid but spec requires brackets
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dlang.org
          Assignee: nobody at puremagic.com
          Reporter: alphaglosined at gmail.com

From: https://forum.dlang.org/post/hnjcuvuzytbuvgfdhfkd@forum.dlang.org

The lambda here is valid, even though it is not in a brackets.

```d
@a=>7 int b;
pragma(msg, __traits(getAttributes, b)); // AliasSeq!((a) => 7)
```

Should only be supported (according to specification):

```d
@(a=>7) int b;
pragma(msg, __traits(getAttributes, b)); // AliasSeq!((a) => 7)
```

Clarification or a compiler bug fix is needed.

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