[Issue 19439] New: Make __traits(getAliasThis) return empty tuple for non-aggregate types

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19439

          Issue ID: 19439
           Summary: Make __traits(getAliasThis) return empty tuple for
                    non-aggregate types
           Product: D
           Version: D2
          Hardware: x86_64
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: n8sh.secondary at hotmail.com

It is frequently necessary to verify that aliasing is not occurring. Checking
that the result of __traits(getAliasThis) has length 0 is a concise and natural
way of doing this. Unfortunately it is currently disallowed to `getAliasThis` a
non-aggregate type. Returning an empty tuple instead of raising a compile-time
error would also be convenient for using `getAliasThis` in type-generic code.
It should not make DMD slower to change this behavior: not raising an error
slightly simplifies the logic.

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