https://issues.dlang.org/show_bug.cgi?id=21192

          Issue ID: 21192
           Summary: std.traits: Add trait for determining if a type has
                    padding/alignment holes
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: phobos
          Assignee: nobody@puremagic.com
          Reporter: ibuclaw@gdcproject.org

Created attachment 1802
  --> https://issues.dlang.org/attachment.cgi?id=1802&action=edit
example implementation

Such a trait could be used by core.internal.convert.toUbyte() to determine whether it is safe to return all bits of a struct to compute the hash, or does it need to selectively copy all fields.

Rationale: structs that are passed around in registers typically discard any memset() operation done to zero all alignment holes, so comparing all bits for equality may not work.

Attached example implementation.

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