[Issue 21364] Passing a struct by-value adds padding that breaks argument access within the function

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21364

--- Comment #4 from Walter Bright <bugzilla at digitalmars.com> ---
Correction: both functions get the size of X right at 16.

But, the alignment of X should be 8. Function foo() gets it right, while main()
sees the alignment as 16.

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