https://issues.dlang.org/show_bug.cgi?id=23789

          Issue ID: 23789
           Summary: ImportC: __declspec(align(n))
           Product: D
           Version: D2
          Hardware: All
                OS: Windows
            Status: NEW
          Keywords: ImportC
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: maxsamukha@gmail.com

Example from Windows SDK:

typedef struct __declspec(align(16)) _M128A {
    ULONGLONG Low;
    LONGLONG High;
} M128A, *PM128A;

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