https://issues.dlang.org/show_bug.cgi?id=24195

          Issue ID: 24195
           Summary: DMD defaults Winver to Windows XP
           Product: D
           Version: D2
          Hardware: All
                OS: Windows
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: grimmaple95@gmail.com

Provided no other stuff is fed to the compiler, it will default the `_WIN32_WINNT` constant to `0x501`, which is Windows XP. This leaves a lot of modern features out, so it should probably be updated to something reasonably modern (eg Windows 8, as Windows 7 is old enough to be officially not supported)

Also, there is no reasonbale hint to why stuff is missing, and the windows versions are not (or poorly) documented.

--