I've ported Vim to Win64. Native binaries for AMD64 can be found on my Vim page.

In the end, it wasn't all that hard. Last weekend, I fixed approximately 400 warnings that were thrown up by the x86_amd64 cross compiler. Most of them were due to the widening of size_t (especially the value returned from strlen()) and ptrdiff_t to 64 bits. Several years ago, I went through a similar exercise in fixing these warnings for Vim6, but I never finished the port.

This week, I scrounged access to an AMD64 box at work. Today, I turned on the /Wp64 flag, which found several new, subtler problems, where pointers where being truncated to __int32s or conversely __int32s were being widened to pointers. Judicious introduction of (the equivalent of) (INT_PTR) casts fixed most of those.

At that point, I tried running the binary. It refused to start! After a few detours, I had WinDbg installed, and ran gvim under WinDbg. That showed that the error was 14001 (ERROR_SXS_CANT_GEN_ACTCTX, "The application has failed to start because its side-by-side configuration is incorrect. Please see the application event log for more detail.") The event log showed nothing.

After more investigation, I found a WinSxS manifest for the Windows Common Controls:

 
 
        processorArchitecture="X86"
     version="6.2.0.0"
     type="win32"
     name="Vim"
   />
   Vi Improved - A Text Editor
   
     
                type="win32"
         name="Microsoft.Windows.Common-Controls"
         version="6.0.0.0"
         publicKeyToken="6595b64144ccf1df"
         language="*"
         processorArchitecture="X86"
       />
     
   
 

Once the two instances of processorArchitecture="X86" were set to processorArchitecture="AMD64", Vim started working without a hitch. Despite my naïve expectations, none of the other fields in the comctl32 assembly needed to be changed.