Problem with opBinary

[realhet]

Hi,

Just a little weird thing I noticed and don't know why it is:

I have a FilePath struct and I wanted to make it work with the 
"~" operator and an additional string.

So I've created a global funct:

   FilePath opBinary(string op:"~")(FilePath p1, string p2){
     return FilePath(p1, p2);
   }

The problem is that this funct is only callable with the 
following code:

   auto vlcPath = programFilesPath.opBinary!"~"(`VideoLAN\VLC`);

And it is not callable using the ~ operator directly. It says 
unable to call with types  FilePath and string

When I rewrite the opBinary funct as a member of the FilePath 
struct, everything is working fine. The problem is only happening 
when opBinary is a global funct. (I'm using LDC Win64)

Is it a bug or is there an explanation to this?