Privatize a few members to allow messing with them #11353

[matheus]

Hi, I was looking the PR in DMD and I found this one: 
https://github.com/dlang/dmd/pull/11353/

One of the changes was:

-            loc.linnum += incrementLoc;
+            loc.linnum = loc.linnum + incrementLoc;

I usually do the former and I particularly hate the later, so my 
question is, in this case this was more a style thing than 
anything else right? Or is there something I'm not able to see?

Thanks,

Matheus.