Since implicit conversion warnings are not 'on' by default in GCC or Clang, and not part of -Wall, I decided to give it a shot.
It worked out great for my code, and gave me all the same implicit conversion warnings Visual Studio does... and more!
This flag seems more strict and thorough than VS, and pointed out a wadof conversions in JUCE. There are some fishy ones, like passing signed integers (which may be set to -1 by JUCE) to OpenGL functions that support only unsigned integers.
Ah, thanks.. I thought I'd already nailed all of those, but I guess the projects in which I've enabled that flag don't include modules like openGL, so I've missed a few warnings. Will skip through and sort that out!
Have you tried the vs 2015 compiler preview? It generates a lot of new warnings. Most are just cases where local names hides globals / members, but there are a couple of cases with inconsistent alignment specifications, unsafe functions and at one point I saw a place with an apparantly unavoidable recursion, but can't trace it currently..