How to run lit tests on Mac OSX without gcc?

[Thomas Mader via digitalmars-d-ldc]

On Monday, 28 August 2017 at 20:18:30 UTC, David Nadlinger wrote:
> None of these should be relevant if CC is set, as per the 
> snippet I linked. Note that the default is only used after the 
> env check. The fact that this doesn't seem to work indicates a 
> bug in that logic, or in the way the environment is set up. 
> What is CC actually set to?

CC is set to the full path to clang 
(/nix/store/<hash>-<packagename>-<version>/bin)

So it seems that findProgramByName returns empty because it's 
already a full path. 
(https://github.com/ldc-developers/ldc/blob/master/driver/tool.cpp#L48)

A check is missing to see if there already is a full path given 
in CC.