What is the right way to change the clang compiler version for one port?

[Yuri]

When I need to use clang60, I add these lines:

LLVM_VER=       60
BUILD_DEPENDS+= clang${LLVM_VER}:devel/llvm${LLVM_VER}
CPP=            clang-cpp${LLVM_VER}
CC=             clang${LLVM_VER}
CXX=            clang++${LLVM_VER}

This works, but it also prints this warning in poudriere:

[00:00:02] Gathering ports metadata
[00:00:02] Warning: (graphics/myport): clang60: not found
[00:00:02] Warning: (graphics/myport): make: 
"/usr/ports/Mk/Uses/compiler.mk" line 75: warning: "clang60 --version" 
returned non-zero status
[00:00:02] Warning: (graphics/myport): make: 
"/usr/ports/Mk/Uses/compiler.mk" line 130: warning: "clang++60 -### 
/dev/null 2>&1" returned non-zero status
[00:00:07] Calculating ports order and dependencies


Should this message be ignored (it's only a warning), or otherwise how 
to fix it?


Thanks,

Yuri