If you are compiling Android and getting this error message:
frameworks/compile/slang/slang_rs_export_foreach.cpp:249:23: error: variable ‘ParamName’ set but not used [-Werror=unused-but-set-variable]
Then edit frameworks/compile/slang/slang_rs_export_foreach.cpp and just remove the line:
llvm::StringRef ParamName = PVD->getName();
Note there are other place with this line, just remove at position 250, since ParamName is not used there.