While debugging a codegen issue, I tried adding LLVM options with
the rustc -Cllvm-args option, and was confused by the error and usage
messaging.
The LLVM "program name" argument is set to "rustc", and command line
error messages make it look like invalid arguments are "rustc"
arguments, not LLVM.
I changed this argument so error messages and the "-help" usage feedback
is easier to understand and react to. (Clang does something similar.)
Rich Kadel