-Z llvm-plugins=val -- a list LLVM plugins to enable (space separated)
-Z llvm-time-trace=val -- generate JSON tracing data file from LLVM data (default: no)
-Z location-detail=val -- what location details should be tracked when using caller_location, either `none`, or a comma separated list of location details, for which valid options are `file`, `line`, and `column` (default: `file,line,column`)
- -Z log-backtrace=val -- add a backtrace along with logging
-Z ls=val -- list the symbols defined by a library crate (default: no)
-Z macro-backtrace=val -- show macro backtraces (default: no)
-Z maximal-hir-to-mir-coverage=val -- save as much information as possible about the correspondence between MIR and HIR as source scopes (default: no)