Forgot to hide Usage: rustc [OPTIONS] INPUT

Options:
    --bin               Compile an executable crate (default)
    -c                  Compile and assemble, but do not link
    --cfg SPEC          Configure the compilation environment
    --emit-llvm         Produce an LLVM assembly file if used with -S option;
                        produce an LLVM bitcode file otherwise
    -h --help           Display this message
    -L PATH             Add a directory to the library search path
    --lib               Compile a library crate
    --linker LINKER     Program to use for linking instead of the default.
    --link-args FLAGS   FLAGS is a space-separated list of flags passed to the
                        linker
    --ls                List the symbols defined by a library crate
    --no-trans          Run all passes except translation; no output
    -O                  Equivalent to --opt-level=2
    -o FILENAME         Write output to <filename>
    --opt-level LEVEL   Optimize with possible levels 0-3
    --passes NAMES      Comma or space separated list of pass names to use.
                        Appends to the default list of passes to run for the
                        specified current optimization level. A value of
                        "list" will list all of the available passes
    --llvm-args ARGS    A list of arguments to pass to llvm, comma separated
    --out-dir DIR       Write output to compiler-chosen filename in <dir>
    --parse-only        Parse only; do not compile, assemble, or link
    --pretty [TYPE]     Pretty-print the input instead of compiling; valid
                        types are: normal (un-annotated source), expanded
                        (crates expanded), typed (crates expanded, with type
                        annotations), or identified (fully parenthesized, AST
                        nodes and blocks with IDs)
    -S                  Compile only; do not assemble or link
    --save-temps        Write intermediate files (.bc, .opt.bc, .o) in
                        addition to normal output
    --sysroot PATH      Override the system root
    --test              Build a test harness
    --target TRIPLE     Target triple cpu-manufacturer-kernel[-os] to compile
                        for (see chapter 3.4 of
                        http://www.sourceware.org/autobook/ for details)
    --target-cpu CPU    Select target processor (llc -mcpu=help for details)
    --target-feature FEATURE
                        Target specific attributes (llc -mattr=help for
                        details)
    --android-cross-path PATH
                        The path to the Android NDK
    -W --warn [OPT]     Set lint warnings
    -A --allow OPT      Set lint allowed
    -D --deny OPT       Set lint denied
    -F --forbid OPT     Set lint forbidden
    -Z FLAG             Set internal debugging options
    -v --version        Print version info and exit

Additional help:
    -W help             Print 'lint' options and default settings
    -Z help             Print internal options for debugging rustc calls (Makefile).
Renamed src/fe/kernel/zero.rs to src/fe/kernel/freestanding.rs (clarifies purpose).