Constant USAGE 

pub const USAGE: &str = "\
rucc, an optimizing C compiler

usage: rucc [options] file...

options:
  -c                     compile and assemble, do not link
  -S                     compile only, emit assembly
  -E                     preprocess only
  -o <file>              write output to <file>, or to standard output for -
  -D <name>[=<value>], -U <name>      define a macro, or undefine one after every -D
  -I <dir>               add <dir> to the include search path
  -iquote -isystem -idirafter <dir>   the other chains, -nostdinc drops ours
  --sysroot=<dir>        look for the library's headers under <dir>, -isysroot too
  -P, -dM                with -E: leave out the markers, or dump the macros
  -std=<dialect>         c89 through c23, and the gnu spellings
  -fgnuc-version=<v>     the GCC release to claim, default 7.0.0
  -x <lang>              treat later inputs as <lang>, or none to stop
  -O<level>              optimize: 0, 1, 2, 3, s, z
  -fsafety=<tier>        check memory safety: off, detect, enforce, kernel
  -f<pass> -fno-<pass> -fdump-ir=<what> -fopt-info[-<kind>][=FILE]
  -fpass-fuel=<pass>=<n>, -fpass-fuel-global=<n>   stop a pass, or all of them, after n
  -fdisable-<pass>[=<funcs>], -fenable-<pass>[=<funcs>]   run a pass on some functions only
  -g -g0 -gdwarf-5, -fno-omit-frame-pointer, -mno-red-zone   debug info, frame pointer, red zone
  -l<name>, -L <dir>, -B <dir>   link a library, where to look for one, where our own tools are
  -static -shared -pie -no-pie -nostdlib -nostartfiles -nodefaultlibs -rdynamic -s   how to link
  -Wl,<arg>, -Xlinker <arg>, -fuse-ld=<name>   hand an argument to the linker, or pick one
  -Werror -pedantic -pedantic-errors -w   how much to say, and whether it is fatal
  -m64 -march= -mtune= -mcpu= -mabi= -mcmodel=   what machine to generate for
  -pthread               build for more than one thread, and link the library for it
  -dumpmachine -dumpversion -print-multiarch -print-search-dirs   what this compiler is
  -print-file-name=<name> -print-prog-name=<name>   where a file or a program is
  -j[n]                  compile n translation units at once, default all
  -v, -###               print each phase as it runs, or without running any
  --target=<triple>      generate code for <triple>
  --emit=<kind>          exe, obj, asm, preprocessed, tast, ir, mir-final,
                         safety-summary, type-granules
  --print-config, --print-pipeline    print the configuration or the pipeline, and exit
  --version              print the version and exit
  -h, --help             print this message and exit

See spec/04-driver-and-cli.md for the full flag reference.
";

Usage text.

Deliberately short. spec/04-driver-and-cli.md puts the full flag reference in the manual page, because a --help nobody can read in one screen is a --help nobody reads.