$ syn-file-expand-cli src/lib.rs | rustfmt
# ! [doc = include_str ! ("../README.md")]
#![forbid(unsafe_code)]
...
mod attrs {
    use super::AttrParseError;
    ...
}
mod expand_impl {
    use crate::{attrs, Error, ErrorCase, Resolver};
    ...
}

$ syn-file-expand-cli --help
Usage: target/q/debug/syn-file-expand-cli [OPTIONS]

Reads rust source file, including referred modules and expands them into a single source with all modules inline
Apart from respective dedicated command line arguments, conditional paths like
`#[cfg_attr(feature="qqq"),path=...)` are resolved using
environment variables like SYN_FILE_EXPAND_FEATURE_QQQ=1
Other influential envvars: SYN_FILE_EXPAND_DEBUGVARS=1 SYN_FILE_EXPAND_DEFAULTTRUE=1

Positional arguments:
  input_file                 Input Rust source file to start crawling from

Optional arguments:
  -h, --help
  -l, --loopify              Convert all blocks and expressions to `loop{}`s.
                      Note that inner items within blocks get lost in the process.
  -D, --undoc                Strip all documentation attributes. Note that inner items within blocks are not processed and may retain their attributes.
  -T, --cfg-true-by-default  Assume all `#[cfg]`s and `#[cfg_attr]`s are true. May lead to errors
  -c, --cfg CFG              Set this cfg check result to true.
                                Note that `all` or `any` are not handled.
                                You need to set all needed expression results one by one.
  -u, --unset-cfg UNSET-CFG  In `--cfg-true-by-default` mode, explicitly unset given cfg expression outcome.
  -d, --debug-cfg            Print each encountered cfg check to stderr, in form suitable for `--cfg` parameter
                   Note that the format is different from the one used by `SYN_FILE_EXPAND_DEBUGVARS=1` environment variable.
  -o, --output OUTPUT        Use given file for output instead of stdout