warning: this `let...else` may be rewritten with the `?` operator
  --> cling/src/extractors.rs:42:9
   |
42 | /         let Some(state) = args.get::<State<S>>() else {
43 | |             return None;
44 | |         };
   | |__________^ help: replace it with: `let state = args.get::<State<S>>()?;`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#question_mark
   = note: `#[warn(clippy::question_mark)]` on by default

warning: empty string literal in `writeln!`
   --> cling/src/error.rs:240:25
    |
240 |                 let _ = writeln!(f, "");
    |                         ^^^^^^^^^^----^
    |                                   |
    |                                   help: remove the empty string
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#writeln_empty_string
    = note: `#[warn(clippy::writeln_empty_string)]` on by default

warning: unexpected `cfg` condition name: `unstable`
  --> cling/src/params.rs:14:7
   |
14 | #[cfg(unstable)]
   |       ^^^^^^^^
   |
   = help: consider using a Cargo feature instead
   = help: or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:
            [lints.rust]
            unexpected_cfgs = { level = "warn", check-cfg = ['cfg(unstable)'] }
   = help: or consider adding `println!("cargo::rustc-check-cfg=cfg(unstable)");` to the top of the `build.rs`
   = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition name: `unstable`
  --> cling/src/params.rs:12:7
   |
12 | #[cfg(unstable)]
   |       ^^^^^^^^
   |
   = help: consider using a Cargo feature instead
   = help: or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:
            [lints.rust]
            unexpected_cfgs = { level = "warn", check-cfg = ['cfg(unstable)'] }
   = help: or consider adding `println!("cargo::rustc-check-cfg=cfg(unstable)");` to the top of the `build.rs`
   = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition name: `unstable`
 --> cling/src/params.rs:9:12
  |
9 | #[cfg_attr(unstable, marker)]
  |            ^^^^^^^^
  |
  = help: consider using a Cargo feature instead
  = help: or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:
           [lints.rust]
           unexpected_cfgs = { level = "warn", check-cfg = ['cfg(unstable)'] }
  = help: or consider adding `println!("cargo::rustc-check-cfg=cfg(unstable)");` to the top of the `build.rs`
  = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition name: `unstable`
 --> cling/src/lib.rs:2:13
  |
2 | #![cfg_attr(unstable, feature(marker_trait_attr))]
  |             ^^^^^^^^
  |
  = help: expected names are: `clippy`, `debug_assertions`, `doc`, `docsrs`, `doctest`, `feature`, `fmt_debug`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `rustfmt`, `sanitize`, `sanitizer_cfi_generalize_pointers`, `sanitizer_cfi_normalize_integers`, `target_abi`, `target_arch`, `target_endian`, `target_env`, `target_family`, `target_feature`, `target_has_atomic`, `target_has_atomic_equal_alignment`, `target_has_atomic_load_store`, `target_os`, `target_pointer_width`, `target_thread_local`, `target_vendor`, `test`, `ub_checks`, `unix`, and `windows`
  = help: consider using a Cargo feature instead
  = help: or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:
           [lints.rust]
           unexpected_cfgs = { level = "warn", check-cfg = ['cfg(unstable)'] }
  = help: or consider adding `println!("cargo::rustc-check-cfg=cfg(unstable)");` to the top of the `build.rs`
  = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
  = note: `#[warn(unexpected_cfgs)]` on by default