skip compiling C++ code when running clippy

[Firestar99]

Requires #17

[Firestar99]

newer clippy and deny versions broke stuff...

[LegNeato]

Or CLIPPY or CARGO_CFG_CLIPPY ? How did you choose that one?

[Firestar99]

I've added this to the build script:

let vars = std::env::vars().collect::<Vec<_>>();
panic!("vars: {vars:#?}");

Which printed only the following CLIPPY* vars:

(
    "CARGO_ENCODED_RUSTFLAGS",
    "-C\u{1f}link-arg=-fuse-ld=mold\u{1f}-Dunsafe_code\u{1f}-Wclippy::all\u{1f}-Wclippy::await_holding_lock\u{1f}-Wclippy::char_lit_as_u8\u{1f}-Wclippy::checked_conversions\u{1f}-Wclippy::dbg_macro\u{1f}-Wclippy::debug_assert_with_mut_call\u{1f}-Wclippy::doc_markdown\u{1f}-Wclippy::empty_enum\u{1f}-Wclippy::enum_glob_use\u{1f}-Wclippy::exit\u{1f}-Wclippy::expl_impl_clone_on_copy\u{1f}-Wclippy::explicit_deref_methods\u{1f}-Wclippy::explicit_into_iter_loop\u{1f}-Wclippy::fallible_impl_from\u{1f}-Wclippy::filter_map_next\u{1f}-Wclippy::flat_map_option\u{1f}-Wclippy::float_cmp_const\u{1f}-Wclippy::fn_params_excessive_bools\u{1f}-Wclippy::from_iter_instead_of_collect\u{1f}-Wclippy::if_let_mutex\u{1f}-Wclippy::implicit_clone\u{1f}-Wclippy::imprecise_flops\u{1f}-Wclippy::inefficient_to_string\u{1f}-Wclippy::invalid_upcast_comparisons\u{1f}-Wclippy::large_digit_groups\u{1f}-Wclippy::large_stack_arrays\u{1f}-Wclippy::large_types_passed_by_value\u{1f}-Wclippy::let_unit_value\u{1f}-Wclippy::linkedlist\u{1f}-Wclippy::lossy_float_literal\u{1f}-Wclippy::macro_use_imports\u{1f}-Wclippy::manual_ok_or\u{1f}-Wclippy::map_err_ignore\u{1f}-Wclippy::map_flatten\u{1f}-Wclippy::map_unwrap_or\u{1f}-Wclippy::indexing_slicing\u{1f}-Wclippy::match_same_arms\u{1f}-Wclippy::match_wild_err_arm\u{1f}-Wclippy::match_wildcard_for_single_variants\u{1f}-Wclippy::mem_forget\u{1f}-Wclippy::missing_enforced_import_renames\u{1f}-Wclippy::mut_mut\u{1f}-Wclippy::mutex_integer\u{1f}-Wclippy::needless_borrow\u{1f}-Wclippy::needless_continue\u{1f}-Wclippy::needless_for_each\u{1f}-Wclippy::option_option\u{1f}-Wclippy::path_buf_push_overwrite\u{1f}-Wclippy::ptr_as_ptr\u{1f}-Wclippy::rc_mutex\u{1f}-Wclippy::ref_option_ref\u{1f}-Wclippy::rest_pat_in_fully_bound_structs\u{1f}-Wclippy::same_functions_in_if_condition\u{1f}-Wclippy::semicolon_if_nothing_returned\u{1f}-Wclippy::single_match_else\u{1f}-Wclippy::string_add_assign\u{1f}-Wclippy::string_add\u{1f}-Wclippy::string_lit_as_bytes\u{1f}-Wclippy::string_to_string\u{1f}-Wclippy::todo\u{1f}-Wclippy::trait_duplication_in_bounds\u{1f}-Wclippy::unimplemented\u{1f}-Wclippy::unnested_or_patterns\u{1f}-Wclippy::unused_self\u{1f}-Wclippy::useless_transmute\u{1f}-Wclippy::verbose_file_reads\u{1f}-Wclippy::zero_sized_map_values\u{1f}-Wfuture_incompatible\u{1f}-Wnonstandard_style\u{1f}-Wrust_2018_idioms\u{1f}-C\u{1f}link-arg=-fuse-ld=lld",
),
(
    "CLIPPY_ARGS",
    "",
),
(
    "CLIPPY_TERMINAL_WIDTH",
    "203",
),
(
    "RUSTC_WORKSPACE_WRAPPER",
    "/home/firestar99/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/clippy-driver",
),

Could CLIPPY or CARGO_CFG_CLIPPY not be exposed in build scripts?

(also rebased it)

[LegNeato]

How about using #[cfg(clippy)]? It seems to be officially supported:

https://doc.rust-lang.org/nightly/clippy/configuration.html#disabling-evaluation-of-certain-code

[Firestar99]

How about using #[cfg(clippy)]? It seems to be officially supported:

https://doc.rust-lang.org/nightly/clippy/configuration.html#disabling-evaluation-of-certain-code

This works as well and is probably a lot cleaner than my solution. Feel free to merge. As discussed, once merged I'll release version 0.12.1 so we can start using it in rust-gpu.