Configuring `[workspace.lints.clippy]` in workspace-level Cargo.toml files

[tarcieri]

Perhaps we can put together a set of clippy lints we want to apply everywhere and start setting these at the workspace level in Cargo.toml.

clippy::restriction lints seem particularly interesting, e.g. mod_module_files

[newpavlov]

Sounds interesting.

[tarcieri]

missing_debug_impls and missing_docs might be good lints to apply at a workspace level

[tarcieri]

Alright, just landed the first real example of this in RustCrypto/utils#1411

For posterity, here's the config I used:

[workspace.lints.clippy]
borrow_as_ptr = "warn"
cast_lossless = "warn"
cast_possible_truncation = "warn"
cast_possible_wrap = "warn"
cast_precision_loss = "warn"
cast_sign_loss = "warn"
checked_conversions = "warn"
doc_markdown = "warn"
from_iter_instead_of_collect = "warn"
implicit_saturating_sub = "warn"
manual_assert = "warn"
map_unwrap_or = "warn"
missing_errors_doc = "warn"
missing_panics_doc = "warn"
mod_module_files = "warn"
must_use_candidate = "warn"
needless_range_loop = "allow"
ptr_as_ptr = "warn"
redundant_closure_for_method_calls = "warn"
ref_as_ptr = "warn"
return_self_not_must_use = "warn"
semicolon_if_nothing_returned = "warn"
trivially_copy_pass_by_ref = "warn"
std_instead_of_alloc = "warn"
std_instead_of_core = "warn"
undocumented_unsafe_blocks = "warn"
unnecessary_safety_comment = "warn"
unwrap_in_result = "warn"
unwrap_used = "warn"

[workspace.lints.rust]
missing_copy_implementations = "warn"
missing_debug_implementations = "warn"
missing_docs = "warn"
trivial_casts = "warn"
trivial_numeric_casts = "warn"
unused_lifetimes = "warn"
unused_qualifications = "warn"

This is augmented by the following .clippy.toml:

allow-unwrap-in-consts = true
allow-unwrap-in-tests = true