OCD: clippy issues

[nyurik]

Here's the statistics of the Clippy issues to see which may need to be fixed. I excluded bindgen-integration and tests_expectations as they seem to have some other issues.

echo '|count|lint|' && echo '|---|---|' && \
   cargo clippy --all-targets --workspace --exclude bindgen-integration --exclude tests_expectations --message-format=json --quiet -- -W clippy::pedantic \
    | jq -r '.message.code.code | select(. != null and startswith("clippy::")) | "| [" + . + "](https://rust-lang.github.io/rust-clippy/master/index.html#" + .[8:] + ") |"' \
    | sort | uniq -c | sort -h -r | sed 's/^/|/' 

count	lint	fixes
271	clippy::doc_markdown	#3026
226	clippy::return_self_not_must_use
183	clippy::unreadable_literal
156	clippy::must_use_candidate
54	clippy::too_many_lines
47	clippy::default_trait_access
46	clippy::manual_let_else	#3019
44	clippy::trivially_copy_pass_by_ref
40	clippy::needless_pass_by_value
40	clippy::match_same_arms
40	clippy::ignored_unit_patterns
34	clippy::redundant_closure_for_method_calls
34	clippy::cast_possible_truncation
33	clippy::single_match_else	#3019
32	clippy::explicit_iter_loop	#3020
28	clippy::cast_lossless	#3021
26	clippy::items_after_statements
26	clippy::cast_sign_loss
24	clippy::used_underscore_binding
20	clippy::wildcard_imports
17	clippy::if_not_else	#3022
16	clippy::map_unwrap_or	#3023
16	clippy::implicit_hasher
12	clippy::unused_self
12	clippy::missing_errors_doc
11	clippy::unnested_or_patterns
10	clippy::unnecessary_wraps
10	clippy::struct_excessive_bools
10	clippy::module_name_repetitions
10	clippy::cast_possible_wrap
9	clippy::missing_panics_doc
6	clippy::ptr_as_ptr
6	clippy::case_sensitive_file_extension_comparisons
4	clippy::struct_field_names
4	clippy::redundant_else
3	clippy::manual_string_new
3	clippy::enum_glob_use
2	clippy::similar_names
2	clippy::range_plus_one
2	clippy::maybe_infinite_iter
2	clippy::match_wildcard_for_single_variants
2	clippy::match_bool
2	clippy::manual_instant_elapsed
2	clippy::inconsistent_struct_constructor
2	clippy::flat_map_option
2	clippy::explicit_into_iter_loop
2	clippy::checked_conversions
2	clippy::cast_precision_loss
2	clippy::borrow_as_ptr
1	clippy::should_panic_without_expect
1	clippy::manual_assert