2385 lines
78 KiB
Rust
2385 lines
78 KiB
Rust
mod bind_instead_of_map;
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mod bytes_nth;
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mod clone_on_copy;
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mod clone_on_ref_ptr;
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mod expect_fun_call;
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mod expect_used;
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mod filetype_is_file;
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mod filter_flat_map;
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mod filter_map;
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mod filter_map_flat_map;
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mod filter_map_identity;
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mod filter_map_map;
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mod filter_map_next;
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mod filter_next;
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mod flat_map_identity;
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mod from_iter_instead_of_collect;
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mod get_unwrap;
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mod implicit_clone;
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mod inefficient_to_string;
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mod inspect_for_each;
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mod into_iter_on_ref;
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mod iter_cloned_collect;
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mod iter_count;
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mod iter_next_slice;
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mod iter_nth;
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mod iter_nth_zero;
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mod iter_skip_next;
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mod iterator_step_by_zero;
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mod manual_saturating_arithmetic;
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mod map_collect_result_unit;
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mod map_flatten;
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mod map_unwrap_or;
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mod ok_expect;
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mod option_as_ref_deref;
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mod option_map_or_none;
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mod option_map_unwrap_or;
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mod or_fun_call;
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mod search_is_some;
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mod single_char_insert_string;
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mod single_char_pattern;
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mod single_char_push_string;
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mod skip_while_next;
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mod string_extend_chars;
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mod suspicious_map;
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mod uninit_assumed_init;
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mod unnecessary_filter_map;
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mod unnecessary_fold;
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mod unnecessary_lazy_eval;
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mod unwrap_used;
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mod useless_asref;
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mod wrong_self_convention;
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mod zst_offset;
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use bind_instead_of_map::BindInsteadOfMap;
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use clippy_utils::source::snippet_with_applicability;
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use clippy_utils::ty::{contains_ty, implements_trait, is_copy, is_type_diagnostic_item};
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use if_chain::if_chain;
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use rustc_ast::ast;
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use rustc_errors::Applicability;
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use rustc_hir as hir;
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use rustc_hir::{TraitItem, TraitItemKind};
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use rustc_lint::{LateContext, LateLintPass, Lint, LintContext};
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use rustc_middle::lint::in_external_macro;
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use rustc_middle::ty::{self, TraitRef, Ty, TyS};
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use rustc_semver::RustcVersion;
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use rustc_session::{declare_tool_lint, impl_lint_pass};
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use rustc_span::symbol::{sym, SymbolStr};
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use rustc_typeck::hir_ty_to_ty;
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use crate::utils::{
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contains_return, get_trait_def_id, in_macro, iter_input_pats, match_def_path, match_qpath, method_calls,
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method_chain_args, paths, return_ty, single_segment_path, span_lint, span_lint_and_help, span_lint_and_sugg,
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SpanlessEq,
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};
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declare_clippy_lint! {
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/// **What it does:** Checks for `.unwrap()` calls on `Option`s and on `Result`s.
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///
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/// **Why is this bad?** It is better to handle the `None` or `Err` case,
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/// or at least call `.expect(_)` with a more helpful message. Still, for a lot of
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/// quick-and-dirty code, `unwrap` is a good choice, which is why this lint is
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/// `Allow` by default.
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///
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/// `result.unwrap()` will let the thread panic on `Err` values.
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/// Normally, you want to implement more sophisticated error handling,
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/// and propagate errors upwards with `?` operator.
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///
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/// Even if you want to panic on errors, not all `Error`s implement good
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/// messages on display. Therefore, it may be beneficial to look at the places
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/// where they may get displayed. Activate this lint to do just that.
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///
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/// **Known problems:** None.
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///
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/// **Examples:**
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/// ```rust
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/// # let opt = Some(1);
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///
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/// // Bad
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/// opt.unwrap();
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///
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/// // Good
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/// opt.expect("more helpful message");
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/// ```
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///
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/// // or
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///
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/// ```rust
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/// # let res: Result<usize, ()> = Ok(1);
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///
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/// // Bad
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/// res.unwrap();
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///
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/// // Good
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/// res.expect("more helpful message");
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/// ```
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pub UNWRAP_USED,
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restriction,
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"using `.unwrap()` on `Result` or `Option`, which should at least get a better message using `expect()`"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for `.expect()` calls on `Option`s and `Result`s.
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///
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/// **Why is this bad?** Usually it is better to handle the `None` or `Err` case.
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/// Still, for a lot of quick-and-dirty code, `expect` is a good choice, which is why
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/// this lint is `Allow` by default.
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///
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/// `result.expect()` will let the thread panic on `Err`
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/// values. Normally, you want to implement more sophisticated error handling,
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/// and propagate errors upwards with `?` operator.
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///
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/// **Known problems:** None.
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///
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/// **Examples:**
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/// ```rust,ignore
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/// # let opt = Some(1);
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///
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/// // Bad
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/// opt.expect("one");
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///
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/// // Good
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/// let opt = Some(1);
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/// opt?;
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/// ```
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///
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/// // or
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///
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/// ```rust
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/// # let res: Result<usize, ()> = Ok(1);
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///
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/// // Bad
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/// res.expect("one");
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///
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/// // Good
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/// res?;
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/// # Ok::<(), ()>(())
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/// ```
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pub EXPECT_USED,
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restriction,
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"using `.expect()` on `Result` or `Option`, which might be better handled"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for methods that should live in a trait
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/// implementation of a `std` trait (see [llogiq's blog
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/// post](http://llogiq.github.io/2015/07/30/traits.html) for further
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/// information) instead of an inherent implementation.
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///
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/// **Why is this bad?** Implementing the traits improve ergonomics for users of
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/// the code, often with very little cost. Also people seeing a `mul(...)`
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/// method
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/// may expect `*` to work equally, so you should have good reason to disappoint
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/// them.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// struct X;
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/// impl X {
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/// fn add(&self, other: &X) -> X {
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/// // ..
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/// # X
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/// }
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/// }
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/// ```
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pub SHOULD_IMPLEMENT_TRAIT,
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style,
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"defining a method that should be implementing a std trait"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for methods with certain name prefixes and which
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/// doesn't match how self is taken. The actual rules are:
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///
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/// |Prefix |Postfix |`self` taken |
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/// |-------|------------|----------------------|
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/// |`as_` | none |`&self` or `&mut self`|
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/// |`from_`| none | none |
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/// |`into_`| none |`self` |
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/// |`is_` | none |`&self` or none |
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/// |`to_` | `_mut` |`&mut &self` |
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/// |`to_` | not `_mut` |`&self` |
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///
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/// **Why is this bad?** Consistency breeds readability. If you follow the
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/// conventions, your users won't be surprised that they, e.g., need to supply a
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/// mutable reference to a `as_..` function.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// # struct X;
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/// impl X {
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/// fn as_str(self) -> &'static str {
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/// // ..
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/// # ""
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/// }
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/// }
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/// ```
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pub WRONG_SELF_CONVENTION,
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style,
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"defining a method named with an established prefix (like \"into_\") that takes `self` with the wrong convention"
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}
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declare_clippy_lint! {
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/// **What it does:** This is the same as
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/// [`wrong_self_convention`](#wrong_self_convention), but for public items.
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///
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/// **Why is this bad?** See [`wrong_self_convention`](#wrong_self_convention).
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///
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/// **Known problems:** Actually *renaming* the function may break clients if
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/// the function is part of the public interface. In that case, be mindful of
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/// the stability guarantees you've given your users.
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///
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/// **Example:**
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/// ```rust
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/// # struct X;
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/// impl<'a> X {
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/// pub fn as_str(self) -> &'a str {
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/// "foo"
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/// }
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/// }
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/// ```
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pub WRONG_PUB_SELF_CONVENTION,
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restriction,
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"defining a public method named with an established prefix (like \"into_\") that takes `self` with the wrong convention"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for usage of `ok().expect(..)`.
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///
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/// **Why is this bad?** Because you usually call `expect()` on the `Result`
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/// directly to get a better error message.
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///
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/// **Known problems:** The error type needs to implement `Debug`
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///
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/// **Example:**
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/// ```rust
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/// # let x = Ok::<_, ()>(());
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///
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/// // Bad
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/// x.ok().expect("why did I do this again?");
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///
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/// // Good
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/// x.expect("why did I do this again?");
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/// ```
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pub OK_EXPECT,
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style,
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"using `ok().expect()`, which gives worse error messages than calling `expect` directly on the Result"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for usage of `option.map(_).unwrap_or(_)` or `option.map(_).unwrap_or_else(_)` or
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/// `result.map(_).unwrap_or_else(_)`.
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///
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/// **Why is this bad?** Readability, these can be written more concisely (resp.) as
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/// `option.map_or(_, _)`, `option.map_or_else(_, _)` and `result.map_or_else(_, _)`.
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///
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/// **Known problems:** The order of the arguments is not in execution order
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///
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/// **Examples:**
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/// ```rust
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/// # let x = Some(1);
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///
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/// // Bad
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/// x.map(|a| a + 1).unwrap_or(0);
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///
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/// // Good
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/// x.map_or(0, |a| a + 1);
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/// ```
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///
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/// // or
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///
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/// ```rust
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/// # let x: Result<usize, ()> = Ok(1);
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/// # fn some_function(foo: ()) -> usize { 1 }
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///
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/// // Bad
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/// x.map(|a| a + 1).unwrap_or_else(some_function);
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///
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/// // Good
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/// x.map_or_else(some_function, |a| a + 1);
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/// ```
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pub MAP_UNWRAP_OR,
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pedantic,
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"using `.map(f).unwrap_or(a)` or `.map(f).unwrap_or_else(func)`, which are more succinctly expressed as `map_or(a, f)` or `map_or_else(a, f)`"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for usage of `_.map_or(None, _)`.
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///
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/// **Why is this bad?** Readability, this can be written more concisely as
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/// `_.and_then(_)`.
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///
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/// **Known problems:** The order of the arguments is not in execution order.
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///
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|
/// **Example:**
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/// ```rust
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/// # let opt = Some(1);
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///
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/// // Bad
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/// opt.map_or(None, |a| Some(a + 1));
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///
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/// // Good
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/// opt.and_then(|a| Some(a + 1));
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/// ```
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pub OPTION_MAP_OR_NONE,
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style,
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"using `Option.map_or(None, f)`, which is more succinctly expressed as `and_then(f)`"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for usage of `_.map_or(None, Some)`.
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///
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|
/// **Why is this bad?** Readability, this can be written more concisely as
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/// `_.ok()`.
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///
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/// **Known problems:** None.
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///
|
|
/// **Example:**
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///
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/// Bad:
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/// ```rust
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/// # let r: Result<u32, &str> = Ok(1);
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/// assert_eq!(Some(1), r.map_or(None, Some));
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/// ```
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///
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/// Good:
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/// ```rust
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/// # let r: Result<u32, &str> = Ok(1);
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/// assert_eq!(Some(1), r.ok());
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/// ```
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pub RESULT_MAP_OR_INTO_OPTION,
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style,
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"using `Result.map_or(None, Some)`, which is more succinctly expressed as `ok()`"
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}
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|
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declare_clippy_lint! {
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/// **What it does:** Checks for usage of `_.and_then(|x| Some(y))`, `_.and_then(|x| Ok(y))` or
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/// `_.or_else(|x| Err(y))`.
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///
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/// **Why is this bad?** Readability, this can be written more concisely as
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/// `_.map(|x| y)` or `_.map_err(|x| y)`.
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|
///
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|
/// **Known problems:** None
|
|
///
|
|
/// **Example:**
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|
///
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|
/// ```rust
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/// # fn opt() -> Option<&'static str> { Some("42") }
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/// # fn res() -> Result<&'static str, &'static str> { Ok("42") }
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/// let _ = opt().and_then(|s| Some(s.len()));
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/// let _ = res().and_then(|s| if s.len() == 42 { Ok(10) } else { Ok(20) });
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/// let _ = res().or_else(|s| if s.len() == 42 { Err(10) } else { Err(20) });
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/// ```
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///
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|
/// The correct use would be:
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|
///
|
|
/// ```rust
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|
/// # fn opt() -> Option<&'static str> { Some("42") }
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|
/// # fn res() -> Result<&'static str, &'static str> { Ok("42") }
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/// let _ = opt().map(|s| s.len());
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/// let _ = res().map(|s| if s.len() == 42 { 10 } else { 20 });
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/// let _ = res().map_err(|s| if s.len() == 42 { 10 } else { 20 });
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/// ```
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pub BIND_INSTEAD_OF_MAP,
|
|
complexity,
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|
"using `Option.and_then(|x| Some(y))`, which is more succinctly expressed as `map(|x| y)`"
|
|
}
|
|
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|
declare_clippy_lint! {
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|
/// **What it does:** Checks for usage of `_.filter(_).next()`.
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|
///
|
|
/// **Why is this bad?** Readability, this can be written more concisely as
|
|
/// `_.find(_)`.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// # let vec = vec![1];
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|
/// vec.iter().filter(|x| **x == 0).next();
|
|
/// ```
|
|
/// Could be written as
|
|
/// ```rust
|
|
/// # let vec = vec![1];
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|
/// vec.iter().find(|x| **x == 0);
|
|
/// ```
|
|
pub FILTER_NEXT,
|
|
complexity,
|
|
"using `filter(p).next()`, which is more succinctly expressed as `.find(p)`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `_.skip_while(condition).next()`.
|
|
///
|
|
/// **Why is this bad?** Readability, this can be written more concisely as
|
|
/// `_.find(!condition)`.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// # let vec = vec![1];
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|
/// vec.iter().skip_while(|x| **x == 0).next();
|
|
/// ```
|
|
/// Could be written as
|
|
/// ```rust
|
|
/// # let vec = vec![1];
|
|
/// vec.iter().find(|x| **x != 0);
|
|
/// ```
|
|
pub SKIP_WHILE_NEXT,
|
|
complexity,
|
|
"using `skip_while(p).next()`, which is more succinctly expressed as `.find(!p)`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `_.map(_).flatten(_)` on `Iterator` and `Option`
|
|
///
|
|
/// **Why is this bad?** Readability, this can be written more concisely as
|
|
/// `_.flat_map(_)`
|
|
///
|
|
/// **Known problems:**
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let vec = vec![vec![1]];
|
|
///
|
|
/// // Bad
|
|
/// vec.iter().map(|x| x.iter()).flatten();
|
|
///
|
|
/// // Good
|
|
/// vec.iter().flat_map(|x| x.iter());
|
|
/// ```
|
|
pub MAP_FLATTEN,
|
|
pedantic,
|
|
"using combinations of `flatten` and `map` which can usually be written as a single method call"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `_.filter(_).map(_)`,
|
|
/// `_.filter(_).flat_map(_)`, `_.filter_map(_).flat_map(_)` and similar.
|
|
///
|
|
/// **Why is this bad?** Readability, this can be written more concisely as
|
|
/// `_.filter_map(_)`.
|
|
///
|
|
/// **Known problems:** Often requires a condition + Option/Iterator creation
|
|
/// inside the closure.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let vec = vec![1];
|
|
///
|
|
/// // Bad
|
|
/// vec.iter().filter(|x| **x == 0).map(|x| *x * 2);
|
|
///
|
|
/// // Good
|
|
/// vec.iter().filter_map(|x| if *x == 0 {
|
|
/// Some(*x * 2)
|
|
/// } else {
|
|
/// None
|
|
/// });
|
|
/// ```
|
|
pub FILTER_MAP,
|
|
pedantic,
|
|
"using combinations of `filter`, `map`, `filter_map` and `flat_map` which can usually be written as a single method call"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `_.filter(_).map(_)` that can be written more simply
|
|
/// as `filter_map(_)`.
|
|
///
|
|
/// **Why is this bad?** Redundant code in the `filter` and `map` operations is poor style and
|
|
/// less performant.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// Bad:
|
|
/// ```rust
|
|
/// (0_i32..10)
|
|
/// .filter(|n| n.checked_add(1).is_some())
|
|
/// .map(|n| n.checked_add(1).unwrap());
|
|
/// ```
|
|
///
|
|
/// Good:
|
|
/// ```rust
|
|
/// (0_i32..10).filter_map(|n| n.checked_add(1));
|
|
/// ```
|
|
pub MANUAL_FILTER_MAP,
|
|
complexity,
|
|
"using `_.filter(_).map(_)` in a way that can be written more simply as `filter_map(_)`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `_.find(_).map(_)` that can be written more simply
|
|
/// as `find_map(_)`.
|
|
///
|
|
/// **Why is this bad?** Redundant code in the `find` and `map` operations is poor style and
|
|
/// less performant.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// Bad:
|
|
/// ```rust
|
|
/// (0_i32..10)
|
|
/// .find(|n| n.checked_add(1).is_some())
|
|
/// .map(|n| n.checked_add(1).unwrap());
|
|
/// ```
|
|
///
|
|
/// Good:
|
|
/// ```rust
|
|
/// (0_i32..10).find_map(|n| n.checked_add(1));
|
|
/// ```
|
|
pub MANUAL_FIND_MAP,
|
|
complexity,
|
|
"using `_.find(_).map(_)` in a way that can be written more simply as `find_map(_)`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `_.filter_map(_).next()`.
|
|
///
|
|
/// **Why is this bad?** Readability, this can be written more concisely as
|
|
/// `_.find_map(_)`.
|
|
///
|
|
/// **Known problems:** None
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// (0..3).filter_map(|x| if x == 2 { Some(x) } else { None }).next();
|
|
/// ```
|
|
/// Can be written as
|
|
///
|
|
/// ```rust
|
|
/// (0..3).find_map(|x| if x == 2 { Some(x) } else { None });
|
|
/// ```
|
|
pub FILTER_MAP_NEXT,
|
|
pedantic,
|
|
"using combination of `filter_map` and `next` which can usually be written as a single method call"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `flat_map(|x| x)`.
|
|
///
|
|
/// **Why is this bad?** Readability, this can be written more concisely by using `flatten`.
|
|
///
|
|
/// **Known problems:** None
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// # let iter = vec![vec![0]].into_iter();
|
|
/// iter.flat_map(|x| x);
|
|
/// ```
|
|
/// Can be written as
|
|
/// ```rust
|
|
/// # let iter = vec![vec![0]].into_iter();
|
|
/// iter.flatten();
|
|
/// ```
|
|
pub FLAT_MAP_IDENTITY,
|
|
complexity,
|
|
"call to `flat_map` where `flatten` is sufficient"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for an iterator or string search (such as `find()`,
|
|
/// `position()`, or `rposition()`) followed by a call to `is_some()`.
|
|
///
|
|
/// **Why is this bad?** Readability, this can be written more concisely as
|
|
/// `_.any(_)` or `_.contains(_)`.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// # let vec = vec![1];
|
|
/// vec.iter().find(|x| **x == 0).is_some();
|
|
/// ```
|
|
/// Could be written as
|
|
/// ```rust
|
|
/// # let vec = vec![1];
|
|
/// vec.iter().any(|x| *x == 0);
|
|
/// ```
|
|
pub SEARCH_IS_SOME,
|
|
complexity,
|
|
"using an iterator or string search followed by `is_some()`, which is more succinctly expressed as a call to `any()` or `contains()`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `.chars().next()` on a `str` to check
|
|
/// if it starts with a given char.
|
|
///
|
|
/// **Why is this bad?** Readability, this can be written more concisely as
|
|
/// `_.starts_with(_)`.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let name = "foo";
|
|
/// if name.chars().next() == Some('_') {};
|
|
/// ```
|
|
/// Could be written as
|
|
/// ```rust
|
|
/// let name = "foo";
|
|
/// if name.starts_with('_') {};
|
|
/// ```
|
|
pub CHARS_NEXT_CMP,
|
|
style,
|
|
"using `.chars().next()` to check if a string starts with a char"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for calls to `.or(foo(..))`, `.unwrap_or(foo(..))`,
|
|
/// etc., and suggests to use `or_else`, `unwrap_or_else`, etc., or
|
|
/// `unwrap_or_default` instead.
|
|
///
|
|
/// **Why is this bad?** The function will always be called and potentially
|
|
/// allocate an object acting as the default.
|
|
///
|
|
/// **Known problems:** If the function has side-effects, not calling it will
|
|
/// change the semantic of the program, but you shouldn't rely on that anyway.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// # let foo = Some(String::new());
|
|
/// foo.unwrap_or(String::new());
|
|
/// ```
|
|
/// this can instead be written:
|
|
/// ```rust
|
|
/// # let foo = Some(String::new());
|
|
/// foo.unwrap_or_else(String::new);
|
|
/// ```
|
|
/// or
|
|
/// ```rust
|
|
/// # let foo = Some(String::new());
|
|
/// foo.unwrap_or_default();
|
|
/// ```
|
|
pub OR_FUN_CALL,
|
|
perf,
|
|
"using any `*or` method with a function call, which suggests `*or_else`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for calls to `.expect(&format!(...))`, `.expect(foo(..))`,
|
|
/// etc., and suggests to use `unwrap_or_else` instead
|
|
///
|
|
/// **Why is this bad?** The function will always be called.
|
|
///
|
|
/// **Known problems:** If the function has side-effects, not calling it will
|
|
/// change the semantics of the program, but you shouldn't rely on that anyway.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// # let foo = Some(String::new());
|
|
/// # let err_code = "418";
|
|
/// # let err_msg = "I'm a teapot";
|
|
/// foo.expect(&format!("Err {}: {}", err_code, err_msg));
|
|
/// ```
|
|
/// or
|
|
/// ```rust
|
|
/// # let foo = Some(String::new());
|
|
/// # let err_code = "418";
|
|
/// # let err_msg = "I'm a teapot";
|
|
/// foo.expect(format!("Err {}: {}", err_code, err_msg).as_str());
|
|
/// ```
|
|
/// this can instead be written:
|
|
/// ```rust
|
|
/// # let foo = Some(String::new());
|
|
/// # let err_code = "418";
|
|
/// # let err_msg = "I'm a teapot";
|
|
/// foo.unwrap_or_else(|| panic!("Err {}: {}", err_code, err_msg));
|
|
/// ```
|
|
pub EXPECT_FUN_CALL,
|
|
perf,
|
|
"using any `expect` method with a function call"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `.clone()` on a `Copy` type.
|
|
///
|
|
/// **Why is this bad?** The only reason `Copy` types implement `Clone` is for
|
|
/// generics, not for using the `clone` method on a concrete type.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// 42u64.clone();
|
|
/// ```
|
|
pub CLONE_ON_COPY,
|
|
complexity,
|
|
"using `clone` on a `Copy` type"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `.clone()` on a ref-counted pointer,
|
|
/// (`Rc`, `Arc`, `rc::Weak`, or `sync::Weak`), and suggests calling Clone via unified
|
|
/// function syntax instead (e.g., `Rc::clone(foo)`).
|
|
///
|
|
/// **Why is this bad?** Calling '.clone()' on an Rc, Arc, or Weak
|
|
/// can obscure the fact that only the pointer is being cloned, not the underlying
|
|
/// data.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// # use std::rc::Rc;
|
|
/// let x = Rc::new(1);
|
|
///
|
|
/// // Bad
|
|
/// x.clone();
|
|
///
|
|
/// // Good
|
|
/// Rc::clone(&x);
|
|
/// ```
|
|
pub CLONE_ON_REF_PTR,
|
|
restriction,
|
|
"using 'clone' on a ref-counted pointer"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `.clone()` on an `&&T`.
|
|
///
|
|
/// **Why is this bad?** Cloning an `&&T` copies the inner `&T`, instead of
|
|
/// cloning the underlying `T`.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// fn main() {
|
|
/// let x = vec![1];
|
|
/// let y = &&x;
|
|
/// let z = y.clone();
|
|
/// println!("{:p} {:p}", *y, z); // prints out the same pointer
|
|
/// }
|
|
/// ```
|
|
pub CLONE_DOUBLE_REF,
|
|
correctness,
|
|
"using `clone` on `&&T`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `.to_string()` on an `&&T` where
|
|
/// `T` implements `ToString` directly (like `&&str` or `&&String`).
|
|
///
|
|
/// **Why is this bad?** This bypasses the specialized implementation of
|
|
/// `ToString` and instead goes through the more expensive string formatting
|
|
/// facilities.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// // Generic implementation for `T: Display` is used (slow)
|
|
/// ["foo", "bar"].iter().map(|s| s.to_string());
|
|
///
|
|
/// // OK, the specialized impl is used
|
|
/// ["foo", "bar"].iter().map(|&s| s.to_string());
|
|
/// ```
|
|
pub INEFFICIENT_TO_STRING,
|
|
pedantic,
|
|
"using `to_string` on `&&T` where `T: ToString`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for `new` not returning a type that contains `Self`.
|
|
///
|
|
/// **Why is this bad?** As a convention, `new` methods are used to make a new
|
|
/// instance of a type.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// In an impl block:
|
|
/// ```rust
|
|
/// # struct Foo;
|
|
/// # struct NotAFoo;
|
|
/// impl Foo {
|
|
/// fn new() -> NotAFoo {
|
|
/// # NotAFoo
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// ```rust
|
|
/// # struct Foo;
|
|
/// struct Bar(Foo);
|
|
/// impl Foo {
|
|
/// // Bad. The type name must contain `Self`
|
|
/// fn new() -> Bar {
|
|
/// # Bar(Foo)
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// ```rust
|
|
/// # struct Foo;
|
|
/// # struct FooError;
|
|
/// impl Foo {
|
|
/// // Good. Return type contains `Self`
|
|
/// fn new() -> Result<Foo, FooError> {
|
|
/// # Ok(Foo)
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// Or in a trait definition:
|
|
/// ```rust
|
|
/// pub trait Trait {
|
|
/// // Bad. The type name must contain `Self`
|
|
/// fn new();
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// ```rust
|
|
/// pub trait Trait {
|
|
/// // Good. Return type contains `Self`
|
|
/// fn new() -> Self;
|
|
/// }
|
|
/// ```
|
|
pub NEW_RET_NO_SELF,
|
|
style,
|
|
"not returning type containing `Self` in a `new` method"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for string methods that receive a single-character
|
|
/// `str` as an argument, e.g., `_.split("x")`.
|
|
///
|
|
/// **Why is this bad?** Performing these methods using a `char` is faster than
|
|
/// using a `str`.
|
|
///
|
|
/// **Known problems:** Does not catch multi-byte unicode characters.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust,ignore
|
|
/// // Bad
|
|
/// _.split("x");
|
|
///
|
|
/// // Good
|
|
/// _.split('x');
|
|
pub SINGLE_CHAR_PATTERN,
|
|
perf,
|
|
"using a single-character str where a char could be used, e.g., `_.split(\"x\")`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for calling `.step_by(0)` on iterators which panics.
|
|
///
|
|
/// **Why is this bad?** This very much looks like an oversight. Use `panic!()` instead if you
|
|
/// actually intend to panic.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust,should_panic
|
|
/// for x in (0..100).step_by(0) {
|
|
/// //..
|
|
/// }
|
|
/// ```
|
|
pub ITERATOR_STEP_BY_ZERO,
|
|
correctness,
|
|
"using `Iterator::step_by(0)`, which will panic at runtime"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for the use of `iter.nth(0)`.
|
|
///
|
|
/// **Why is this bad?** `iter.next()` is equivalent to
|
|
/// `iter.nth(0)`, as they both consume the next element,
|
|
/// but is more readable.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// # use std::collections::HashSet;
|
|
/// // Bad
|
|
/// # let mut s = HashSet::new();
|
|
/// # s.insert(1);
|
|
/// let x = s.iter().nth(0);
|
|
///
|
|
/// // Good
|
|
/// # let mut s = HashSet::new();
|
|
/// # s.insert(1);
|
|
/// let x = s.iter().next();
|
|
/// ```
|
|
pub ITER_NTH_ZERO,
|
|
style,
|
|
"replace `iter.nth(0)` with `iter.next()`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for use of `.iter().nth()` (and the related
|
|
/// `.iter_mut().nth()`) on standard library types with O(1) element access.
|
|
///
|
|
/// **Why is this bad?** `.get()` and `.get_mut()` are more efficient and more
|
|
/// readable.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let some_vec = vec![0, 1, 2, 3];
|
|
/// let bad_vec = some_vec.iter().nth(3);
|
|
/// let bad_slice = &some_vec[..].iter().nth(3);
|
|
/// ```
|
|
/// The correct use would be:
|
|
/// ```rust
|
|
/// let some_vec = vec![0, 1, 2, 3];
|
|
/// let bad_vec = some_vec.get(3);
|
|
/// let bad_slice = &some_vec[..].get(3);
|
|
/// ```
|
|
pub ITER_NTH,
|
|
perf,
|
|
"using `.iter().nth()` on a standard library type with O(1) element access"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for use of `.skip(x).next()` on iterators.
|
|
///
|
|
/// **Why is this bad?** `.nth(x)` is cleaner
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let some_vec = vec![0, 1, 2, 3];
|
|
/// let bad_vec = some_vec.iter().skip(3).next();
|
|
/// let bad_slice = &some_vec[..].iter().skip(3).next();
|
|
/// ```
|
|
/// The correct use would be:
|
|
/// ```rust
|
|
/// let some_vec = vec![0, 1, 2, 3];
|
|
/// let bad_vec = some_vec.iter().nth(3);
|
|
/// let bad_slice = &some_vec[..].iter().nth(3);
|
|
/// ```
|
|
pub ITER_SKIP_NEXT,
|
|
style,
|
|
"using `.skip(x).next()` on an iterator"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for use of `.get().unwrap()` (or
|
|
/// `.get_mut().unwrap`) on a standard library type which implements `Index`
|
|
///
|
|
/// **Why is this bad?** Using the Index trait (`[]`) is more clear and more
|
|
/// concise.
|
|
///
|
|
/// **Known problems:** Not a replacement for error handling: Using either
|
|
/// `.unwrap()` or the Index trait (`[]`) carries the risk of causing a `panic`
|
|
/// if the value being accessed is `None`. If the use of `.get().unwrap()` is a
|
|
/// temporary placeholder for dealing with the `Option` type, then this does
|
|
/// not mitigate the need for error handling. If there is a chance that `.get()`
|
|
/// will be `None` in your program, then it is advisable that the `None` case
|
|
/// is handled in a future refactor instead of using `.unwrap()` or the Index
|
|
/// trait.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let mut some_vec = vec![0, 1, 2, 3];
|
|
/// let last = some_vec.get(3).unwrap();
|
|
/// *some_vec.get_mut(0).unwrap() = 1;
|
|
/// ```
|
|
/// The correct use would be:
|
|
/// ```rust
|
|
/// let mut some_vec = vec![0, 1, 2, 3];
|
|
/// let last = some_vec[3];
|
|
/// some_vec[0] = 1;
|
|
/// ```
|
|
pub GET_UNWRAP,
|
|
restriction,
|
|
"using `.get().unwrap()` or `.get_mut().unwrap()` when using `[]` would work instead"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for the use of `.extend(s.chars())` where s is a
|
|
/// `&str` or `String`.
|
|
///
|
|
/// **Why is this bad?** `.push_str(s)` is clearer
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let abc = "abc";
|
|
/// let def = String::from("def");
|
|
/// let mut s = String::new();
|
|
/// s.extend(abc.chars());
|
|
/// s.extend(def.chars());
|
|
/// ```
|
|
/// The correct use would be:
|
|
/// ```rust
|
|
/// let abc = "abc";
|
|
/// let def = String::from("def");
|
|
/// let mut s = String::new();
|
|
/// s.push_str(abc);
|
|
/// s.push_str(&def);
|
|
/// ```
|
|
pub STRING_EXTEND_CHARS,
|
|
style,
|
|
"using `x.extend(s.chars())` where s is a `&str` or `String`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for the use of `.cloned().collect()` on slice to
|
|
/// create a `Vec`.
|
|
///
|
|
/// **Why is this bad?** `.to_vec()` is clearer
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let s = [1, 2, 3, 4, 5];
|
|
/// let s2: Vec<isize> = s[..].iter().cloned().collect();
|
|
/// ```
|
|
/// The better use would be:
|
|
/// ```rust
|
|
/// let s = [1, 2, 3, 4, 5];
|
|
/// let s2: Vec<isize> = s.to_vec();
|
|
/// ```
|
|
pub ITER_CLONED_COLLECT,
|
|
style,
|
|
"using `.cloned().collect()` on slice to create a `Vec`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `_.chars().last()` or
|
|
/// `_.chars().next_back()` on a `str` to check if it ends with a given char.
|
|
///
|
|
/// **Why is this bad?** Readability, this can be written more concisely as
|
|
/// `_.ends_with(_)`.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// # let name = "_";
|
|
///
|
|
/// // Bad
|
|
/// name.chars().last() == Some('_') || name.chars().next_back() == Some('-');
|
|
///
|
|
/// // Good
|
|
/// name.ends_with('_') || name.ends_with('-');
|
|
/// ```
|
|
pub CHARS_LAST_CMP,
|
|
style,
|
|
"using `.chars().last()` or `.chars().next_back()` to check if a string ends with a char"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `.as_ref()` or `.as_mut()` where the
|
|
/// types before and after the call are the same.
|
|
///
|
|
/// **Why is this bad?** The call is unnecessary.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// # fn do_stuff(x: &[i32]) {}
|
|
/// let x: &[i32] = &[1, 2, 3, 4, 5];
|
|
/// do_stuff(x.as_ref());
|
|
/// ```
|
|
/// The correct use would be:
|
|
/// ```rust
|
|
/// # fn do_stuff(x: &[i32]) {}
|
|
/// let x: &[i32] = &[1, 2, 3, 4, 5];
|
|
/// do_stuff(x);
|
|
/// ```
|
|
pub USELESS_ASREF,
|
|
complexity,
|
|
"using `as_ref` where the types before and after the call are the same"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for using `fold` when a more succinct alternative exists.
|
|
/// Specifically, this checks for `fold`s which could be replaced by `any`, `all`,
|
|
/// `sum` or `product`.
|
|
///
|
|
/// **Why is this bad?** Readability.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let _ = (0..3).fold(false, |acc, x| acc || x > 2);
|
|
/// ```
|
|
/// This could be written as:
|
|
/// ```rust
|
|
/// let _ = (0..3).any(|x| x > 2);
|
|
/// ```
|
|
pub UNNECESSARY_FOLD,
|
|
style,
|
|
"using `fold` when a more succinct alternative exists"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for `filter_map` calls which could be replaced by `filter` or `map`.
|
|
/// More specifically it checks if the closure provided is only performing one of the
|
|
/// filter or map operations and suggests the appropriate option.
|
|
///
|
|
/// **Why is this bad?** Complexity. The intent is also clearer if only a single
|
|
/// operation is being performed.
|
|
///
|
|
/// **Known problems:** None
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let _ = (0..3).filter_map(|x| if x > 2 { Some(x) } else { None });
|
|
///
|
|
/// // As there is no transformation of the argument this could be written as:
|
|
/// let _ = (0..3).filter(|&x| x > 2);
|
|
/// ```
|
|
///
|
|
/// ```rust
|
|
/// let _ = (0..4).filter_map(|x| Some(x + 1));
|
|
///
|
|
/// // As there is no conditional check on the argument this could be written as:
|
|
/// let _ = (0..4).map(|x| x + 1);
|
|
/// ```
|
|
pub UNNECESSARY_FILTER_MAP,
|
|
complexity,
|
|
"using `filter_map` when a more succinct alternative exists"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for `into_iter` calls on references which should be replaced by `iter`
|
|
/// or `iter_mut`.
|
|
///
|
|
/// **Why is this bad?** Readability. Calling `into_iter` on a reference will not move out its
|
|
/// content into the resulting iterator, which is confusing. It is better just call `iter` or
|
|
/// `iter_mut` directly.
|
|
///
|
|
/// **Known problems:** None
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// // Bad
|
|
/// let _ = (&vec![3, 4, 5]).into_iter();
|
|
///
|
|
/// // Good
|
|
/// let _ = (&vec![3, 4, 5]).iter();
|
|
/// ```
|
|
pub INTO_ITER_ON_REF,
|
|
style,
|
|
"using `.into_iter()` on a reference"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for calls to `map` followed by a `count`.
|
|
///
|
|
/// **Why is this bad?** It looks suspicious. Maybe `map` was confused with `filter`.
|
|
/// If the `map` call is intentional, this should be rewritten. Or, if you intend to
|
|
/// drive the iterator to completion, you can just use `for_each` instead.
|
|
///
|
|
/// **Known problems:** None
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// let _ = (0..3).map(|x| x + 2).count();
|
|
/// ```
|
|
pub SUSPICIOUS_MAP,
|
|
complexity,
|
|
"suspicious usage of map"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for `MaybeUninit::uninit().assume_init()`.
|
|
///
|
|
/// **Why is this bad?** For most types, this is undefined behavior.
|
|
///
|
|
/// **Known problems:** For now, we accept empty tuples and tuples / arrays
|
|
/// of `MaybeUninit`. There may be other types that allow uninitialized
|
|
/// data, but those are not yet rigorously defined.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// // Beware the UB
|
|
/// use std::mem::MaybeUninit;
|
|
///
|
|
/// let _: usize = unsafe { MaybeUninit::uninit().assume_init() };
|
|
/// ```
|
|
///
|
|
/// Note that the following is OK:
|
|
///
|
|
/// ```rust
|
|
/// use std::mem::MaybeUninit;
|
|
///
|
|
/// let _: [MaybeUninit<bool>; 5] = unsafe {
|
|
/// MaybeUninit::uninit().assume_init()
|
|
/// };
|
|
/// ```
|
|
pub UNINIT_ASSUMED_INIT,
|
|
correctness,
|
|
"`MaybeUninit::uninit().assume_init()`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for `.checked_add/sub(x).unwrap_or(MAX/MIN)`.
|
|
///
|
|
/// **Why is this bad?** These can be written simply with `saturating_add/sub` methods.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// # let y: u32 = 0;
|
|
/// # let x: u32 = 100;
|
|
/// let add = x.checked_add(y).unwrap_or(u32::MAX);
|
|
/// let sub = x.checked_sub(y).unwrap_or(u32::MIN);
|
|
/// ```
|
|
///
|
|
/// can be written using dedicated methods for saturating addition/subtraction as:
|
|
///
|
|
/// ```rust
|
|
/// # let y: u32 = 0;
|
|
/// # let x: u32 = 100;
|
|
/// let add = x.saturating_add(y);
|
|
/// let sub = x.saturating_sub(y);
|
|
/// ```
|
|
pub MANUAL_SATURATING_ARITHMETIC,
|
|
style,
|
|
"`.chcked_add/sub(x).unwrap_or(MAX/MIN)`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for `offset(_)`, `wrapping_`{`add`, `sub`}, etc. on raw pointers to
|
|
/// zero-sized types
|
|
///
|
|
/// **Why is this bad?** This is a no-op, and likely unintended
|
|
///
|
|
/// **Known problems:** None
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// unsafe { (&() as *const ()).offset(1) };
|
|
/// ```
|
|
pub ZST_OFFSET,
|
|
correctness,
|
|
"Check for offset calculations on raw pointers to zero-sized types"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for `FileType::is_file()`.
|
|
///
|
|
/// **Why is this bad?** When people testing a file type with `FileType::is_file`
|
|
/// they are testing whether a path is something they can get bytes from. But
|
|
/// `is_file` doesn't cover special file types in unix-like systems, and doesn't cover
|
|
/// symlink in windows. Using `!FileType::is_dir()` is a better way to that intention.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// # || {
|
|
/// let metadata = std::fs::metadata("foo.txt")?;
|
|
/// let filetype = metadata.file_type();
|
|
///
|
|
/// if filetype.is_file() {
|
|
/// // read file
|
|
/// }
|
|
/// # Ok::<_, std::io::Error>(())
|
|
/// # };
|
|
/// ```
|
|
///
|
|
/// should be written as:
|
|
///
|
|
/// ```rust
|
|
/// # || {
|
|
/// let metadata = std::fs::metadata("foo.txt")?;
|
|
/// let filetype = metadata.file_type();
|
|
///
|
|
/// if !filetype.is_dir() {
|
|
/// // read file
|
|
/// }
|
|
/// # Ok::<_, std::io::Error>(())
|
|
/// # };
|
|
/// ```
|
|
pub FILETYPE_IS_FILE,
|
|
restriction,
|
|
"`FileType::is_file` is not recommended to test for readable file type"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `_.as_ref().map(Deref::deref)` or it's aliases (such as String::as_str).
|
|
///
|
|
/// **Why is this bad?** Readability, this can be written more concisely as
|
|
/// `_.as_deref()`.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// # let opt = Some("".to_string());
|
|
/// opt.as_ref().map(String::as_str)
|
|
/// # ;
|
|
/// ```
|
|
/// Can be written as
|
|
/// ```rust
|
|
/// # let opt = Some("".to_string());
|
|
/// opt.as_deref()
|
|
/// # ;
|
|
/// ```
|
|
pub OPTION_AS_REF_DEREF,
|
|
complexity,
|
|
"using `as_ref().map(Deref::deref)`, which is more succinctly expressed as `as_deref()`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `iter().next()` on a Slice or an Array
|
|
///
|
|
/// **Why is this bad?** These can be shortened into `.get()`
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// # let a = [1, 2, 3];
|
|
/// # let b = vec![1, 2, 3];
|
|
/// a[2..].iter().next();
|
|
/// b.iter().next();
|
|
/// ```
|
|
/// should be written as:
|
|
/// ```rust
|
|
/// # let a = [1, 2, 3];
|
|
/// # let b = vec![1, 2, 3];
|
|
/// a.get(2);
|
|
/// b.get(0);
|
|
/// ```
|
|
pub ITER_NEXT_SLICE,
|
|
style,
|
|
"using `.iter().next()` on a sliced array, which can be shortened to just `.get()`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Warns when using `push_str`/`insert_str` with a single-character string literal
|
|
/// where `push`/`insert` with a `char` would work fine.
|
|
///
|
|
/// **Why is this bad?** It's less clear that we are pushing a single character.
|
|
///
|
|
/// **Known problems:** None
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let mut string = String::new();
|
|
/// string.insert_str(0, "R");
|
|
/// string.push_str("R");
|
|
/// ```
|
|
/// Could be written as
|
|
/// ```rust
|
|
/// let mut string = String::new();
|
|
/// string.insert(0, 'R');
|
|
/// string.push('R');
|
|
/// ```
|
|
pub SINGLE_CHAR_ADD_STR,
|
|
style,
|
|
"`push_str()` or `insert_str()` used with a single-character string literal as parameter"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** As the counterpart to `or_fun_call`, this lint looks for unnecessary
|
|
/// lazily evaluated closures on `Option` and `Result`.
|
|
///
|
|
/// This lint suggests changing the following functions, when eager evaluation results in
|
|
/// simpler code:
|
|
/// - `unwrap_or_else` to `unwrap_or`
|
|
/// - `and_then` to `and`
|
|
/// - `or_else` to `or`
|
|
/// - `get_or_insert_with` to `get_or_insert`
|
|
/// - `ok_or_else` to `ok_or`
|
|
///
|
|
/// **Why is this bad?** Using eager evaluation is shorter and simpler in some cases.
|
|
///
|
|
/// **Known problems:** It is possible, but not recommended for `Deref` and `Index` to have
|
|
/// side effects. Eagerly evaluating them can change the semantics of the program.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// // example code where clippy issues a warning
|
|
/// let opt: Option<u32> = None;
|
|
///
|
|
/// opt.unwrap_or_else(|| 42);
|
|
/// ```
|
|
/// Use instead:
|
|
/// ```rust
|
|
/// let opt: Option<u32> = None;
|
|
///
|
|
/// opt.unwrap_or(42);
|
|
/// ```
|
|
pub UNNECESSARY_LAZY_EVALUATIONS,
|
|
style,
|
|
"using unnecessary lazy evaluation, which can be replaced with simpler eager evaluation"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `_.map(_).collect::<Result<(), _>()`.
|
|
///
|
|
/// **Why is this bad?** Using `try_for_each` instead is more readable and idiomatic.
|
|
///
|
|
/// **Known problems:** None
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// (0..3).map(|t| Err(t)).collect::<Result<(), _>>();
|
|
/// ```
|
|
/// Use instead:
|
|
/// ```rust
|
|
/// (0..3).try_for_each(|t| Err(t));
|
|
/// ```
|
|
pub MAP_COLLECT_RESULT_UNIT,
|
|
style,
|
|
"using `.map(_).collect::<Result<(),_>()`, which can be replaced with `try_for_each`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for `from_iter()` function calls on types that implement the `FromIterator`
|
|
/// trait.
|
|
///
|
|
/// **Why is this bad?** It is recommended style to use collect. See
|
|
/// [FromIterator documentation](https://doc.rust-lang.org/std/iter/trait.FromIterator.html)
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// use std::iter::FromIterator;
|
|
///
|
|
/// let five_fives = std::iter::repeat(5).take(5);
|
|
///
|
|
/// let v = Vec::from_iter(five_fives);
|
|
///
|
|
/// assert_eq!(v, vec![5, 5, 5, 5, 5]);
|
|
/// ```
|
|
/// Use instead:
|
|
/// ```rust
|
|
/// let five_fives = std::iter::repeat(5).take(5);
|
|
///
|
|
/// let v: Vec<i32> = five_fives.collect();
|
|
///
|
|
/// assert_eq!(v, vec![5, 5, 5, 5, 5]);
|
|
/// ```
|
|
pub FROM_ITER_INSTEAD_OF_COLLECT,
|
|
style,
|
|
"use `.collect()` instead of `::from_iter()`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `inspect().for_each()`.
|
|
///
|
|
/// **Why is this bad?** It is the same as performing the computation
|
|
/// inside `inspect` at the beginning of the closure in `for_each`.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// [1,2,3,4,5].iter()
|
|
/// .inspect(|&x| println!("inspect the number: {}", x))
|
|
/// .for_each(|&x| {
|
|
/// assert!(x >= 0);
|
|
/// });
|
|
/// ```
|
|
/// Can be written as
|
|
/// ```rust
|
|
/// [1,2,3,4,5].iter()
|
|
/// .for_each(|&x| {
|
|
/// println!("inspect the number: {}", x);
|
|
/// assert!(x >= 0);
|
|
/// });
|
|
/// ```
|
|
pub INSPECT_FOR_EACH,
|
|
complexity,
|
|
"using `.inspect().for_each()`, which can be replaced with `.for_each()`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `filter_map(|x| x)`.
|
|
///
|
|
/// **Why is this bad?** Readability, this can be written more concisely by using `flatten`.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// # let iter = vec![Some(1)].into_iter();
|
|
/// iter.filter_map(|x| x);
|
|
/// ```
|
|
/// Use instead:
|
|
/// ```rust
|
|
/// # let iter = vec![Some(1)].into_iter();
|
|
/// iter.flatten();
|
|
/// ```
|
|
pub FILTER_MAP_IDENTITY,
|
|
complexity,
|
|
"call to `filter_map` where `flatten` is sufficient"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for the use of `.bytes().nth()`.
|
|
///
|
|
/// **Why is this bad?** `.as_bytes().get()` is more efficient and more
|
|
/// readable.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// // Bad
|
|
/// let _ = "Hello".bytes().nth(3);
|
|
///
|
|
/// // Good
|
|
/// let _ = "Hello".as_bytes().get(3);
|
|
/// ```
|
|
pub BYTES_NTH,
|
|
style,
|
|
"replace `.bytes().nth()` with `.as_bytes().get()`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for the usage of `_.to_owned()`, `vec.to_vec()`, or similar when calling `_.clone()` would be clearer.
|
|
///
|
|
/// **Why is this bad?** These methods do the same thing as `_.clone()` but may be confusing as
|
|
/// to why we are calling `to_vec` on something that is already a `Vec` or calling `to_owned` on something that is already owned.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// let a = vec![1, 2, 3];
|
|
/// let b = a.to_vec();
|
|
/// let c = a.to_owned();
|
|
/// ```
|
|
/// Use instead:
|
|
/// ```rust
|
|
/// let a = vec![1, 2, 3];
|
|
/// let b = a.clone();
|
|
/// let c = a.clone();
|
|
/// ```
|
|
pub IMPLICIT_CLONE,
|
|
pedantic,
|
|
"implicitly cloning a value by invoking a function on its dereferenced type"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for the use of `.iter().count()`.
|
|
///
|
|
/// **Why is this bad?** `.len()` is more efficient and more
|
|
/// readable.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// // Bad
|
|
/// let some_vec = vec![0, 1, 2, 3];
|
|
/// let _ = some_vec.iter().count();
|
|
/// let _ = &some_vec[..].iter().count();
|
|
///
|
|
/// // Good
|
|
/// let some_vec = vec![0, 1, 2, 3];
|
|
/// let _ = some_vec.len();
|
|
/// let _ = &some_vec[..].len();
|
|
/// ```
|
|
pub ITER_COUNT,
|
|
complexity,
|
|
"replace `.iter().count()` with `.len()`"
|
|
}
|
|
|
|
pub struct Methods {
|
|
msrv: Option<RustcVersion>,
|
|
}
|
|
|
|
impl Methods {
|
|
#[must_use]
|
|
pub fn new(msrv: Option<RustcVersion>) -> Self {
|
|
Self { msrv }
|
|
}
|
|
}
|
|
|
|
impl_lint_pass!(Methods => [
|
|
UNWRAP_USED,
|
|
EXPECT_USED,
|
|
SHOULD_IMPLEMENT_TRAIT,
|
|
WRONG_SELF_CONVENTION,
|
|
WRONG_PUB_SELF_CONVENTION,
|
|
OK_EXPECT,
|
|
MAP_UNWRAP_OR,
|
|
RESULT_MAP_OR_INTO_OPTION,
|
|
OPTION_MAP_OR_NONE,
|
|
BIND_INSTEAD_OF_MAP,
|
|
OR_FUN_CALL,
|
|
EXPECT_FUN_CALL,
|
|
CHARS_NEXT_CMP,
|
|
CHARS_LAST_CMP,
|
|
CLONE_ON_COPY,
|
|
CLONE_ON_REF_PTR,
|
|
CLONE_DOUBLE_REF,
|
|
INEFFICIENT_TO_STRING,
|
|
NEW_RET_NO_SELF,
|
|
SINGLE_CHAR_PATTERN,
|
|
SINGLE_CHAR_ADD_STR,
|
|
SEARCH_IS_SOME,
|
|
FILTER_NEXT,
|
|
SKIP_WHILE_NEXT,
|
|
FILTER_MAP,
|
|
FILTER_MAP_IDENTITY,
|
|
MANUAL_FILTER_MAP,
|
|
MANUAL_FIND_MAP,
|
|
FILTER_MAP_NEXT,
|
|
FLAT_MAP_IDENTITY,
|
|
MAP_FLATTEN,
|
|
ITERATOR_STEP_BY_ZERO,
|
|
ITER_NEXT_SLICE,
|
|
ITER_COUNT,
|
|
ITER_NTH,
|
|
ITER_NTH_ZERO,
|
|
BYTES_NTH,
|
|
ITER_SKIP_NEXT,
|
|
GET_UNWRAP,
|
|
STRING_EXTEND_CHARS,
|
|
ITER_CLONED_COLLECT,
|
|
USELESS_ASREF,
|
|
UNNECESSARY_FOLD,
|
|
UNNECESSARY_FILTER_MAP,
|
|
INTO_ITER_ON_REF,
|
|
SUSPICIOUS_MAP,
|
|
UNINIT_ASSUMED_INIT,
|
|
MANUAL_SATURATING_ARITHMETIC,
|
|
ZST_OFFSET,
|
|
FILETYPE_IS_FILE,
|
|
OPTION_AS_REF_DEREF,
|
|
UNNECESSARY_LAZY_EVALUATIONS,
|
|
MAP_COLLECT_RESULT_UNIT,
|
|
FROM_ITER_INSTEAD_OF_COLLECT,
|
|
INSPECT_FOR_EACH,
|
|
IMPLICIT_CLONE
|
|
]);
|
|
|
|
impl<'tcx> LateLintPass<'tcx> for Methods {
|
|
#[allow(clippy::too_many_lines)]
|
|
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
|
|
if in_macro(expr.span) {
|
|
return;
|
|
}
|
|
|
|
let (method_names, arg_lists, method_spans) = method_calls(expr, 2);
|
|
let method_names: Vec<SymbolStr> = method_names.iter().map(|s| s.as_str()).collect();
|
|
let method_names: Vec<&str> = method_names.iter().map(|s| &**s).collect();
|
|
|
|
match method_names.as_slice() {
|
|
["unwrap", "get"] => get_unwrap::check(cx, expr, arg_lists[1], false),
|
|
["unwrap", "get_mut"] => get_unwrap::check(cx, expr, arg_lists[1], true),
|
|
["unwrap", ..] => unwrap_used::check(cx, expr, arg_lists[0]),
|
|
["expect", "ok"] => ok_expect::check(cx, expr, arg_lists[1]),
|
|
["expect", ..] => expect_used::check(cx, expr, arg_lists[0]),
|
|
["unwrap_or", "map"] => option_map_unwrap_or::check(cx, expr, arg_lists[1], arg_lists[0], method_spans[1]),
|
|
["unwrap_or_else", "map"] => {
|
|
if !map_unwrap_or::check(cx, expr, arg_lists[1], arg_lists[0], self.msrv.as_ref()) {
|
|
unnecessary_lazy_eval::check(cx, expr, arg_lists[0], "unwrap_or");
|
|
}
|
|
},
|
|
["map_or", ..] => option_map_or_none::check(cx, expr, arg_lists[0]),
|
|
["and_then", ..] => {
|
|
let biom_option_linted = bind_instead_of_map::OptionAndThenSome::check(cx, expr, arg_lists[0]);
|
|
let biom_result_linted = bind_instead_of_map::ResultAndThenOk::check(cx, expr, arg_lists[0]);
|
|
if !biom_option_linted && !biom_result_linted {
|
|
unnecessary_lazy_eval::check(cx, expr, arg_lists[0], "and");
|
|
}
|
|
},
|
|
["or_else", ..] => {
|
|
if !bind_instead_of_map::ResultOrElseErrInfo::check(cx, expr, arg_lists[0]) {
|
|
unnecessary_lazy_eval::check(cx, expr, arg_lists[0], "or");
|
|
}
|
|
},
|
|
["next", "filter"] => filter_next::check(cx, expr, arg_lists[1]),
|
|
["next", "skip_while"] => skip_while_next::check(cx, expr, arg_lists[1]),
|
|
["next", "iter"] => iter_next_slice::check(cx, expr, arg_lists[1]),
|
|
["map", "filter"] => filter_map::check(cx, expr, false),
|
|
["map", "filter_map"] => filter_map_map::check(cx, expr, arg_lists[1], arg_lists[0]),
|
|
["next", "filter_map"] => filter_map_next::check(cx, expr, arg_lists[1], self.msrv.as_ref()),
|
|
["map", "find"] => filter_map::check(cx, expr, true),
|
|
["flat_map", "filter"] => filter_flat_map::check(cx, expr, arg_lists[1], arg_lists[0]),
|
|
["flat_map", "filter_map"] => filter_map_flat_map::check(cx, expr, arg_lists[1], arg_lists[0]),
|
|
["flat_map", ..] => flat_map_identity::check(cx, expr, arg_lists[0], method_spans[0]),
|
|
["flatten", "map"] => map_flatten::check(cx, expr, arg_lists[1]),
|
|
["is_some", "find"] => search_is_some::check(cx, expr, "find", arg_lists[1], arg_lists[0], method_spans[1]),
|
|
["is_some", "position"] => {
|
|
search_is_some::check(cx, expr, "position", arg_lists[1], arg_lists[0], method_spans[1])
|
|
},
|
|
["is_some", "rposition"] => {
|
|
search_is_some::check(cx, expr, "rposition", arg_lists[1], arg_lists[0], method_spans[1])
|
|
},
|
|
["extend", ..] => string_extend_chars::check(cx, expr, arg_lists[0]),
|
|
["count", "into_iter"] => iter_count::check(cx, expr, &arg_lists[1], "into_iter"),
|
|
["count", "iter"] => iter_count::check(cx, expr, &arg_lists[1], "iter"),
|
|
["count", "iter_mut"] => iter_count::check(cx, expr, &arg_lists[1], "iter_mut"),
|
|
["nth", "iter"] => iter_nth::check(cx, expr, &arg_lists, false),
|
|
["nth", "iter_mut"] => iter_nth::check(cx, expr, &arg_lists, true),
|
|
["nth", "bytes"] => bytes_nth::check(cx, expr, &arg_lists[1]),
|
|
["nth", ..] => iter_nth_zero::check(cx, expr, arg_lists[0]),
|
|
["step_by", ..] => iterator_step_by_zero::check(cx, expr, arg_lists[0]),
|
|
["next", "skip"] => iter_skip_next::check(cx, expr, arg_lists[1]),
|
|
["collect", "cloned"] => iter_cloned_collect::check(cx, expr, arg_lists[1]),
|
|
["as_ref"] => useless_asref::check(cx, expr, "as_ref", arg_lists[0]),
|
|
["as_mut"] => useless_asref::check(cx, expr, "as_mut", arg_lists[0]),
|
|
["fold", ..] => unnecessary_fold::check(cx, expr, arg_lists[0], method_spans[0]),
|
|
["filter_map", ..] => {
|
|
unnecessary_filter_map::check(cx, expr, arg_lists[0]);
|
|
filter_map_identity::check(cx, expr, arg_lists[0], method_spans[0]);
|
|
},
|
|
["count", "map"] => suspicious_map::check(cx, expr, arg_lists[1], arg_lists[0]),
|
|
["assume_init"] => uninit_assumed_init::check(cx, &arg_lists[0][0], expr),
|
|
["unwrap_or", arith @ ("checked_add" | "checked_sub" | "checked_mul")] => {
|
|
manual_saturating_arithmetic::check(cx, expr, &arg_lists, &arith["checked_".len()..])
|
|
},
|
|
["add" | "offset" | "sub" | "wrapping_offset" | "wrapping_add" | "wrapping_sub"] => {
|
|
zst_offset::check(cx, expr, arg_lists[0])
|
|
},
|
|
["is_file", ..] => filetype_is_file::check(cx, expr, arg_lists[0]),
|
|
["map", "as_ref"] => {
|
|
option_as_ref_deref::check(cx, expr, arg_lists[1], arg_lists[0], false, self.msrv.as_ref())
|
|
},
|
|
["map", "as_mut"] => {
|
|
option_as_ref_deref::check(cx, expr, arg_lists[1], arg_lists[0], true, self.msrv.as_ref())
|
|
},
|
|
["unwrap_or_else", ..] => unnecessary_lazy_eval::check(cx, expr, arg_lists[0], "unwrap_or"),
|
|
["get_or_insert_with", ..] => unnecessary_lazy_eval::check(cx, expr, arg_lists[0], "get_or_insert"),
|
|
["ok_or_else", ..] => unnecessary_lazy_eval::check(cx, expr, arg_lists[0], "ok_or"),
|
|
["collect", "map"] => map_collect_result_unit::check(cx, expr, arg_lists[1], arg_lists[0]),
|
|
["for_each", "inspect"] => inspect_for_each::check(cx, expr, method_spans[1]),
|
|
["to_owned", ..] => implicit_clone::check(cx, expr, sym::ToOwned),
|
|
["to_os_string", ..] => implicit_clone::check(cx, expr, sym::OsStr),
|
|
["to_path_buf", ..] => implicit_clone::check(cx, expr, sym::Path),
|
|
["to_vec", ..] => implicit_clone::check(cx, expr, sym::slice),
|
|
_ => {},
|
|
}
|
|
|
|
match expr.kind {
|
|
hir::ExprKind::Call(ref func, ref args) => {
|
|
if let hir::ExprKind::Path(path) = &func.kind {
|
|
if match_qpath(path, &["from_iter"]) {
|
|
from_iter_instead_of_collect::check(cx, expr, args);
|
|
}
|
|
}
|
|
},
|
|
hir::ExprKind::MethodCall(ref method_call, ref method_span, ref args, _) => {
|
|
or_fun_call::check(cx, expr, *method_span, &method_call.ident.as_str(), args);
|
|
expect_fun_call::check(cx, expr, *method_span, &method_call.ident.as_str(), args);
|
|
|
|
let self_ty = cx.typeck_results().expr_ty_adjusted(&args[0]);
|
|
if args.len() == 1 && method_call.ident.name == sym::clone {
|
|
clone_on_copy::check(cx, expr, &args[0], self_ty);
|
|
clone_on_ref_ptr::check(cx, expr, &args[0]);
|
|
}
|
|
if args.len() == 1 && method_call.ident.name == sym!(to_string) {
|
|
inefficient_to_string::check(cx, expr, &args[0], self_ty);
|
|
}
|
|
|
|
if let Some(fn_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id) {
|
|
if match_def_path(cx, fn_def_id, &paths::PUSH_STR) {
|
|
single_char_push_string::check(cx, expr, args);
|
|
} else if match_def_path(cx, fn_def_id, &paths::INSERT_STR) {
|
|
single_char_insert_string::check(cx, expr, args);
|
|
}
|
|
}
|
|
|
|
match self_ty.kind() {
|
|
ty::Ref(_, ty, _) if *ty.kind() == ty::Str => {
|
|
for &(method, pos) in &PATTERN_METHODS {
|
|
if method_call.ident.name.as_str() == method && args.len() > pos {
|
|
single_char_pattern::check(cx, expr, &args[pos]);
|
|
}
|
|
}
|
|
},
|
|
ty::Ref(..) if method_call.ident.name == sym::into_iter => {
|
|
into_iter_on_ref::check(cx, expr, self_ty, *method_span);
|
|
},
|
|
_ => (),
|
|
}
|
|
},
|
|
hir::ExprKind::Binary(op, ref lhs, ref rhs)
|
|
if op.node == hir::BinOpKind::Eq || op.node == hir::BinOpKind::Ne =>
|
|
{
|
|
let mut info = BinaryExprInfo {
|
|
expr,
|
|
chain: lhs,
|
|
other: rhs,
|
|
eq: op.node == hir::BinOpKind::Eq,
|
|
};
|
|
lint_binary_expr_with_method_call(cx, &mut info);
|
|
}
|
|
_ => (),
|
|
}
|
|
}
|
|
|
|
#[allow(clippy::too_many_lines)]
|
|
fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx hir::ImplItem<'_>) {
|
|
if in_external_macro(cx.sess(), impl_item.span) {
|
|
return;
|
|
}
|
|
let name = impl_item.ident.name.as_str();
|
|
let parent = cx.tcx.hir().get_parent_item(impl_item.hir_id());
|
|
let item = cx.tcx.hir().expect_item(parent);
|
|
let self_ty = cx.tcx.type_of(item.def_id);
|
|
|
|
// if this impl block implements a trait, lint in trait definition instead
|
|
if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = item.kind {
|
|
return;
|
|
}
|
|
|
|
if_chain! {
|
|
if let hir::ImplItemKind::Fn(ref sig, id) = impl_item.kind;
|
|
if let Some(first_arg) = iter_input_pats(&sig.decl, cx.tcx.hir().body(id)).next();
|
|
|
|
let method_sig = cx.tcx.fn_sig(impl_item.def_id);
|
|
let method_sig = cx.tcx.erase_late_bound_regions(method_sig);
|
|
|
|
let first_arg_ty = &method_sig.inputs().iter().next();
|
|
|
|
// check conventions w.r.t. conversion method names and predicates
|
|
if let Some(first_arg_ty) = first_arg_ty;
|
|
|
|
then {
|
|
if cx.access_levels.is_exported(impl_item.hir_id()) {
|
|
// check missing trait implementations
|
|
for method_config in &TRAIT_METHODS {
|
|
if name == method_config.method_name &&
|
|
sig.decl.inputs.len() == method_config.param_count &&
|
|
method_config.output_type.matches(cx, &sig.decl.output) &&
|
|
method_config.self_kind.matches(cx, self_ty, first_arg_ty) &&
|
|
fn_header_equals(method_config.fn_header, sig.header) &&
|
|
method_config.lifetime_param_cond(&impl_item)
|
|
{
|
|
span_lint_and_help(
|
|
cx,
|
|
SHOULD_IMPLEMENT_TRAIT,
|
|
impl_item.span,
|
|
&format!(
|
|
"method `{}` can be confused for the standard trait method `{}::{}`",
|
|
method_config.method_name,
|
|
method_config.trait_name,
|
|
method_config.method_name
|
|
),
|
|
None,
|
|
&format!(
|
|
"consider implementing the trait `{}` or choosing a less ambiguous method name",
|
|
method_config.trait_name
|
|
)
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
wrong_self_convention::check(
|
|
cx,
|
|
&name,
|
|
item.vis.node.is_pub(),
|
|
self_ty,
|
|
first_arg_ty,
|
|
first_arg.pat.span
|
|
);
|
|
}
|
|
}
|
|
|
|
if let hir::ImplItemKind::Fn(_, _) = impl_item.kind {
|
|
let ret_ty = return_ty(cx, impl_item.hir_id());
|
|
|
|
// walk the return type and check for Self (this does not check associated types)
|
|
if contains_ty(ret_ty, self_ty) {
|
|
return;
|
|
}
|
|
|
|
// if return type is impl trait, check the associated types
|
|
if let ty::Opaque(def_id, _) = *ret_ty.kind() {
|
|
// one of the associated types must be Self
|
|
for &(predicate, _span) in cx.tcx.explicit_item_bounds(def_id) {
|
|
if let ty::PredicateKind::Projection(projection_predicate) = predicate.kind().skip_binder() {
|
|
// walk the associated type and check for Self
|
|
if contains_ty(projection_predicate.ty, self_ty) {
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if name == "new" && !TyS::same_type(ret_ty, self_ty) {
|
|
span_lint(
|
|
cx,
|
|
NEW_RET_NO_SELF,
|
|
impl_item.span,
|
|
"methods called `new` usually return `Self`",
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>) {
|
|
if in_external_macro(cx.tcx.sess, item.span) {
|
|
return;
|
|
}
|
|
|
|
if_chain! {
|
|
if let TraitItemKind::Fn(ref sig, _) = item.kind;
|
|
if let Some(first_arg_ty) = sig.decl.inputs.iter().next();
|
|
let first_arg_span = first_arg_ty.span;
|
|
let first_arg_ty = hir_ty_to_ty(cx.tcx, first_arg_ty);
|
|
let self_ty = TraitRef::identity(cx.tcx, item.def_id.to_def_id()).self_ty();
|
|
|
|
then {
|
|
wrong_self_convention::check(
|
|
cx,
|
|
&item.ident.name.as_str(),
|
|
false,
|
|
self_ty,
|
|
first_arg_ty,
|
|
first_arg_span
|
|
);
|
|
}
|
|
}
|
|
|
|
if_chain! {
|
|
if item.ident.name == sym::new;
|
|
if let TraitItemKind::Fn(_, _) = item.kind;
|
|
let ret_ty = return_ty(cx, item.hir_id());
|
|
let self_ty = TraitRef::identity(cx.tcx, item.def_id.to_def_id()).self_ty();
|
|
if !contains_ty(ret_ty, self_ty);
|
|
|
|
then {
|
|
span_lint(
|
|
cx,
|
|
NEW_RET_NO_SELF,
|
|
item.span,
|
|
"methods called `new` usually return `Self`",
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
extract_msrv_attr!(LateContext);
|
|
}
|
|
|
|
fn derefs_to_slice<'tcx>(
|
|
cx: &LateContext<'tcx>,
|
|
expr: &'tcx hir::Expr<'tcx>,
|
|
ty: Ty<'tcx>,
|
|
) -> Option<&'tcx hir::Expr<'tcx>> {
|
|
fn may_slice<'a>(cx: &LateContext<'a>, ty: Ty<'a>) -> bool {
|
|
match ty.kind() {
|
|
ty::Slice(_) => true,
|
|
ty::Adt(def, _) if def.is_box() => may_slice(cx, ty.boxed_ty()),
|
|
ty::Adt(..) => is_type_diagnostic_item(cx, ty, sym::vec_type),
|
|
ty::Array(_, size) => size
|
|
.try_eval_usize(cx.tcx, cx.param_env)
|
|
.map_or(false, |size| size < 32),
|
|
ty::Ref(_, inner, _) => may_slice(cx, inner),
|
|
_ => false,
|
|
}
|
|
}
|
|
|
|
if let hir::ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind {
|
|
if path.ident.name == sym::iter && may_slice(cx, cx.typeck_results().expr_ty(&args[0])) {
|
|
Some(&args[0])
|
|
} else {
|
|
None
|
|
}
|
|
} else {
|
|
match ty.kind() {
|
|
ty::Slice(_) => Some(expr),
|
|
ty::Adt(def, _) if def.is_box() && may_slice(cx, ty.boxed_ty()) => Some(expr),
|
|
ty::Ref(_, inner, _) => {
|
|
if may_slice(cx, inner) {
|
|
Some(expr)
|
|
} else {
|
|
None
|
|
}
|
|
},
|
|
_ => None,
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Used for `lint_binary_expr_with_method_call`.
|
|
#[derive(Copy, Clone)]
|
|
struct BinaryExprInfo<'a> {
|
|
expr: &'a hir::Expr<'a>,
|
|
chain: &'a hir::Expr<'a>,
|
|
other: &'a hir::Expr<'a>,
|
|
eq: bool,
|
|
}
|
|
|
|
/// Checks for the `CHARS_NEXT_CMP` and `CHARS_LAST_CMP` lints.
|
|
fn lint_binary_expr_with_method_call(cx: &LateContext<'_>, info: &mut BinaryExprInfo<'_>) {
|
|
macro_rules! lint_with_both_lhs_and_rhs {
|
|
($func:ident, $cx:expr, $info:ident) => {
|
|
if !$func($cx, $info) {
|
|
::std::mem::swap(&mut $info.chain, &mut $info.other);
|
|
if $func($cx, $info) {
|
|
return;
|
|
}
|
|
}
|
|
};
|
|
}
|
|
|
|
lint_with_both_lhs_and_rhs!(lint_chars_next_cmp, cx, info);
|
|
lint_with_both_lhs_and_rhs!(lint_chars_last_cmp, cx, info);
|
|
lint_with_both_lhs_and_rhs!(lint_chars_next_cmp_with_unwrap, cx, info);
|
|
lint_with_both_lhs_and_rhs!(lint_chars_last_cmp_with_unwrap, cx, info);
|
|
}
|
|
|
|
/// Wrapper fn for `CHARS_NEXT_CMP` and `CHARS_LAST_CMP` lints.
|
|
fn lint_chars_cmp(
|
|
cx: &LateContext<'_>,
|
|
info: &BinaryExprInfo<'_>,
|
|
chain_methods: &[&str],
|
|
lint: &'static Lint,
|
|
suggest: &str,
|
|
) -> bool {
|
|
if_chain! {
|
|
if let Some(args) = method_chain_args(info.chain, chain_methods);
|
|
if let hir::ExprKind::Call(ref fun, ref arg_char) = info.other.kind;
|
|
if arg_char.len() == 1;
|
|
if let hir::ExprKind::Path(ref qpath) = fun.kind;
|
|
if let Some(segment) = single_segment_path(qpath);
|
|
if segment.ident.name == sym::Some;
|
|
then {
|
|
let mut applicability = Applicability::MachineApplicable;
|
|
let self_ty = cx.typeck_results().expr_ty_adjusted(&args[0][0]).peel_refs();
|
|
|
|
if *self_ty.kind() != ty::Str {
|
|
return false;
|
|
}
|
|
|
|
span_lint_and_sugg(
|
|
cx,
|
|
lint,
|
|
info.expr.span,
|
|
&format!("you should use the `{}` method", suggest),
|
|
"like this",
|
|
format!("{}{}.{}({})",
|
|
if info.eq { "" } else { "!" },
|
|
snippet_with_applicability(cx, args[0][0].span, "..", &mut applicability),
|
|
suggest,
|
|
snippet_with_applicability(cx, arg_char[0].span, "..", &mut applicability)),
|
|
applicability,
|
|
);
|
|
|
|
return true;
|
|
}
|
|
}
|
|
|
|
false
|
|
}
|
|
|
|
/// Checks for the `CHARS_NEXT_CMP` lint.
|
|
fn lint_chars_next_cmp<'tcx>(cx: &LateContext<'tcx>, info: &BinaryExprInfo<'_>) -> bool {
|
|
lint_chars_cmp(cx, info, &["chars", "next"], CHARS_NEXT_CMP, "starts_with")
|
|
}
|
|
|
|
/// Checks for the `CHARS_LAST_CMP` lint.
|
|
fn lint_chars_last_cmp<'tcx>(cx: &LateContext<'tcx>, info: &BinaryExprInfo<'_>) -> bool {
|
|
if lint_chars_cmp(cx, info, &["chars", "last"], CHARS_LAST_CMP, "ends_with") {
|
|
true
|
|
} else {
|
|
lint_chars_cmp(cx, info, &["chars", "next_back"], CHARS_LAST_CMP, "ends_with")
|
|
}
|
|
}
|
|
|
|
/// Wrapper fn for `CHARS_NEXT_CMP` and `CHARS_LAST_CMP` lints with `unwrap()`.
|
|
fn lint_chars_cmp_with_unwrap<'tcx>(
|
|
cx: &LateContext<'tcx>,
|
|
info: &BinaryExprInfo<'_>,
|
|
chain_methods: &[&str],
|
|
lint: &'static Lint,
|
|
suggest: &str,
|
|
) -> bool {
|
|
if_chain! {
|
|
if let Some(args) = method_chain_args(info.chain, chain_methods);
|
|
if let hir::ExprKind::Lit(ref lit) = info.other.kind;
|
|
if let ast::LitKind::Char(c) = lit.node;
|
|
then {
|
|
let mut applicability = Applicability::MachineApplicable;
|
|
span_lint_and_sugg(
|
|
cx,
|
|
lint,
|
|
info.expr.span,
|
|
&format!("you should use the `{}` method", suggest),
|
|
"like this",
|
|
format!("{}{}.{}('{}')",
|
|
if info.eq { "" } else { "!" },
|
|
snippet_with_applicability(cx, args[0][0].span, "..", &mut applicability),
|
|
suggest,
|
|
c),
|
|
applicability,
|
|
);
|
|
|
|
true
|
|
} else {
|
|
false
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Checks for the `CHARS_NEXT_CMP` lint with `unwrap()`.
|
|
fn lint_chars_next_cmp_with_unwrap<'tcx>(cx: &LateContext<'tcx>, info: &BinaryExprInfo<'_>) -> bool {
|
|
lint_chars_cmp_with_unwrap(cx, info, &["chars", "next", "unwrap"], CHARS_NEXT_CMP, "starts_with")
|
|
}
|
|
|
|
/// Checks for the `CHARS_LAST_CMP` lint with `unwrap()`.
|
|
fn lint_chars_last_cmp_with_unwrap<'tcx>(cx: &LateContext<'tcx>, info: &BinaryExprInfo<'_>) -> bool {
|
|
if lint_chars_cmp_with_unwrap(cx, info, &["chars", "last", "unwrap"], CHARS_LAST_CMP, "ends_with") {
|
|
true
|
|
} else {
|
|
lint_chars_cmp_with_unwrap(cx, info, &["chars", "next_back", "unwrap"], CHARS_LAST_CMP, "ends_with")
|
|
}
|
|
}
|
|
|
|
fn get_hint_if_single_char_arg(
|
|
cx: &LateContext<'_>,
|
|
arg: &hir::Expr<'_>,
|
|
applicability: &mut Applicability,
|
|
) -> Option<String> {
|
|
if_chain! {
|
|
if let hir::ExprKind::Lit(lit) = &arg.kind;
|
|
if let ast::LitKind::Str(r, style) = lit.node;
|
|
let string = r.as_str();
|
|
if string.chars().count() == 1;
|
|
then {
|
|
let snip = snippet_with_applicability(cx, arg.span, &string, applicability);
|
|
let ch = if let ast::StrStyle::Raw(nhash) = style {
|
|
let nhash = nhash as usize;
|
|
// for raw string: r##"a"##
|
|
&snip[(nhash + 2)..(snip.len() - 1 - nhash)]
|
|
} else {
|
|
// for regular string: "a"
|
|
&snip[1..(snip.len() - 1)]
|
|
};
|
|
let hint = format!("'{}'", if ch == "'" { "\\'" } else { ch });
|
|
Some(hint)
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
}
|
|
|
|
const FN_HEADER: hir::FnHeader = hir::FnHeader {
|
|
unsafety: hir::Unsafety::Normal,
|
|
constness: hir::Constness::NotConst,
|
|
asyncness: hir::IsAsync::NotAsync,
|
|
abi: rustc_target::spec::abi::Abi::Rust,
|
|
};
|
|
|
|
struct ShouldImplTraitCase {
|
|
trait_name: &'static str,
|
|
method_name: &'static str,
|
|
param_count: usize,
|
|
fn_header: hir::FnHeader,
|
|
// implicit self kind expected (none, self, &self, ...)
|
|
self_kind: SelfKind,
|
|
// checks against the output type
|
|
output_type: OutType,
|
|
// certain methods with explicit lifetimes can't implement the equivalent trait method
|
|
lint_explicit_lifetime: bool,
|
|
}
|
|
impl ShouldImplTraitCase {
|
|
const fn new(
|
|
trait_name: &'static str,
|
|
method_name: &'static str,
|
|
param_count: usize,
|
|
fn_header: hir::FnHeader,
|
|
self_kind: SelfKind,
|
|
output_type: OutType,
|
|
lint_explicit_lifetime: bool,
|
|
) -> ShouldImplTraitCase {
|
|
ShouldImplTraitCase {
|
|
trait_name,
|
|
method_name,
|
|
param_count,
|
|
fn_header,
|
|
self_kind,
|
|
output_type,
|
|
lint_explicit_lifetime,
|
|
}
|
|
}
|
|
|
|
fn lifetime_param_cond(&self, impl_item: &hir::ImplItem<'_>) -> bool {
|
|
self.lint_explicit_lifetime
|
|
|| !impl_item.generics.params.iter().any(|p| {
|
|
matches!(
|
|
p.kind,
|
|
hir::GenericParamKind::Lifetime {
|
|
kind: hir::LifetimeParamKind::Explicit
|
|
}
|
|
)
|
|
})
|
|
}
|
|
}
|
|
|
|
#[rustfmt::skip]
|
|
const TRAIT_METHODS: [ShouldImplTraitCase; 30] = [
|
|
ShouldImplTraitCase::new("std::ops::Add", "add", 2, FN_HEADER, SelfKind::Value, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::convert::AsMut", "as_mut", 1, FN_HEADER, SelfKind::RefMut, OutType::Ref, true),
|
|
ShouldImplTraitCase::new("std::convert::AsRef", "as_ref", 1, FN_HEADER, SelfKind::Ref, OutType::Ref, true),
|
|
ShouldImplTraitCase::new("std::ops::BitAnd", "bitand", 2, FN_HEADER, SelfKind::Value, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::ops::BitOr", "bitor", 2, FN_HEADER, SelfKind::Value, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::ops::BitXor", "bitxor", 2, FN_HEADER, SelfKind::Value, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::borrow::Borrow", "borrow", 1, FN_HEADER, SelfKind::Ref, OutType::Ref, true),
|
|
ShouldImplTraitCase::new("std::borrow::BorrowMut", "borrow_mut", 1, FN_HEADER, SelfKind::RefMut, OutType::Ref, true),
|
|
ShouldImplTraitCase::new("std::clone::Clone", "clone", 1, FN_HEADER, SelfKind::Ref, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::cmp::Ord", "cmp", 2, FN_HEADER, SelfKind::Ref, OutType::Any, true),
|
|
// FIXME: default doesn't work
|
|
ShouldImplTraitCase::new("std::default::Default", "default", 0, FN_HEADER, SelfKind::No, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::ops::Deref", "deref", 1, FN_HEADER, SelfKind::Ref, OutType::Ref, true),
|
|
ShouldImplTraitCase::new("std::ops::DerefMut", "deref_mut", 1, FN_HEADER, SelfKind::RefMut, OutType::Ref, true),
|
|
ShouldImplTraitCase::new("std::ops::Div", "div", 2, FN_HEADER, SelfKind::Value, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::ops::Drop", "drop", 1, FN_HEADER, SelfKind::RefMut, OutType::Unit, true),
|
|
ShouldImplTraitCase::new("std::cmp::PartialEq", "eq", 2, FN_HEADER, SelfKind::Ref, OutType::Bool, true),
|
|
ShouldImplTraitCase::new("std::iter::FromIterator", "from_iter", 1, FN_HEADER, SelfKind::No, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::str::FromStr", "from_str", 1, FN_HEADER, SelfKind::No, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::hash::Hash", "hash", 2, FN_HEADER, SelfKind::Ref, OutType::Unit, true),
|
|
ShouldImplTraitCase::new("std::ops::Index", "index", 2, FN_HEADER, SelfKind::Ref, OutType::Ref, true),
|
|
ShouldImplTraitCase::new("std::ops::IndexMut", "index_mut", 2, FN_HEADER, SelfKind::RefMut, OutType::Ref, true),
|
|
ShouldImplTraitCase::new("std::iter::IntoIterator", "into_iter", 1, FN_HEADER, SelfKind::Value, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::ops::Mul", "mul", 2, FN_HEADER, SelfKind::Value, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::ops::Neg", "neg", 1, FN_HEADER, SelfKind::Value, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::iter::Iterator", "next", 1, FN_HEADER, SelfKind::RefMut, OutType::Any, false),
|
|
ShouldImplTraitCase::new("std::ops::Not", "not", 1, FN_HEADER, SelfKind::Value, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::ops::Rem", "rem", 2, FN_HEADER, SelfKind::Value, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::ops::Shl", "shl", 2, FN_HEADER, SelfKind::Value, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::ops::Shr", "shr", 2, FN_HEADER, SelfKind::Value, OutType::Any, true),
|
|
ShouldImplTraitCase::new("std::ops::Sub", "sub", 2, FN_HEADER, SelfKind::Value, OutType::Any, true),
|
|
];
|
|
|
|
#[rustfmt::skip]
|
|
const PATTERN_METHODS: [(&str, usize); 17] = [
|
|
("contains", 1),
|
|
("starts_with", 1),
|
|
("ends_with", 1),
|
|
("find", 1),
|
|
("rfind", 1),
|
|
("split", 1),
|
|
("rsplit", 1),
|
|
("split_terminator", 1),
|
|
("rsplit_terminator", 1),
|
|
("splitn", 2),
|
|
("rsplitn", 2),
|
|
("matches", 1),
|
|
("rmatches", 1),
|
|
("match_indices", 1),
|
|
("rmatch_indices", 1),
|
|
("trim_start_matches", 1),
|
|
("trim_end_matches", 1),
|
|
];
|
|
|
|
#[derive(Clone, Copy, PartialEq, Debug)]
|
|
enum SelfKind {
|
|
Value,
|
|
Ref,
|
|
RefMut,
|
|
No,
|
|
}
|
|
|
|
impl SelfKind {
|
|
fn matches<'a>(self, cx: &LateContext<'a>, parent_ty: Ty<'a>, ty: Ty<'a>) -> bool {
|
|
fn matches_value<'a>(cx: &LateContext<'a>, parent_ty: Ty<'_>, ty: Ty<'_>) -> bool {
|
|
if ty == parent_ty {
|
|
true
|
|
} else if ty.is_box() {
|
|
ty.boxed_ty() == parent_ty
|
|
} else if is_type_diagnostic_item(cx, ty, sym::Rc) || is_type_diagnostic_item(cx, ty, sym::Arc) {
|
|
if let ty::Adt(_, substs) = ty.kind() {
|
|
substs.types().next().map_or(false, |t| t == parent_ty)
|
|
} else {
|
|
false
|
|
}
|
|
} else {
|
|
false
|
|
}
|
|
}
|
|
|
|
fn matches_ref<'a>(cx: &LateContext<'a>, mutability: hir::Mutability, parent_ty: Ty<'a>, ty: Ty<'a>) -> bool {
|
|
if let ty::Ref(_, t, m) = *ty.kind() {
|
|
return m == mutability && t == parent_ty;
|
|
}
|
|
|
|
let trait_path = match mutability {
|
|
hir::Mutability::Not => &paths::ASREF_TRAIT,
|
|
hir::Mutability::Mut => &paths::ASMUT_TRAIT,
|
|
};
|
|
|
|
let trait_def_id = match get_trait_def_id(cx, trait_path) {
|
|
Some(did) => did,
|
|
None => return false,
|
|
};
|
|
implements_trait(cx, ty, trait_def_id, &[parent_ty.into()])
|
|
}
|
|
|
|
match self {
|
|
Self::Value => matches_value(cx, parent_ty, ty),
|
|
Self::Ref => matches_ref(cx, hir::Mutability::Not, parent_ty, ty) || ty == parent_ty && is_copy(cx, ty),
|
|
Self::RefMut => matches_ref(cx, hir::Mutability::Mut, parent_ty, ty),
|
|
Self::No => ty != parent_ty,
|
|
}
|
|
}
|
|
|
|
#[must_use]
|
|
fn description(self) -> &'static str {
|
|
match self {
|
|
Self::Value => "self by value",
|
|
Self::Ref => "self by reference",
|
|
Self::RefMut => "self by mutable reference",
|
|
Self::No => "no self",
|
|
}
|
|
}
|
|
}
|
|
|
|
#[derive(Clone, Copy)]
|
|
enum OutType {
|
|
Unit,
|
|
Bool,
|
|
Any,
|
|
Ref,
|
|
}
|
|
|
|
impl OutType {
|
|
fn matches(self, cx: &LateContext<'_>, ty: &hir::FnRetTy<'_>) -> bool {
|
|
let is_unit = |ty: &hir::Ty<'_>| SpanlessEq::new(cx).eq_ty_kind(&ty.kind, &hir::TyKind::Tup(&[]));
|
|
match (self, ty) {
|
|
(Self::Unit, &hir::FnRetTy::DefaultReturn(_)) => true,
|
|
(Self::Unit, &hir::FnRetTy::Return(ref ty)) if is_unit(ty) => true,
|
|
(Self::Bool, &hir::FnRetTy::Return(ref ty)) if is_bool(ty) => true,
|
|
(Self::Any, &hir::FnRetTy::Return(ref ty)) if !is_unit(ty) => true,
|
|
(Self::Ref, &hir::FnRetTy::Return(ref ty)) => matches!(ty.kind, hir::TyKind::Rptr(_, _)),
|
|
_ => false,
|
|
}
|
|
}
|
|
}
|
|
|
|
fn is_bool(ty: &hir::Ty<'_>) -> bool {
|
|
if let hir::TyKind::Path(ref p) = ty.kind {
|
|
match_qpath(p, &["bool"])
|
|
} else {
|
|
false
|
|
}
|
|
}
|
|
|
|
fn fn_header_equals(expected: hir::FnHeader, actual: hir::FnHeader) -> bool {
|
|
expected.constness == actual.constness
|
|
&& expected.unsafety == actual.unsafety
|
|
&& expected.asyncness == actual.asyncness
|
|
}
|