mod bind_instead_of_map;
mod bytes_nth;
+mod chars_cmp;
+mod chars_cmp_with_unwrap;
+mod chars_last_cmp;
+mod chars_last_cmp_with_unwrap;
+mod chars_next_cmp;
+mod chars_next_cmp_with_unwrap;
+mod clone_on_copy;
+mod clone_on_ref_ptr;
+mod cloned_instead_of_copied;
+mod expect_fun_call;
+mod expect_used;
+mod extend_with_drain;
+mod filetype_is_file;
+mod filter_map;
mod filter_map_identity;
+mod filter_map_next;
+mod filter_next;
+mod flat_map_identity;
+mod flat_map_option;
+mod from_iter_instead_of_collect;
+mod get_unwrap;
+mod implicit_clone;
mod inefficient_to_string;
mod inspect_for_each;
+mod into_iter_on_ref;
+mod iter_cloned_collect;
+mod iter_count;
+mod iter_next_slice;
+mod iter_nth;
+mod iter_nth_zero;
+mod iter_overeager_cloned;
+mod iter_skip_next;
+mod iter_with_drain;
+mod iterator_step_by_zero;
mod manual_saturating_arithmetic;
+mod manual_str_repeat;
+mod map_collect_result_unit;
+mod map_flatten;
+mod map_identity;
+mod map_unwrap_or;
+mod ok_expect;
+mod option_as_ref_deref;
+mod option_map_or_none;
mod option_map_unwrap_or;
+mod or_fun_call;
+mod or_then_unwrap;
+mod search_is_some;
+mod single_char_add_str;
+mod single_char_insert_string;
+mod single_char_pattern;
+mod single_char_push_string;
+mod skip_while_next;
+mod str_splitn;
+mod string_extend_chars;
+mod suspicious_map;
+mod suspicious_splitn;
+mod uninit_assumed_init;
mod unnecessary_filter_map;
+mod unnecessary_fold;
+mod unnecessary_iter_cloned;
+mod unnecessary_join;
mod unnecessary_lazy_eval;
-
-use std::borrow::Cow;
-use std::fmt;
-use std::iter;
+mod unnecessary_to_owned;
+mod unwrap_or_else_default;
+mod unwrap_used;
+mod useless_asref;
+mod utils;
+mod wrong_self_convention;
+mod zst_offset;
use bind_instead_of_map::BindInsteadOfMap;
+use clippy_utils::consts::{constant, Constant};
+use clippy_utils::diagnostics::{span_lint, span_lint_and_help};
+use clippy_utils::ty::{contains_adt_constructor, contains_ty, implements_trait, is_copy, is_type_diagnostic_item};
+use clippy_utils::{contains_return, get_trait_def_id, iter_input_pats, meets_msrv, msrvs, paths, return_ty};
use if_chain::if_chain;
-use rustc_ast::ast;
-use rustc_errors::Applicability;
use rustc_hir as hir;
-use rustc_hir::{Expr, ExprKind, PatKind, TraitItem, TraitItemKind, UnOp};
-use rustc_lint::{LateContext, LateLintPass, Lint, LintContext};
+use rustc_hir::def::Res;
+use rustc_hir::{Expr, ExprKind, PrimTy, QPath, TraitItem, TraitItemKind};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::lint::in_external_macro;
-use rustc_middle::ty::{self, TraitRef, Ty, TyS};
+use rustc_middle::ty::{self, TraitRef, Ty};
use rustc_semver::RustcVersion;
use rustc_session::{declare_tool_lint, impl_lint_pass};
-use rustc_span::source_map::Span;
-use rustc_span::symbol::{sym, SymbolStr};
+use rustc_span::{sym, Span};
use rustc_typeck::hir_ty_to_ty;
-use crate::consts::{constant, Constant};
-use crate::utils::eager_or_lazy::is_lazyness_candidate;
-use crate::utils::usage::mutated_variables;
-use crate::utils::{
- contains_return, contains_ty, get_parent_expr, get_trait_def_id, has_iter_method, higher, implements_trait,
- in_macro, is_copy, is_expn_of, is_type_diagnostic_item, iter_input_pats, last_path_segment, match_def_path,
- match_qpath, match_trait_method, match_type, meets_msrv, method_calls, method_chain_args, path_to_local_id, paths,
- remove_blocks, return_ty, single_segment_path, snippet, snippet_with_applicability, snippet_with_macro_callsite,
- span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then, strip_pat_refs, sugg, walk_ptrs_ty_depth,
- SpanlessEq,
-};
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for usages of `cloned()` on an `Iterator` or `Option` where
+ /// `copied()` could be used instead.
+ ///
+ /// ### Why is this bad?
+ /// `copied()` is better because it guarantees that the type being cloned
+ /// implements `Copy`.
+ ///
+ /// ### Example
+ /// ```rust
+ /// [1, 2, 3].iter().cloned();
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// [1, 2, 3].iter().copied();
+ /// ```
+ #[clippy::version = "1.53.0"]
+ pub CLONED_INSTEAD_OF_COPIED,
+ pedantic,
+ "used `cloned` where `copied` could be used instead"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for usage of `_.cloned().<func>()` where call to `.cloned()` can be postponed.
+ ///
+ /// ### Why is this bad?
+ /// It's often inefficient to clone all elements of an iterator, when eventually, only some
+ /// of them will be consumed.
+ ///
+ /// ### Examples
+ /// ```rust
+ /// # let vec = vec!["string".to_string()];
+ ///
+ /// // Bad
+ /// vec.iter().cloned().take(10);
+ ///
+ /// // Good
+ /// vec.iter().take(10).cloned();
+ ///
+ /// // Bad
+ /// vec.iter().cloned().last();
+ ///
+ /// // Good
+ /// vec.iter().last().cloned();
+ ///
+ /// ```
+ /// ### Known Problems
+ /// This `lint` removes the side of effect of cloning items in the iterator.
+ /// A code that relies on that side-effect could fail.
+ ///
+ #[clippy::version = "1.59.0"]
+ pub ITER_OVEREAGER_CLONED,
+ perf,
+ "using `cloned()` early with `Iterator::iter()` can lead to some performance inefficiencies"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for usages of `Iterator::flat_map()` where `filter_map()` could be
+ /// used instead.
+ ///
+ /// ### Why is this bad?
+ /// When applicable, `filter_map()` is more clear since it shows that
+ /// `Option` is used to produce 0 or 1 items.
+ ///
+ /// ### Example
+ /// ```rust
+ /// let nums: Vec<i32> = ["1", "2", "whee!"].iter().flat_map(|x| x.parse().ok()).collect();
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// let nums: Vec<i32> = ["1", "2", "whee!"].iter().filter_map(|x| x.parse().ok()).collect();
+ /// ```
+ #[clippy::version = "1.53.0"]
+ pub FLAT_MAP_OPTION,
+ pedantic,
+ "used `flat_map` where `filter_map` could be used instead"
+}
declare_clippy_lint! {
- /// **What it does:** Checks for `.unwrap()` calls on `Option`s and on `Result`s.
+ /// ### What it does
+ /// Checks for `.unwrap()` calls on `Option`s and on `Result`s.
///
- /// **Why is this bad?** It is better to handle the `None` or `Err` case,
+ /// ### Why is this bad?
+ /// It is better to handle the `None` or `Err` case,
/// or at least call `.expect(_)` with a more helpful message. Still, for a lot of
/// quick-and-dirty code, `unwrap` is a good choice, which is why this lint is
/// `Allow` by default.
/// messages on display. Therefore, it may be beneficial to look at the places
/// where they may get displayed. Activate this lint to do just that.
///
- /// **Known problems:** None.
- ///
- /// **Examples:**
+ /// ### Examples
/// ```rust
/// # let opt = Some(1);
///
/// // Good
/// res.expect("more helpful message");
/// ```
+ #[clippy::version = "1.45.0"]
pub UNWRAP_USED,
restriction,
"using `.unwrap()` on `Result` or `Option`, which should at least get a better message using `expect()`"
}
declare_clippy_lint! {
- /// **What it does:** Checks for `.expect()` calls on `Option`s and `Result`s.
+ /// ### What it does
+ /// Checks for `.expect()` calls on `Option`s and `Result`s.
///
- /// **Why is this bad?** Usually it is better to handle the `None` or `Err` case.
+ /// ### Why is this bad?
+ /// Usually it is better to handle the `None` or `Err` case.
/// Still, for a lot of quick-and-dirty code, `expect` is a good choice, which is why
/// this lint is `Allow` by default.
///
/// values. Normally, you want to implement more sophisticated error handling,
/// and propagate errors upwards with `?` operator.
///
- /// **Known problems:** None.
- ///
- /// **Examples:**
+ /// ### Examples
/// ```rust,ignore
/// # let opt = Some(1);
///
/// res?;
/// # Ok::<(), ()>(())
/// ```
+ #[clippy::version = "1.45.0"]
pub EXPECT_USED,
restriction,
"using `.expect()` on `Result` or `Option`, which might be better handled"
}
declare_clippy_lint! {
- /// **What it does:** Checks for methods that should live in a trait
+ /// ### What it does
+ /// Checks for methods that should live in a trait
/// implementation of a `std` trait (see [llogiq's blog
/// post](http://llogiq.github.io/2015/07/30/traits.html) for further
/// information) instead of an inherent implementation.
///
- /// **Why is this bad?** Implementing the traits improve ergonomics for users of
+ /// ### Why is this bad?
+ /// Implementing the traits improve ergonomics for users of
/// the code, often with very little cost. Also people seeing a `mul(...)`
/// method
/// may expect `*` to work equally, so you should have good reason to disappoint
/// them.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// struct X;
/// impl X {
/// }
/// }
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub SHOULD_IMPLEMENT_TRAIT,
style,
"defining a method that should be implementing a std trait"
}
declare_clippy_lint! {
- /// **What it does:** Checks for methods with certain name prefixes and which
+ /// ### What it does
+ /// Checks for methods with certain name prefixes and which
/// doesn't match how self is taken. The actual rules are:
///
- /// |Prefix |`self` taken |
- /// |-------|----------------------|
- /// |`as_` |`&self` or `&mut self`|
- /// |`from_`| none |
- /// |`into_`|`self` |
- /// |`is_` |`&self` or none |
- /// |`to_` |`&self` |
- ///
- /// **Why is this bad?** Consistency breeds readability. If you follow the
+ /// |Prefix |Postfix |`self` taken | `self` type |
+ /// |-------|------------|-----------------------|--------------|
+ /// |`as_` | none |`&self` or `&mut self` | any |
+ /// |`from_`| none | none | any |
+ /// |`into_`| none |`self` | any |
+ /// |`is_` | none |`&self` or none | any |
+ /// |`to_` | `_mut` |`&mut self` | any |
+ /// |`to_` | not `_mut` |`self` | `Copy` |
+ /// |`to_` | not `_mut` |`&self` | not `Copy` |
+ ///
+ /// Note: Clippy doesn't trigger methods with `to_` prefix in:
+ /// - Traits definition.
+ /// Clippy can not tell if a type that implements a trait is `Copy` or not.
+ /// - Traits implementation, when `&self` is taken.
+ /// The method signature is controlled by the trait and often `&self` is required for all types that implement the trait
+ /// (see e.g. the `std::string::ToString` trait).
+ ///
+ /// Clippy allows `Pin<&Self>` and `Pin<&mut Self>` if `&self` and `&mut self` is required.
+ ///
+ /// Please find more info here:
+ /// https://rust-lang.github.io/api-guidelines/naming.html#ad-hoc-conversions-follow-as_-to_-into_-conventions-c-conv
+ ///
+ /// ### Why is this bad?
+ /// Consistency breeds readability. If you follow the
/// conventions, your users won't be surprised that they, e.g., need to supply a
/// mutable reference to a `as_..` function.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # struct X;
/// impl X {
/// }
/// }
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub WRONG_SELF_CONVENTION,
style,
"defining a method named with an established prefix (like \"into_\") that takes `self` with the wrong convention"
}
declare_clippy_lint! {
- /// **What it does:** This is the same as
- /// [`wrong_self_convention`](#wrong_self_convention), but for public items.
+ /// ### What it does
+ /// Checks for usage of `ok().expect(..)`.
///
- /// **Why is this bad?** See [`wrong_self_convention`](#wrong_self_convention).
+ /// ### Why is this bad?
+ /// Because you usually call `expect()` on the `Result`
+ /// directly to get a better error message.
///
- /// **Known problems:** Actually *renaming* the function may break clients if
- /// the function is part of the public interface. In that case, be mindful of
- /// the stability guarantees you've given your users.
+ /// ### Known problems
+ /// The error type needs to implement `Debug`
///
- /// **Example:**
+ /// ### Example
/// ```rust
- /// # struct X;
- /// impl<'a> X {
- /// pub fn as_str(self) -> &'a str {
- /// "foo"
- /// }
- /// }
+ /// # let x = Ok::<_, ()>(());
+ ///
+ /// // Bad
+ /// x.ok().expect("why did I do this again?");
+ ///
+ /// // Good
+ /// x.expect("why did I do this again?");
/// ```
- pub WRONG_PUB_SELF_CONVENTION,
- restriction,
- "defining a public method named with an established prefix (like \"into_\") that takes `self` with the wrong convention"
+ #[clippy::version = "pre 1.29.0"]
+ pub OK_EXPECT,
+ style,
+ "using `ok().expect()`, which gives worse error messages than calling `expect` directly on the Result"
}
declare_clippy_lint! {
- /// **What it does:** Checks for usage of `ok().expect(..)`.
- ///
- /// **Why is this bad?** Because you usually call `expect()` on the `Result`
- /// directly to get a better error message.
+ /// ### What it does
+ /// Checks for usages of `_.unwrap_or_else(Default::default)` on `Option` and
+ /// `Result` values.
///
- /// **Known problems:** The error type needs to implement `Debug`
+ /// ### Why is this bad?
+ /// Readability, these can be written as `_.unwrap_or_default`, which is
+ /// simpler and more concise.
///
- /// **Example:**
+ /// ### Examples
/// ```rust
- /// # let x = Ok::<_, ()>(());
+ /// # let x = Some(1);
///
/// // Bad
- /// x.ok().expect("why did I do this again?");
+ /// x.unwrap_or_else(Default::default);
+ /// x.unwrap_or_else(u32::default);
///
/// // Good
- /// x.expect("why did I do this again?");
+ /// x.unwrap_or_default();
/// ```
- pub OK_EXPECT,
+ #[clippy::version = "1.56.0"]
+ pub UNWRAP_OR_ELSE_DEFAULT,
style,
- "using `ok().expect()`, which gives worse error messages than calling `expect` directly on the Result"
+ "using `.unwrap_or_else(Default::default)`, which is more succinctly expressed as `.unwrap_or_default()`"
}
declare_clippy_lint! {
- /// **What it does:** Checks for usage of `option.map(_).unwrap_or(_)` or `option.map(_).unwrap_or_else(_)` or
+ /// ### What it does
+ /// Checks for usage of `option.map(_).unwrap_or(_)` or `option.map(_).unwrap_or_else(_)` or
/// `result.map(_).unwrap_or_else(_)`.
///
- /// **Why is this bad?** Readability, these can be written more concisely (resp.) as
+ /// ### Why is this bad?
+ /// Readability, these can be written more concisely (resp.) as
/// `option.map_or(_, _)`, `option.map_or_else(_, _)` and `result.map_or_else(_, _)`.
///
- /// **Known problems:** The order of the arguments is not in execution order
+ /// ### Known problems
+ /// The order of the arguments is not in execution order
///
- /// **Examples:**
+ /// ### Examples
/// ```rust
/// # let x = Some(1);
///
/// // Good
/// x.map_or_else(some_function, |a| a + 1);
/// ```
+ #[clippy::version = "1.45.0"]
pub MAP_UNWRAP_OR,
pedantic,
"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)`"
}
declare_clippy_lint! {
- /// **What it does:** Checks for usage of `_.map_or(None, _)`.
+ /// ### What it does
+ /// Checks for usage of `_.map_or(None, _)`.
///
- /// **Why is this bad?** Readability, this can be written more concisely as
+ /// ### Why is this bad?
+ /// Readability, this can be written more concisely as
/// `_.and_then(_)`.
///
- /// **Known problems:** The order of the arguments is not in execution order.
+ /// ### Known problems
+ /// The order of the arguments is not in execution order.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # let opt = Some(1);
///
/// // Good
/// opt.and_then(|a| Some(a + 1));
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub OPTION_MAP_OR_NONE,
style,
"using `Option.map_or(None, f)`, which is more succinctly expressed as `and_then(f)`"
}
declare_clippy_lint! {
- /// **What it does:** Checks for usage of `_.map_or(None, Some)`.
+ /// ### What it does
+ /// Checks for usage of `_.map_or(None, Some)`.
///
- /// **Why is this bad?** Readability, this can be written more concisely as
+ /// ### Why is this bad?
+ /// Readability, this can be written more concisely as
/// `_.ok()`.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
- ///
+ /// ### Example
/// Bad:
/// ```rust
/// # let r: Result<u32, &str> = Ok(1);
/// # let r: Result<u32, &str> = Ok(1);
/// assert_eq!(Some(1), r.ok());
/// ```
+ #[clippy::version = "1.44.0"]
pub RESULT_MAP_OR_INTO_OPTION,
style,
"using `Result.map_or(None, Some)`, which is more succinctly expressed as `ok()`"
}
declare_clippy_lint! {
- /// **What it does:** Checks for usage of `_.and_then(|x| Some(y))`, `_.and_then(|x| Ok(y))` or
+ /// ### What it does
+ /// Checks for usage of `_.and_then(|x| Some(y))`, `_.and_then(|x| Ok(y))` or
/// `_.or_else(|x| Err(y))`.
///
- /// **Why is this bad?** Readability, this can be written more concisely as
+ /// ### Why is this bad?
+ /// Readability, this can be written more concisely as
/// `_.map(|x| y)` or `_.map_err(|x| y)`.
///
- /// **Known problems:** None
- ///
- /// **Example:**
- ///
+ /// ### Example
/// ```rust
/// # fn opt() -> Option<&'static str> { Some("42") }
/// # fn res() -> Result<&'static str, &'static str> { Ok("42") }
/// let _ = res().map(|s| if s.len() == 42 { 10 } else { 20 });
/// let _ = res().map_err(|s| if s.len() == 42 { 10 } else { 20 });
/// ```
+ #[clippy::version = "1.45.0"]
pub BIND_INSTEAD_OF_MAP,
complexity,
"using `Option.and_then(|x| Some(y))`, which is more succinctly expressed as `map(|x| y)`"
}
declare_clippy_lint! {
- /// **What it does:** Checks for usage of `_.filter(_).next()`.
+ /// ### What it does
+ /// Checks for usage of `_.filter(_).next()`.
///
- /// **Why is this bad?** Readability, this can be written more concisely as
+ /// ### Why is this bad?
+ /// Readability, this can be written more concisely as
/// `_.find(_)`.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # let vec = vec![1];
/// vec.iter().filter(|x| **x == 0).next();
/// # let vec = vec![1];
/// vec.iter().find(|x| **x == 0);
/// ```
+ #[clippy::version = "pre 1.29.0"]
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()`.
+ /// ### What it does
+ /// Checks for usage of `_.skip_while(condition).next()`.
///
- /// **Why is this bad?** Readability, this can be written more concisely as
+ /// ### Why is this bad?
+ /// Readability, this can be written more concisely as
/// `_.find(!condition)`.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # let vec = vec![1];
/// vec.iter().skip_while(|x| **x == 0).next();
/// # let vec = vec![1];
/// vec.iter().find(|x| **x != 0);
/// ```
+ #[clippy::version = "1.42.0"]
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(_)`,
- ///
- /// **Why is this bad?** Readability, this can be written more concisely as
- /// `_.flat_map(_)`
+ /// ### What it does
+ /// Checks for usage of `_.map(_).flatten(_)` on `Iterator` and `Option`
///
- /// **Known problems:**
+ /// ### Why is this bad?
+ /// Readability, this can be written more concisely as
+ /// `_.flat_map(_)` for `Iterator` or `_.and_then(_)` for `Option`
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let vec = vec![vec![1]];
+ /// let opt = Some(5);
///
/// // Bad
/// vec.iter().map(|x| x.iter()).flatten();
+ /// opt.map(|x| Some(x * 2)).flatten();
///
/// // Good
/// vec.iter().flat_map(|x| x.iter());
+ /// opt.and_then(|x| Some(x * 2));
/// ```
+ #[clippy::version = "1.31.0"]
pub MAP_FLATTEN,
- pedantic,
+ complexity,
"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
+ /// ### 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
+ /// ### Why is this bad?
+ /// Redundant code in the `filter` and `map` operations is poor style and
/// less performant.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// Bad:
/// ```rust
/// (0_i32..10)
/// ```rust
/// (0_i32..10).filter_map(|n| n.checked_add(1));
/// ```
+ #[clippy::version = "1.51.0"]
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
+ /// ### 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
+ /// ### Why is this bad?
+ /// Redundant code in the `find` and `map` operations is poor style and
/// less performant.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// Bad:
/// ```rust
/// (0_i32..10)
/// ```rust
/// (0_i32..10).find_map(|n| n.checked_add(1));
/// ```
+ #[clippy::version = "1.51.0"]
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()`.
+ /// ### What it does
+ /// Checks for usage of `_.filter_map(_).next()`.
///
- /// **Why is this bad?** Readability, this can be written more concisely as
+ /// ### Why is this bad?
+ /// Readability, this can be written more concisely as
/// `_.find_map(_)`.
///
- /// **Known problems:** None
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// (0..3).filter_map(|x| if x == 2 { Some(x) } else { None }).next();
/// ```
/// ```rust
/// (0..3).find_map(|x| if x == 2 { Some(x) } else { None });
/// ```
+ #[clippy::version = "1.36.0"]
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)`.
+ /// ### 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`.
+ /// ### Why is this bad?
+ /// Readability, this can be written more concisely by using `flatten`.
///
- /// **Known problems:** None
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # let iter = vec![vec![0]].into_iter();
/// iter.flat_map(|x| x);
/// # let iter = vec![vec![0]].into_iter();
/// iter.flatten();
/// ```
+ #[clippy::version = "1.39.0"]
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(_)`.
+ /// ### What it does
+ /// Checks for an iterator or string search (such as `find()`,
+ /// `position()`, or `rposition()`) followed by a call to `is_some()` or `is_none()`.
///
- /// **Known problems:** None.
+ /// ### Why is this bad?
+ /// Readability, this can be written more concisely as:
+ /// * `_.any(_)`, or `_.contains(_)` for `is_some()`,
+ /// * `!_.any(_)`, or `!_.contains(_)` for `is_none()`.
///
- /// **Example:**
+ /// ### Example
/// ```rust
- /// # let vec = vec![1];
+ /// let vec = vec![1];
/// vec.iter().find(|x| **x == 0).is_some();
+ ///
+ /// let _ = "hello world".find("world").is_none();
/// ```
/// Could be written as
/// ```rust
- /// # let vec = vec![1];
+ /// let vec = vec![1];
/// vec.iter().any(|x| *x == 0);
+ ///
+ /// let _ = !"hello world".contains("world");
/// ```
+ #[clippy::version = "pre 1.29.0"]
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()`"
+ "using an iterator or string search followed by `is_some()` or `is_none()`, which is more succinctly expressed as a call to `any()` or `contains()` (with negation in case of `is_none()`)"
}
declare_clippy_lint! {
- /// **What it does:** Checks for usage of `.chars().next()` on a `str` to check
+ /// ### 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
+ /// ### Why is this bad?
+ /// Readability, this can be written more concisely as
/// `_.starts_with(_)`.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let name = "foo";
/// if name.chars().next() == Some('_') {};
/// let name = "foo";
/// if name.starts_with('_') {};
/// ```
+ #[clippy::version = "pre 1.29.0"]
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(..))`,
+ /// ### 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
+ /// ### 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
+ /// ### 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:**
+ /// ### Example
/// ```rust
/// # let foo = Some(String::new());
/// foo.unwrap_or(String::new());
/// # let foo = Some(String::new());
/// foo.unwrap_or_default();
/// ```
+ #[clippy::version = "pre 1.29.0"]
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(..))`,
+ /// ### What it does
+ /// Checks for `.or(…).unwrap()` calls to Options and Results.
+ ///
+ /// ### Why is this bad?
+ /// You should use `.unwrap_or(…)` instead for clarity.
+ ///
+ /// ### Example
+ /// ```rust
+ /// # let fallback = "fallback";
+ /// // Result
+ /// # type Error = &'static str;
+ /// # let result: Result<&str, Error> = Err("error");
+ /// let value = result.or::<Error>(Ok(fallback)).unwrap();
+ ///
+ /// // Option
+ /// # let option: Option<&str> = None;
+ /// let value = option.or(Some(fallback)).unwrap();
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// # let fallback = "fallback";
+ /// // Result
+ /// # let result: Result<&str, &str> = Err("error");
+ /// let value = result.unwrap_or(fallback);
+ ///
+ /// // Option
+ /// # let option: Option<&str> = None;
+ /// let value = option.unwrap_or(fallback);
+ /// ```
+ #[clippy::version = "1.61.0"]
+ pub OR_THEN_UNWRAP,
+ complexity,
+ "checks for `.or(…).unwrap()` calls to Options and Results."
+}
+
+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.
+ /// ### Why is this bad?
+ /// The function will always be called.
///
- /// **Known problems:** If the function has side-effects, not calling it will
+ /// ### 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:**
+ /// ### Example
/// ```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));
/// ```
+ #[clippy::version = "pre 1.29.0"]
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.
+ /// ### 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
+ /// ### 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:**
+ /// ### Example
/// ```rust
/// 42u64.clone();
/// ```
+ #[clippy::version = "pre 1.29.0"]
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,
+ /// ### 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
+ /// ### 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:**
+ /// ### Example
/// ```rust
/// # use std::rc::Rc;
/// let x = Rc::new(1);
/// // Good
/// Rc::clone(&x);
/// ```
+ #[clippy::version = "pre 1.29.0"]
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`.
+ /// ### What it does
+ /// Checks for usage of `.clone()` on an `&&T`.
///
- /// **Why is this bad?** Cloning an `&&T` copies the inner `&T`, instead of
+ /// ### Why is this bad?
+ /// Cloning an `&&T` copies the inner `&T`, instead of
/// cloning the underlying `T`.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// fn main() {
/// let x = vec![1];
/// println!("{:p} {:p}", *y, z); // prints out the same pointer
/// }
/// ```
+ #[clippy::version = "pre 1.29.0"]
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
+ /// ### 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
+ /// ### 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:**
+ /// ### 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());
/// ```
+ #[clippy::version = "1.40.0"]
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`.
+ /// ### 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
+ /// ### Why is this bad?
+ /// As a convention, `new` methods are used to make a new
/// instance of a type.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// In an impl block:
/// ```rust
/// # struct Foo;
/// fn new() -> Self;
/// }
/// ```
+ #[clippy::version = "pre 1.29.0"]
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
+ /// ### 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
+ /// ### 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.
+ /// ### Known problems
+ /// Does not catch multi-byte unicode characters.
///
- /// **Example:**
+ /// ### Example
/// ```rust,ignore
/// // Bad
/// _.split("x");
///
/// // Good
/// _.split('x');
+ #[clippy::version = "pre 1.29.0"]
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.
+ /// ### 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
+ /// ### Why is this bad?
+ /// This very much looks like an oversight. Use `panic!()` instead if you
/// actually intend to panic.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust,should_panic
/// for x in (0..100).step_by(0) {
/// //..
/// }
/// ```
+ #[clippy::version = "pre 1.29.0"]
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)`.
+ /// ### What it does
+ /// Checks for indirect collection of populated `Option`
///
- /// **Why is this bad?** `iter.next()` is equivalent to
- /// `iter.nth(0)`, as they both consume the next element,
- /// but is more readable.
+ /// ### Why is this bad?
+ /// `Option` is like a collection of 0-1 things, so `flatten`
+ /// automatically does this without suspicious-looking `unwrap` calls.
///
- /// **Known problems:** None.
+ /// ### Example
+ /// ```rust
+ /// let _ = std::iter::empty::<Option<i32>>().filter(Option::is_some).map(Option::unwrap);
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// let _ = std::iter::empty::<Option<i32>>().flatten();
+ /// ```
+ #[clippy::version = "1.53.0"]
+ pub OPTION_FILTER_MAP,
+ complexity,
+ "filtering `Option` for `Some` then force-unwrapping, which can be one type-safe operation"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for the use of `iter.nth(0)`.
///
- /// **Example:**
+ /// ### Why is this bad?
+ /// `iter.next()` is equivalent to
+ /// `iter.nth(0)`, as they both consume the next element,
+ /// but is more readable.
///
+ /// ### Example
/// ```rust
/// # use std::collections::HashSet;
/// // Bad
/// # s.insert(1);
/// let x = s.iter().next();
/// ```
+ #[clippy::version = "1.42.0"]
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.
+ /// ### 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
+ /// ### Why is this bad?
+ /// `.get()` and `.get_mut()` are more efficient and more
/// readable.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let some_vec = vec![0, 1, 2, 3];
/// let bad_vec = some_vec.iter().nth(3);
/// let bad_vec = some_vec.get(3);
/// let bad_slice = &some_vec[..].get(3);
/// ```
+ #[clippy::version = "pre 1.29.0"]
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
+ /// ### What it does
+ /// Checks for use of `.skip(x).next()` on iterators.
///
- /// **Known problems:** None.
+ /// ### Why is this bad?
+ /// `.nth(x)` is cleaner
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let some_vec = vec![0, 1, 2, 3];
/// let bad_vec = some_vec.iter().skip(3).next();
/// let bad_vec = some_vec.iter().nth(3);
/// let bad_slice = &some_vec[..].iter().nth(3);
/// ```
+ #[clippy::version = "pre 1.29.0"]
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
+ /// ### What it does
+ /// Checks for use of `.drain(..)` on `Vec` and `VecDeque` for iteration.
+ ///
+ /// ### Why is this bad?
+ /// `.into_iter()` is simpler with better performance.
+ ///
+ /// ### Example
+ /// ```rust
+ /// # use std::collections::HashSet;
+ /// let mut foo = vec![0, 1, 2, 3];
+ /// let bar: HashSet<usize> = foo.drain(..).collect();
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// # use std::collections::HashSet;
+ /// let foo = vec![0, 1, 2, 3];
+ /// let bar: HashSet<usize> = foo.into_iter().collect();
+ /// ```
+ #[clippy::version = "1.61.0"]
+ pub ITER_WITH_DRAIN,
+ nursery,
+ "replace `.drain(..)` with `.into_iter()`"
+}
+
+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
+ /// ### Why is this bad?
+ /// Using the Index trait (`[]`) is more clear and more
/// concise.
///
- /// **Known problems:** Not a replacement for error handling: Using either
+ /// ### 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
/// is handled in a future refactor instead of using `.unwrap()` or the Index
/// trait.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let mut some_vec = vec![0, 1, 2, 3];
/// let last = some_vec.get(3).unwrap();
/// let last = some_vec[3];
/// some_vec[0] = 1;
/// ```
+ #[clippy::version = "pre 1.29.0"]
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`.
+ /// ### What it does
+ /// Checks for occurrences where one vector gets extended instead of append
+ ///
+ /// ### Why is this bad?
+ /// Using `append` instead of `extend` is more concise and faster
///
- /// **Why is this bad?** `.push_str(s)` is clearer
+ /// ### Example
+ /// ```rust
+ /// let mut a = vec![1, 2, 3];
+ /// let mut b = vec![4, 5, 6];
+ ///
+ /// // Bad
+ /// a.extend(b.drain(..));
+ ///
+ /// // Good
+ /// a.append(&mut b);
+ /// ```
+ #[clippy::version = "1.55.0"]
+ pub EXTEND_WITH_DRAIN,
+ perf,
+ "using vec.append(&mut vec) to move the full range of a vecor to another"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for the use of `.extend(s.chars())` where s is a
+ /// `&str` or `String`.
///
- /// **Known problems:** None.
+ /// ### Why is this bad?
+ /// `.push_str(s)` is clearer
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let abc = "abc";
/// let def = String::from("def");
/// s.push_str(abc);
/// s.push_str(&def);
/// ```
+ #[clippy::version = "pre 1.29.0"]
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
+ /// ### 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.
+ /// ### Why is this bad?
+ /// `.to_vec()` is clearer
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let s = [1, 2, 3, 4, 5];
/// let s2: Vec<isize> = s[..].iter().cloned().collect();
/// let s = [1, 2, 3, 4, 5];
/// let s2: Vec<isize> = s.to_vec();
/// ```
+ #[clippy::version = "pre 1.29.0"]
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
+ /// ### 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
+ /// ### Why is this bad?
+ /// Readability, this can be written more concisely as
/// `_.ends_with(_)`.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # let name = "_";
///
/// // Good
/// name.ends_with('_') || name.ends_with('-');
/// ```
+ #[clippy::version = "pre 1.29.0"]
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
+ /// ### 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.
+ /// ### Why is this bad?
+ /// The call is unnecessary.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # fn do_stuff(x: &[i32]) {}
/// let x: &[i32] = &[1, 2, 3, 4, 5];
/// let x: &[i32] = &[1, 2, 3, 4, 5];
/// do_stuff(x);
/// ```
+ #[clippy::version = "pre 1.29.0"]
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.
+ /// ### 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.
+ /// ### Why is this bad?
+ /// Readability.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let _ = (0..3).fold(false, |acc, x| acc || x > 2);
/// ```
/// ```rust
/// let _ = (0..3).any(|x| x > 2);
/// ```
+ #[clippy::version = "pre 1.29.0"]
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`.
+ /// ### What it does
+ /// Checks for `filter_map` calls that 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
+ /// ### Why is this bad?
+ /// Complexity. The intent is also clearer if only a single
/// operation is being performed.
///
- /// **Known problems:** None
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let _ = (0..3).filter_map(|x| if x > 2 { Some(x) } else { None });
///
/// // As there is no conditional check on the argument this could be written as:
/// let _ = (0..4).map(|x| x + 1);
/// ```
+ #[clippy::version = "1.31.0"]
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`
+ /// ### What it does
+ /// Checks for `find_map` calls that could be replaced by `find` or `map`. More
+ /// specifically it checks if the closure provided is only performing one of the
+ /// find 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.
+ ///
+ /// ### Example
+ /// ```rust
+ /// let _ = (0..3).find_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).find(|&x| x > 2);
+ /// ```
+ ///
+ /// ```rust
+ /// let _ = (0..4).find_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).next();
+ /// ```
+ #[clippy::version = "1.61.0"]
+ pub UNNECESSARY_FIND_MAP,
+ complexity,
+ "using `find_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
+ /// ### 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:**
- ///
+ /// ### Example
/// ```rust
/// // Bad
/// let _ = (&vec![3, 4, 5]).into_iter();
/// // Good
/// let _ = (&vec![3, 4, 5]).iter();
/// ```
+ #[clippy::version = "1.32.0"]
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
+ /// ### What it does
+ /// Checks for calls to `map` followed by a `count`.
///
- /// **Example:**
+ /// ### Why is this bad?
+ /// It looks suspicious. Maybe `map` was confused with `filter`.
+ /// If the `map` call is intentional, this should be rewritten
+ /// using `inspect`. Or, if you intend to drive the iterator to
+ /// completion, you can just use `for_each` instead.
///
+ /// ### Example
/// ```rust
/// let _ = (0..3).map(|x| x + 2).count();
/// ```
+ #[clippy::version = "1.39.0"]
pub SUSPICIOUS_MAP,
- complexity,
+ suspicious,
"suspicious usage of map"
}
declare_clippy_lint! {
- /// **What it does:** Checks for `MaybeUninit::uninit().assume_init()`.
+ /// ### What it does
+ /// Checks for `MaybeUninit::uninit().assume_init()`.
///
- /// **Why is this bad?** For most types, this is undefined behavior.
+ /// ### Why is this bad?
+ /// For most types, this is undefined behavior.
///
- /// **Known problems:** For now, we accept empty tuples and tuples / arrays
+ /// ### 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:**
- ///
+ /// ### Example
/// ```rust
/// // Beware the UB
/// use std::mem::MaybeUninit;
/// MaybeUninit::uninit().assume_init()
/// };
/// ```
+ #[clippy::version = "1.39.0"]
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)`.
+ /// ### 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:**
+ /// ### 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.saturating_add(y);
/// let sub = x.saturating_sub(y);
/// ```
+ #[clippy::version = "1.39.0"]
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
+ /// ### 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
+ /// ### Why is this bad?
+ /// This is a no-op, and likely unintended
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// unsafe { (&() as *const ()).offset(1) };
/// ```
+ #[clippy::version = "1.41.0"]
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()`.
+ /// ### What it does
+ /// Checks for `FileType::is_file()`.
///
- /// **Why is this bad?** When people testing a file type with `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:**
- ///
+ /// ### Example
/// ```rust
/// # || {
/// let metadata = std::fs::metadata("foo.txt")?;
/// # Ok::<_, std::io::Error>(())
/// # };
/// ```
+ #[clippy::version = "1.42.0"]
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).
+ /// ### 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
+ /// ### Why is this bad?
+ /// Readability, this can be written more concisely as
/// `_.as_deref()`.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # let opt = Some("".to_string());
/// opt.as_ref().map(String::as_str)
/// opt.as_deref()
/// # ;
/// ```
+ #[clippy::version = "1.42.0"]
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
+ /// ### 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()`
+ /// ### Why is this bad?
+ /// These can be shortened into `.get()`
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # let a = [1, 2, 3];
/// # let b = vec![1, 2, 3];
/// a.get(2);
/// b.get(0);
/// ```
+ #[clippy::version = "1.46.0"]
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
+ /// ### 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
+ /// ### Why is this bad?
+ /// It's less clear that we are pushing a single character.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let mut string = String::new();
/// string.insert_str(0, "R");
/// string.insert(0, 'R');
/// string.push('R');
/// ```
+ #[clippy::version = "1.49.0"]
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
+ /// ### 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
/// - `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.
+ /// ### 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
+ /// ### 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:**
- ///
+ /// ### Example
/// ```rust
/// // example code where clippy issues a warning
/// let opt: Option<u32> = None;
///
/// opt.unwrap_or(42);
/// ```
+ #[clippy::version = "1.48.0"]
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.
+ /// ### What it does
+ /// Checks for usage of `_.map(_).collect::<Result<(), _>()`.
///
- /// **Known problems:** None
- ///
- /// **Example:**
+ /// ### Why is this bad?
+ /// Using `try_for_each` instead is more readable and idiomatic.
///
+ /// ### Example
/// ```rust
/// (0..3).map(|t| Err(t)).collect::<Result<(), _>>();
/// ```
/// ```rust
/// (0..3).try_for_each(|t| Err(t));
/// ```
+ #[clippy::version = "1.49.0"]
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`
+ /// ### 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
+ /// ### 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:**
- ///
+ /// ### Example
/// ```rust
/// use std::iter::FromIterator;
///
///
/// assert_eq!(v, vec![5, 5, 5, 5, 5]);
/// ```
+ #[clippy::version = "1.49.0"]
pub FROM_ITER_INSTEAD_OF_COLLECT,
- style,
+ pedantic,
"use `.collect()` instead of `::from_iter()`"
}
declare_clippy_lint! {
- /// **What it does:** Checks for usage of `inspect().for_each()`.
+ /// ### What it does
+ /// Checks for usage of `inspect().for_each()`.
///
- /// **Why is this bad?** It is the same as performing the computation
+ /// ### 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:**
- ///
+ /// ### Example
/// ```rust
/// [1,2,3,4,5].iter()
/// .inspect(|&x| println!("inspect the number: {}", x))
/// assert!(x >= 0);
/// });
/// ```
+ #[clippy::version = "1.51.0"]
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`.
+ /// ### What it does
+ /// Checks for usage of `filter_map(|x| x)`.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Why is this bad?
+ /// Readability, this can be written more concisely by using `flatten`.
///
+ /// ### Example
/// ```rust
/// # let iter = vec![Some(1)].into_iter();
/// iter.filter_map(|x| x);
/// # let iter = vec![Some(1)].into_iter();
/// iter.flatten();
/// ```
+ #[clippy::version = "1.52.0"]
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()`.
+ /// ### What it does
+ /// Checks for instances of `map(f)` where `f` is the identity function.
///
- /// **Why is this bad?** `.as_bytes().get()` is more efficient and more
- /// readable.
+ /// ### Why is this bad?
+ /// It can be written more concisely without the call to `map`.
///
- /// **Known problems:** None.
+ /// ### Example
+ /// ```rust
+ /// let x = [1, 2, 3];
+ /// let y: Vec<_> = x.iter().map(|x| x).map(|x| 2*x).collect();
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// let x = [1, 2, 3];
+ /// let y: Vec<_> = x.iter().map(|x| 2*x).collect();
+ /// ```
+ #[clippy::version = "1.52.0"]
+ pub MAP_IDENTITY,
+ complexity,
+ "using iterator.map(|x| x)"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for the use of `.bytes().nth()`.
///
- /// **Example:**
+ /// ### Why is this bad?
+ /// `.as_bytes().get()` is more efficient and more
+ /// readable.
///
+ /// ### Example
/// ```rust
/// // Bad
/// let _ = "Hello".bytes().nth(3);
/// // Good
/// let _ = "Hello".as_bytes().get(3);
/// ```
+ #[clippy::version = "1.52.0"]
pub BYTES_NTH,
style,
"replace `.bytes().nth()` with `.as_bytes().get()`"
}
-pub struct Methods {
- msrv: Option<RustcVersion>,
+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.
+ ///
+ /// ### 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();
+ /// ```
+ #[clippy::version = "1.52.0"]
+ pub IMPLICIT_CLONE,
+ pedantic,
+ "implicitly cloning a value by invoking a function on its dereferenced type"
}
-impl Methods {
- #[must_use]
- pub fn new(msrv: Option<RustcVersion>) -> Self {
- Self { msrv }
- }
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for the use of `.iter().count()`.
+ ///
+ /// ### Why is this bad?
+ /// `.len()` is more efficient and more
+ /// readable.
+ ///
+ /// ### 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();
+ /// ```
+ #[clippy::version = "1.52.0"]
+ pub ITER_COUNT,
+ complexity,
+ "replace `.iter().count()` with `.len()`"
}
-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,
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for calls to [`splitn`]
+ /// (https://doc.rust-lang.org/std/primitive.str.html#method.splitn) and
+ /// related functions with either zero or one splits.
+ ///
+ /// ### Why is this bad?
+ /// These calls don't actually split the value and are
+ /// likely to be intended as a different number.
+ ///
+ /// ### Example
+ /// ```rust
+ /// // Bad
+ /// let s = "";
+ /// for x in s.splitn(1, ":") {
+ /// // use x
+ /// }
+ ///
+ /// // Good
+ /// let s = "";
+ /// for x in s.splitn(2, ":") {
+ /// // use x
+ /// }
+ /// ```
+ #[clippy::version = "1.54.0"]
+ pub SUSPICIOUS_SPLITN,
+ correctness,
+ "checks for `.splitn(0, ..)` and `.splitn(1, ..)`"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for manual implementations of `str::repeat`
+ ///
+ /// ### Why is this bad?
+ /// These are both harder to read, as well as less performant.
+ ///
+ /// ### Example
+ /// ```rust
+ /// // Bad
+ /// let x: String = std::iter::repeat('x').take(10).collect();
+ ///
+ /// // Good
+ /// let x: String = "x".repeat(10);
+ /// ```
+ #[clippy::version = "1.54.0"]
+ pub MANUAL_STR_REPEAT,
+ perf,
+ "manual implementation of `str::repeat`"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for usages of `str::splitn(2, _)`
+ ///
+ /// ### Why is this bad?
+ /// `split_once` is both clearer in intent and slightly more efficient.
+ ///
+ /// ### Example
+ /// ```rust,ignore
+ /// // Bad
+ /// let (key, value) = _.splitn(2, '=').next_tuple()?;
+ /// let value = _.splitn(2, '=').nth(1)?;
+ ///
+ /// // Good
+ /// let (key, value) = _.split_once('=')?;
+ /// let value = _.split_once('=')?.1;
+ /// ```
+ #[clippy::version = "1.57.0"]
+ pub MANUAL_SPLIT_ONCE,
+ complexity,
+ "replace `.splitn(2, pat)` with `.split_once(pat)`"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for usages of `str::splitn` (or `str::rsplitn`) where using `str::split` would be the same.
+ /// ### Why is this bad?
+ /// The function `split` is simpler and there is no performance difference in these cases, considering
+ /// that both functions return a lazy iterator.
+ /// ### Example
+ /// ```rust
+ /// // Bad
+ /// let str = "key=value=add";
+ /// let _ = str.splitn(3, '=').next().unwrap();
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// // Good
+ /// let str = "key=value=add";
+ /// let _ = str.split('=').next().unwrap();
+ /// ```
+ #[clippy::version = "1.58.0"]
+ pub NEEDLESS_SPLITN,
+ complexity,
+ "usages of `str::splitn` that can be replaced with `str::split`"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for unnecessary calls to [`ToOwned::to_owned`](https://doc.rust-lang.org/std/borrow/trait.ToOwned.html#tymethod.to_owned)
+ /// and other `to_owned`-like functions.
+ ///
+ /// ### Why is this bad?
+ /// The unnecessary calls result in useless allocations.
+ ///
+ /// ### Known problems
+ /// `unnecessary_to_owned` can falsely trigger if `IntoIterator::into_iter` is applied to an
+ /// owned copy of a resource and the resource is later used mutably. See
+ /// [#8148](https://github.com/rust-lang/rust-clippy/issues/8148).
+ ///
+ /// ### Example
+ /// ```rust
+ /// let path = std::path::Path::new("x");
+ /// foo(&path.to_string_lossy().to_string());
+ /// fn foo(s: &str) {}
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// let path = std::path::Path::new("x");
+ /// foo(&path.to_string_lossy());
+ /// fn foo(s: &str) {}
+ /// ```
+ #[clippy::version = "1.58.0"]
+ pub UNNECESSARY_TO_OWNED,
+ perf,
+ "unnecessary calls to `to_owned`-like functions"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for use of `.collect::<Vec<String>>().join("")` on iterators.
+ ///
+ /// ### Why is this bad?
+ /// `.collect::<String>()` is more concise and usually more performant
+ ///
+ /// ### Example
+ /// ```rust
+ /// let vector = vec!["hello", "world"];
+ /// let output = vector.iter().map(|item| item.to_uppercase()).collect::<Vec<String>>().join("");
+ /// println!("{}", output);
+ /// ```
+ /// The correct use would be:
+ /// ```rust
+ /// let vector = vec!["hello", "world"];
+ /// let output = vector.iter().map(|item| item.to_uppercase()).collect::<String>();
+ /// println!("{}", output);
+ /// ```
+ /// ### Known problems
+ /// While `.collect::<String>()` is more performant in most cases, there are cases where
+ /// using `.collect::<String>()` over `.collect::<Vec<String>>().join("")`
+ /// will prevent loop unrolling and will result in a negative performance impact.
+ #[clippy::version = "1.61.0"]
+ pub UNNECESSARY_JOIN,
+ pedantic,
+ "using `.collect::<Vec<String>>().join(\"\")` on an iterator"
+}
+
+pub struct Methods {
+ avoid_breaking_exported_api: bool,
+ msrv: Option<RustcVersion>,
+}
+
+impl Methods {
+ #[must_use]
+ pub fn new(avoid_breaking_exported_api: bool, msrv: Option<RustcVersion>) -> Self {
+ Self {
+ avoid_breaking_exported_api,
+ msrv,
+ }
+ }
+}
+
+impl_lint_pass!(Methods => [
+ UNWRAP_USED,
+ EXPECT_USED,
+ SHOULD_IMPLEMENT_TRAIT,
+ WRONG_SELF_CONVENTION,
+ OK_EXPECT,
+ UNWRAP_OR_ELSE_DEFAULT,
+ MAP_UNWRAP_OR,
+ RESULT_MAP_OR_INTO_OPTION,
+ OPTION_MAP_OR_NONE,
+ BIND_INSTEAD_OF_MAP,
+ OR_FUN_CALL,
+ OR_THEN_UNWRAP,
+ EXPECT_FUN_CALL,
CHARS_NEXT_CMP,
CHARS_LAST_CMP,
CLONE_ON_COPY,
CLONE_ON_REF_PTR,
CLONE_DOUBLE_REF,
+ ITER_OVEREAGER_CLONED,
+ CLONED_INSTEAD_OF_COPIED,
+ FLAT_MAP_OPTION,
INEFFICIENT_TO_STRING,
NEW_RET_NO_SELF,
SINGLE_CHAR_PATTERN,
SEARCH_IS_SOME,
FILTER_NEXT,
SKIP_WHILE_NEXT,
- FILTER_MAP,
FILTER_MAP_IDENTITY,
+ MAP_IDENTITY,
MANUAL_FILTER_MAP,
MANUAL_FIND_MAP,
+ OPTION_FILTER_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,
GET_UNWRAP,
STRING_EXTEND_CHARS,
ITER_CLONED_COLLECT,
+ ITER_WITH_DRAIN,
USELESS_ASREF,
UNNECESSARY_FOLD,
UNNECESSARY_FILTER_MAP,
+ UNNECESSARY_FIND_MAP,
INTO_ITER_ON_REF,
SUSPICIOUS_MAP,
UNINIT_ASSUMED_INIT,
MAP_COLLECT_RESULT_UNIT,
FROM_ITER_INSTEAD_OF_COLLECT,
INSPECT_FOR_EACH,
+ IMPLICIT_CLONE,
+ SUSPICIOUS_SPLITN,
+ MANUAL_STR_REPEAT,
+ EXTEND_WITH_DRAIN,
+ MANUAL_SPLIT_ONCE,
+ NEEDLESS_SPLITN,
+ UNNECESSARY_TO_OWNED,
+ UNNECESSARY_JOIN,
]);
+/// Extracts a method call name, args, and `Span` of the method name.
+fn method_call<'tcx>(recv: &'tcx hir::Expr<'tcx>) -> Option<(&'tcx str, &'tcx [hir::Expr<'tcx>], Span)> {
+ if let ExprKind::MethodCall(path, args, _) = recv.kind {
+ if !args.iter().any(|e| e.span.from_expansion()) {
+ let name = path.ident.name.as_str();
+ return Some((name, args, path.ident.span));
+ }
+ }
+ None
+}
+
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) {
+ if expr.span.from_expansion() {
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"] => lint_get_unwrap(cx, expr, arg_lists[1], false),
- ["unwrap", "get_mut"] => lint_get_unwrap(cx, expr, arg_lists[1], true),
- ["unwrap", ..] => lint_unwrap(cx, expr, arg_lists[0]),
- ["expect", "ok"] => lint_ok_expect(cx, expr, arg_lists[1]),
- ["expect", ..] => lint_expect(cx, expr, arg_lists[0]),
- ["unwrap_or", "map"] => option_map_unwrap_or::lint(cx, expr, arg_lists[1], arg_lists[0], method_spans[1]),
- ["unwrap_or_else", "map"] => {
- if !lint_map_unwrap_or_else(cx, expr, arg_lists[1], arg_lists[0], self.msrv.as_ref()) {
- unnecessary_lazy_eval::lint(cx, expr, arg_lists[0], "unwrap_or");
- }
- },
- ["map_or", ..] => lint_map_or_none(cx, expr, arg_lists[0]),
- ["and_then", ..] => {
- let biom_option_linted = bind_instead_of_map::OptionAndThenSome::lint(cx, expr, arg_lists[0]);
- let biom_result_linted = bind_instead_of_map::ResultAndThenOk::lint(cx, expr, arg_lists[0]);
- if !biom_option_linted && !biom_result_linted {
- unnecessary_lazy_eval::lint(cx, expr, arg_lists[0], "and");
- }
- },
- ["or_else", ..] => {
- if !bind_instead_of_map::ResultOrElseErrInfo::lint(cx, expr, arg_lists[0]) {
- unnecessary_lazy_eval::lint(cx, expr, arg_lists[0], "or");
- }
- },
- ["next", "filter"] => lint_filter_next(cx, expr, arg_lists[1]),
- ["next", "skip_while"] => lint_skip_while_next(cx, expr, arg_lists[1]),
- ["next", "iter"] => lint_iter_next(cx, expr, arg_lists[1]),
- ["map", "filter"] => lint_filter_map(cx, expr, false),
- ["map", "filter_map"] => lint_filter_map_map(cx, expr, arg_lists[1], arg_lists[0]),
- ["next", "filter_map"] => lint_filter_map_next(cx, expr, arg_lists[1], self.msrv.as_ref()),
- ["map", "find"] => lint_filter_map(cx, expr, true),
- ["flat_map", "filter"] => lint_filter_flat_map(cx, expr, arg_lists[1], arg_lists[0]),
- ["flat_map", "filter_map"] => lint_filter_map_flat_map(cx, expr, arg_lists[1], arg_lists[0]),
- ["flat_map", ..] => lint_flat_map_identity(cx, expr, arg_lists[0], method_spans[0]),
- ["flatten", "map"] => lint_map_flatten(cx, expr, arg_lists[1]),
- ["is_some", "find"] => lint_search_is_some(cx, expr, "find", arg_lists[1], arg_lists[0], method_spans[1]),
- ["is_some", "position"] => {
- lint_search_is_some(cx, expr, "position", arg_lists[1], arg_lists[0], method_spans[1])
- },
- ["is_some", "rposition"] => {
- lint_search_is_some(cx, expr, "rposition", arg_lists[1], arg_lists[0], method_spans[1])
- },
- ["extend", ..] => lint_extend(cx, expr, arg_lists[0]),
- ["nth", "iter"] => lint_iter_nth(cx, expr, &arg_lists, false),
- ["nth", "iter_mut"] => lint_iter_nth(cx, expr, &arg_lists, true),
- ["nth", "bytes"] => bytes_nth::lints(cx, expr, &arg_lists[1]),
- ["nth", ..] => lint_iter_nth_zero(cx, expr, arg_lists[0]),
- ["step_by", ..] => lint_step_by(cx, expr, arg_lists[0]),
- ["next", "skip"] => lint_iter_skip_next(cx, expr, arg_lists[1]),
- ["collect", "cloned"] => lint_iter_cloned_collect(cx, expr, arg_lists[1]),
- ["as_ref"] => lint_asref(cx, expr, "as_ref", arg_lists[0]),
- ["as_mut"] => lint_asref(cx, expr, "as_mut", arg_lists[0]),
- ["fold", ..] => lint_unnecessary_fold(cx, expr, arg_lists[0], method_spans[0]),
- ["filter_map", ..] => {
- unnecessary_filter_map::lint(cx, expr, arg_lists[0]);
- filter_map_identity::check(cx, expr, arg_lists[0], method_spans[0]);
- },
- ["count", "map"] => lint_suspicious_map(cx, expr),
- ["assume_init"] => lint_maybe_uninit(cx, &arg_lists[0][0], expr),
- ["unwrap_or", arith @ ("checked_add" | "checked_sub" | "checked_mul")] => {
- manual_saturating_arithmetic::lint(cx, expr, &arg_lists, &arith["checked_".len()..])
- },
- ["add" | "offset" | "sub" | "wrapping_offset" | "wrapping_add" | "wrapping_sub"] => {
- check_pointer_offset(cx, expr, arg_lists[0])
- },
- ["is_file", ..] => lint_filetype_is_file(cx, expr, arg_lists[0]),
- ["map", "as_ref"] => {
- lint_option_as_ref_deref(cx, expr, arg_lists[1], arg_lists[0], false, self.msrv.as_ref())
- },
- ["map", "as_mut"] => {
- lint_option_as_ref_deref(cx, expr, arg_lists[1], arg_lists[0], true, self.msrv.as_ref())
- },
- ["unwrap_or_else", ..] => unnecessary_lazy_eval::lint(cx, expr, arg_lists[0], "unwrap_or"),
- ["get_or_insert_with", ..] => unnecessary_lazy_eval::lint(cx, expr, arg_lists[0], "get_or_insert"),
- ["ok_or_else", ..] => unnecessary_lazy_eval::lint(cx, expr, arg_lists[0], "ok_or"),
- ["collect", "map"] => lint_map_collect(cx, expr, arg_lists[1], arg_lists[0]),
- ["for_each", "inspect"] => inspect_for_each::lint(cx, expr, method_spans[1]),
- _ => {},
- }
+ check_methods(cx, expr, self.msrv.as_ref());
match expr.kind {
- hir::ExprKind::Call(ref func, ref args) => {
- if let hir::ExprKind::Path(path) = &func.kind {
- if match_qpath(path, &["from_iter"]) {
- lint_from_iter(cx, expr, args);
- }
- }
+ hir::ExprKind::Call(func, args) => {
+ from_iter_instead_of_collect::check(cx, expr, args, func);
},
- hir::ExprKind::MethodCall(ref method_call, ref method_span, ref args, _) => {
- lint_or_fun_call(cx, expr, *method_span, &method_call.ident.as_str(), args);
- lint_expect_fun_call(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 {
- lint_clone_on_copy(cx, expr, &args[0], self_ty);
- lint_clone_on_ref_ptr(cx, expr, &args[0]);
- }
- if args.len() == 1 && method_call.ident.name == sym!(to_string) {
- inefficient_to_string::lint(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) {
- lint_single_char_push_string(cx, expr, args);
- } else if match_def_path(cx, fn_def_id, &paths::INSERT_STR) {
- lint_single_char_insert_string(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 {
- lint_single_char_pattern(cx, expr, &args[pos]);
- }
- }
- },
- ty::Ref(..) if method_call.ident.name == sym::into_iter => {
- lint_into_iter(cx, expr, self_ty, *method_span);
- },
- _ => (),
- }
+ hir::ExprKind::MethodCall(method_call, args, _) => {
+ let method_span = method_call.ident.span;
+ 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);
+ clone_on_copy::check(cx, expr, method_call.ident.name, args);
+ clone_on_ref_ptr::check(cx, expr, method_call.ident.name, args);
+ inefficient_to_string::check(cx, expr, method_call.ident.name, args);
+ single_char_add_str::check(cx, expr, args);
+ into_iter_on_ref::check(cx, expr, method_span, method_call.ident.name, args);
+ single_char_pattern::check(cx, expr, method_call.ident.name, args);
+ unnecessary_to_owned::check(cx, expr, method_call.ident.name, args);
},
- hir::ExprKind::Binary(op, ref lhs, ref rhs)
- if op.node == hir::BinOpKind::Eq || op.node == hir::BinOpKind::Ne =>
- {
+ hir::ExprKind::Binary(op, lhs, rhs) if op.node == hir::BinOpKind::Eq || op.node == hir::BinOpKind::Ne => {
let mut info = BinaryExprInfo {
expr,
chain: lhs,
eq: op.node == hir::BinOpKind::Eq,
};
lint_binary_expr_with_method_call(cx, &mut info);
- }
+ },
_ => (),
}
}
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;
- }
-
+ let implements_trait = matches!(item.kind, hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }));
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();
+ 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();
+ 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()) {
+ // if this impl block implements a trait, lint in trait definition instead
+ if !implements_trait && cx.access_levels.is_exported(impl_item.def_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) &&
+ method_config.output_type.matches(&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)
+ method_config.lifetime_param_cond(impl_item)
{
span_lint_and_help(
cx,
}
}
- lint_wrong_self_convention(
- cx,
- &name,
- item.vis.node.is_pub(),
- self_ty,
- first_arg_ty,
- first_arg.pat.span
- );
+ if sig.decl.implicit_self.has_implicit_self()
+ && !(self.avoid_breaking_exported_api
+ && cx.access_levels.is_exported(impl_item.def_id))
+ {
+ wrong_self_convention::check(
+ cx,
+ name,
+ self_ty,
+ *first_arg_ty,
+ first_arg.pat.span,
+ implements_trait,
+ false
+ );
+ }
}
}
+ // if this impl block implements a trait, lint in trait definition instead
+ if implements_trait {
+ return;
+ }
+
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) {
+ if let Some(self_adt) = self_ty.ty_adt_def() {
+ if contains_adt_constructor(ret_ty, self_adt) {
+ return;
+ }
+ } else if contains_ty(ret_ty, self_ty) {
return;
}
// 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() {
+ let assoc_ty = match projection_predicate.term {
+ ty::Term::Ty(ty) => ty,
+ ty::Term::Const(_c) => continue,
+ };
// walk the associated type and check for Self
- if contains_ty(projection_predicate.ty, self_ty) {
+ if let Some(self_adt) = self_ty.ty_adt_def() {
+ if contains_adt_constructor(assoc_ty, self_adt) {
+ return;
+ }
+ } else if contains_ty(assoc_ty, self_ty) {
return;
}
}
}
}
- if name == "new" && !TyS::same_type(ret_ty, self_ty) {
+ if name == "new" && ret_ty != self_ty {
span_lint(
cx,
NEW_RET_NO_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 {
- lint_wrong_self_convention(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 lint_wrong_self_convention<'tcx>(
- cx: &LateContext<'tcx>,
- item_name: &str,
- is_pub: bool,
- self_ty: &'tcx TyS<'tcx>,
- first_arg_ty: &'tcx TyS<'tcx>,
- first_arg_span: Span,
-) {
- let lint = if is_pub {
- WRONG_PUB_SELF_CONVENTION
- } else {
- WRONG_SELF_CONVENTION
- };
- if let Some((ref conv, self_kinds)) = &CONVENTIONS.iter().find(|(ref conv, _)| conv.check(item_name)) {
- if !self_kinds.iter().any(|k| k.matches(cx, self_ty, first_arg_ty)) {
- span_lint(
- cx,
- lint,
- first_arg_span,
- &format!(
- "methods called `{}` usually take {}; consider choosing a less ambiguous name",
- conv,
- &self_kinds
- .iter()
- .map(|k| k.description())
- .collect::<Vec<_>>()
- .join(" or ")
- ),
- );
- }
- }
-}
-
-/// Checks for the `OR_FUN_CALL` lint.
-#[allow(clippy::too_many_lines)]
-fn lint_or_fun_call<'tcx>(
- cx: &LateContext<'tcx>,
- expr: &hir::Expr<'_>,
- method_span: Span,
- name: &str,
- args: &'tcx [hir::Expr<'_>],
-) {
- /// Checks for `unwrap_or(T::new())` or `unwrap_or(T::default())`.
- fn check_unwrap_or_default(
- cx: &LateContext<'_>,
- name: &str,
- fun: &hir::Expr<'_>,
- self_expr: &hir::Expr<'_>,
- arg: &hir::Expr<'_>,
- or_has_args: bool,
- span: Span,
- ) -> bool {
- if_chain! {
- if !or_has_args;
- if name == "unwrap_or";
- if let hir::ExprKind::Path(ref qpath) = fun.kind;
- let path = &*last_path_segment(qpath).ident.as_str();
- if ["default", "new"].contains(&path);
- let arg_ty = cx.typeck_results().expr_ty(arg);
- if let Some(default_trait_id) = get_trait_def_id(cx, &paths::DEFAULT_TRAIT);
- if implements_trait(cx, arg_ty, default_trait_id, &[]);
-
- then {
- let mut applicability = Applicability::MachineApplicable;
- span_lint_and_sugg(
- cx,
- OR_FUN_CALL,
- span,
- &format!("use of `{}` followed by a call to `{}`", name, path),
- "try this",
- format!(
- "{}.unwrap_or_default()",
- snippet_with_applicability(cx, self_expr.span, "..", &mut applicability)
- ),
- applicability,
- );
-
- true
- } else {
- false
- }
- }
- }
-
- /// Checks for `*or(foo())`.
- #[allow(clippy::too_many_arguments)]
- fn check_general_case<'tcx>(
- cx: &LateContext<'tcx>,
- name: &str,
- method_span: Span,
- self_expr: &hir::Expr<'_>,
- arg: &'tcx hir::Expr<'_>,
- span: Span,
- // None if lambda is required
- fun_span: Option<Span>,
- ) {
- // (path, fn_has_argument, methods, suffix)
- static KNOW_TYPES: [(&[&str], bool, &[&str], &str); 4] = [
- (&paths::BTREEMAP_ENTRY, false, &["or_insert"], "with"),
- (&paths::HASHMAP_ENTRY, false, &["or_insert"], "with"),
- (&paths::OPTION, false, &["map_or", "ok_or", "or", "unwrap_or"], "else"),
- (&paths::RESULT, true, &["or", "unwrap_or"], "else"),
- ];
-
- if let hir::ExprKind::MethodCall(ref path, _, ref args, _) = &arg.kind {
- if path.ident.as_str() == "len" {
- let ty = cx.typeck_results().expr_ty(&args[0]).peel_refs();
-
- match ty.kind() {
- ty::Slice(_) | ty::Array(_, _) => return,
- _ => (),
- }
-
- if is_type_diagnostic_item(cx, ty, sym::vec_type) {
- return;
- }
- }
- }
-
- if_chain! {
- if KNOW_TYPES.iter().any(|k| k.2.contains(&name));
-
- if is_lazyness_candidate(cx, arg);
- if !contains_return(&arg);
-
- let self_ty = cx.typeck_results().expr_ty(self_expr);
-
- if let Some(&(_, fn_has_arguments, poss, suffix)) =
- KNOW_TYPES.iter().find(|&&i| match_type(cx, self_ty, i.0));
-
- if poss.contains(&name);
-
- then {
- let sugg: Cow<'_, str> = {
- let (snippet_span, use_lambda) = match (fn_has_arguments, fun_span) {
- (false, Some(fun_span)) => (fun_span, false),
- _ => (arg.span, true),
- };
- let snippet = snippet_with_macro_callsite(cx, snippet_span, "..");
- if use_lambda {
- let l_arg = if fn_has_arguments { "_" } else { "" };
- format!("|{}| {}", l_arg, snippet).into()
- } else {
- snippet
- }
- };
- let span_replace_word = method_span.with_hi(span.hi());
- span_lint_and_sugg(
- cx,
- OR_FUN_CALL,
- span_replace_word,
- &format!("use of `{}` followed by a function call", name),
- "try this",
- format!("{}_{}({})", name, suffix, sugg),
- Applicability::HasPlaceholders,
- );
- }
- }
- }
-
- if args.len() == 2 {
- match args[1].kind {
- hir::ExprKind::Call(ref fun, ref or_args) => {
- let or_has_args = !or_args.is_empty();
- if !check_unwrap_or_default(cx, name, fun, &args[0], &args[1], or_has_args, expr.span) {
- let fun_span = if or_has_args { None } else { Some(fun.span) };
- check_general_case(cx, name, method_span, &args[0], &args[1], expr.span, fun_span);
- }
- },
- hir::ExprKind::Index(..) | hir::ExprKind::MethodCall(..) => {
- check_general_case(cx, name, method_span, &args[0], &args[1], expr.span, None);
- },
- _ => {},
- }
- }
-}
-
-/// Checks for the `EXPECT_FUN_CALL` lint.
-#[allow(clippy::too_many_lines)]
-fn lint_expect_fun_call(
- cx: &LateContext<'_>,
- expr: &hir::Expr<'_>,
- method_span: Span,
- name: &str,
- args: &[hir::Expr<'_>],
-) {
- // Strip `&`, `as_ref()` and `as_str()` off `arg` until we're left with either a `String` or
- // `&str`
- fn get_arg_root<'a>(cx: &LateContext<'_>, arg: &'a hir::Expr<'a>) -> &'a hir::Expr<'a> {
- let mut arg_root = arg;
- loop {
- arg_root = match &arg_root.kind {
- hir::ExprKind::AddrOf(hir::BorrowKind::Ref, _, expr) => expr,
- hir::ExprKind::MethodCall(method_name, _, call_args, _) => {
- if call_args.len() == 1
- && (method_name.ident.name == sym::as_str || method_name.ident.name == sym!(as_ref))
- && {
- let arg_type = cx.typeck_results().expr_ty(&call_args[0]);
- let base_type = arg_type.peel_refs();
- *base_type.kind() == ty::Str || is_type_diagnostic_item(cx, base_type, sym::string_type)
- }
- {
- &call_args[0]
- } else {
- break;
- }
- },
- _ => break,
- };
- }
- arg_root
- }
-
- // Only `&'static str` or `String` can be used directly in the `panic!`. Other types should be
- // converted to string.
- fn requires_to_string(cx: &LateContext<'_>, arg: &hir::Expr<'_>) -> bool {
- let arg_ty = cx.typeck_results().expr_ty(arg);
- if is_type_diagnostic_item(cx, arg_ty, sym::string_type) {
- return false;
- }
- if let ty::Ref(_, ty, ..) = arg_ty.kind() {
- if *ty.kind() == ty::Str && can_be_static_str(cx, arg) {
- return false;
- }
- };
- true
- }
-
- // Check if an expression could have type `&'static str`, knowing that it
- // has type `&str` for some lifetime.
- fn can_be_static_str(cx: &LateContext<'_>, arg: &hir::Expr<'_>) -> bool {
- match arg.kind {
- hir::ExprKind::Lit(_) => true,
- hir::ExprKind::Call(fun, _) => {
- if let hir::ExprKind::Path(ref p) = fun.kind {
- match cx.qpath_res(p, fun.hir_id) {
- hir::def::Res::Def(hir::def::DefKind::Fn | hir::def::DefKind::AssocFn, def_id) => matches!(
- cx.tcx.fn_sig(def_id).output().skip_binder().kind(),
- ty::Ref(ty::ReStatic, ..)
- ),
- _ => false,
- }
- } else {
- false
- }
- },
- hir::ExprKind::MethodCall(..) => {
- cx.typeck_results()
- .type_dependent_def_id(arg.hir_id)
- .map_or(false, |method_id| {
- matches!(
- cx.tcx.fn_sig(method_id).output().skip_binder().kind(),
- ty::Ref(ty::ReStatic, ..)
- )
- })
- },
- hir::ExprKind::Path(ref p) => matches!(
- cx.qpath_res(p, arg.hir_id),
- hir::def::Res::Def(hir::def::DefKind::Const | hir::def::DefKind::Static, _)
- ),
- _ => false,
- }
- }
-
- fn generate_format_arg_snippet(
- cx: &LateContext<'_>,
- a: &hir::Expr<'_>,
- applicability: &mut Applicability,
- ) -> Vec<String> {
- if_chain! {
- if let hir::ExprKind::AddrOf(hir::BorrowKind::Ref, _, ref format_arg) = a.kind;
- if let hir::ExprKind::Match(ref format_arg_expr, _, _) = format_arg.kind;
- if let hir::ExprKind::Tup(ref format_arg_expr_tup) = format_arg_expr.kind;
-
- then {
- format_arg_expr_tup
- .iter()
- .map(|a| snippet_with_applicability(cx, a.span, "..", applicability).into_owned())
- .collect()
- } else {
- unreachable!()
- }
- }
- }
-
- fn is_call(node: &hir::ExprKind<'_>) -> bool {
- match node {
- hir::ExprKind::AddrOf(hir::BorrowKind::Ref, _, expr) => {
- is_call(&expr.kind)
- },
- hir::ExprKind::Call(..)
- | hir::ExprKind::MethodCall(..)
- // These variants are debatable or require further examination
- | hir::ExprKind::If(..)
- | hir::ExprKind::Match(..)
- | hir::ExprKind::Block{ .. } => true,
- _ => false,
- }
- }
-
- if args.len() != 2 || name != "expect" || !is_call(&args[1].kind) {
- return;
- }
-
- let receiver_type = cx.typeck_results().expr_ty_adjusted(&args[0]);
- let closure_args = if is_type_diagnostic_item(cx, receiver_type, sym::option_type) {
- "||"
- } else if is_type_diagnostic_item(cx, receiver_type, sym::result_type) {
- "|_|"
- } else {
- return;
- };
-
- let arg_root = get_arg_root(cx, &args[1]);
-
- let span_replace_word = method_span.with_hi(expr.span.hi());
-
- let mut applicability = Applicability::MachineApplicable;
-
- //Special handling for `format!` as arg_root
- if_chain! {
- if let hir::ExprKind::Block(block, None) = &arg_root.kind;
- if block.stmts.len() == 1;
- if let hir::StmtKind::Local(local) = &block.stmts[0].kind;
- if let Some(arg_root) = &local.init;
- if let hir::ExprKind::Call(ref inner_fun, ref inner_args) = arg_root.kind;
- if is_expn_of(inner_fun.span, "format").is_some() && inner_args.len() == 1;
- if let hir::ExprKind::Call(_, format_args) = &inner_args[0].kind;
- then {
- let fmt_spec = &format_args[0];
- let fmt_args = &format_args[1];
-
- let mut args = vec![snippet(cx, fmt_spec.span, "..").into_owned()];
-
- args.extend(generate_format_arg_snippet(cx, fmt_args, &mut applicability));
-
- let sugg = args.join(", ");
-
- span_lint_and_sugg(
- cx,
- EXPECT_FUN_CALL,
- span_replace_word,
- &format!("use of `{}` followed by a function call", name),
- "try this",
- format!("unwrap_or_else({} panic!({}))", closure_args, sugg),
- applicability,
- );
-
- return;
- }
- }
-
- let mut arg_root_snippet: Cow<'_, _> = snippet_with_applicability(cx, arg_root.span, "..", &mut applicability);
- if requires_to_string(cx, arg_root) {
- arg_root_snippet.to_mut().push_str(".to_string()");
- }
-
- span_lint_and_sugg(
- cx,
- EXPECT_FUN_CALL,
- span_replace_word,
- &format!("use of `{}` followed by a function call", name),
- "try this",
- format!(
- "unwrap_or_else({} {{ panic!(\"{{}}\", {}) }})",
- closure_args, arg_root_snippet
- ),
- applicability,
- );
-}
-
-/// Checks for the `CLONE_ON_COPY` lint.
-fn lint_clone_on_copy(cx: &LateContext<'_>, expr: &hir::Expr<'_>, arg: &hir::Expr<'_>, arg_ty: Ty<'_>) {
- let ty = cx.typeck_results().expr_ty(expr);
- if let ty::Ref(_, inner, _) = arg_ty.kind() {
- if let ty::Ref(_, innermost, _) = inner.kind() {
- span_lint_and_then(
- cx,
- CLONE_DOUBLE_REF,
- expr.span,
- &format!(
- "using `clone` on a double-reference; \
- this will copy the reference of type `{}` instead of cloning the inner type",
- ty
- ),
- |diag| {
- if let Some(snip) = sugg::Sugg::hir_opt(cx, arg) {
- let mut ty = innermost;
- let mut n = 0;
- while let ty::Ref(_, inner, _) = ty.kind() {
- ty = inner;
- n += 1;
- }
- let refs: String = iter::repeat('&').take(n + 1).collect();
- let derefs: String = iter::repeat('*').take(n).collect();
- let explicit = format!("<{}{}>::clone({})", refs, ty, snip);
- diag.span_suggestion(
- expr.span,
- "try dereferencing it",
- format!("{}({}{}).clone()", refs, derefs, snip.deref()),
- Applicability::MaybeIncorrect,
- );
- diag.span_suggestion(
- expr.span,
- "or try being explicit if you are sure, that you want to clone a reference",
- explicit,
- Applicability::MaybeIncorrect,
- );
- }
- },
- );
- return; // don't report clone_on_copy
- }
- }
-
- if is_copy(cx, ty) {
- let snip;
- if let Some(snippet) = sugg::Sugg::hir_opt(cx, arg) {
- let parent = cx.tcx.hir().get_parent_node(expr.hir_id);
- match &cx.tcx.hir().get(parent) {
- hir::Node::Expr(parent) => match parent.kind {
- // &*x is a nop, &x.clone() is not
- hir::ExprKind::AddrOf(..) => return,
- // (*x).func() is useless, x.clone().func() can work in case func borrows mutably
- hir::ExprKind::MethodCall(_, _, parent_args, _) if expr.hir_id == parent_args[0].hir_id => {
- return;
- },
-
- _ => {},
- },
- hir::Node::Stmt(stmt) => {
- if let hir::StmtKind::Local(ref loc) = stmt.kind {
- if let hir::PatKind::Ref(..) = loc.pat.kind {
- // let ref y = *x borrows x, let ref y = x.clone() does not
- return;
- }
- }
- },
- _ => {},
- }
-
- // x.clone() might have dereferenced x, possibly through Deref impls
- if cx.typeck_results().expr_ty(arg) == ty {
- snip = Some(("try removing the `clone` call", format!("{}", snippet)));
- } else {
- let deref_count = cx
- .typeck_results()
- .expr_adjustments(arg)
- .iter()
- .filter(|adj| matches!(adj.kind, ty::adjustment::Adjust::Deref(_)))
- .count();
- let derefs: String = iter::repeat('*').take(deref_count).collect();
- snip = Some(("try dereferencing it", format!("{}{}", derefs, snippet)));
- }
- } else {
- snip = None;
- }
- span_lint_and_then(
- cx,
- CLONE_ON_COPY,
- expr.span,
- &format!("using `clone` on type `{}` which implements the `Copy` trait", ty),
- |diag| {
- if let Some((text, snip)) = snip {
- diag.span_suggestion(expr.span, text, snip, Applicability::MachineApplicable);
- }
- },
- );
- }
-}
-
-fn lint_clone_on_ref_ptr(cx: &LateContext<'_>, expr: &hir::Expr<'_>, arg: &hir::Expr<'_>) {
- let obj_ty = cx.typeck_results().expr_ty(arg).peel_refs();
-
- if let ty::Adt(_, subst) = obj_ty.kind() {
- let caller_type = if is_type_diagnostic_item(cx, obj_ty, sym::Rc) {
- "Rc"
- } else if is_type_diagnostic_item(cx, obj_ty, sym::Arc) {
- "Arc"
- } else if match_type(cx, obj_ty, &paths::WEAK_RC) || match_type(cx, obj_ty, &paths::WEAK_ARC) {
- "Weak"
- } else {
- return;
- };
-
- let snippet = snippet_with_macro_callsite(cx, arg.span, "..");
-
- span_lint_and_sugg(
- cx,
- CLONE_ON_REF_PTR,
- expr.span,
- "using `.clone()` on a ref-counted pointer",
- "try this",
- format!("{}::<{}>::clone(&{})", caller_type, subst.type_at(0), snippet),
- Applicability::Unspecified, // Sometimes unnecessary ::<_> after Rc/Arc/Weak
- );
- }
-}
-
-fn lint_string_extend(cx: &LateContext<'_>, expr: &hir::Expr<'_>, args: &[hir::Expr<'_>]) {
- let arg = &args[1];
- if let Some(arglists) = method_chain_args(arg, &["chars"]) {
- let target = &arglists[0][0];
- let self_ty = cx.typeck_results().expr_ty(target).peel_refs();
- let ref_str = if *self_ty.kind() == ty::Str {
- ""
- } else if is_type_diagnostic_item(cx, self_ty, sym::string_type) {
- "&"
- } else {
- return;
- };
-
- let mut applicability = Applicability::MachineApplicable;
- span_lint_and_sugg(
- cx,
- STRING_EXTEND_CHARS,
- expr.span,
- "calling `.extend(_.chars())`",
- "try this",
- format!(
- "{}.push_str({}{})",
- snippet_with_applicability(cx, args[0].span, "..", &mut applicability),
- ref_str,
- snippet_with_applicability(cx, target.span, "..", &mut applicability)
- ),
- applicability,
- );
- }
-}
-
-fn lint_extend(cx: &LateContext<'_>, expr: &hir::Expr<'_>, args: &[hir::Expr<'_>]) {
- let obj_ty = cx.typeck_results().expr_ty(&args[0]).peel_refs();
- if is_type_diagnostic_item(cx, obj_ty, sym::string_type) {
- lint_string_extend(cx, expr, args);
- }
-}
-
-fn lint_iter_cloned_collect<'tcx>(cx: &LateContext<'tcx>, expr: &hir::Expr<'_>, iter_args: &'tcx [hir::Expr<'_>]) {
- if_chain! {
- if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(expr), sym::vec_type);
- if let Some(slice) = derefs_to_slice(cx, &iter_args[0], cx.typeck_results().expr_ty(&iter_args[0]));
- if let Some(to_replace) = expr.span.trim_start(slice.span.source_callsite());
-
- then {
- span_lint_and_sugg(
- cx,
- ITER_CLONED_COLLECT,
- to_replace,
- "called `iter().cloned().collect()` on a slice to create a `Vec`. Calling `to_vec()` is both faster and \
- more readable",
- "try",
- ".to_vec()".to_string(),
- Applicability::MachineApplicable,
- );
- }
- }
-}
-
-fn lint_unnecessary_fold(cx: &LateContext<'_>, expr: &hir::Expr<'_>, fold_args: &[hir::Expr<'_>], fold_span: Span) {
- fn check_fold_with_op(
- cx: &LateContext<'_>,
- expr: &hir::Expr<'_>,
- fold_args: &[hir::Expr<'_>],
- fold_span: Span,
- op: hir::BinOpKind,
- replacement_method_name: &str,
- replacement_has_args: bool,
- ) {
- if_chain! {
- // Extract the body of the closure passed to fold
- if let hir::ExprKind::Closure(_, _, body_id, _, _) = fold_args[2].kind;
- let closure_body = cx.tcx.hir().body(body_id);
- let closure_expr = remove_blocks(&closure_body.value);
-
- // Check if the closure body is of the form `acc <op> some_expr(x)`
- if let hir::ExprKind::Binary(ref bin_op, ref left_expr, ref right_expr) = closure_expr.kind;
- if bin_op.node == op;
-
- // Extract the names of the two arguments to the closure
- if let [param_a, param_b] = closure_body.params;
- if let PatKind::Binding(_, first_arg_id, ..) = strip_pat_refs(¶m_a.pat).kind;
- if let PatKind::Binding(_, second_arg_id, second_arg_ident, _) = strip_pat_refs(¶m_b.pat).kind;
-
- if path_to_local_id(left_expr, first_arg_id);
- if replacement_has_args || path_to_local_id(right_expr, second_arg_id);
-
- then {
- let mut applicability = Applicability::MachineApplicable;
- let sugg = if replacement_has_args {
- format!(
- "{replacement}(|{s}| {r})",
- replacement = replacement_method_name,
- s = second_arg_ident,
- r = snippet_with_applicability(cx, right_expr.span, "EXPR", &mut applicability),
- )
- } else {
- format!(
- "{replacement}()",
- replacement = replacement_method_name,
- )
- };
-
- span_lint_and_sugg(
- cx,
- UNNECESSARY_FOLD,
- fold_span.with_hi(expr.span.hi()),
- // TODO #2371 don't suggest e.g., .any(|x| f(x)) if we can suggest .any(f)
- "this `.fold` can be written more succinctly using another method",
- "try",
- sugg,
- applicability,
- );
- }
- }
- }
-
- // Check that this is a call to Iterator::fold rather than just some function called fold
- if !match_trait_method(cx, expr, &paths::ITERATOR) {
- return;
- }
-
- assert!(
- fold_args.len() == 3,
- "Expected fold_args to have three entries - the receiver, the initial value and the closure"
- );
-
- // Check if the first argument to .fold is a suitable literal
- if let hir::ExprKind::Lit(ref lit) = fold_args[1].kind {
- match lit.node {
- ast::LitKind::Bool(false) => {
- check_fold_with_op(cx, expr, fold_args, fold_span, hir::BinOpKind::Or, "any", true)
- },
- ast::LitKind::Bool(true) => {
- check_fold_with_op(cx, expr, fold_args, fold_span, hir::BinOpKind::And, "all", true)
- },
- ast::LitKind::Int(0, _) => {
- check_fold_with_op(cx, expr, fold_args, fold_span, hir::BinOpKind::Add, "sum", false)
- },
- ast::LitKind::Int(1, _) => {
- check_fold_with_op(cx, expr, fold_args, fold_span, hir::BinOpKind::Mul, "product", false)
- },
- _ => (),
- }
- }
-}
-
-fn lint_step_by<'tcx>(cx: &LateContext<'tcx>, expr: &hir::Expr<'_>, args: &'tcx [hir::Expr<'_>]) {
- if match_trait_method(cx, expr, &paths::ITERATOR) {
- if let Some((Constant::Int(0), _)) = constant(cx, cx.typeck_results(), &args[1]) {
- span_lint(
- cx,
- ITERATOR_STEP_BY_ZERO,
- expr.span,
- "Iterator::step_by(0) will panic at runtime",
- );
- }
- }
-}
-
-fn lint_iter_next<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>, iter_args: &'tcx [hir::Expr<'_>]) {
- let caller_expr = &iter_args[0];
-
- // Skip lint if the `iter().next()` expression is a for loop argument,
- // since it is already covered by `&loops::ITER_NEXT_LOOP`
- let mut parent_expr_opt = get_parent_expr(cx, expr);
- while let Some(parent_expr) = parent_expr_opt {
- if higher::for_loop(parent_expr).is_some() {
- return;
- }
- parent_expr_opt = get_parent_expr(cx, parent_expr);
- }
-
- if derefs_to_slice(cx, caller_expr, cx.typeck_results().expr_ty(caller_expr)).is_some() {
- // caller is a Slice
- if_chain! {
- if let hir::ExprKind::Index(ref caller_var, ref index_expr) = &caller_expr.kind;
- if let Some(higher::Range { start: Some(start_expr), end: None, limits: ast::RangeLimits::HalfOpen })
- = higher::range(index_expr);
- if let hir::ExprKind::Lit(ref start_lit) = &start_expr.kind;
- if let ast::LitKind::Int(start_idx, _) = start_lit.node;
- then {
- let mut applicability = Applicability::MachineApplicable;
- span_lint_and_sugg(
- cx,
- ITER_NEXT_SLICE,
- expr.span,
- "using `.iter().next()` on a Slice without end index",
- "try calling",
- format!("{}.get({})", snippet_with_applicability(cx, caller_var.span, "..", &mut applicability), start_idx),
- applicability,
- );
- }
- }
- } else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(caller_expr), sym::vec_type)
- || matches!(
- &cx.typeck_results().expr_ty(caller_expr).peel_refs().kind(),
- ty::Array(_, _)
- )
- {
- // caller is a Vec or an Array
- let mut applicability = Applicability::MachineApplicable;
- span_lint_and_sugg(
- cx,
- ITER_NEXT_SLICE,
- expr.span,
- "using `.iter().next()` on an array",
- "try calling",
- format!(
- "{}.get(0)",
- snippet_with_applicability(cx, caller_expr.span, "..", &mut applicability)
- ),
- applicability,
- );
- }
-}
-
-fn lint_iter_nth<'tcx>(
- cx: &LateContext<'tcx>,
- expr: &hir::Expr<'_>,
- nth_and_iter_args: &[&'tcx [hir::Expr<'tcx>]],
- is_mut: bool,
-) {
- let iter_args = nth_and_iter_args[1];
- let mut_str = if is_mut { "_mut" } else { "" };
- let caller_type = if derefs_to_slice(cx, &iter_args[0], cx.typeck_results().expr_ty(&iter_args[0])).is_some() {
- "slice"
- } else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&iter_args[0]), sym::vec_type) {
- "Vec"
- } else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&iter_args[0]), sym!(vecdeque_type)) {
- "VecDeque"
- } else {
- let nth_args = nth_and_iter_args[0];
- lint_iter_nth_zero(cx, expr, &nth_args);
- return; // caller is not a type that we want to lint
- };
-
- span_lint_and_help(
- cx,
- ITER_NTH,
- expr.span,
- &format!("called `.iter{0}().nth()` on a {1}", mut_str, caller_type),
- None,
- &format!("calling `.get{}()` is both faster and more readable", mut_str),
- );
-}
-
-fn lint_iter_nth_zero<'tcx>(cx: &LateContext<'tcx>, expr: &hir::Expr<'_>, nth_args: &'tcx [hir::Expr<'_>]) {
- if_chain! {
- if match_trait_method(cx, expr, &paths::ITERATOR);
- if let Some((Constant::Int(0), _)) = constant(cx, cx.typeck_results(), &nth_args[1]);
- then {
- let mut applicability = Applicability::MachineApplicable;
- span_lint_and_sugg(
- cx,
- ITER_NTH_ZERO,
- expr.span,
- "called `.nth(0)` on a `std::iter::Iterator`, when `.next()` is equivalent",
- "try calling `.next()` instead of `.nth(0)`",
- format!("{}.next()", snippet_with_applicability(cx, nth_args[0].span, "..", &mut applicability)),
- applicability,
- );
- }
- }
-}
-
-fn lint_get_unwrap<'tcx>(cx: &LateContext<'tcx>, expr: &hir::Expr<'_>, get_args: &'tcx [hir::Expr<'_>], is_mut: bool) {
- // Note: we don't want to lint `get_mut().unwrap` for `HashMap` or `BTreeMap`,
- // because they do not implement `IndexMut`
- let mut applicability = Applicability::MachineApplicable;
- let expr_ty = cx.typeck_results().expr_ty(&get_args[0]);
- let get_args_str = if get_args.len() > 1 {
- snippet_with_applicability(cx, get_args[1].span, "..", &mut applicability)
- } else {
- return; // not linting on a .get().unwrap() chain or variant
- };
- let mut needs_ref;
- let caller_type = if derefs_to_slice(cx, &get_args[0], expr_ty).is_some() {
- needs_ref = get_args_str.parse::<usize>().is_ok();
- "slice"
- } else if is_type_diagnostic_item(cx, expr_ty, sym::vec_type) {
- needs_ref = get_args_str.parse::<usize>().is_ok();
- "Vec"
- } else if is_type_diagnostic_item(cx, expr_ty, sym!(vecdeque_type)) {
- needs_ref = get_args_str.parse::<usize>().is_ok();
- "VecDeque"
- } else if !is_mut && is_type_diagnostic_item(cx, expr_ty, sym!(hashmap_type)) {
- needs_ref = true;
- "HashMap"
- } else if !is_mut && match_type(cx, expr_ty, &paths::BTREEMAP) {
- needs_ref = true;
- "BTreeMap"
- } else {
- return; // caller is not a type that we want to lint
- };
-
- let mut span = expr.span;
-
- // Handle the case where the result is immediately dereferenced
- // by not requiring ref and pulling the dereference into the
- // suggestion.
- if_chain! {
- if needs_ref;
- if let Some(parent) = get_parent_expr(cx, expr);
- if let hir::ExprKind::Unary(hir::UnOp::Deref, _) = parent.kind;
- then {
- needs_ref = false;
- span = parent.span;
- }
- }
-
- let mut_str = if is_mut { "_mut" } else { "" };
- let borrow_str = if !needs_ref {
- ""
- } else if is_mut {
- "&mut "
- } else {
- "&"
- };
-
- span_lint_and_sugg(
- cx,
- GET_UNWRAP,
- span,
- &format!(
- "called `.get{0}().unwrap()` on a {1}. Using `[]` is more clear and more concise",
- mut_str, caller_type
- ),
- "try this",
- format!(
- "{}{}[{}]",
- borrow_str,
- snippet_with_applicability(cx, get_args[0].span, "..", &mut applicability),
- get_args_str
- ),
- applicability,
- );
-}
-
-fn lint_iter_skip_next(cx: &LateContext<'_>, expr: &hir::Expr<'_>, skip_args: &[hir::Expr<'_>]) {
- // lint if caller of skip is an Iterator
- if match_trait_method(cx, expr, &paths::ITERATOR) {
- if let [caller, n] = skip_args {
- let hint = format!(".nth({})", snippet(cx, n.span, ".."));
- span_lint_and_sugg(
- cx,
- ITER_SKIP_NEXT,
- expr.span.trim_start(caller.span).unwrap(),
- "called `skip(..).next()` on an iterator",
- "use `nth` instead",
- hint,
- Applicability::MachineApplicable,
- );
- }
- }
-}
-
-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,
- }
- }
-}
-
-/// lint use of `unwrap()` for `Option`s and `Result`s
-fn lint_unwrap(cx: &LateContext<'_>, expr: &hir::Expr<'_>, unwrap_args: &[hir::Expr<'_>]) {
- let obj_ty = cx.typeck_results().expr_ty(&unwrap_args[0]).peel_refs();
-
- let mess = if is_type_diagnostic_item(cx, obj_ty, sym::option_type) {
- Some((UNWRAP_USED, "an Option", "None"))
- } else if is_type_diagnostic_item(cx, obj_ty, sym::result_type) {
- Some((UNWRAP_USED, "a Result", "Err"))
- } else {
- None
- };
-
- if let Some((lint, kind, none_value)) = mess {
- span_lint_and_help(
- cx,
- lint,
- expr.span,
- &format!("used `unwrap()` on `{}` value", kind,),
- None,
- &format!(
- "if you don't want to handle the `{}` case gracefully, consider \
- using `expect()` to provide a better panic message",
- none_value,
- ),
- );
- }
-}
-
-/// lint use of `expect()` for `Option`s and `Result`s
-fn lint_expect(cx: &LateContext<'_>, expr: &hir::Expr<'_>, expect_args: &[hir::Expr<'_>]) {
- let obj_ty = cx.typeck_results().expr_ty(&expect_args[0]).peel_refs();
-
- let mess = if is_type_diagnostic_item(cx, obj_ty, sym::option_type) {
- Some((EXPECT_USED, "an Option", "None"))
- } else if is_type_diagnostic_item(cx, obj_ty, sym::result_type) {
- Some((EXPECT_USED, "a Result", "Err"))
- } else {
- None
- };
-
- if let Some((lint, kind, none_value)) = mess {
- span_lint_and_help(
- cx,
- lint,
- expr.span,
- &format!("used `expect()` on `{}` value", kind,),
- None,
- &format!("if this value is an `{}`, it will panic", none_value,),
- );
- }
-}
-
-/// lint use of `ok().expect()` for `Result`s
-fn lint_ok_expect(cx: &LateContext<'_>, expr: &hir::Expr<'_>, ok_args: &[hir::Expr<'_>]) {
- if_chain! {
- // lint if the caller of `ok()` is a `Result`
- if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&ok_args[0]), sym::result_type);
- let result_type = cx.typeck_results().expr_ty(&ok_args[0]);
- if let Some(error_type) = get_error_type(cx, result_type);
- if has_debug_impl(error_type, cx);
-
- then {
- span_lint_and_help(
- cx,
- OK_EXPECT,
- expr.span,
- "called `ok().expect()` on a `Result` value",
- None,
- "you can call `expect()` directly on the `Result`",
- );
- }
- }
-}
-
-/// lint use of `map().flatten()` for `Iterators` and 'Options'
-fn lint_map_flatten<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>, map_args: &'tcx [hir::Expr<'_>]) {
- // lint if caller of `.map().flatten()` is an Iterator
- if match_trait_method(cx, expr, &paths::ITERATOR) {
- let map_closure_ty = cx.typeck_results().expr_ty(&map_args[1]);
- let is_map_to_option = match map_closure_ty.kind() {
- ty::Closure(_, _) | ty::FnDef(_, _) | ty::FnPtr(_) => {
- let map_closure_sig = match map_closure_ty.kind() {
- ty::Closure(_, substs) => substs.as_closure().sig(),
- _ => map_closure_ty.fn_sig(cx.tcx),
- };
- let map_closure_return_ty = cx.tcx.erase_late_bound_regions(map_closure_sig.output());
- is_type_diagnostic_item(cx, map_closure_return_ty, sym::option_type)
- },
- _ => false,
- };
-
- let method_to_use = if is_map_to_option {
- // `(...).map(...)` has type `impl Iterator<Item=Option<...>>
- "filter_map"
- } else {
- // `(...).map(...)` has type `impl Iterator<Item=impl Iterator<...>>
- "flat_map"
- };
- let func_snippet = snippet(cx, map_args[1].span, "..");
- let hint = format!(".{0}({1})", method_to_use, func_snippet);
- span_lint_and_sugg(
- cx,
- MAP_FLATTEN,
- expr.span.with_lo(map_args[0].span.hi()),
- "called `map(..).flatten()` on an `Iterator`",
- &format!("try using `{}` instead", method_to_use),
- hint,
- Applicability::MachineApplicable,
- );
- }
-
- // lint if caller of `.map().flatten()` is an Option
- if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&map_args[0]), sym::option_type) {
- let func_snippet = snippet(cx, map_args[1].span, "..");
- let hint = format!(".and_then({})", func_snippet);
- span_lint_and_sugg(
- cx,
- MAP_FLATTEN,
- expr.span.with_lo(map_args[0].span.hi()),
- "called `map(..).flatten()` on an `Option`",
- "try using `and_then` instead",
- hint,
- Applicability::MachineApplicable,
- );
- }
-}
-
-const MAP_UNWRAP_OR_MSRV: RustcVersion = RustcVersion::new(1, 41, 0);
-
-/// lint use of `map().unwrap_or_else()` for `Option`s and `Result`s
-/// Return true if lint triggered
-fn lint_map_unwrap_or_else<'tcx>(
- cx: &LateContext<'tcx>,
- expr: &'tcx hir::Expr<'_>,
- map_args: &'tcx [hir::Expr<'_>],
- unwrap_args: &'tcx [hir::Expr<'_>],
- msrv: Option<&RustcVersion>,
-) -> bool {
- if !meets_msrv(msrv, &MAP_UNWRAP_OR_MSRV) {
- return false;
- }
- // lint if the caller of `map()` is an `Option`
- let is_option = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&map_args[0]), sym::option_type);
- let is_result = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&map_args[0]), sym::result_type);
-
- if is_option || is_result {
- // Don't make a suggestion that may fail to compile due to mutably borrowing
- // the same variable twice.
- let map_mutated_vars = mutated_variables(&map_args[0], cx);
- let unwrap_mutated_vars = mutated_variables(&unwrap_args[1], cx);
- if let (Some(map_mutated_vars), Some(unwrap_mutated_vars)) = (map_mutated_vars, unwrap_mutated_vars) {
- if map_mutated_vars.intersection(&unwrap_mutated_vars).next().is_some() {
- return false;
- }
- } else {
- return false;
- }
-
- // lint message
- let msg = if is_option {
- "called `map(<f>).unwrap_or_else(<g>)` on an `Option` value. This can be done more directly by calling \
- `map_or_else(<g>, <f>)` instead"
- } else {
- "called `map(<f>).unwrap_or_else(<g>)` on a `Result` value. This can be done more directly by calling \
- `.map_or_else(<g>, <f>)` instead"
- };
- // get snippets for args to map() and unwrap_or_else()
- let map_snippet = snippet(cx, map_args[1].span, "..");
- let unwrap_snippet = snippet(cx, unwrap_args[1].span, "..");
- // lint, with note if neither arg is > 1 line and both map() and
- // unwrap_or_else() have the same span
- let multiline = map_snippet.lines().count() > 1 || unwrap_snippet.lines().count() > 1;
- let same_span = map_args[1].span.ctxt() == unwrap_args[1].span.ctxt();
- if same_span && !multiline {
- let var_snippet = snippet(cx, map_args[0].span, "..");
- span_lint_and_sugg(
- cx,
- MAP_UNWRAP_OR,
- expr.span,
- msg,
- "try this",
- format!("{}.map_or_else({}, {})", var_snippet, unwrap_snippet, map_snippet),
- Applicability::MachineApplicable,
- );
- return true;
- } else if same_span && multiline {
- span_lint(cx, MAP_UNWRAP_OR, expr.span, msg);
- return true;
- }
- }
-
- false
-}
-
-/// lint use of `_.map_or(None, _)` for `Option`s and `Result`s
-fn lint_map_or_none<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>, map_or_args: &'tcx [hir::Expr<'_>]) {
- let is_option = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&map_or_args[0]), sym::option_type);
- let is_result = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&map_or_args[0]), sym::result_type);
-
- // There are two variants of this `map_or` lint:
- // (1) using `map_or` as an adapter from `Result<T,E>` to `Option<T>`
- // (2) using `map_or` as a combinator instead of `and_then`
- //
- // (For this lint) we don't care if any other type calls `map_or`
- if !is_option && !is_result {
- return;
- }
-
- let (lint_name, msg, instead, hint) = {
- let default_arg_is_none = if let hir::ExprKind::Path(ref qpath) = map_or_args[1].kind {
- match_qpath(qpath, &paths::OPTION_NONE)
- } else {
- return;
- };
-
- if !default_arg_is_none {
- // nothing to lint!
- return;
- }
-
- let f_arg_is_some = if let hir::ExprKind::Path(ref qpath) = map_or_args[2].kind {
- match_qpath(qpath, &paths::OPTION_SOME)
- } else {
- false
- };
-
- if is_option {
- let self_snippet = snippet(cx, map_or_args[0].span, "..");
- let func_snippet = snippet(cx, map_or_args[2].span, "..");
- let msg = "called `map_or(None, ..)` on an `Option` value. This can be done more directly by calling \
- `and_then(..)` instead";
- (
- OPTION_MAP_OR_NONE,
- msg,
- "try using `and_then` instead",
- format!("{0}.and_then({1})", self_snippet, func_snippet),
- )
- } else if f_arg_is_some {
- let msg = "called `map_or(None, Some)` on a `Result` value. This can be done more directly by calling \
- `ok()` instead";
- let self_snippet = snippet(cx, map_or_args[0].span, "..");
- (
- RESULT_MAP_OR_INTO_OPTION,
- msg,
- "try using `ok` instead",
- format!("{0}.ok()", self_snippet),
- )
- } else {
- // nothing to lint!
- return;
- }
- };
-
- span_lint_and_sugg(
- cx,
- lint_name,
- expr.span,
- msg,
- instead,
- hint,
- Applicability::MachineApplicable,
- );
-}
-
-/// lint use of `filter().next()` for `Iterators`
-fn lint_filter_next<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>, filter_args: &'tcx [hir::Expr<'_>]) {
- // lint if caller of `.filter().next()` is an Iterator
- if match_trait_method(cx, expr, &paths::ITERATOR) {
- let msg = "called `filter(..).next()` on an `Iterator`. This is more succinctly expressed by calling \
- `.find(..)` instead.";
- let filter_snippet = snippet(cx, filter_args[1].span, "..");
- if filter_snippet.lines().count() <= 1 {
- let iter_snippet = snippet(cx, filter_args[0].span, "..");
- // add note if not multi-line
- span_lint_and_sugg(
- cx,
- FILTER_NEXT,
- expr.span,
- msg,
- "try this",
- format!("{}.find({})", iter_snippet, filter_snippet),
- Applicability::MachineApplicable,
- );
- } else {
- span_lint(cx, FILTER_NEXT, expr.span, msg);
- }
- }
-}
-
-/// lint use of `skip_while().next()` for `Iterators`
-fn lint_skip_while_next<'tcx>(
- cx: &LateContext<'tcx>,
- expr: &'tcx hir::Expr<'_>,
- _skip_while_args: &'tcx [hir::Expr<'_>],
-) {
- // lint if caller of `.skip_while().next()` is an Iterator
- if match_trait_method(cx, expr, &paths::ITERATOR) {
- span_lint_and_help(
- cx,
- SKIP_WHILE_NEXT,
- expr.span,
- "called `skip_while(<p>).next()` on an `Iterator`",
- None,
- "this is more succinctly expressed by calling `.find(!<p>)` instead",
- );
- }
-}
-
-/// lint use of `filter().map()` or `find().map()` for `Iterators`
-fn lint_filter_map<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>, is_find: bool) {
- if_chain! {
- if let ExprKind::MethodCall(_, _, [map_recv, map_arg], map_span) = expr.kind;
- if let ExprKind::MethodCall(_, _, [_, filter_arg], filter_span) = map_recv.kind;
- if match_trait_method(cx, map_recv, &paths::ITERATOR);
-
- // filter(|x| ...is_some())...
- if let ExprKind::Closure(_, _, filter_body_id, ..) = filter_arg.kind;
- let filter_body = cx.tcx.hir().body(filter_body_id);
- if let [filter_param] = filter_body.params;
- // optional ref pattern: `filter(|&x| ..)`
- let (filter_pat, is_filter_param_ref) = if let PatKind::Ref(ref_pat, _) = filter_param.pat.kind {
- (ref_pat, true)
- } else {
- (filter_param.pat, false)
- };
- // closure ends with is_some() or is_ok()
- if let PatKind::Binding(_, filter_param_id, _, None) = filter_pat.kind;
- if let ExprKind::MethodCall(path, _, [filter_arg], _) = filter_body.value.kind;
- if let Some(opt_ty) = cx.typeck_results().expr_ty(filter_arg).ty_adt_def();
- if let Some(is_result) = if cx.tcx.is_diagnostic_item(sym::option_type, opt_ty.did) {
- Some(false)
- } else if cx.tcx.is_diagnostic_item(sym::result_type, opt_ty.did) {
- Some(true)
- } else {
- None
- };
- if path.ident.name.as_str() == if is_result { "is_ok" } else { "is_some" };
-
- // ...map(|x| ...unwrap())
- if let ExprKind::Closure(_, _, map_body_id, ..) = map_arg.kind;
- let map_body = cx.tcx.hir().body(map_body_id);
- if let [map_param] = map_body.params;
- if let PatKind::Binding(_, map_param_id, map_param_ident, None) = map_param.pat.kind;
- // closure ends with expect() or unwrap()
- if let ExprKind::MethodCall(seg, _, [map_arg, ..], _) = map_body.value.kind;
- if matches!(seg.ident.name, sym::expect | sym::unwrap | sym::unwrap_or);
-
- let eq_fallback = |a: &Expr<'_>, b: &Expr<'_>| {
- // in `filter(|x| ..)`, replace `*x` with `x`
- let a_path = if_chain! {
- if !is_filter_param_ref;
- if let ExprKind::Unary(UnOp::Deref, expr_path) = a.kind;
- then { expr_path } else { a }
- };
- // let the filter closure arg and the map closure arg be equal
- if_chain! {
- if path_to_local_id(a_path, filter_param_id);
- if path_to_local_id(b, map_param_id);
- if TyS::same_type(cx.typeck_results().expr_ty_adjusted(a), cx.typeck_results().expr_ty_adjusted(b));
- then {
- return true;
- }
- }
- false
- };
- if SpanlessEq::new(cx).expr_fallback(eq_fallback).eq_expr(filter_arg, map_arg);
- then {
- let span = filter_span.to(map_span);
- let (filter_name, lint) = if is_find {
- ("find", MANUAL_FIND_MAP)
- } else {
- ("filter", MANUAL_FILTER_MAP)
- };
- let msg = format!("`{}(..).map(..)` can be simplified as `{0}_map(..)`", filter_name);
- let to_opt = if is_result { ".ok()" } else { "" };
- let sugg = format!("{}_map(|{}| {}{})", filter_name, map_param_ident,
- snippet(cx, map_arg.span, ".."), to_opt);
- span_lint_and_sugg(cx, lint, span, &msg, "try", sugg, Applicability::MachineApplicable);
- }
- }
-}
-
-const FILTER_MAP_NEXT_MSRV: RustcVersion = RustcVersion::new(1, 30, 0);
-
-/// lint use of `filter_map().next()` for `Iterators`
-fn lint_filter_map_next<'tcx>(
- cx: &LateContext<'tcx>,
- expr: &'tcx hir::Expr<'_>,
- filter_args: &'tcx [hir::Expr<'_>],
- msrv: Option<&RustcVersion>,
-) {
- if match_trait_method(cx, expr, &paths::ITERATOR) {
- if !meets_msrv(msrv, &FILTER_MAP_NEXT_MSRV) {
+ fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>) {
+ if in_external_macro(cx.tcx.sess, item.span) {
return;
}
- let msg = "called `filter_map(..).next()` on an `Iterator`. This is more succinctly expressed by calling \
- `.find_map(..)` instead.";
- let filter_snippet = snippet(cx, filter_args[1].span, "..");
- if filter_snippet.lines().count() <= 1 {
- let iter_snippet = snippet(cx, filter_args[0].span, "..");
- span_lint_and_sugg(
- cx,
- FILTER_MAP_NEXT,
- expr.span,
- msg,
- "try this",
- format!("{}.find_map({})", iter_snippet, filter_snippet),
- Applicability::MachineApplicable,
- );
- } else {
- span_lint(cx, FILTER_MAP_NEXT, expr.span, msg);
- }
- }
-}
-
-/// lint use of `filter_map().map()` for `Iterators`
-fn lint_filter_map_map<'tcx>(
- cx: &LateContext<'tcx>,
- expr: &'tcx hir::Expr<'_>,
- _filter_args: &'tcx [hir::Expr<'_>],
- _map_args: &'tcx [hir::Expr<'_>],
-) {
- // lint if caller of `.filter_map().map()` is an Iterator
- if match_trait_method(cx, expr, &paths::ITERATOR) {
- let msg = "called `filter_map(..).map(..)` on an `Iterator`";
- let hint = "this is more succinctly expressed by only calling `.filter_map(..)` instead";
- span_lint_and_help(cx, FILTER_MAP, expr.span, msg, None, hint);
- }
-}
-
-/// lint use of `filter().flat_map()` for `Iterators`
-fn lint_filter_flat_map<'tcx>(
- cx: &LateContext<'tcx>,
- expr: &'tcx hir::Expr<'_>,
- _filter_args: &'tcx [hir::Expr<'_>],
- _map_args: &'tcx [hir::Expr<'_>],
-) {
- // lint if caller of `.filter().flat_map()` is an Iterator
- if match_trait_method(cx, expr, &paths::ITERATOR) {
- let msg = "called `filter(..).flat_map(..)` on an `Iterator`";
- let hint = "this is more succinctly expressed by calling `.flat_map(..)` \
- and filtering by returning `iter::empty()`";
- span_lint_and_help(cx, FILTER_MAP, expr.span, msg, None, hint);
- }
-}
-
-/// lint use of `filter_map().flat_map()` for `Iterators`
-fn lint_filter_map_flat_map<'tcx>(
- cx: &LateContext<'tcx>,
- expr: &'tcx hir::Expr<'_>,
- _filter_args: &'tcx [hir::Expr<'_>],
- _map_args: &'tcx [hir::Expr<'_>],
-) {
- // lint if caller of `.filter_map().flat_map()` is an Iterator
- if match_trait_method(cx, expr, &paths::ITERATOR) {
- let msg = "called `filter_map(..).flat_map(..)` on an `Iterator`";
- let hint = "this is more succinctly expressed by calling `.flat_map(..)` \
- and filtering by returning `iter::empty()`";
- span_lint_and_help(cx, FILTER_MAP, expr.span, msg, None, hint);
- }
-}
-
-/// lint use of `flat_map` for `Iterators` where `flatten` would be sufficient
-fn lint_flat_map_identity<'tcx>(
- cx: &LateContext<'tcx>,
- expr: &'tcx hir::Expr<'_>,
- flat_map_args: &'tcx [hir::Expr<'_>],
- flat_map_span: Span,
-) {
- if match_trait_method(cx, expr, &paths::ITERATOR) {
- let arg_node = &flat_map_args[1].kind;
-
- let apply_lint = |message: &str| {
- span_lint_and_sugg(
- cx,
- FLAT_MAP_IDENTITY,
- flat_map_span.with_hi(expr.span.hi()),
- message,
- "try",
- "flatten()".to_string(),
- Applicability::MachineApplicable,
- );
- };
-
if_chain! {
- if let hir::ExprKind::Closure(_, _, body_id, _, _) = arg_node;
- let body = cx.tcx.hir().body(*body_id);
-
- if let hir::PatKind::Binding(_, _, binding_ident, _) = body.params[0].pat.kind;
- if let hir::ExprKind::Path(hir::QPath::Resolved(_, ref path)) = body.value.kind;
-
- if path.segments.len() == 1;
- if path.segments[0].ident.name == binding_ident.name;
+ if let TraitItemKind::Fn(ref sig, _) = item.kind;
+ if sig.decl.implicit_self.has_implicit_self();
+ if let Some(first_arg_ty) = sig.decl.inputs.iter().next();
then {
- apply_lint("called `flat_map(|x| x)` on an `Iterator`");
+ 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().skip_binder();
+ wrong_self_convention::check(
+ cx,
+ item.ident.name.as_str(),
+ self_ty,
+ first_arg_ty,
+ first_arg_span,
+ false,
+ true
+ );
}
}
if_chain! {
- if let hir::ExprKind::Path(ref qpath) = arg_node;
-
- if match_qpath(qpath, &paths::STD_CONVERT_IDENTITY);
+ 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().skip_binder();
+ if !contains_ty(ret_ty, self_ty);
then {
- apply_lint("called `flat_map(std::convert::identity)` on an `Iterator`");
+ span_lint(
+ cx,
+ NEW_RET_NO_SELF,
+ item.span,
+ "methods called `new` usually return `Self`",
+ );
}
}
}
+
+ extract_msrv_attr!(LateContext);
}
-/// lint searching an Iterator followed by `is_some()`
-/// or calling `find()` on a string followed by `is_some()`
-fn lint_search_is_some<'tcx>(
- cx: &LateContext<'tcx>,
- expr: &'tcx hir::Expr<'_>,
- search_method: &str,
- search_args: &'tcx [hir::Expr<'_>],
- is_some_args: &'tcx [hir::Expr<'_>],
- method_span: Span,
-) {
- // lint if caller of search is an Iterator
- if match_trait_method(cx, &is_some_args[0], &paths::ITERATOR) {
- let msg = format!(
- "called `is_some()` after searching an `Iterator` with `{}`",
- search_method
- );
- let hint = "this is more succinctly expressed by calling `any()`";
- let search_snippet = snippet(cx, search_args[1].span, "..");
- if search_snippet.lines().count() <= 1 {
- // suggest `any(|x| ..)` instead of `any(|&x| ..)` for `find(|&x| ..).is_some()`
- // suggest `any(|..| *..)` instead of `any(|..| **..)` for `find(|..| **..).is_some()`
- let any_search_snippet = if_chain! {
- if search_method == "find";
- if let hir::ExprKind::Closure(_, _, body_id, ..) = search_args[1].kind;
- let closure_body = cx.tcx.hir().body(body_id);
- if let Some(closure_arg) = closure_body.params.get(0);
- then {
- if let hir::PatKind::Ref(..) = closure_arg.pat.kind {
- Some(search_snippet.replacen('&', "", 1))
- } else if let PatKind::Binding(_, _, ident, _) = strip_pat_refs(&closure_arg.pat).kind {
- let name = &*ident.name.as_str();
- Some(search_snippet.replace(&format!("*{}", name), name))
- } else {
- None
+#[allow(clippy::too_many_lines)]
+fn check_methods<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, msrv: Option<&RustcVersion>) {
+ if let Some((name, [recv, args @ ..], span)) = method_call(expr) {
+ match (name, args) {
+ ("add" | "offset" | "sub" | "wrapping_offset" | "wrapping_add" | "wrapping_sub", [_arg]) => {
+ zst_offset::check(cx, expr, recv);
+ },
+ ("and_then", [arg]) => {
+ let biom_option_linted = bind_instead_of_map::OptionAndThenSome::check(cx, expr, recv, arg);
+ let biom_result_linted = bind_instead_of_map::ResultAndThenOk::check(cx, expr, recv, arg);
+ if !biom_option_linted && !biom_result_linted {
+ unnecessary_lazy_eval::check(cx, expr, recv, arg, "and");
+ }
+ },
+ ("as_mut", []) => useless_asref::check(cx, expr, "as_mut", recv),
+ ("as_ref", []) => useless_asref::check(cx, expr, "as_ref", recv),
+ ("assume_init", []) => uninit_assumed_init::check(cx, expr, recv),
+ ("cloned", []) => cloned_instead_of_copied::check(cx, expr, recv, span, msrv),
+ ("collect", []) => match method_call(recv) {
+ Some((name @ ("cloned" | "copied"), [recv2], _)) => {
+ iter_cloned_collect::check(cx, name, expr, recv2);
+ },
+ Some(("map", [m_recv, m_arg], _)) => {
+ map_collect_result_unit::check(cx, expr, m_recv, m_arg, recv);
+ },
+ Some(("take", [take_self_arg, take_arg], _)) => {
+ if meets_msrv(msrv, &msrvs::STR_REPEAT) {
+ manual_str_repeat::check(cx, expr, recv, take_self_arg, take_arg);
}
- } else {
- None
+ },
+ _ => {},
+ },
+ (name @ "count", args @ []) => match method_call(recv) {
+ Some(("cloned", [recv2], _)) => iter_overeager_cloned::check(cx, expr, recv2, name, args),
+ Some((name2 @ ("into_iter" | "iter" | "iter_mut"), [recv2], _)) => {
+ iter_count::check(cx, expr, recv2, name2);
+ },
+ Some(("map", [_, arg], _)) => suspicious_map::check(cx, expr, recv, arg),
+ _ => {},
+ },
+ ("drain", [arg]) => {
+ iter_with_drain::check(cx, expr, recv, span, arg);
+ },
+ ("expect", [_]) => match method_call(recv) {
+ Some(("ok", [recv], _)) => ok_expect::check(cx, expr, recv),
+ _ => expect_used::check(cx, expr, recv),
+ },
+ ("extend", [arg]) => {
+ string_extend_chars::check(cx, expr, recv, arg);
+ extend_with_drain::check(cx, expr, recv, arg);
+ },
+ ("filter_map", [arg]) => {
+ unnecessary_filter_map::check(cx, expr, arg, name);
+ filter_map_identity::check(cx, expr, arg, span);
+ },
+ ("find_map", [arg]) => {
+ unnecessary_filter_map::check(cx, expr, arg, name);
+ },
+ ("flat_map", [arg]) => {
+ flat_map_identity::check(cx, expr, arg, span);
+ flat_map_option::check(cx, expr, arg, span);
+ },
+ (name @ "flatten", args @ []) => match method_call(recv) {
+ Some(("map", [recv, map_arg], map_span)) => map_flatten::check(cx, expr, recv, map_arg, map_span),
+ Some(("cloned", [recv2], _)) => iter_overeager_cloned::check(cx, expr, recv2, name, args),
+ _ => {},
+ },
+ ("fold", [init, acc]) => unnecessary_fold::check(cx, expr, init, acc, span),
+ ("for_each", [_]) => {
+ if let Some(("inspect", [_, _], span2)) = method_call(recv) {
+ inspect_for_each::check(cx, expr, span2);
}
- };
- // add note if not multi-line
- span_lint_and_sugg(
- cx,
- SEARCH_IS_SOME,
- method_span.with_hi(expr.span.hi()),
- &msg,
- "use `any()` instead",
- format!(
- "any({})",
- any_search_snippet.as_ref().map_or(&*search_snippet, String::as_str)
- ),
- Applicability::MachineApplicable,
- );
- } else {
- span_lint_and_help(cx, SEARCH_IS_SOME, expr.span, &msg, None, hint);
+ },
+ ("get_or_insert_with", [arg]) => unnecessary_lazy_eval::check(cx, expr, recv, arg, "get_or_insert"),
+ ("is_file", []) => filetype_is_file::check(cx, expr, recv),
+ ("is_none", []) => check_is_some_is_none(cx, expr, recv, false),
+ ("is_some", []) => check_is_some_is_none(cx, expr, recv, true),
+ ("join", [join_arg]) => {
+ if let Some(("collect", _, span)) = method_call(recv) {
+ unnecessary_join::check(cx, expr, recv, join_arg, span);
+ }
+ },
+ ("last", args @ []) | ("skip", args @ [_]) => {
+ if let Some((name2, [recv2, args2 @ ..], _span2)) = method_call(recv) {
+ if let ("cloned", []) = (name2, args2) {
+ iter_overeager_cloned::check(cx, expr, recv2, name, args);
+ }
+ }
+ },
+ ("map", [m_arg]) => {
+ if let Some((name, [recv2, args @ ..], span2)) = method_call(recv) {
+ match (name, args) {
+ ("as_mut", []) => option_as_ref_deref::check(cx, expr, recv2, m_arg, true, msrv),
+ ("as_ref", []) => option_as_ref_deref::check(cx, expr, recv2, m_arg, false, msrv),
+ ("filter", [f_arg]) => {
+ filter_map::check(cx, expr, recv2, f_arg, span2, recv, m_arg, span, false);
+ },
+ ("find", [f_arg]) => filter_map::check(cx, expr, recv2, f_arg, span2, recv, m_arg, span, true),
+ _ => {},
+ }
+ }
+ map_identity::check(cx, expr, recv, m_arg, span);
+ },
+ ("map_or", [def, map]) => option_map_or_none::check(cx, expr, recv, def, map),
+ (name @ "next", args @ []) => {
+ if let Some((name2, [recv2, args2 @ ..], _)) = method_call(recv) {
+ match (name2, args2) {
+ ("cloned", []) => iter_overeager_cloned::check(cx, expr, recv2, name, args),
+ ("filter", [arg]) => filter_next::check(cx, expr, recv2, arg),
+ ("filter_map", [arg]) => filter_map_next::check(cx, expr, recv2, arg, msrv),
+ ("iter", []) => iter_next_slice::check(cx, expr, recv2),
+ ("skip", [arg]) => iter_skip_next::check(cx, expr, recv2, arg),
+ ("skip_while", [_]) => skip_while_next::check(cx, expr),
+ _ => {},
+ }
+ }
+ },
+ ("nth", args @ [n_arg]) => match method_call(recv) {
+ Some(("bytes", [recv2], _)) => bytes_nth::check(cx, expr, recv2, n_arg),
+ Some(("cloned", [recv2], _)) => iter_overeager_cloned::check(cx, expr, recv2, name, args),
+ Some(("iter", [recv2], _)) => iter_nth::check(cx, expr, recv2, recv, n_arg, false),
+ Some(("iter_mut", [recv2], _)) => iter_nth::check(cx, expr, recv2, recv, n_arg, true),
+ _ => iter_nth_zero::check(cx, expr, recv, n_arg),
+ },
+ ("ok_or_else", [arg]) => unnecessary_lazy_eval::check(cx, expr, recv, arg, "ok_or"),
+ ("or_else", [arg]) => {
+ if !bind_instead_of_map::ResultOrElseErrInfo::check(cx, expr, recv, arg) {
+ unnecessary_lazy_eval::check(cx, expr, recv, arg, "or");
+ }
+ },
+ ("splitn" | "rsplitn", [count_arg, pat_arg]) => {
+ if let Some((Constant::Int(count), _)) = constant(cx, cx.typeck_results(), count_arg) {
+ suspicious_splitn::check(cx, name, expr, recv, count);
+ if count == 2 && meets_msrv(msrv, &msrvs::STR_SPLIT_ONCE) {
+ str_splitn::check_manual_split_once(cx, name, expr, recv, pat_arg);
+ }
+ if count >= 2 {
+ str_splitn::check_needless_splitn(cx, name, expr, recv, pat_arg, count);
+ }
+ }
+ },
+ ("splitn_mut" | "rsplitn_mut", [count_arg, _]) => {
+ if let Some((Constant::Int(count), _)) = constant(cx, cx.typeck_results(), count_arg) {
+ suspicious_splitn::check(cx, name, expr, recv, count);
+ }
+ },
+ ("step_by", [arg]) => iterator_step_by_zero::check(cx, expr, arg),
+ ("take", args @ [_arg]) => {
+ if let Some((name2, [recv2, args2 @ ..], _span2)) = method_call(recv) {
+ if let ("cloned", []) = (name2, args2) {
+ iter_overeager_cloned::check(cx, expr, recv2, name, args);
+ }
+ }
+ },
+ ("to_os_string" | "to_owned" | "to_path_buf" | "to_vec", []) => {
+ implicit_clone::check(cx, name, expr, recv);
+ },
+ ("unwrap", []) => {
+ match method_call(recv) {
+ Some(("get", [recv, get_arg], _)) => {
+ get_unwrap::check(cx, expr, recv, get_arg, false);
+ },
+ Some(("get_mut", [recv, get_arg], _)) => {
+ get_unwrap::check(cx, expr, recv, get_arg, true);
+ },
+ Some(("or", [recv, or_arg], or_span)) => {
+ or_then_unwrap::check(cx, expr, recv, or_arg, or_span);
+ },
+ _ => {},
+ }
+ unwrap_used::check(cx, expr, recv);
+ },
+ ("unwrap_or", [u_arg]) => match method_call(recv) {
+ Some((arith @ ("checked_add" | "checked_sub" | "checked_mul"), [lhs, rhs], _)) => {
+ manual_saturating_arithmetic::check(cx, expr, lhs, rhs, u_arg, &arith["checked_".len()..]);
+ },
+ Some(("map", [m_recv, m_arg], span)) => {
+ option_map_unwrap_or::check(cx, expr, m_recv, m_arg, recv, u_arg, span);
+ },
+ _ => {},
+ },
+ ("unwrap_or_else", [u_arg]) => match method_call(recv) {
+ Some(("map", [recv, map_arg], _)) if map_unwrap_or::check(cx, expr, recv, map_arg, u_arg, msrv) => {},
+ _ => {
+ unwrap_or_else_default::check(cx, expr, recv, u_arg);
+ unnecessary_lazy_eval::check(cx, expr, recv, u_arg, "unwrap_or");
+ },
+ },
+ _ => {},
}
}
- // lint if `find()` is called by `String` or `&str`
- else if search_method == "find" {
- let is_string_or_str_slice = |e| {
- let self_ty = cx.typeck_results().expr_ty(e).peel_refs();
- if is_type_diagnostic_item(cx, self_ty, sym::string_type) {
- true
- } else {
- *self_ty.kind() == ty::Str
- }
- };
- if_chain! {
- if is_string_or_str_slice(&search_args[0]);
- if is_string_or_str_slice(&search_args[1]);
- then {
- let msg = "called `is_some()` after calling `find()` on a string";
- let mut applicability = Applicability::MachineApplicable;
- let find_arg = snippet_with_applicability(cx, search_args[1].span, "..", &mut applicability);
- span_lint_and_sugg(
- cx,
- SEARCH_IS_SOME,
- method_span.with_hi(expr.span.hi()),
- msg,
- "use `contains()` instead",
- format!("contains({})", find_arg),
- applicability,
- );
- }
- }
+}
+
+fn check_is_some_is_none(cx: &LateContext<'_>, expr: &Expr<'_>, recv: &Expr<'_>, is_some: bool) {
+ if let Some((name @ ("find" | "position" | "rposition"), [f_recv, arg], span)) = method_call(recv) {
+ search_is_some::check(cx, expr, name, is_some, f_recv, arg, recv, span);
}
}
/// 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, $info:ident) => {
+ ($func:expr, $cx:expr, $info:ident) => {
if !$func($cx, $info) {
::std::mem::swap(&mut $info.chain, &mut $info.other);
if $func($cx, $info) {
};
}
- 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
- }
- }
-}
-
-/// lint for length-1 `str`s for methods in `PATTERN_METHODS`
-fn lint_single_char_pattern(cx: &LateContext<'_>, _expr: &hir::Expr<'_>, arg: &hir::Expr<'_>) {
- let mut applicability = Applicability::MachineApplicable;
- if let Some(hint) = get_hint_if_single_char_arg(cx, arg, &mut applicability) {
- span_lint_and_sugg(
- cx,
- SINGLE_CHAR_PATTERN,
- arg.span,
- "single-character string constant used as pattern",
- "try using a `char` instead",
- hint,
- applicability,
- );
- }
-}
-
-/// lint for length-1 `str`s as argument for `push_str`
-fn lint_single_char_push_string(cx: &LateContext<'_>, expr: &hir::Expr<'_>, args: &[hir::Expr<'_>]) {
- let mut applicability = Applicability::MachineApplicable;
- if let Some(extension_string) = get_hint_if_single_char_arg(cx, &args[1], &mut applicability) {
- let base_string_snippet =
- snippet_with_applicability(cx, args[0].span.source_callsite(), "..", &mut applicability);
- let sugg = format!("{}.push({})", base_string_snippet, extension_string);
- span_lint_and_sugg(
- cx,
- SINGLE_CHAR_ADD_STR,
- expr.span,
- "calling `push_str()` using a single-character string literal",
- "consider using `push` with a character literal",
- sugg,
- applicability,
- );
- }
-}
-
-/// lint for length-1 `str`s as argument for `insert_str`
-fn lint_single_char_insert_string(cx: &LateContext<'_>, expr: &hir::Expr<'_>, args: &[hir::Expr<'_>]) {
- let mut applicability = Applicability::MachineApplicable;
- if let Some(extension_string) = get_hint_if_single_char_arg(cx, &args[2], &mut applicability) {
- let base_string_snippet =
- snippet_with_applicability(cx, args[0].span.source_callsite(), "_", &mut applicability);
- let pos_arg = snippet_with_applicability(cx, args[1].span, "..", &mut applicability);
- let sugg = format!("{}.insert({}, {})", base_string_snippet, pos_arg, extension_string);
- span_lint_and_sugg(
- cx,
- SINGLE_CHAR_ADD_STR,
- expr.span,
- "calling `insert_str()` using a single-character string literal",
- "consider using `insert` with a character literal",
- sugg,
- applicability,
- );
- }
-}
-
-/// Checks for the `USELESS_ASREF` lint.
-fn lint_asref(cx: &LateContext<'_>, expr: &hir::Expr<'_>, call_name: &str, as_ref_args: &[hir::Expr<'_>]) {
- // when we get here, we've already checked that the call name is "as_ref" or "as_mut"
- // check if the call is to the actual `AsRef` or `AsMut` trait
- if match_trait_method(cx, expr, &paths::ASREF_TRAIT) || match_trait_method(cx, expr, &paths::ASMUT_TRAIT) {
- // check if the type after `as_ref` or `as_mut` is the same as before
- let recvr = &as_ref_args[0];
- let rcv_ty = cx.typeck_results().expr_ty(recvr);
- let res_ty = cx.typeck_results().expr_ty(expr);
- let (base_res_ty, res_depth) = walk_ptrs_ty_depth(res_ty);
- let (base_rcv_ty, rcv_depth) = walk_ptrs_ty_depth(rcv_ty);
- if base_rcv_ty == base_res_ty && rcv_depth >= res_depth {
- // allow the `as_ref` or `as_mut` if it is followed by another method call
- if_chain! {
- if let Some(parent) = get_parent_expr(cx, expr);
- if let hir::ExprKind::MethodCall(_, ref span, _, _) = parent.kind;
- if span != &expr.span;
- then {
- return;
- }
- }
-
- let mut applicability = Applicability::MachineApplicable;
- span_lint_and_sugg(
- cx,
- USELESS_ASREF,
- expr.span,
- &format!("this call to `{}` does nothing", call_name),
- "try this",
- snippet_with_applicability(cx, recvr.span, "..", &mut applicability).to_string(),
- applicability,
- );
- }
- }
-}
-
-fn ty_has_iter_method(cx: &LateContext<'_>, self_ref_ty: Ty<'_>) -> Option<(&'static str, &'static str)> {
- has_iter_method(cx, self_ref_ty).map(|ty_name| {
- let mutbl = match self_ref_ty.kind() {
- ty::Ref(_, _, mutbl) => mutbl,
- _ => unreachable!(),
- };
- let method_name = match mutbl {
- hir::Mutability::Not => "iter",
- hir::Mutability::Mut => "iter_mut",
- };
- (ty_name, method_name)
- })
-}
-
-fn lint_into_iter(cx: &LateContext<'_>, expr: &hir::Expr<'_>, self_ref_ty: Ty<'_>, method_span: Span) {
- if !match_trait_method(cx, expr, &paths::INTO_ITERATOR) {
- return;
- }
- if let Some((kind, method_name)) = ty_has_iter_method(cx, self_ref_ty) {
- span_lint_and_sugg(
- cx,
- INTO_ITER_ON_REF,
- method_span,
- &format!(
- "this `.into_iter()` call is equivalent to `.{}()` and will not consume the `{}`",
- method_name, kind,
- ),
- "call directly",
- method_name.to_string(),
- Applicability::MachineApplicable,
- );
- }
-}
-
-/// lint for `MaybeUninit::uninit().assume_init()` (we already have the latter)
-fn lint_maybe_uninit(cx: &LateContext<'_>, expr: &hir::Expr<'_>, outer: &hir::Expr<'_>) {
- if_chain! {
- if let hir::ExprKind::Call(ref callee, ref args) = expr.kind;
- if args.is_empty();
- if let hir::ExprKind::Path(ref path) = callee.kind;
- if match_qpath(path, &paths::MEM_MAYBEUNINIT_UNINIT);
- if !is_maybe_uninit_ty_valid(cx, cx.typeck_results().expr_ty_adjusted(outer));
- then {
- span_lint(
- cx,
- UNINIT_ASSUMED_INIT,
- outer.span,
- "this call for this type may be undefined behavior"
- );
- }
- }
-}
-
-fn is_maybe_uninit_ty_valid(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
- match ty.kind() {
- ty::Array(ref component, _) => is_maybe_uninit_ty_valid(cx, component),
- ty::Tuple(ref types) => types.types().all(|ty| is_maybe_uninit_ty_valid(cx, ty)),
- ty::Adt(ref adt, _) => match_def_path(cx, adt.did, &paths::MEM_MAYBEUNINIT),
- _ => false,
- }
-}
-
-fn lint_suspicious_map(cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
- span_lint_and_help(
- cx,
- SUSPICIOUS_MAP,
- expr.span,
- "this call to `map()` won't have an effect on the call to `count()`",
- None,
- "make sure you did not confuse `map` with `filter` or `for_each`",
- );
-}
-
-const OPTION_AS_REF_DEREF_MSRV: RustcVersion = RustcVersion::new(1, 40, 0);
-
-/// lint use of `_.as_ref().map(Deref::deref)` for `Option`s
-fn lint_option_as_ref_deref<'tcx>(
- cx: &LateContext<'tcx>,
- expr: &hir::Expr<'_>,
- as_ref_args: &[hir::Expr<'_>],
- map_args: &[hir::Expr<'_>],
- is_mut: bool,
- msrv: Option<&RustcVersion>,
-) {
- if !meets_msrv(msrv, &OPTION_AS_REF_DEREF_MSRV) {
- return;
- }
-
- let same_mutability = |m| (is_mut && m == &hir::Mutability::Mut) || (!is_mut && m == &hir::Mutability::Not);
-
- let option_ty = cx.typeck_results().expr_ty(&as_ref_args[0]);
- if !is_type_diagnostic_item(cx, option_ty, sym::option_type) {
- return;
- }
-
- let deref_aliases: [&[&str]; 9] = [
- &paths::DEREF_TRAIT_METHOD,
- &paths::DEREF_MUT_TRAIT_METHOD,
- &paths::CSTRING_AS_C_STR,
- &paths::OS_STRING_AS_OS_STR,
- &paths::PATH_BUF_AS_PATH,
- &paths::STRING_AS_STR,
- &paths::STRING_AS_MUT_STR,
- &paths::VEC_AS_SLICE,
- &paths::VEC_AS_MUT_SLICE,
- ];
-
- let is_deref = match map_args[1].kind {
- hir::ExprKind::Path(ref expr_qpath) => cx
- .qpath_res(expr_qpath, map_args[1].hir_id)
- .opt_def_id()
- .map_or(false, |fun_def_id| {
- deref_aliases.iter().any(|path| match_def_path(cx, fun_def_id, path))
- }),
- hir::ExprKind::Closure(_, _, body_id, _, _) => {
- let closure_body = cx.tcx.hir().body(body_id);
- let closure_expr = remove_blocks(&closure_body.value);
-
- match &closure_expr.kind {
- hir::ExprKind::MethodCall(_, _, args, _) => {
- if_chain! {
- if args.len() == 1;
- if path_to_local_id(&args[0], closure_body.params[0].pat.hir_id);
- let adj = cx
- .typeck_results()
- .expr_adjustments(&args[0])
- .iter()
- .map(|x| &x.kind)
- .collect::<Box<[_]>>();
- if let [ty::adjustment::Adjust::Deref(None), ty::adjustment::Adjust::Borrow(_)] = *adj;
- then {
- let method_did = cx.typeck_results().type_dependent_def_id(closure_expr.hir_id).unwrap();
- deref_aliases.iter().any(|path| match_def_path(cx, method_did, path))
- } else {
- false
- }
- }
- },
- hir::ExprKind::AddrOf(hir::BorrowKind::Ref, m, ref inner) if same_mutability(m) => {
- if_chain! {
- if let hir::ExprKind::Unary(hir::UnOp::Deref, ref inner1) = inner.kind;
- if let hir::ExprKind::Unary(hir::UnOp::Deref, ref inner2) = inner1.kind;
- then {
- path_to_local_id(inner2, closure_body.params[0].pat.hir_id)
- } else {
- false
- }
- }
- },
- _ => false,
- }
- },
- _ => false,
- };
-
- if is_deref {
- let current_method = if is_mut {
- format!(".as_mut().map({})", snippet(cx, map_args[1].span, ".."))
- } else {
- format!(".as_ref().map({})", snippet(cx, map_args[1].span, ".."))
- };
- let method_hint = if is_mut { "as_deref_mut" } else { "as_deref" };
- let hint = format!("{}.{}()", snippet(cx, as_ref_args[0].span, ".."), method_hint);
- let suggestion = format!("try using {} instead", method_hint);
-
- let msg = format!(
- "called `{0}` on an Option value. This can be done more directly \
- by calling `{1}` instead",
- current_method, hint
- );
- span_lint_and_sugg(
- cx,
- OPTION_AS_REF_DEREF,
- expr.span,
- &msg,
- &suggestion,
- hint,
- Applicability::MachineApplicable,
- );
- }
-}
-
-fn lint_map_collect(
- cx: &LateContext<'_>,
- expr: &hir::Expr<'_>,
- map_args: &[hir::Expr<'_>],
- collect_args: &[hir::Expr<'_>],
-) {
- if_chain! {
- // called on Iterator
- if let [map_expr] = collect_args;
- if match_trait_method(cx, map_expr, &paths::ITERATOR);
- // return of collect `Result<(),_>`
- let collect_ret_ty = cx.typeck_results().expr_ty(expr);
- if is_type_diagnostic_item(cx, collect_ret_ty, sym::result_type);
- if let ty::Adt(_, substs) = collect_ret_ty.kind();
- if let Some(result_t) = substs.types().next();
- if result_t.is_unit();
- // get parts for snippet
- if let [iter, map_fn] = map_args;
- then {
- span_lint_and_sugg(
- cx,
- MAP_COLLECT_RESULT_UNIT,
- expr.span,
- "`.map().collect()` can be replaced with `.try_for_each()`",
- "try this",
- format!(
- "{}.try_for_each({})",
- snippet(cx, iter.span, ".."),
- snippet(cx, map_fn.span, "..")
- ),
- Applicability::MachineApplicable,
- );
- }
- }
-}
-
-/// Given a `Result<T, E>` type, return its error type (`E`).
-fn get_error_type<'a>(cx: &LateContext<'_>, ty: Ty<'a>) -> Option<Ty<'a>> {
- match ty.kind() {
- ty::Adt(_, substs) if is_type_diagnostic_item(cx, ty, sym::result_type) => substs.types().nth(1),
- _ => None,
- }
-}
-
-/// This checks whether a given type is known to implement Debug.
-fn has_debug_impl<'tcx>(ty: Ty<'tcx>, cx: &LateContext<'tcx>) -> bool {
- cx.tcx
- .get_diagnostic_item(sym::debug_trait)
- .map_or(false, |debug| implements_trait(cx, ty, debug, &[]))
-}
-
-enum Convention {
- Eq(&'static str),
- StartsWith(&'static str),
+ lint_with_both_lhs_and_rhs!(chars_next_cmp::check, cx, info);
+ lint_with_both_lhs_and_rhs!(chars_last_cmp::check, cx, info);
+ lint_with_both_lhs_and_rhs!(chars_next_cmp_with_unwrap::check, cx, info);
+ lint_with_both_lhs_and_rhs!(chars_last_cmp_with_unwrap::check, cx, info);
}
-#[rustfmt::skip]
-const CONVENTIONS: [(Convention, &[SelfKind]); 7] = [
- (Convention::Eq("new"), &[SelfKind::No]),
- (Convention::StartsWith("as_"), &[SelfKind::Ref, SelfKind::RefMut]),
- (Convention::StartsWith("from_"), &[SelfKind::No]),
- (Convention::StartsWith("into_"), &[SelfKind::Value]),
- (Convention::StartsWith("is_"), &[SelfKind::Ref, SelfKind::No]),
- (Convention::Eq("to_mut"), &[SelfKind::RefMut]),
- (Convention::StartsWith("to_"), &[SelfKind::Ref]),
-];
-
const FN_HEADER: hir::FnHeader = hir::FnHeader {
unsafety: hir::Unsafety::Normal,
constness: hir::Constness::NotConst,
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,
implements_trait(cx, ty, trait_def_id, &[parent_ty.into()])
}
+ fn matches_none<'a>(cx: &LateContext<'a>, parent_ty: Ty<'a>, ty: Ty<'a>) -> bool {
+ !matches_value(cx, parent_ty, ty)
+ && !matches_ref(cx, hir::Mutability::Not, parent_ty, ty)
+ && !matches_ref(cx, hir::Mutability::Mut, parent_ty, ty)
+ }
+
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,
+ Self::No => matches_none(cx, parent_ty, 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",
- }
- }
-}
-
-impl Convention {
- #[must_use]
- fn check(&self, other: &str) -> bool {
- match *self {
- Self::Eq(this) => this == other,
- Self::StartsWith(this) => other.starts_with(this) && this != other,
- }
- }
-}
-
-impl fmt::Display for Convention {
- fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
- match *self {
- Self::Eq(this) => this.fmt(f),
- Self::StartsWith(this) => this.fmt(f).and_then(|_| '*'.fmt(f)),
+ Self::Value => "`self` by value",
+ Self::Ref => "`self` by reference",
+ Self::RefMut => "`self` by mutable reference",
+ Self::No => "no `self`",
}
}
}
}
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(&[]));
+ fn matches(self, ty: &hir::FnRetTy<'_>) -> bool {
+ let is_unit = |ty: &hir::Ty<'_>| matches!(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(_, _)),
+ (Self::Unit, &hir::FnRetTy::Return(ty)) if is_unit(ty) => true,
+ (Self::Bool, &hir::FnRetTy::Return(ty)) if is_bool(ty) => true,
+ (Self::Any, &hir::FnRetTy::Return(ty)) if !is_unit(ty) => true,
+ (Self::Ref, &hir::FnRetTy::Return(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"])
+ if let hir::TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
+ matches!(path.res, Res::PrimTy(PrimTy::Bool))
} else {
false
}
}
-fn check_pointer_offset(cx: &LateContext<'_>, expr: &hir::Expr<'_>, args: &[hir::Expr<'_>]) {
- if_chain! {
- if args.len() == 2;
- if let ty::RawPtr(ty::TypeAndMut { ref ty, .. }) = cx.typeck_results().expr_ty(&args[0]).kind();
- if let Ok(layout) = cx.tcx.layout_of(cx.param_env.and(ty));
- if layout.is_zst();
- then {
- span_lint(cx, ZST_OFFSET, expr.span, "offset calculation on zero-sized value");
- }
- }
-}
-
-fn lint_filetype_is_file(cx: &LateContext<'_>, expr: &hir::Expr<'_>, args: &[hir::Expr<'_>]) {
- let ty = cx.typeck_results().expr_ty(&args[0]);
-
- if !match_type(cx, ty, &paths::FILE_TYPE) {
- return;
- }
-
- let span: Span;
- let verb: &str;
- let lint_unary: &str;
- let help_unary: &str;
- if_chain! {
- if let Some(parent) = get_parent_expr(cx, expr);
- if let hir::ExprKind::Unary(op, _) = parent.kind;
- if op == hir::UnOp::Not;
- then {
- lint_unary = "!";
- verb = "denies";
- help_unary = "";
- span = parent.span;
- } else {
- lint_unary = "";
- verb = "covers";
- help_unary = "!";
- span = expr.span;
- }
- }
- let lint_msg = format!("`{}FileType::is_file()` only {} regular files", lint_unary, verb);
- let help_msg = format!("use `{}FileType::is_dir()` instead", help_unary);
- span_lint_and_help(cx, FILETYPE_IS_FILE, span, &lint_msg, None, &help_msg);
-}
-
-fn lint_from_iter(cx: &LateContext<'_>, expr: &hir::Expr<'_>, args: &[hir::Expr<'_>]) {
- let ty = cx.typeck_results().expr_ty(expr);
- let arg_ty = cx.typeck_results().expr_ty(&args[0]);
-
- if_chain! {
- if let Some(from_iter_id) = get_trait_def_id(cx, &paths::FROM_ITERATOR);
- if let Some(iter_id) = get_trait_def_id(cx, &paths::ITERATOR);
-
- if implements_trait(cx, ty, from_iter_id, &[]) && implements_trait(cx, arg_ty, iter_id, &[]);
- then {
- // `expr` implements `FromIterator` trait
- let iter_expr = sugg::Sugg::hir(cx, &args[0], "..").maybe_par();
- let turbofish = extract_turbofish(cx, expr, ty);
- let sugg = format!("{}.collect::<{}>()", iter_expr, turbofish);
- span_lint_and_sugg(
- cx,
- FROM_ITER_INSTEAD_OF_COLLECT,
- expr.span,
- "usage of `FromIterator::from_iter`",
- "use `.collect()` instead of `::from_iter()`",
- sugg,
- Applicability::MaybeIncorrect,
- );
- }
- }
-}
-
-fn extract_turbofish(cx: &LateContext<'_>, expr: &hir::Expr<'_>, ty: Ty<'tcx>) -> String {
- if_chain! {
- let call_site = expr.span.source_callsite();
- if let Ok(snippet) = cx.sess().source_map().span_to_snippet(call_site);
- let snippet_split = snippet.split("::").collect::<Vec<_>>();
- if let Some((_, elements)) = snippet_split.split_last();
-
- then {
- // is there a type specifier? (i.e.: like `<u32>` in `collections::BTreeSet::<u32>::`)
- if let Some(type_specifier) = snippet_split.iter().find(|e| e.starts_with('<') && e.ends_with('>')) {
- // remove the type specifier from the path elements
- let without_ts = elements.iter().filter_map(|e| {
- if e == type_specifier { None } else { Some((*e).to_string()) }
- }).collect::<Vec<_>>();
- // join and add the type specifier at the end (i.e.: `collections::BTreeSet<u32>`)
- format!("{}{}", without_ts.join("::"), type_specifier)
- } else {
- // type is not explicitly specified so wildcards are needed
- // i.e.: 2 wildcards in `std::collections::BTreeMap<&i32, &char>`
- let ty_str = ty.to_string();
- let start = ty_str.find('<').unwrap_or(0);
- let end = ty_str.find('>').unwrap_or_else(|| ty_str.len());
- let nb_wildcard = ty_str[start..end].split(',').count();
- let wildcards = format!("_{}", ", _".repeat(nb_wildcard - 1));
- format!("{}<{}>", elements.join("::"), wildcards)
- }
- } else {
- ty.to_string()
- }
- }
-}
-
fn fn_header_equals(expected: hir::FnHeader, actual: hir::FnHeader) -> bool {
expected.constness == actual.constness
&& expected.unsafety == actual.unsafety
projects / rust.git / blobdiff