1447 lines
53 KiB
Rust
1447 lines
53 KiB
Rust
use rustc::hir;
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use rustc::lint::*;
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use rustc::middle::const_val::ConstVal;
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use rustc::ty;
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use rustc::hir::def::Def;
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use rustc_const_eval::EvalHint::ExprTypeChecked;
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use rustc_const_eval::ConstContext;
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use std::borrow::Cow;
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use std::fmt;
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use syntax::codemap::Span;
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use utils::{get_trait_def_id, implements_trait, in_external_macro, in_macro, is_copy, match_path, match_trait_method,
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match_type, method_chain_args, return_ty, same_tys, snippet, span_lint, span_lint_and_then,
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span_note_and_lint, walk_ptrs_ty, walk_ptrs_ty_depth, last_path_segment, single_segment_path,
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match_def_path, is_self, is_self_ty, iter_input_pats};
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use utils::paths;
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use utils::sugg;
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#[derive(Clone)]
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pub struct Pass;
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/// **What it does:** Checks for `.unwrap()` calls on `Option`s.
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///
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/// **Why is this bad?** Usually it is better to handle the `None` case, or to
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/// at least call `.expect(_)` with a more helpful message. Still, for a lot of
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/// quick-and-dirty code, `unwrap` is a good choice, which is why this lint is
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/// `Allow` by default.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// x.unwrap()
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/// ```
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declare_lint! {
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pub OPTION_UNWRAP_USED,
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Allow,
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"using `Option.unwrap()`, which should at least get a better message using `expect()`"
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}
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/// **What it does:** Checks for `.unwrap()` calls on `Result`s.
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///
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/// **Why is this bad?** `result.unwrap()` will let the thread panic on `Err`
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/// values. Normally, you want to implement more sophisticated error handling,
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/// and propagate errors upwards with `try!`.
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///
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/// Even if you want to panic on errors, not all `Error`s implement good
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/// messages on display. Therefore it may be beneficial to look at the places
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/// where they may get displayed. Activate this lint to do just that.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// x.unwrap()
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/// ```
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declare_lint! {
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pub RESULT_UNWRAP_USED,
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Allow,
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"using `Result.unwrap()`, which might be better handled"
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}
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/// **What it does:** Checks for methods that should live in a trait
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/// implementation of a `std` trait (see [llogiq's blog
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/// post](http://llogiq.github.io/2015/07/30/traits.html) for further
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/// information) instead of an inherent implementation.
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///
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/// **Why is this bad?** Implementing the traits improve ergonomics for users of
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/// the code, often with very little cost. Also people seeing a `mul(...)` method
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/// may expect `*` to work equally, so you should have good reason to disappoint
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/// them.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// struct X;
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/// impl X {
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/// fn add(&self, other: &X) -> X { .. }
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/// }
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/// ```
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declare_lint! {
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pub SHOULD_IMPLEMENT_TRAIT,
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Warn,
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"defining a method that should be implementing a std trait"
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}
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/// **What it does:** Checks for methods with certain name prefixes and which
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/// doesn't match how self is taken. The actual rules are:
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///
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/// |Prefix |`self` taken |
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/// |-------|----------------------|
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/// |`as_` |`&self` or `&mut self`|
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/// |`from_`| none |
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/// |`into_`|`self` |
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/// |`is_` |`&self` or none |
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/// |`to_` |`&self` |
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///
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/// **Why is this bad?** Consistency breeds readability. If you follow the
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/// conventions, your users won't be surprised that they, e.g., need to supply a
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/// mutable reference to a `as_..` function.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// impl X {
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/// fn as_str(self) -> &str { .. }
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/// }
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/// ```
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declare_lint! {
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pub WRONG_SELF_CONVENTION,
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Warn,
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"defining a method named with an established prefix (like \"into_\") that takes \
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`self` with the wrong convention"
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}
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/// **What it does:** This is the same as
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/// [`wrong_self_convention`](#wrong_self_convention), but for public items.
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///
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/// **Why is this bad?** See [`wrong_self_convention`](#wrong_self_convention).
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///
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/// **Known problems:** Actually *renaming* the function may break clients if
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/// the function is part of the public interface. In that case, be mindful of
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/// the stability guarantees you've given your users.
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///
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/// **Example:**
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/// ```rust
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/// impl X {
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/// pub fn as_str(self) -> &str { .. }
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/// }
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/// ```
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declare_lint! {
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pub WRONG_PUB_SELF_CONVENTION,
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Allow,
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"defining a public method named with an established prefix (like \"into_\") that takes \
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`self` with the wrong convention"
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}
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/// **What it does:** Checks for usage of `ok().expect(..)`.
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///
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/// **Why is this bad?** Because you usually call `expect()` on the `Result`
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/// directly to get a better error message.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// x.ok().expect("why did I do this again?")
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/// ```
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declare_lint! {
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pub OK_EXPECT,
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Warn,
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"using `ok().expect()`, which gives worse error messages than \
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calling `expect` directly on the Result"
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}
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/// **What it does:** Checks for usage of `_.map(_).unwrap_or(_)`.
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///
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/// **Why is this bad?** Readability, this can be written more concisely as
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/// `_.map_or(_, _)`.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// x.map(|a| a + 1).unwrap_or(0)
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/// ```
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declare_lint! {
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pub OPTION_MAP_UNWRAP_OR,
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Allow,
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"using `Option.map(f).unwrap_or(a)`, which is more succinctly expressed as \
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`map_or(a, f)`"
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}
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/// **What it does:** Checks for usage of `_.map(_).unwrap_or_else(_)`.
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///
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/// **Why is this bad?** Readability, this can be written more concisely as
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/// `_.map_or_else(_, _)`.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// x.map(|a| a + 1).unwrap_or_else(some_function)
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/// ```
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declare_lint! {
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pub OPTION_MAP_UNWRAP_OR_ELSE,
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Allow,
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"using `Option.map(f).unwrap_or_else(g)`, which is more succinctly expressed as \
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`map_or_else(g, f)`"
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}
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/// **What it does:** Checks for usage of `_.filter(_).next()`.
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///
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/// **Why is this bad?** Readability, this can be written more concisely as
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/// `_.find(_)`.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// iter.filter(|x| x == 0).next()
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/// ```
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declare_lint! {
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pub FILTER_NEXT,
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Warn,
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"using `filter(p).next()`, which is more succinctly expressed as `.find(p)`"
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}
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/// **What it does:** Checks for usage of `_.filter(_).map(_)`,
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/// `_.filter(_).flat_map(_)`, `_.filter_map(_).flat_map(_)` and similar.
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///
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/// **Why is this bad?** Readability, this can be written more concisely as a
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/// single method call.
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///
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/// **Known problems:** Often requires a condition + Option/Iterator creation
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/// inside the closure.
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///
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/// **Example:**
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/// ```rust
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/// iter.filter(|x| x == 0).map(|x| x * 2)
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/// ```
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declare_lint! {
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pub FILTER_MAP,
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Allow,
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"using combinations of `filter`, `map`, `filter_map` and `flat_map` which can \
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usually be written as a single method call"
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}
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/// **What it does:** Checks for an iterator search (such as `find()`,
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/// `position()`, or `rposition()`) followed by a call to `is_some()`.
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///
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/// **Why is this bad?** Readability, this can be written more concisely as
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/// `_.any(_)`.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// iter.find(|x| x == 0).is_some()
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/// ```
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declare_lint! {
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pub SEARCH_IS_SOME,
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Warn,
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"using an iterator search followed by `is_some()`, which is more succinctly \
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expressed as a call to `any()`"
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}
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/// **What it does:** Checks for usage of `.chars().next()` on a `str` to check
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/// if it starts with a given char.
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///
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/// **Why is this bad?** Readability, this can be written more concisely as
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/// `_.starts_with(_)`.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// name.chars().next() == Some('_')
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/// ```
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declare_lint! {
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pub CHARS_NEXT_CMP,
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Warn,
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"using `.chars().next()` to check if a string starts with a char"
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}
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/// **What it does:** Checks for calls to `.or(foo(..))`, `.unwrap_or(foo(..))`,
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/// etc., and suggests to use `or_else`, `unwrap_or_else`, etc., or
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/// `unwrap_or_default` instead.
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///
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/// **Why is this bad?** The function will always be called and potentially
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/// allocate an object acting as the default.
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///
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/// **Known problems:** If the function has side-effects, not calling it will
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/// change the semantic of the program, but you shouldn't rely on that anyway.
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///
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/// **Example:**
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/// ```rust
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/// foo.unwrap_or(String::new())
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/// ```
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/// this can instead be written:
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/// ```rust
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/// foo.unwrap_or_else(String::new)
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/// ```
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/// or
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/// ```rust
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/// foo.unwrap_or_default()
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/// ```
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declare_lint! {
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pub OR_FUN_CALL,
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Warn,
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"using any `*or` method with a function call, which suggests `*or_else`"
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}
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/// **What it does:** Checks for usage of `.clone()` on a `Copy` type.
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///
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/// **Why is this bad?** The only reason `Copy` types implement `Clone` is for
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/// generics, not for using the `clone` method on a concrete type.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// 42u64.clone()
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/// ```
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declare_lint! {
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pub CLONE_ON_COPY,
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Warn,
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"using `clone` on a `Copy` type"
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}
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/// **What it does:** Checks for usage of `.clone()` on an `&&T`.
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///
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/// **Why is this bad?** Cloning an `&&T` copies the inner `&T`, instead of
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/// cloning the underlying `T`.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// fn main() {
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/// let x = vec![1];
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/// let y = &&x;
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/// let z = y.clone();
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/// println!("{:p} {:p}",*y, z); // prints out the same pointer
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/// }
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/// ```
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declare_lint! {
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pub CLONE_DOUBLE_REF,
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Warn,
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"using `clone` on `&&T`"
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}
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/// **What it does:** Checks for `new` not returning `Self`.
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///
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/// **Why is this bad?** As a convention, `new` methods are used to make a new
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/// instance of a type.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// impl Foo {
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/// fn new(..) -> NotAFoo {
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/// }
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/// }
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/// ```
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declare_lint! {
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pub NEW_RET_NO_SELF,
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Warn,
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"not returning `Self` in a `new` method"
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}
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/// **What it does:** Checks for string methods that receive a single-character
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/// `str` as an argument, e.g. `_.split("x")`.
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///
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/// **Why is this bad?** Performing these methods using a `char` is faster than
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/// using a `str`.
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///
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/// **Known problems:** Does not catch multi-byte unicode characters.
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///
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/// **Example:**
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/// `_.split("x")` could be `_.split('x')
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declare_lint! {
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pub SINGLE_CHAR_PATTERN,
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Warn,
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"using a single-character str where a char could be used, e.g. \
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`_.split(\"x\")`"
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}
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/// **What it does:** Checks for getting the inner pointer of a temporary `CString`.
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///
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/// **Why is this bad?** The inner pointer of a `CString` is only valid as long
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/// as the `CString` is alive.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust,ignore
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/// let c_str = CString::new("foo").unwrap().as_ptr();
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/// unsafe {
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/// call_some_ffi_func(c_str);
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/// }
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/// ```
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/// Here `c_str` point to a freed address. The correct use would be:
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/// ```rust,ignore
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/// let c_str = CString::new("foo").unwrap();
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/// unsafe {
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/// call_some_ffi_func(c_str.as_ptr());
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/// }
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/// ```
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declare_lint! {
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pub TEMPORARY_CSTRING_AS_PTR,
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Warn,
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"getting the inner pointer of a temporary `CString`"
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}
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|
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|
/// **What it does:** Checks for use of `.iter().nth()` (and the related
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/// `.iter_mut().nth()`) on standard library types with O(1) element access.
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///
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/// **Why is this bad?** `.get()` and `.get_mut()` are more efficient and more
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/// readable.
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|
///
|
|
/// **Known problems:** None.
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|
///
|
|
/// **Example:**
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/// ```rust
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/// let some_vec = vec![0, 1, 2, 3];
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/// let bad_vec = some_vec.iter().nth(3);
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/// let bad_slice = &some_vec[..].iter().nth(3);
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/// ```
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|
/// The correct use would be:
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|
/// ```rust
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/// let some_vec = vec![0, 1, 2, 3];
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/// let bad_vec = some_vec.get(3);
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/// let bad_slice = &some_vec[..].get(3);
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|
/// ```
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|
declare_lint! {
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|
pub ITER_NTH,
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|
Warn,
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|
"using `.iter().nth()` on a standard library type with O(1) element access"
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|
}
|
|
|
|
/// **What it does:** Checks for use of `.skip(x).next()` on iterators.
|
|
///
|
|
/// **Why is this bad?** `.nth(x)` is cleaner
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
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/// let some_vec = vec![0, 1, 2, 3];
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/// let bad_vec = some_vec.iter().skip(3).next();
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|
/// let bad_slice = &some_vec[..].iter().skip(3).next();
|
|
/// ```
|
|
/// The correct use would be:
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|
/// ```rust
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|
/// let some_vec = vec![0, 1, 2, 3];
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|
/// let bad_vec = some_vec.iter().nth(3);
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|
/// let bad_slice = &some_vec[..].iter().nth(3);
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|
/// ```
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|
declare_lint! {
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|
pub ITER_SKIP_NEXT,
|
|
Warn,
|
|
"using `.skip(x).next()` on an iterator"
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|
}
|
|
|
|
/// **What it does:** Checks for use of `.get().unwrap()` (or
|
|
/// `.get_mut().unwrap`) on a standard library type which implements `Index`
|
|
///
|
|
/// **Why is this bad?** Using the Index trait (`[]`) is more clear and more
|
|
/// concise.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
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|
/// let some_vec = vec![0, 1, 2, 3];
|
|
/// let last = some_vec.get(3).unwrap();
|
|
/// *some_vec.get_mut(0).unwrap() = 1;
|
|
/// ```
|
|
/// The correct use would be:
|
|
/// ```rust
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|
/// let some_vec = vec![0, 1, 2, 3];
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|
/// let last = some_vec[3];
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|
/// some_vec[0] = 1;
|
|
/// ```
|
|
declare_lint! {
|
|
pub GET_UNWRAP,
|
|
Warn,
|
|
"using `.get().unwrap()` or `.get_mut().unwrap()` when using `[]` would work instead"
|
|
}
|
|
|
|
/// **What it does:** Checks for the use of `.extend(s.chars())` where s is a
|
|
/// `&str` or `String`.
|
|
///
|
|
/// **Why is this bad?** `.push_str(s)` is clearer
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let abc = "abc";
|
|
/// let def = String::from("def");
|
|
/// let mut s = String::new();
|
|
/// s.extend(abc.chars());
|
|
/// s.extend(def.chars());
|
|
/// ```
|
|
/// The correct use would be:
|
|
/// ```rust
|
|
/// let abc = "abc";
|
|
/// let def = String::from("def");
|
|
/// let mut s = String::new();
|
|
/// s.push_str(abc);
|
|
/// s.push_str(&def));
|
|
/// ```
|
|
declare_lint! {
|
|
pub STRING_EXTEND_CHARS,
|
|
Warn,
|
|
"using `x.extend(s.chars())` where s is a `&str` or `String`"
|
|
}
|
|
|
|
/// **What it does:** Checks for the use of `.cloned().collect()` on slice to create a `Vec`.
|
|
///
|
|
/// **Why is this bad?** `.to_vec()` is clearer
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let s = [1,2,3,4,5];
|
|
/// let s2 : Vec<isize> = s[..].iter().cloned().collect();
|
|
/// ```
|
|
/// The better use would be:
|
|
/// ```rust
|
|
/// let s = [1,2,3,4,5];
|
|
/// let s2 : Vec<isize> = s.to_vec();
|
|
/// ```
|
|
declare_lint! {
|
|
pub ITER_CLONED_COLLECT,
|
|
Warn,
|
|
"using `.cloned().collect()` on slice to create a `Vec`"
|
|
}
|
|
|
|
impl LintPass for Pass {
|
|
fn get_lints(&self) -> LintArray {
|
|
lint_array!(OPTION_UNWRAP_USED,
|
|
RESULT_UNWRAP_USED,
|
|
SHOULD_IMPLEMENT_TRAIT,
|
|
WRONG_SELF_CONVENTION,
|
|
WRONG_PUB_SELF_CONVENTION,
|
|
OK_EXPECT,
|
|
OPTION_MAP_UNWRAP_OR,
|
|
OPTION_MAP_UNWRAP_OR_ELSE,
|
|
OR_FUN_CALL,
|
|
CHARS_NEXT_CMP,
|
|
CLONE_ON_COPY,
|
|
CLONE_DOUBLE_REF,
|
|
NEW_RET_NO_SELF,
|
|
SINGLE_CHAR_PATTERN,
|
|
SEARCH_IS_SOME,
|
|
TEMPORARY_CSTRING_AS_PTR,
|
|
FILTER_NEXT,
|
|
FILTER_MAP,
|
|
ITER_NTH,
|
|
ITER_SKIP_NEXT,
|
|
GET_UNWRAP,
|
|
STRING_EXTEND_CHARS,
|
|
ITER_CLONED_COLLECT)
|
|
}
|
|
}
|
|
|
|
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
|
|
#[allow(unused_attributes)]
|
|
// ^ required because `cyclomatic_complexity` attribute shows up as unused
|
|
#[cyclomatic_complexity = "30"]
|
|
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr) {
|
|
if in_macro(cx, expr.span) {
|
|
return;
|
|
}
|
|
|
|
match expr.node {
|
|
hir::ExprMethodCall(name, _, ref args) => {
|
|
// Chain calls
|
|
// GET_UNWRAP needs to be checked before general `UNWRAP` lints
|
|
if let Some(arglists) = method_chain_args(expr, &["get", "unwrap"]) {
|
|
lint_get_unwrap(cx, expr, arglists[0], false);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["get_mut", "unwrap"]) {
|
|
lint_get_unwrap(cx, expr, arglists[0], true);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["unwrap"]) {
|
|
lint_unwrap(cx, expr, arglists[0]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["ok", "expect"]) {
|
|
lint_ok_expect(cx, expr, arglists[0]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["map", "unwrap_or"]) {
|
|
lint_map_unwrap_or(cx, expr, arglists[0], arglists[1]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["map", "unwrap_or_else"]) {
|
|
lint_map_unwrap_or_else(cx, expr, arglists[0], arglists[1]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["filter", "next"]) {
|
|
lint_filter_next(cx, expr, arglists[0]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["filter", "map"]) {
|
|
lint_filter_map(cx, expr, arglists[0], arglists[1]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["filter_map", "map"]) {
|
|
lint_filter_map_map(cx, expr, arglists[0], arglists[1]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["filter", "flat_map"]) {
|
|
lint_filter_flat_map(cx, expr, arglists[0], arglists[1]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["filter_map", "flat_map"]) {
|
|
lint_filter_map_flat_map(cx, expr, arglists[0], arglists[1]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["find", "is_some"]) {
|
|
lint_search_is_some(cx, expr, "find", arglists[0], arglists[1]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["position", "is_some"]) {
|
|
lint_search_is_some(cx, expr, "position", arglists[0], arglists[1]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["rposition", "is_some"]) {
|
|
lint_search_is_some(cx, expr, "rposition", arglists[0], arglists[1]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["extend"]) {
|
|
lint_extend(cx, expr, arglists[0]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["unwrap", "as_ptr"]) {
|
|
lint_cstring_as_ptr(cx, expr, &arglists[0][0], &arglists[1][0]);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["iter", "nth"]) {
|
|
lint_iter_nth(cx, expr, arglists[0], false);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["iter_mut", "nth"]) {
|
|
lint_iter_nth(cx, expr, arglists[0], true);
|
|
} else if method_chain_args(expr, &["skip", "next"]).is_some() {
|
|
lint_iter_skip_next(cx, expr);
|
|
} else if let Some(arglists) = method_chain_args(expr, &["cloned", "collect"]) {
|
|
lint_iter_cloned_collect(cx, expr, arglists[0]);
|
|
}
|
|
|
|
lint_or_fun_call(cx, expr, &name.node.as_str(), args);
|
|
|
|
let self_ty = cx.tables.expr_ty_adjusted(&args[0]);
|
|
if args.len() == 1 && &*name.node.as_str() == "clone" {
|
|
lint_clone_on_copy(cx, expr, &args[0], self_ty);
|
|
}
|
|
|
|
match self_ty.sty {
|
|
ty::TyRef(_, ty) if ty.ty.sty == ty::TyStr => {
|
|
for &(method, pos) in &PATTERN_METHODS {
|
|
if &*name.node.as_str() == method && args.len() > pos {
|
|
lint_single_char_pattern(cx, expr, &args[pos]);
|
|
}
|
|
}
|
|
},
|
|
_ => (),
|
|
}
|
|
},
|
|
hir::ExprBinary(op, ref lhs, ref rhs) if op.node == hir::BiEq || op.node == hir::BiNe => {
|
|
if !lint_chars_next(cx, expr, lhs, rhs, op.node == hir::BiEq) {
|
|
lint_chars_next(cx, expr, rhs, lhs, op.node == hir::BiEq);
|
|
}
|
|
},
|
|
_ => (),
|
|
}
|
|
}
|
|
|
|
fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, implitem: &'tcx hir::ImplItem) {
|
|
if in_external_macro(cx, implitem.span) {
|
|
return;
|
|
}
|
|
let name = implitem.name;
|
|
let parent = cx.tcx.hir.get_parent(implitem.id);
|
|
let item = cx.tcx.hir.expect_item(parent);
|
|
if_let_chain! {[
|
|
let hir::ImplItemKind::Method(ref sig, id) = implitem.node,
|
|
let Some(first_arg_ty) = sig.decl.inputs.get(0),
|
|
let Some(first_arg) = iter_input_pats(&sig.decl, cx.tcx.hir.body(id)).next(),
|
|
let hir::ItemImpl(_, _, _, None, ref self_ty, _) = item.node,
|
|
], {
|
|
// check missing trait implementations
|
|
for &(method_name, n_args, self_kind, out_type, trait_name) in &TRAIT_METHODS {
|
|
if &*name.as_str() == method_name &&
|
|
sig.decl.inputs.len() == n_args &&
|
|
out_type.matches(&sig.decl.output) &&
|
|
self_kind.matches(&first_arg_ty, &first_arg, &self_ty, false) {
|
|
span_lint(cx, SHOULD_IMPLEMENT_TRAIT, implitem.span, &format!(
|
|
"defining a method called `{}` on this type; consider implementing \
|
|
the `{}` trait or choosing a less ambiguous name", name, trait_name));
|
|
}
|
|
}
|
|
|
|
// check conventions w.r.t. conversion method names and predicates
|
|
let ty = cx.tcx.item_type(cx.tcx.hir.local_def_id(item.id));
|
|
let is_copy = is_copy(cx, ty, item.id);
|
|
for &(ref conv, self_kinds) in &CONVENTIONS {
|
|
if_let_chain! {[
|
|
conv.check(&name.as_str()),
|
|
!self_kinds.iter().any(|k| k.matches(&first_arg_ty, &first_arg, &self_ty, is_copy)),
|
|
], {
|
|
let lint = if item.vis == hir::Visibility::Public {
|
|
WRONG_PUB_SELF_CONVENTION
|
|
} else {
|
|
WRONG_SELF_CONVENTION
|
|
};
|
|
span_lint(cx,
|
|
lint,
|
|
first_arg.pat.span,
|
|
&format!("methods called `{}` usually take {}; consider choosing a less \
|
|
ambiguous name",
|
|
conv,
|
|
&self_kinds.iter()
|
|
.map(|k| k.description())
|
|
.collect::<Vec<_>>()
|
|
.join(" or ")));
|
|
}}
|
|
}
|
|
|
|
let ret_ty = return_ty(cx, implitem.id);
|
|
if &*name.as_str() == "new" &&
|
|
!ret_ty.walk().any(|t| same_tys(cx, t, ty, implitem.id)) {
|
|
span_lint(cx,
|
|
NEW_RET_NO_SELF,
|
|
implitem.span,
|
|
"methods called `new` usually return `Self`");
|
|
}
|
|
}}
|
|
}
|
|
}
|
|
|
|
/// Checks for the `OR_FUN_CALL` lint.
|
|
fn lint_or_fun_call(cx: &LateContext, expr: &hir::Expr, name: &str, args: &[hir::Expr]) {
|
|
/// Check 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 or_has_args {
|
|
return false;
|
|
}
|
|
|
|
if name == "unwrap_or" {
|
|
if let hir::ExprPath(ref qpath) = fun.node {
|
|
let path: &str = &*last_path_segment(qpath).name.as_str();
|
|
|
|
if ["default", "new"].contains(&path) {
|
|
let arg_ty = cx.tables.expr_ty(arg);
|
|
let default_trait_id = if let Some(default_trait_id) =
|
|
get_trait_def_id(cx, &paths::DEFAULT_TRAIT) {
|
|
default_trait_id
|
|
} else {
|
|
return false;
|
|
};
|
|
|
|
if implements_trait(cx, arg_ty, default_trait_id, Vec::new()) {
|
|
span_lint_and_then(cx,
|
|
OR_FUN_CALL,
|
|
span,
|
|
&format!("use of `{}` followed by a call to `{}`", name, path),
|
|
|db| {
|
|
db.span_suggestion(span,
|
|
"try this",
|
|
format!("{}.unwrap_or_default()", snippet(cx, self_expr.span, "_")));
|
|
});
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
false
|
|
}
|
|
|
|
/// Check for `*or(foo())`.
|
|
fn check_general_case(
|
|
cx: &LateContext,
|
|
name: &str,
|
|
fun_span: Span,
|
|
self_expr: &hir::Expr,
|
|
arg: &hir::Expr,
|
|
or_has_args: bool,
|
|
span: Span
|
|
) {
|
|
// don't lint for constant values
|
|
// FIXME: can we `expect` here instead of match?
|
|
let promotable = cx.tcx
|
|
.rvalue_promotable_to_static
|
|
.borrow()
|
|
.get(&arg.id)
|
|
.cloned()
|
|
.unwrap_or(true);
|
|
if promotable {
|
|
return;
|
|
}
|
|
|
|
// (path, fn_has_argument, methods, suffix)
|
|
let know_types: &[(&[_], _, &[_], _)] =
|
|
&[(&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")];
|
|
|
|
let self_ty = cx.tables.expr_ty(self_expr);
|
|
|
|
let (fn_has_arguments, poss, suffix) = if let Some(&(_, fn_has_arguments, poss, suffix)) =
|
|
know_types.iter().find(|&&i| match_type(cx, self_ty, i.0)) {
|
|
(fn_has_arguments, poss, suffix)
|
|
} else {
|
|
return;
|
|
};
|
|
|
|
if !poss.contains(&name) {
|
|
return;
|
|
}
|
|
|
|
let sugg: Cow<_> = match (fn_has_arguments, !or_has_args) {
|
|
(true, _) => format!("|_| {}", snippet(cx, arg.span, "..")).into(),
|
|
(false, false) => format!("|| {}", snippet(cx, arg.span, "..")).into(),
|
|
(false, true) => snippet(cx, fun_span, ".."),
|
|
};
|
|
|
|
span_lint_and_then(cx,
|
|
OR_FUN_CALL,
|
|
span,
|
|
&format!("use of `{}` followed by a function call", name),
|
|
|db| {
|
|
db.span_suggestion(span,
|
|
"try this",
|
|
format!("{}.{}_{}({})", snippet(cx, self_expr.span, "_"), name, suffix, sugg));
|
|
});
|
|
}
|
|
|
|
if args.len() == 2 {
|
|
match args[1].node {
|
|
hir::ExprCall(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) {
|
|
check_general_case(cx, name, fun.span, &args[0], &args[1], or_has_args, expr.span);
|
|
}
|
|
},
|
|
hir::ExprMethodCall(fun, _, ref or_args) => {
|
|
check_general_case(cx, name, fun.span, &args[0], &args[1], !or_args.is_empty(), expr.span)
|
|
},
|
|
_ => {},
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Checks for the `CLONE_ON_COPY` lint.
|
|
fn lint_clone_on_copy(cx: &LateContext, expr: &hir::Expr, arg: &hir::Expr, arg_ty: ty::Ty) {
|
|
let ty = cx.tables.expr_ty(expr);
|
|
let parent = cx.tcx.hir.get_parent(expr.id);
|
|
let parameter_environment = ty::ParameterEnvironment::for_item(cx.tcx, parent);
|
|
if let ty::TyRef(_, ty::TypeAndMut { ty: inner, .. }) = arg_ty.sty {
|
|
if let ty::TyRef(..) = inner.sty {
|
|
span_lint_and_then(cx,
|
|
CLONE_DOUBLE_REF,
|
|
expr.span,
|
|
"using `clone` on a double-reference; \
|
|
this will copy the reference instead of cloning the inner type",
|
|
|db| if let Some(snip) = sugg::Sugg::hir_opt(cx, arg) {
|
|
db.span_suggestion(expr.span,
|
|
"try dereferencing it",
|
|
format!("({}).clone()", snip.deref()));
|
|
});
|
|
return; // don't report clone_on_copy
|
|
}
|
|
}
|
|
|
|
if !ty.moves_by_default(cx.tcx.global_tcx(), ¶meter_environment, expr.span) {
|
|
span_lint_and_then(cx,
|
|
CLONE_ON_COPY,
|
|
expr.span,
|
|
"using `clone` on a `Copy` type",
|
|
|db| if let Some(snip) = sugg::Sugg::hir_opt(cx, arg) {
|
|
if let ty::TyRef(..) = cx.tables.expr_ty(arg).sty {
|
|
db.span_suggestion(expr.span, "try dereferencing it", format!("{}", snip.deref()));
|
|
} else {
|
|
db.span_suggestion(expr.span, "try removing the `clone` call", format!("{}", snip));
|
|
}
|
|
});
|
|
}
|
|
}
|
|
|
|
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, _) = walk_ptrs_ty_depth(cx.tables.expr_ty(target));
|
|
let ref_str = if self_ty.sty == ty::TyStr {
|
|
""
|
|
} else if match_type(cx, self_ty, &paths::STRING) {
|
|
"&"
|
|
} else {
|
|
return;
|
|
};
|
|
|
|
span_lint_and_then(cx, STRING_EXTEND_CHARS, expr.span, "calling `.extend(_.chars())`", |db| {
|
|
db.span_suggestion(expr.span,
|
|
"try this",
|
|
format!("{}.push_str({}{})",
|
|
snippet(cx, args[0].span, "_"),
|
|
ref_str,
|
|
snippet(cx, target.span, "_")));
|
|
});
|
|
}
|
|
}
|
|
|
|
fn lint_extend(cx: &LateContext, expr: &hir::Expr, args: &[hir::Expr]) {
|
|
let (obj_ty, _) = walk_ptrs_ty_depth(cx.tables.expr_ty(&args[0]));
|
|
if match_type(cx, obj_ty, &paths::STRING) {
|
|
lint_string_extend(cx, expr, args);
|
|
}
|
|
}
|
|
|
|
fn lint_cstring_as_ptr(cx: &LateContext, expr: &hir::Expr, new: &hir::Expr, unwrap: &hir::Expr) {
|
|
if_let_chain!{[
|
|
let hir::ExprCall(ref fun, ref args) = new.node,
|
|
args.len() == 1,
|
|
let hir::ExprPath(ref path) = fun.node,
|
|
let Def::Method(did) = cx.tables.qpath_def(path, fun.id),
|
|
match_def_path(cx.tcx, did, &paths::CSTRING_NEW)
|
|
], {
|
|
span_lint_and_then(cx, TEMPORARY_CSTRING_AS_PTR, expr.span,
|
|
"you are getting the inner pointer of a temporary `CString`",
|
|
|db| {
|
|
db.note("that pointer will be invalid outside this expression");
|
|
db.span_help(unwrap.span, "assign the `CString` to a variable to extend its lifetime");
|
|
});
|
|
}}
|
|
}
|
|
|
|
fn lint_iter_cloned_collect(cx: &LateContext, expr: &hir::Expr, iter_args: &[hir::Expr]) {
|
|
if match_type(cx, cx.tables.expr_ty(expr), &paths::VEC) &&
|
|
derefs_to_slice(cx, &iter_args[0], cx.tables.expr_ty(&iter_args[0])).is_some() {
|
|
span_lint(cx,
|
|
ITER_CLONED_COLLECT,
|
|
expr.span,
|
|
"called `cloned().collect()` on a slice to create a `Vec`. Calling `to_vec()` is both faster and \
|
|
more readable");
|
|
}
|
|
}
|
|
|
|
fn lint_iter_nth(cx: &LateContext, expr: &hir::Expr, iter_args: &[hir::Expr], is_mut: bool) {
|
|
let mut_str = if is_mut { "_mut" } else { "" };
|
|
let caller_type = if derefs_to_slice(cx, &iter_args[0], cx.tables.expr_ty(&iter_args[0])).is_some() {
|
|
"slice"
|
|
} else if match_type(cx, cx.tables.expr_ty(&iter_args[0]), &paths::VEC) {
|
|
"Vec"
|
|
} else if match_type(cx, cx.tables.expr_ty(&iter_args[0]), &paths::VEC_DEQUE) {
|
|
"VecDeque"
|
|
} else {
|
|
return; // caller is not a type that we want to lint
|
|
};
|
|
|
|
span_lint(cx,
|
|
ITER_NTH,
|
|
expr.span,
|
|
&format!("called `.iter{0}().nth()` on a {1}. Calling `.get{0}()` is both faster and more readable",
|
|
mut_str,
|
|
caller_type));
|
|
}
|
|
|
|
fn lint_get_unwrap(cx: &LateContext, expr: &hir::Expr, get_args: &[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 expr_ty = cx.tables.expr_ty(&get_args[0]);
|
|
let caller_type = if derefs_to_slice(cx, &get_args[0], expr_ty).is_some() {
|
|
"slice"
|
|
} else if match_type(cx, expr_ty, &paths::VEC) {
|
|
"Vec"
|
|
} else if match_type(cx, expr_ty, &paths::VEC_DEQUE) {
|
|
"VecDeque"
|
|
} else if !is_mut && match_type(cx, expr_ty, &paths::HASHMAP) {
|
|
"HashMap"
|
|
} else if !is_mut && match_type(cx, expr_ty, &paths::BTREEMAP) {
|
|
"BTreeMap"
|
|
} else {
|
|
return; // caller is not a type that we want to lint
|
|
};
|
|
|
|
let mut_str = if is_mut { "_mut" } else { "" };
|
|
let borrow_str = if is_mut { "&mut " } else { "&" };
|
|
span_lint_and_then(cx,
|
|
GET_UNWRAP,
|
|
expr.span,
|
|
&format!("called `.get{0}().unwrap()` on a {1}. Using `[]` is more clear and more concise",
|
|
mut_str,
|
|
caller_type),
|
|
|db| {
|
|
db.span_suggestion(expr.span,
|
|
"try this",
|
|
format!("{}{}[{}]",
|
|
borrow_str,
|
|
snippet(cx, get_args[0].span, "_"),
|
|
snippet(cx, get_args[1].span, "_")));
|
|
});
|
|
}
|
|
|
|
fn lint_iter_skip_next(cx: &LateContext, expr: &hir::Expr) {
|
|
// lint if caller of skip is an Iterator
|
|
if match_trait_method(cx, expr, &paths::ITERATOR) {
|
|
span_lint(cx,
|
|
ITER_SKIP_NEXT,
|
|
expr.span,
|
|
"called `skip(x).next()` on an iterator. This is more succinctly expressed by calling `nth(x)`");
|
|
}
|
|
}
|
|
|
|
fn derefs_to_slice(cx: &LateContext, expr: &hir::Expr, ty: ty::Ty) -> Option<sugg::Sugg<'static>> {
|
|
fn may_slice(cx: &LateContext, ty: ty::Ty) -> bool {
|
|
match ty.sty {
|
|
ty::TySlice(_) => true,
|
|
ty::TyAdt(def, _) if def.is_box() => may_slice(cx, ty.boxed_ty()),
|
|
ty::TyAdt(..) => match_type(cx, ty, &paths::VEC),
|
|
ty::TyArray(_, size) => size < 32,
|
|
ty::TyRef(_, ty::TypeAndMut { ty: inner, .. }) => may_slice(cx, inner),
|
|
_ => false,
|
|
}
|
|
}
|
|
|
|
if let hir::ExprMethodCall(name, _, ref args) = expr.node {
|
|
if &*name.node.as_str() == "iter" && may_slice(cx, cx.tables.expr_ty(&args[0])) {
|
|
sugg::Sugg::hir_opt(cx, &args[0]).map(|sugg| sugg.addr())
|
|
} else {
|
|
None
|
|
}
|
|
} else {
|
|
match ty.sty {
|
|
ty::TySlice(_) => sugg::Sugg::hir_opt(cx, expr),
|
|
ty::TyAdt(def, _) if def.is_box() && may_slice(cx, ty.boxed_ty()) => sugg::Sugg::hir_opt(cx, expr),
|
|
ty::TyRef(_, ty::TypeAndMut { ty: inner, .. }) => {
|
|
if may_slice(cx, inner) {
|
|
sugg::Sugg::hir_opt(cx, 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, _) = walk_ptrs_ty_depth(cx.tables.expr_ty(&unwrap_args[0]));
|
|
|
|
let mess = if match_type(cx, obj_ty, &paths::OPTION) {
|
|
Some((OPTION_UNWRAP_USED, "an Option", "None"))
|
|
} else if match_type(cx, obj_ty, &paths::RESULT) {
|
|
Some((RESULT_UNWRAP_USED, "a Result", "Err"))
|
|
} else {
|
|
None
|
|
};
|
|
|
|
if let Some((lint, kind, none_value)) = mess {
|
|
span_lint(cx,
|
|
lint,
|
|
expr.span,
|
|
&format!("used unwrap() on {} value. If you don't want to handle the {} case gracefully, consider \
|
|
using expect() to provide a better panic \
|
|
message",
|
|
kind,
|
|
none_value));
|
|
}
|
|
}
|
|
|
|
/// lint use of `ok().expect()` for `Result`s
|
|
fn lint_ok_expect(cx: &LateContext, expr: &hir::Expr, ok_args: &[hir::Expr]) {
|
|
// lint if the caller of `ok()` is a `Result`
|
|
if match_type(cx, cx.tables.expr_ty(&ok_args[0]), &paths::RESULT) {
|
|
let result_type = cx.tables.expr_ty(&ok_args[0]);
|
|
if let Some(error_type) = get_error_type(cx, result_type) {
|
|
if has_debug_impl(error_type, cx) {
|
|
span_lint(cx,
|
|
OK_EXPECT,
|
|
expr.span,
|
|
"called `ok().expect()` on a Result value. You can call `expect` directly on the `Result`");
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// lint use of `map().unwrap_or()` for `Option`s
|
|
fn lint_map_unwrap_or(cx: &LateContext, expr: &hir::Expr, map_args: &[hir::Expr], unwrap_args: &[hir::Expr]) {
|
|
// lint if the caller of `map()` is an `Option`
|
|
if match_type(cx, cx.tables.expr_ty(&map_args[0]), &paths::OPTION) {
|
|
// lint message
|
|
let msg = "called `map(f).unwrap_or(a)` on an Option value. This can be done more directly by calling \
|
|
`map_or(a, f)` instead";
|
|
// get snippets for args to map() and unwrap_or()
|
|
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() have the same span
|
|
let multiline = map_snippet.lines().count() > 1 || unwrap_snippet.lines().count() > 1;
|
|
let same_span = map_args[1].span.expn_id == unwrap_args[1].span.expn_id;
|
|
if same_span && !multiline {
|
|
span_note_and_lint(cx,
|
|
OPTION_MAP_UNWRAP_OR,
|
|
expr.span,
|
|
msg,
|
|
expr.span,
|
|
&format!("replace `map({0}).unwrap_or({1})` with `map_or({1}, {0})`",
|
|
map_snippet,
|
|
unwrap_snippet));
|
|
} else if same_span && multiline {
|
|
span_lint(cx, OPTION_MAP_UNWRAP_OR, expr.span, msg);
|
|
};
|
|
}
|
|
}
|
|
|
|
/// lint use of `map().unwrap_or_else()` for `Option`s
|
|
fn lint_map_unwrap_or_else(cx: &LateContext, expr: &hir::Expr, map_args: &[hir::Expr], unwrap_args: &[hir::Expr]) {
|
|
// lint if the caller of `map()` is an `Option`
|
|
if match_type(cx, cx.tables.expr_ty(&map_args[0]), &paths::OPTION) {
|
|
// lint message
|
|
let msg = "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";
|
|
// 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.expn_id == unwrap_args[1].span.expn_id;
|
|
if same_span && !multiline {
|
|
span_note_and_lint(cx,
|
|
OPTION_MAP_UNWRAP_OR_ELSE,
|
|
expr.span,
|
|
msg,
|
|
expr.span,
|
|
&format!("replace `map({0}).unwrap_or_else({1})` with `with map_or_else({1}, {0})`",
|
|
map_snippet,
|
|
unwrap_snippet));
|
|
} else if same_span && multiline {
|
|
span_lint(cx, OPTION_MAP_UNWRAP_OR_ELSE, expr.span, msg);
|
|
};
|
|
}
|
|
}
|
|
|
|
/// lint use of `filter().next()` for `Iterators`
|
|
fn lint_filter_next(cx: &LateContext, expr: &hir::Expr, filter_args: &[hir::Expr]) {
|
|
// lint if caller of `.filter().next()` is an Iterator
|
|
if match_trait_method(cx, expr, &paths::ITERATOR) {
|
|
let msg = "called `filter(p).next()` on an `Iterator`. This is more succinctly expressed by calling \
|
|
`.find(p)` instead.";
|
|
let filter_snippet = snippet(cx, filter_args[1].span, "..");
|
|
if filter_snippet.lines().count() <= 1 {
|
|
// add note if not multi-line
|
|
span_note_and_lint(cx,
|
|
FILTER_NEXT,
|
|
expr.span,
|
|
msg,
|
|
expr.span,
|
|
&format!("replace `filter({0}).next()` with `find({0})`", filter_snippet));
|
|
} else {
|
|
span_lint(cx, FILTER_NEXT, expr.span, msg);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// lint use of `filter().map()` for `Iterators`
|
|
fn lint_filter_map(cx: &LateContext, expr: &hir::Expr, _filter_args: &[hir::Expr], _map_args: &[hir::Expr]) {
|
|
// lint if caller of `.filter().map()` is an Iterator
|
|
if match_trait_method(cx, expr, &paths::ITERATOR) {
|
|
let msg = "called `filter(p).map(q)` on an `Iterator`. \
|
|
This is more succinctly expressed by calling `.filter_map(..)` instead.";
|
|
span_lint(cx, FILTER_MAP, expr.span, msg);
|
|
}
|
|
}
|
|
|
|
/// lint use of `filter().map()` for `Iterators`
|
|
fn lint_filter_map_map(cx: &LateContext, expr: &hir::Expr, _filter_args: &[hir::Expr], _map_args: &[hir::Expr]) {
|
|
// lint if caller of `.filter().map()` is an Iterator
|
|
if match_trait_method(cx, expr, &paths::ITERATOR) {
|
|
let msg = "called `filter_map(p).map(q)` on an `Iterator`. \
|
|
This is more succinctly expressed by only calling `.filter_map(..)` instead.";
|
|
span_lint(cx, FILTER_MAP, expr.span, msg);
|
|
}
|
|
}
|
|
|
|
/// lint use of `filter().flat_map()` for `Iterators`
|
|
fn lint_filter_flat_map(cx: &LateContext, expr: &hir::Expr, _filter_args: &[hir::Expr], _map_args: &[hir::Expr]) {
|
|
// lint if caller of `.filter().flat_map()` is an Iterator
|
|
if match_trait_method(cx, expr, &paths::ITERATOR) {
|
|
let msg = "called `filter(p).flat_map(q)` on an `Iterator`. \
|
|
This is more succinctly expressed by calling `.flat_map(..)` \
|
|
and filtering by returning an empty Iterator.";
|
|
span_lint(cx, FILTER_MAP, expr.span, msg);
|
|
}
|
|
}
|
|
|
|
/// lint use of `filter_map().flat_map()` for `Iterators`
|
|
fn lint_filter_map_flat_map(cx: &LateContext, expr: &hir::Expr, _filter_args: &[hir::Expr], _map_args: &[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(p).flat_map(q)` on an `Iterator`. \
|
|
This is more succinctly expressed by calling `.flat_map(..)` \
|
|
and filtering by returning an empty Iterator.";
|
|
span_lint(cx, FILTER_MAP, expr.span, msg);
|
|
}
|
|
}
|
|
|
|
/// lint searching an Iterator followed by `is_some()`
|
|
fn lint_search_is_some(
|
|
cx: &LateContext,
|
|
expr: &hir::Expr,
|
|
search_method: &str,
|
|
search_args: &[hir::Expr],
|
|
is_some_args: &[hir::Expr]
|
|
) {
|
|
// 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 {}. This is more succinctly \
|
|
expressed by calling `any()`.",
|
|
search_method);
|
|
let search_snippet = snippet(cx, search_args[1].span, "..");
|
|
if search_snippet.lines().count() <= 1 {
|
|
// add note if not multi-line
|
|
span_note_and_lint(cx,
|
|
SEARCH_IS_SOME,
|
|
expr.span,
|
|
&msg,
|
|
expr.span,
|
|
&format!("replace `{0}({1}).is_some()` with `any({1})`", search_method, search_snippet));
|
|
} else {
|
|
span_lint(cx, SEARCH_IS_SOME, expr.span, &msg);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Checks for the `CHARS_NEXT_CMP` lint.
|
|
fn lint_chars_next(cx: &LateContext, expr: &hir::Expr, chain: &hir::Expr, other: &hir::Expr, eq: bool) -> bool {
|
|
if_let_chain! {[
|
|
let Some(args) = method_chain_args(chain, &["chars", "next"]),
|
|
let hir::ExprCall(ref fun, ref arg_char) = other.node,
|
|
arg_char.len() == 1,
|
|
let hir::ExprPath(ref qpath) = fun.node,
|
|
let Some(segment) = single_segment_path(qpath),
|
|
&*segment.name.as_str() == "Some"
|
|
], {
|
|
let self_ty = walk_ptrs_ty(cx.tables.expr_ty_adjusted(&args[0][0]));
|
|
|
|
if self_ty.sty != ty::TyStr {
|
|
return false;
|
|
}
|
|
|
|
span_lint_and_then(cx,
|
|
CHARS_NEXT_CMP,
|
|
expr.span,
|
|
"you should use the `starts_with` method",
|
|
|db| {
|
|
let sugg = format!("{}{}.starts_with({})",
|
|
if eq { "" } else { "!" },
|
|
snippet(cx, args[0][0].span, "_"),
|
|
snippet(cx, arg_char[0].span, "_")
|
|
);
|
|
|
|
db.span_suggestion(expr.span, "like this", sugg);
|
|
});
|
|
|
|
return true;
|
|
}}
|
|
|
|
false
|
|
}
|
|
|
|
/// lint for length-1 `str`s for methods in `PATTERN_METHODS`
|
|
fn lint_single_char_pattern(cx: &LateContext, expr: &hir::Expr, arg: &hir::Expr) {
|
|
if let Ok(ConstVal::Str(r)) = ConstContext::with_tables(cx.tcx, cx.tables).eval(arg, ExprTypeChecked) {
|
|
if r.len() == 1 {
|
|
let hint = snippet(cx, expr.span, "..").replace(&format!("\"{}\"", r), &format!("'{}'", r));
|
|
span_lint_and_then(cx,
|
|
SINGLE_CHAR_PATTERN,
|
|
arg.span,
|
|
"single-character string constant used as pattern",
|
|
|db| { db.span_suggestion(expr.span, "try using a char instead:", hint); });
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Given a `Result<T, E>` type, return its error type (`E`).
|
|
fn get_error_type<'a>(cx: &LateContext, ty: ty::Ty<'a>) -> Option<ty::Ty<'a>> {
|
|
if let ty::TyAdt(_, substs) = ty.sty {
|
|
if match_type(cx, ty, &paths::RESULT) {
|
|
substs.types().nth(1)
|
|
} else {
|
|
None
|
|
}
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// This checks whether a given type is known to implement Debug.
|
|
fn has_debug_impl<'a, 'b>(ty: ty::Ty<'a>, cx: &LateContext<'b, 'a>) -> bool {
|
|
match cx.tcx.lang_items.debug_trait() {
|
|
Some(debug) => implements_trait(cx, ty, debug, Vec::new()),
|
|
None => false,
|
|
}
|
|
}
|
|
|
|
enum Convention {
|
|
Eq(&'static str),
|
|
StartsWith(&'static str),
|
|
}
|
|
|
|
#[cfg_attr(rustfmt, rustfmt_skip)]
|
|
const CONVENTIONS: [(Convention, &'static [SelfKind]); 6] = [
|
|
(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::StartsWith("to_"), &[SelfKind::Ref]),
|
|
];
|
|
|
|
#[cfg_attr(rustfmt, rustfmt_skip)]
|
|
const TRAIT_METHODS: [(&'static str, usize, SelfKind, OutType, &'static str); 30] = [
|
|
("add", 2, SelfKind::Value, OutType::Any, "std::ops::Add"),
|
|
("as_mut", 1, SelfKind::RefMut, OutType::Ref, "std::convert::AsMut"),
|
|
("as_ref", 1, SelfKind::Ref, OutType::Ref, "std::convert::AsRef"),
|
|
("bitand", 2, SelfKind::Value, OutType::Any, "std::ops::BitAnd"),
|
|
("bitor", 2, SelfKind::Value, OutType::Any, "std::ops::BitOr"),
|
|
("bitxor", 2, SelfKind::Value, OutType::Any, "std::ops::BitXor"),
|
|
("borrow", 1, SelfKind::Ref, OutType::Ref, "std::borrow::Borrow"),
|
|
("borrow_mut", 1, SelfKind::RefMut, OutType::Ref, "std::borrow::BorrowMut"),
|
|
("clone", 1, SelfKind::Ref, OutType::Any, "std::clone::Clone"),
|
|
("cmp", 2, SelfKind::Ref, OutType::Any, "std::cmp::Ord"),
|
|
("default", 0, SelfKind::No, OutType::Any, "std::default::Default"),
|
|
("deref", 1, SelfKind::Ref, OutType::Ref, "std::ops::Deref"),
|
|
("deref_mut", 1, SelfKind::RefMut, OutType::Ref, "std::ops::DerefMut"),
|
|
("div", 2, SelfKind::Value, OutType::Any, "std::ops::Div"),
|
|
("drop", 1, SelfKind::RefMut, OutType::Unit, "std::ops::Drop"),
|
|
("eq", 2, SelfKind::Ref, OutType::Bool, "std::cmp::PartialEq"),
|
|
("from_iter", 1, SelfKind::No, OutType::Any, "std::iter::FromIterator"),
|
|
("from_str", 1, SelfKind::No, OutType::Any, "std::str::FromStr"),
|
|
("hash", 2, SelfKind::Ref, OutType::Unit, "std::hash::Hash"),
|
|
("index", 2, SelfKind::Ref, OutType::Ref, "std::ops::Index"),
|
|
("index_mut", 2, SelfKind::RefMut, OutType::Ref, "std::ops::IndexMut"),
|
|
("into_iter", 1, SelfKind::Value, OutType::Any, "std::iter::IntoIterator"),
|
|
("mul", 2, SelfKind::Value, OutType::Any, "std::ops::Mul"),
|
|
("neg", 1, SelfKind::Value, OutType::Any, "std::ops::Neg"),
|
|
("next", 1, SelfKind::RefMut, OutType::Any, "std::iter::Iterator"),
|
|
("not", 1, SelfKind::Value, OutType::Any, "std::ops::Not"),
|
|
("rem", 2, SelfKind::Value, OutType::Any, "std::ops::Rem"),
|
|
("shl", 2, SelfKind::Value, OutType::Any, "std::ops::Shl"),
|
|
("shr", 2, SelfKind::Value, OutType::Any, "std::ops::Shr"),
|
|
("sub", 2, SelfKind::Value, OutType::Any, "std::ops::Sub"),
|
|
];
|
|
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#[cfg_attr(rustfmt, rustfmt_skip)]
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const PATTERN_METHODS: [(&'static str, usize); 17] = [
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("contains", 1),
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("starts_with", 1),
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("ends_with", 1),
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("find", 1),
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("rfind", 1),
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("split", 1),
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("rsplit", 1),
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("split_terminator", 1),
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("rsplit_terminator", 1),
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("splitn", 2),
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("rsplitn", 2),
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("matches", 1),
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("rmatches", 1),
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("match_indices", 1),
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("rmatch_indices", 1),
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("trim_left_matches", 1),
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("trim_right_matches", 1),
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];
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#[derive(Clone, Copy, PartialEq, Debug)]
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enum SelfKind {
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Value,
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Ref,
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RefMut,
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No,
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}
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impl SelfKind {
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fn matches(self, ty: &hir::Ty, arg: &hir::Arg, self_ty: &hir::Ty, allow_value_for_ref: bool) -> bool {
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// Self types in the HIR are desugared to explicit self types. So it will always be `self:
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// SomeType`,
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// where SomeType can be `Self` or an explicit impl self type (e.g. `Foo` if the impl is on `Foo`)
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// Thus, we only need to test equality against the impl self type or if it is an explicit
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// `Self`. Furthermore, the only possible types for `self: ` are `&Self`, `Self`, `&mut Self`,
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// and `Box<Self>`, including the equivalent types with `Foo`.
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let is_actually_self = |ty| is_self_ty(ty) || ty == self_ty;
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if is_self(arg) {
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match self {
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SelfKind::Value => is_actually_self(ty),
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SelfKind::Ref | SelfKind::RefMut => {
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if allow_value_for_ref && is_actually_self(ty) {
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return true;
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}
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match ty.node {
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hir::TyRptr(_, ref mt_ty) => {
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let mutability_match = if self == SelfKind::Ref {
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mt_ty.mutbl == hir::MutImmutable
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} else {
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mt_ty.mutbl == hir::MutMutable
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};
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is_actually_self(&mt_ty.ty) && mutability_match
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},
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_ => false,
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}
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},
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_ => false,
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}
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} else {
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self == SelfKind::No
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}
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}
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fn description(&self) -> &'static str {
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match *self {
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SelfKind::Value => "self by value",
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SelfKind::Ref => "self by reference",
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SelfKind::RefMut => "self by mutable reference",
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SelfKind::No => "no self",
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}
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}
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}
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impl Convention {
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fn check(&self, other: &str) -> bool {
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match *self {
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Convention::Eq(this) => this == other,
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Convention::StartsWith(this) => other.starts_with(this) && this != other,
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}
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}
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}
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impl fmt::Display for Convention {
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fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
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match *self {
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Convention::Eq(this) => this.fmt(f),
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Convention::StartsWith(this) => this.fmt(f).and_then(|_| '*'.fmt(f)),
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}
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}
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}
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#[derive(Clone, Copy)]
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enum OutType {
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Unit,
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Bool,
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Any,
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Ref,
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}
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impl OutType {
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fn matches(&self, ty: &hir::FunctionRetTy) -> bool {
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match (self, ty) {
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(&OutType::Unit, &hir::DefaultReturn(_)) => true,
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(&OutType::Unit, &hir::Return(ref ty)) if ty.node == hir::TyTup(vec![].into()) => true,
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(&OutType::Bool, &hir::Return(ref ty)) if is_bool(ty) => true,
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(&OutType::Any, &hir::Return(ref ty)) if ty.node != hir::TyTup(vec![].into()) => true,
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(&OutType::Ref, &hir::Return(ref ty)) => matches!(ty.node, hir::TyRptr(_, _)),
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_ => false,
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}
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}
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}
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fn is_bool(ty: &hir::Ty) -> bool {
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if let hir::TyPath(ref p) = ty.node {
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match_path(p, &["bool"])
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} else {
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false
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}
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}
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