1669 lines
58 KiB
Rust
1669 lines
58 KiB
Rust
#![allow(rustc::default_hash_types)]
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mod borrowed_box;
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mod box_vec;
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mod linked_list;
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mod option_option;
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mod rc_buffer;
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mod redundant_allocation;
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mod utils;
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mod vec_box;
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use std::borrow::Cow;
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use std::cmp::Ordering;
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use std::collections::BTreeMap;
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use if_chain::if_chain;
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use rustc_errors::{Applicability, DiagnosticBuilder};
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use rustc_hir as hir;
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use rustc_hir::intravisit::{walk_body, walk_expr, walk_ty, FnKind, NestedVisitorMap, Visitor};
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use rustc_hir::{
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BinOpKind, Block, Body, Expr, ExprKind, FnDecl, FnRetTy, FnSig, GenericArg, GenericParamKind, HirId, ImplItem,
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ImplItemKind, Item, ItemKind, Local, MatchSource, MutTy, Node, QPath, Stmt, StmtKind, TraitFn, TraitItem,
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TraitItemKind, TyKind,
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};
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use rustc_lint::{LateContext, LateLintPass, LintContext};
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use rustc_middle::hir::map::Map;
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use rustc_middle::lint::in_external_macro;
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use rustc_middle::ty::{self, IntTy, Ty, TyS, TypeckResults, UintTy};
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use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
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use rustc_span::hygiene::{ExpnKind, MacroKind};
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use rustc_span::source_map::Span;
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use rustc_span::symbol::sym;
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use rustc_target::abi::LayoutOf;
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use rustc_target::spec::abi::Abi;
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use rustc_typeck::hir_ty_to_ty;
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use crate::consts::{constant, Constant};
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use crate::utils::paths;
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use crate::utils::{
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clip, comparisons, differing_macro_contexts, higher, indent_of, int_bits, is_isize_or_usize,
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is_type_diagnostic_item, match_path, multispan_sugg, reindent_multiline, sext, snippet, snippet_opt,
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snippet_with_macro_callsite, span_lint, span_lint_and_help, span_lint_and_then, unsext,
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};
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declare_clippy_lint! {
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/// **What it does:** Checks for use of `Box<Vec<_>>` anywhere in the code.
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/// Check the [Box documentation](https://doc.rust-lang.org/std/boxed/index.html) for more information.
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///
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/// **Why is this bad?** `Vec` already keeps its contents in a separate area on
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/// the heap. So if you `Box` it, you just add another level of indirection
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/// without any benefit whatsoever.
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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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/// struct X {
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/// values: Box<Vec<Foo>>,
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/// }
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/// ```
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///
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/// Better:
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///
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/// ```rust,ignore
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/// struct X {
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/// values: Vec<Foo>,
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/// }
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/// ```
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pub BOX_VEC,
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perf,
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"usage of `Box<Vec<T>>`, vector elements are already on the heap"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for use of `Vec<Box<T>>` where T: Sized anywhere in the code.
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/// Check the [Box documentation](https://doc.rust-lang.org/std/boxed/index.html) for more information.
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///
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/// **Why is this bad?** `Vec` already keeps its contents in a separate area on
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/// the heap. So if you `Box` its contents, you just add another level of indirection.
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///
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/// **Known problems:** Vec<Box<T: Sized>> makes sense if T is a large type (see [#3530](https://github.com/rust-lang/rust-clippy/issues/3530),
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/// 1st comment).
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///
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/// **Example:**
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/// ```rust
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/// struct X {
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/// values: Vec<Box<i32>>,
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/// }
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/// ```
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///
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/// Better:
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///
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/// ```rust
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/// struct X {
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/// values: Vec<i32>,
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/// }
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/// ```
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pub VEC_BOX,
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complexity,
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"usage of `Vec<Box<T>>` where T: Sized, vector elements are already on the heap"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for use of `Option<Option<_>>` in function signatures and type
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/// definitions
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///
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/// **Why is this bad?** `Option<_>` represents an optional value. `Option<Option<_>>`
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/// represents an optional optional value which is logically the same thing as an optional
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/// value but has an unneeded extra level of wrapping.
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///
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/// If you have a case where `Some(Some(_))`, `Some(None)` and `None` are distinct cases,
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/// consider a custom `enum` instead, with clear names for each case.
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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 get_data() -> Option<Option<u32>> {
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/// None
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/// }
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/// ```
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///
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/// Better:
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///
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/// ```rust
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/// pub enum Contents {
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/// Data(Vec<u8>), // Was Some(Some(Vec<u8>))
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/// NotYetFetched, // Was Some(None)
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/// None, // Was None
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/// }
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///
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/// fn get_data() -> Contents {
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/// Contents::None
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/// }
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/// ```
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pub OPTION_OPTION,
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pedantic,
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"usage of `Option<Option<T>>`"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for usage of any `LinkedList`, suggesting to use a
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/// `Vec` or a `VecDeque` (formerly called `RingBuf`).
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///
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/// **Why is this bad?** Gankro says:
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///
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/// > The TL;DR of `LinkedList` is that it's built on a massive amount of
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/// pointers and indirection.
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/// > It wastes memory, it has terrible cache locality, and is all-around slow.
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/// `RingBuf`, while
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/// > "only" amortized for push/pop, should be faster in the general case for
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/// almost every possible
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/// > workload, and isn't even amortized at all if you can predict the capacity
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/// you need.
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/// >
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/// > `LinkedList`s are only really good if you're doing a lot of merging or
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/// splitting of lists.
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/// > This is because they can just mangle some pointers instead of actually
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/// copying the data. Even
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/// > if you're doing a lot of insertion in the middle of the list, `RingBuf`
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/// can still be better
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/// > because of how expensive it is to seek to the middle of a `LinkedList`.
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///
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/// **Known problems:** False positives – the instances where using a
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/// `LinkedList` makes sense are few and far between, but they can still happen.
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///
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/// **Example:**
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/// ```rust
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/// # use std::collections::LinkedList;
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/// let x: LinkedList<usize> = LinkedList::new();
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/// ```
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pub LINKEDLIST,
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pedantic,
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"usage of LinkedList, usually a vector is faster, or a more specialized data structure like a `VecDeque`"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for use of `&Box<T>` anywhere in the code.
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/// Check the [Box documentation](https://doc.rust-lang.org/std/boxed/index.html) for more information.
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///
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/// **Why is this bad?** Any `&Box<T>` can also be a `&T`, which is more
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/// general.
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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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/// fn foo(bar: &Box<T>) { ... }
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/// ```
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///
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/// Better:
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///
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/// ```rust,ignore
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/// fn foo(bar: &T) { ... }
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/// ```
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pub BORROWED_BOX,
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complexity,
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"a borrow of a boxed type"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for use of redundant allocations anywhere in the code.
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///
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/// **Why is this bad?** Expressions such as `Rc<&T>`, `Rc<Rc<T>>`, `Rc<Box<T>>`, `Box<&T>`
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/// add an unnecessary level of indirection.
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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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/// # use std::rc::Rc;
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/// fn foo(bar: Rc<&usize>) {}
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/// ```
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///
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/// Better:
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///
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/// ```rust
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/// fn foo(bar: &usize) {}
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/// ```
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pub REDUNDANT_ALLOCATION,
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perf,
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"redundant allocation"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for `Rc<T>` and `Arc<T>` when `T` is a mutable buffer type such as `String` or `Vec`.
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///
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/// **Why is this bad?** Expressions such as `Rc<String>` usually have no advantage over `Rc<str>`, since
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/// it is larger and involves an extra level of indirection, and doesn't implement `Borrow<str>`.
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///
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/// While mutating a buffer type would still be possible with `Rc::get_mut()`, it only
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/// works if there are no additional references yet, which usually defeats the purpose of
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/// enclosing it in a shared ownership type. Instead, additionally wrapping the inner
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/// type with an interior mutable container (such as `RefCell` or `Mutex`) would normally
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/// be used.
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///
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/// **Known problems:** This pattern can be desirable to avoid the overhead of a `RefCell` or `Mutex` for
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/// cases where mutation only happens before there are any additional references.
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///
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/// **Example:**
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/// ```rust,ignore
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/// # use std::rc::Rc;
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/// fn foo(interned: Rc<String>) { ... }
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/// ```
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///
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/// Better:
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///
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/// ```rust,ignore
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/// fn foo(interned: Rc<str>) { ... }
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/// ```
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pub RC_BUFFER,
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restriction,
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"shared ownership of a buffer type"
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}
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pub struct Types {
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vec_box_size_threshold: u64,
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}
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impl_lint_pass!(Types => [BOX_VEC, VEC_BOX, OPTION_OPTION, LINKEDLIST, BORROWED_BOX, REDUNDANT_ALLOCATION, RC_BUFFER]);
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impl<'tcx> LateLintPass<'tcx> for Types {
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fn check_fn(&mut self, cx: &LateContext<'_>, _: FnKind<'_>, decl: &FnDecl<'_>, _: &Body<'_>, _: Span, id: HirId) {
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// Skip trait implementations; see issue #605.
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if let Some(hir::Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_item(id)) {
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if let ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = item.kind {
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return;
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}
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}
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self.check_fn_decl(cx, decl);
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}
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fn check_field_def(&mut self, cx: &LateContext<'_>, field: &hir::FieldDef<'_>) {
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self.check_ty(cx, &field.ty, false);
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}
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fn check_trait_item(&mut self, cx: &LateContext<'_>, item: &TraitItem<'_>) {
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match item.kind {
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TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => self.check_ty(cx, ty, false),
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TraitItemKind::Fn(ref sig, _) => self.check_fn_decl(cx, &sig.decl),
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_ => (),
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}
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}
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fn check_local(&mut self, cx: &LateContext<'_>, local: &Local<'_>) {
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if let Some(ref ty) = local.ty {
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self.check_ty(cx, ty, true);
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}
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}
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}
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impl Types {
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pub fn new(vec_box_size_threshold: u64) -> Self {
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Self { vec_box_size_threshold }
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}
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fn check_fn_decl(&mut self, cx: &LateContext<'_>, decl: &FnDecl<'_>) {
|
||
for input in decl.inputs {
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self.check_ty(cx, input, false);
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||
}
|
||
|
||
if let FnRetTy::Return(ref ty) = decl.output {
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self.check_ty(cx, ty, false);
|
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}
|
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}
|
||
|
||
/// Recursively check for `TypePass` lints in the given type. Stop at the first
|
||
/// lint found.
|
||
///
|
||
/// The parameter `is_local` distinguishes the context of the type.
|
||
fn check_ty(&mut self, cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, is_local: bool) {
|
||
if hir_ty.span.from_expansion() {
|
||
return;
|
||
}
|
||
match hir_ty.kind {
|
||
TyKind::Path(ref qpath) if !is_local => {
|
||
let hir_id = hir_ty.hir_id;
|
||
let res = cx.qpath_res(qpath, hir_id);
|
||
if let Some(def_id) = res.opt_def_id() {
|
||
let mut triggered = false;
|
||
triggered |= box_vec::check(cx, hir_ty, qpath, def_id);
|
||
triggered |= redundant_allocation::check(cx, hir_ty, qpath, def_id);
|
||
triggered |= rc_buffer::check(cx, hir_ty, qpath, def_id);
|
||
triggered |= vec_box::check(cx, hir_ty, qpath, def_id, self.vec_box_size_threshold);
|
||
triggered |= option_option::check(cx, hir_ty, qpath, def_id);
|
||
triggered |= linked_list::check(cx, hir_ty, def_id);
|
||
|
||
if triggered {
|
||
return;
|
||
}
|
||
}
|
||
match *qpath {
|
||
QPath::Resolved(Some(ref ty), ref p) => {
|
||
self.check_ty(cx, ty, is_local);
|
||
for ty in p.segments.iter().flat_map(|seg| {
|
||
seg.args
|
||
.as_ref()
|
||
.map_or_else(|| [].iter(), |params| params.args.iter())
|
||
.filter_map(|arg| match arg {
|
||
GenericArg::Type(ty) => Some(ty),
|
||
_ => None,
|
||
})
|
||
}) {
|
||
self.check_ty(cx, ty, is_local);
|
||
}
|
||
},
|
||
QPath::Resolved(None, ref p) => {
|
||
for ty in p.segments.iter().flat_map(|seg| {
|
||
seg.args
|
||
.as_ref()
|
||
.map_or_else(|| [].iter(), |params| params.args.iter())
|
||
.filter_map(|arg| match arg {
|
||
GenericArg::Type(ty) => Some(ty),
|
||
_ => None,
|
||
})
|
||
}) {
|
||
self.check_ty(cx, ty, is_local);
|
||
}
|
||
},
|
||
QPath::TypeRelative(ref ty, ref seg) => {
|
||
self.check_ty(cx, ty, is_local);
|
||
if let Some(ref params) = seg.args {
|
||
for ty in params.args.iter().filter_map(|arg| match arg {
|
||
GenericArg::Type(ty) => Some(ty),
|
||
_ => None,
|
||
}) {
|
||
self.check_ty(cx, ty, is_local);
|
||
}
|
||
}
|
||
},
|
||
QPath::LangItem(..) => {},
|
||
}
|
||
},
|
||
TyKind::Rptr(ref lt, ref mut_ty) => {
|
||
if !borrowed_box::check(cx, hir_ty, lt, mut_ty) {
|
||
self.check_ty(cx, &mut_ty.ty, is_local);
|
||
}
|
||
},
|
||
TyKind::Slice(ref ty) | TyKind::Array(ref ty, _) | TyKind::Ptr(MutTy { ref ty, .. }) => {
|
||
self.check_ty(cx, ty, is_local)
|
||
},
|
||
TyKind::Tup(tys) => {
|
||
for ty in tys {
|
||
self.check_ty(cx, ty, is_local);
|
||
}
|
||
},
|
||
_ => {},
|
||
}
|
||
}
|
||
}
|
||
|
||
declare_clippy_lint! {
|
||
/// **What it does:** Checks for binding a unit value.
|
||
///
|
||
/// **Why is this bad?** A unit value cannot usefully be used anywhere. So
|
||
/// binding one is kind of pointless.
|
||
///
|
||
/// **Known problems:** None.
|
||
///
|
||
/// **Example:**
|
||
/// ```rust
|
||
/// let x = {
|
||
/// 1;
|
||
/// };
|
||
/// ```
|
||
pub LET_UNIT_VALUE,
|
||
pedantic,
|
||
"creating a `let` binding to a value of unit type, which usually can't be used afterwards"
|
||
}
|
||
|
||
declare_lint_pass!(LetUnitValue => [LET_UNIT_VALUE]);
|
||
|
||
impl<'tcx> LateLintPass<'tcx> for LetUnitValue {
|
||
fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) {
|
||
if let StmtKind::Local(ref local) = stmt.kind {
|
||
if is_unit(cx.typeck_results().pat_ty(&local.pat)) {
|
||
if in_external_macro(cx.sess(), stmt.span) || local.pat.span.from_expansion() {
|
||
return;
|
||
}
|
||
if higher::is_from_for_desugar(local) {
|
||
return;
|
||
}
|
||
span_lint_and_then(
|
||
cx,
|
||
LET_UNIT_VALUE,
|
||
stmt.span,
|
||
"this let-binding has unit value",
|
||
|diag| {
|
||
if let Some(expr) = &local.init {
|
||
let snip = snippet_with_macro_callsite(cx, expr.span, "()");
|
||
diag.span_suggestion(
|
||
stmt.span,
|
||
"omit the `let` binding",
|
||
format!("{};", snip),
|
||
Applicability::MachineApplicable, // snippet
|
||
);
|
||
}
|
||
},
|
||
);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
declare_clippy_lint! {
|
||
/// **What it does:** Checks for comparisons to unit. This includes all binary
|
||
/// comparisons (like `==` and `<`) and asserts.
|
||
///
|
||
/// **Why is this bad?** Unit is always equal to itself, and thus is just a
|
||
/// clumsily written constant. Mostly this happens when someone accidentally
|
||
/// adds semicolons at the end of the operands.
|
||
///
|
||
/// **Known problems:** None.
|
||
///
|
||
/// **Example:**
|
||
/// ```rust
|
||
/// # fn foo() {};
|
||
/// # fn bar() {};
|
||
/// # fn baz() {};
|
||
/// if {
|
||
/// foo();
|
||
/// } == {
|
||
/// bar();
|
||
/// } {
|
||
/// baz();
|
||
/// }
|
||
/// ```
|
||
/// is equal to
|
||
/// ```rust
|
||
/// # fn foo() {};
|
||
/// # fn bar() {};
|
||
/// # fn baz() {};
|
||
/// {
|
||
/// foo();
|
||
/// bar();
|
||
/// baz();
|
||
/// }
|
||
/// ```
|
||
///
|
||
/// For asserts:
|
||
/// ```rust
|
||
/// # fn foo() {};
|
||
/// # fn bar() {};
|
||
/// assert_eq!({ foo(); }, { bar(); });
|
||
/// ```
|
||
/// will always succeed
|
||
pub UNIT_CMP,
|
||
correctness,
|
||
"comparing unit values"
|
||
}
|
||
|
||
declare_lint_pass!(UnitCmp => [UNIT_CMP]);
|
||
|
||
impl<'tcx> LateLintPass<'tcx> for UnitCmp {
|
||
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
|
||
if expr.span.from_expansion() {
|
||
if let Some(callee) = expr.span.source_callee() {
|
||
if let ExpnKind::Macro(MacroKind::Bang, symbol) = callee.kind {
|
||
if let ExprKind::Binary(ref cmp, ref left, _) = expr.kind {
|
||
let op = cmp.node;
|
||
if op.is_comparison() && is_unit(cx.typeck_results().expr_ty(left)) {
|
||
let result = match &*symbol.as_str() {
|
||
"assert_eq" | "debug_assert_eq" => "succeed",
|
||
"assert_ne" | "debug_assert_ne" => "fail",
|
||
_ => return,
|
||
};
|
||
span_lint(
|
||
cx,
|
||
UNIT_CMP,
|
||
expr.span,
|
||
&format!(
|
||
"`{}` of unit values detected. This will always {}",
|
||
symbol.as_str(),
|
||
result
|
||
),
|
||
);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
return;
|
||
}
|
||
if let ExprKind::Binary(ref cmp, ref left, _) = expr.kind {
|
||
let op = cmp.node;
|
||
if op.is_comparison() && is_unit(cx.typeck_results().expr_ty(left)) {
|
||
let result = match op {
|
||
BinOpKind::Eq | BinOpKind::Le | BinOpKind::Ge => "true",
|
||
_ => "false",
|
||
};
|
||
span_lint(
|
||
cx,
|
||
UNIT_CMP,
|
||
expr.span,
|
||
&format!(
|
||
"{}-comparison of unit values detected. This will always be {}",
|
||
op.as_str(),
|
||
result
|
||
),
|
||
);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
declare_clippy_lint! {
|
||
/// **What it does:** Checks for passing a unit value as an argument to a function without using a
|
||
/// unit literal (`()`).
|
||
///
|
||
/// **Why is this bad?** This is likely the result of an accidental semicolon.
|
||
///
|
||
/// **Known problems:** None.
|
||
///
|
||
/// **Example:**
|
||
/// ```rust,ignore
|
||
/// foo({
|
||
/// let a = bar();
|
||
/// baz(a);
|
||
/// })
|
||
/// ```
|
||
pub UNIT_ARG,
|
||
complexity,
|
||
"passing unit to a function"
|
||
}
|
||
|
||
declare_lint_pass!(UnitArg => [UNIT_ARG]);
|
||
|
||
impl<'tcx> LateLintPass<'tcx> for UnitArg {
|
||
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
|
||
if expr.span.from_expansion() {
|
||
return;
|
||
}
|
||
|
||
// apparently stuff in the desugaring of `?` can trigger this
|
||
// so check for that here
|
||
// only the calls to `Try::from_error` is marked as desugared,
|
||
// so we need to check both the current Expr and its parent.
|
||
if is_questionmark_desugar_marked_call(expr) {
|
||
return;
|
||
}
|
||
if_chain! {
|
||
let map = &cx.tcx.hir();
|
||
let opt_parent_node = map.find(map.get_parent_node(expr.hir_id));
|
||
if let Some(hir::Node::Expr(parent_expr)) = opt_parent_node;
|
||
if is_questionmark_desugar_marked_call(parent_expr);
|
||
then {
|
||
return;
|
||
}
|
||
}
|
||
|
||
match expr.kind {
|
||
ExprKind::Call(_, args) | ExprKind::MethodCall(_, _, args, _) => {
|
||
let args_to_recover = args
|
||
.iter()
|
||
.filter(|arg| {
|
||
if is_unit(cx.typeck_results().expr_ty(arg)) && !is_unit_literal(arg) {
|
||
!matches!(
|
||
&arg.kind,
|
||
ExprKind::Match(.., MatchSource::TryDesugar) | ExprKind::Path(..)
|
||
)
|
||
} else {
|
||
false
|
||
}
|
||
})
|
||
.collect::<Vec<_>>();
|
||
if !args_to_recover.is_empty() {
|
||
lint_unit_args(cx, expr, &args_to_recover);
|
||
}
|
||
},
|
||
_ => (),
|
||
}
|
||
}
|
||
}
|
||
|
||
fn fmt_stmts_and_call(
|
||
cx: &LateContext<'_>,
|
||
call_expr: &Expr<'_>,
|
||
call_snippet: &str,
|
||
args_snippets: &[impl AsRef<str>],
|
||
non_empty_block_args_snippets: &[impl AsRef<str>],
|
||
) -> String {
|
||
let call_expr_indent = indent_of(cx, call_expr.span).unwrap_or(0);
|
||
let call_snippet_with_replacements = args_snippets
|
||
.iter()
|
||
.fold(call_snippet.to_owned(), |acc, arg| acc.replacen(arg.as_ref(), "()", 1));
|
||
|
||
let mut stmts_and_call = non_empty_block_args_snippets
|
||
.iter()
|
||
.map(|it| it.as_ref().to_owned())
|
||
.collect::<Vec<_>>();
|
||
stmts_and_call.push(call_snippet_with_replacements);
|
||
stmts_and_call = stmts_and_call
|
||
.into_iter()
|
||
.map(|v| reindent_multiline(v.into(), true, Some(call_expr_indent)).into_owned())
|
||
.collect();
|
||
|
||
let mut stmts_and_call_snippet = stmts_and_call.join(&format!("{}{}", ";\n", " ".repeat(call_expr_indent)));
|
||
// expr is not in a block statement or result expression position, wrap in a block
|
||
let parent_node = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(call_expr.hir_id));
|
||
if !matches!(parent_node, Some(Node::Block(_))) && !matches!(parent_node, Some(Node::Stmt(_))) {
|
||
let block_indent = call_expr_indent + 4;
|
||
stmts_and_call_snippet =
|
||
reindent_multiline(stmts_and_call_snippet.into(), true, Some(block_indent)).into_owned();
|
||
stmts_and_call_snippet = format!(
|
||
"{{\n{}{}\n{}}}",
|
||
" ".repeat(block_indent),
|
||
&stmts_and_call_snippet,
|
||
" ".repeat(call_expr_indent)
|
||
);
|
||
}
|
||
stmts_and_call_snippet
|
||
}
|
||
|
||
fn lint_unit_args(cx: &LateContext<'_>, expr: &Expr<'_>, args_to_recover: &[&Expr<'_>]) {
|
||
let mut applicability = Applicability::MachineApplicable;
|
||
let (singular, plural) = if args_to_recover.len() > 1 {
|
||
("", "s")
|
||
} else {
|
||
("a ", "")
|
||
};
|
||
span_lint_and_then(
|
||
cx,
|
||
UNIT_ARG,
|
||
expr.span,
|
||
&format!("passing {}unit value{} to a function", singular, plural),
|
||
|db| {
|
||
let mut or = "";
|
||
args_to_recover
|
||
.iter()
|
||
.filter_map(|arg| {
|
||
if_chain! {
|
||
if let ExprKind::Block(block, _) = arg.kind;
|
||
if block.expr.is_none();
|
||
if let Some(last_stmt) = block.stmts.iter().last();
|
||
if let StmtKind::Semi(last_expr) = last_stmt.kind;
|
||
if let Some(snip) = snippet_opt(cx, last_expr.span);
|
||
then {
|
||
Some((
|
||
last_stmt.span,
|
||
snip,
|
||
))
|
||
}
|
||
else {
|
||
None
|
||
}
|
||
}
|
||
})
|
||
.for_each(|(span, sugg)| {
|
||
db.span_suggestion(
|
||
span,
|
||
"remove the semicolon from the last statement in the block",
|
||
sugg,
|
||
Applicability::MaybeIncorrect,
|
||
);
|
||
or = "or ";
|
||
applicability = Applicability::MaybeIncorrect;
|
||
});
|
||
|
||
let arg_snippets: Vec<String> = args_to_recover
|
||
.iter()
|
||
.filter_map(|arg| snippet_opt(cx, arg.span))
|
||
.collect();
|
||
let arg_snippets_without_empty_blocks: Vec<String> = args_to_recover
|
||
.iter()
|
||
.filter(|arg| !is_empty_block(arg))
|
||
.filter_map(|arg| snippet_opt(cx, arg.span))
|
||
.collect();
|
||
|
||
if let Some(call_snippet) = snippet_opt(cx, expr.span) {
|
||
let sugg = fmt_stmts_and_call(
|
||
cx,
|
||
expr,
|
||
&call_snippet,
|
||
&arg_snippets,
|
||
&arg_snippets_without_empty_blocks,
|
||
);
|
||
|
||
if arg_snippets_without_empty_blocks.is_empty() {
|
||
db.multipart_suggestion(
|
||
&format!("use {}unit literal{} instead", singular, plural),
|
||
args_to_recover
|
||
.iter()
|
||
.map(|arg| (arg.span, "()".to_string()))
|
||
.collect::<Vec<_>>(),
|
||
applicability,
|
||
);
|
||
} else {
|
||
let plural = arg_snippets_without_empty_blocks.len() > 1;
|
||
let empty_or_s = if plural { "s" } else { "" };
|
||
let it_or_them = if plural { "them" } else { "it" };
|
||
db.span_suggestion(
|
||
expr.span,
|
||
&format!(
|
||
"{}move the expression{} in front of the call and replace {} with the unit literal `()`",
|
||
or, empty_or_s, it_or_them
|
||
),
|
||
sugg,
|
||
applicability,
|
||
);
|
||
}
|
||
}
|
||
},
|
||
);
|
||
}
|
||
|
||
fn is_empty_block(expr: &Expr<'_>) -> bool {
|
||
matches!(
|
||
expr.kind,
|
||
ExprKind::Block(
|
||
Block {
|
||
stmts: &[],
|
||
expr: None,
|
||
..
|
||
},
|
||
_,
|
||
)
|
||
)
|
||
}
|
||
|
||
fn is_questionmark_desugar_marked_call(expr: &Expr<'_>) -> bool {
|
||
use rustc_span::hygiene::DesugaringKind;
|
||
if let ExprKind::Call(ref callee, _) = expr.kind {
|
||
callee.span.is_desugaring(DesugaringKind::QuestionMark)
|
||
} else {
|
||
false
|
||
}
|
||
}
|
||
|
||
fn is_unit(ty: Ty<'_>) -> bool {
|
||
matches!(ty.kind(), ty::Tuple(slice) if slice.is_empty())
|
||
}
|
||
|
||
fn is_unit_literal(expr: &Expr<'_>) -> bool {
|
||
matches!(expr.kind, ExprKind::Tup(ref slice) if slice.is_empty())
|
||
}
|
||
|
||
declare_clippy_lint! {
|
||
/// **What it does:** Checks for types used in structs, parameters and `let`
|
||
/// declarations above a certain complexity threshold.
|
||
///
|
||
/// **Why is this bad?** Too complex types make the code less readable. Consider
|
||
/// using a `type` definition to simplify them.
|
||
///
|
||
/// **Known problems:** None.
|
||
///
|
||
/// **Example:**
|
||
/// ```rust
|
||
/// # use std::rc::Rc;
|
||
/// struct Foo {
|
||
/// inner: Rc<Vec<Vec<Box<(u32, u32, u32, u32)>>>>,
|
||
/// }
|
||
/// ```
|
||
pub TYPE_COMPLEXITY,
|
||
complexity,
|
||
"usage of very complex types that might be better factored into `type` definitions"
|
||
}
|
||
|
||
pub struct TypeComplexity {
|
||
threshold: u64,
|
||
}
|
||
|
||
impl TypeComplexity {
|
||
#[must_use]
|
||
pub fn new(threshold: u64) -> Self {
|
||
Self { threshold }
|
||
}
|
||
}
|
||
|
||
impl_lint_pass!(TypeComplexity => [TYPE_COMPLEXITY]);
|
||
|
||
impl<'tcx> LateLintPass<'tcx> for TypeComplexity {
|
||
fn check_fn(
|
||
&mut self,
|
||
cx: &LateContext<'tcx>,
|
||
_: FnKind<'tcx>,
|
||
decl: &'tcx FnDecl<'_>,
|
||
_: &'tcx Body<'_>,
|
||
_: Span,
|
||
_: HirId,
|
||
) {
|
||
self.check_fndecl(cx, decl);
|
||
}
|
||
|
||
fn check_field_def(&mut self, cx: &LateContext<'tcx>, field: &'tcx hir::FieldDef<'_>) {
|
||
// enum variants are also struct fields now
|
||
self.check_type(cx, &field.ty);
|
||
}
|
||
|
||
fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
|
||
match item.kind {
|
||
ItemKind::Static(ref ty, _, _) | ItemKind::Const(ref ty, _) => self.check_type(cx, ty),
|
||
// functions, enums, structs, impls and traits are covered
|
||
_ => (),
|
||
}
|
||
}
|
||
|
||
fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>) {
|
||
match item.kind {
|
||
TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => self.check_type(cx, ty),
|
||
TraitItemKind::Fn(FnSig { ref decl, .. }, TraitFn::Required(_)) => self.check_fndecl(cx, decl),
|
||
// methods with default impl are covered by check_fn
|
||
_ => (),
|
||
}
|
||
}
|
||
|
||
fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx ImplItem<'_>) {
|
||
match item.kind {
|
||
ImplItemKind::Const(ref ty, _) | ImplItemKind::TyAlias(ref ty) => self.check_type(cx, ty),
|
||
// methods are covered by check_fn
|
||
_ => (),
|
||
}
|
||
}
|
||
|
||
fn check_local(&mut self, cx: &LateContext<'tcx>, local: &'tcx Local<'_>) {
|
||
if let Some(ref ty) = local.ty {
|
||
self.check_type(cx, ty);
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<'tcx> TypeComplexity {
|
||
fn check_fndecl(&self, cx: &LateContext<'tcx>, decl: &'tcx FnDecl<'_>) {
|
||
for arg in decl.inputs {
|
||
self.check_type(cx, arg);
|
||
}
|
||
if let FnRetTy::Return(ref ty) = decl.output {
|
||
self.check_type(cx, ty);
|
||
}
|
||
}
|
||
|
||
fn check_type(&self, cx: &LateContext<'_>, ty: &hir::Ty<'_>) {
|
||
if ty.span.from_expansion() {
|
||
return;
|
||
}
|
||
let score = {
|
||
let mut visitor = TypeComplexityVisitor { score: 0, nest: 1 };
|
||
visitor.visit_ty(ty);
|
||
visitor.score
|
||
};
|
||
|
||
if score > self.threshold {
|
||
span_lint(
|
||
cx,
|
||
TYPE_COMPLEXITY,
|
||
ty.span,
|
||
"very complex type used. Consider factoring parts into `type` definitions",
|
||
);
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Walks a type and assigns a complexity score to it.
|
||
struct TypeComplexityVisitor {
|
||
/// total complexity score of the type
|
||
score: u64,
|
||
/// current nesting level
|
||
nest: u64,
|
||
}
|
||
|
||
impl<'tcx> Visitor<'tcx> for TypeComplexityVisitor {
|
||
type Map = Map<'tcx>;
|
||
|
||
fn visit_ty(&mut self, ty: &'tcx hir::Ty<'_>) {
|
||
let (add_score, sub_nest) = match ty.kind {
|
||
// _, &x and *x have only small overhead; don't mess with nesting level
|
||
TyKind::Infer | TyKind::Ptr(..) | TyKind::Rptr(..) => (1, 0),
|
||
|
||
// the "normal" components of a type: named types, arrays/tuples
|
||
TyKind::Path(..) | TyKind::Slice(..) | TyKind::Tup(..) | TyKind::Array(..) => (10 * self.nest, 1),
|
||
|
||
// function types bring a lot of overhead
|
||
TyKind::BareFn(ref bare) if bare.abi == Abi::Rust => (50 * self.nest, 1),
|
||
|
||
TyKind::TraitObject(ref param_bounds, ..) => {
|
||
let has_lifetime_parameters = param_bounds.iter().any(|bound| {
|
||
bound
|
||
.bound_generic_params
|
||
.iter()
|
||
.any(|gen| matches!(gen.kind, GenericParamKind::Lifetime { .. }))
|
||
});
|
||
if has_lifetime_parameters {
|
||
// complex trait bounds like A<'a, 'b>
|
||
(50 * self.nest, 1)
|
||
} else {
|
||
// simple trait bounds like A + B
|
||
(20 * self.nest, 0)
|
||
}
|
||
},
|
||
|
||
_ => (0, 0),
|
||
};
|
||
self.score += add_score;
|
||
self.nest += sub_nest;
|
||
walk_ty(self, ty);
|
||
self.nest -= sub_nest;
|
||
}
|
||
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
|
||
NestedVisitorMap::None
|
||
}
|
||
}
|
||
|
||
declare_clippy_lint! {
|
||
/// **What it does:** Checks for comparisons where one side of the relation is
|
||
/// either the minimum or maximum value for its type and warns if it involves a
|
||
/// case that is always true or always false. Only integer and boolean types are
|
||
/// checked.
|
||
///
|
||
/// **Why is this bad?** An expression like `min <= x` may misleadingly imply
|
||
/// that it is possible for `x` to be less than the minimum. Expressions like
|
||
/// `max < x` are probably mistakes.
|
||
///
|
||
/// **Known problems:** For `usize` the size of the current compile target will
|
||
/// be assumed (e.g., 64 bits on 64 bit systems). This means code that uses such
|
||
/// a comparison to detect target pointer width will trigger this lint. One can
|
||
/// use `mem::sizeof` and compare its value or conditional compilation
|
||
/// attributes
|
||
/// like `#[cfg(target_pointer_width = "64")] ..` instead.
|
||
///
|
||
/// **Example:**
|
||
///
|
||
/// ```rust
|
||
/// let vec: Vec<isize> = Vec::new();
|
||
/// if vec.len() <= 0 {}
|
||
/// if 100 > i32::MAX {}
|
||
/// ```
|
||
pub ABSURD_EXTREME_COMPARISONS,
|
||
correctness,
|
||
"a comparison with a maximum or minimum value that is always true or false"
|
||
}
|
||
|
||
declare_lint_pass!(AbsurdExtremeComparisons => [ABSURD_EXTREME_COMPARISONS]);
|
||
|
||
enum ExtremeType {
|
||
Minimum,
|
||
Maximum,
|
||
}
|
||
|
||
struct ExtremeExpr<'a> {
|
||
which: ExtremeType,
|
||
expr: &'a Expr<'a>,
|
||
}
|
||
|
||
enum AbsurdComparisonResult {
|
||
AlwaysFalse,
|
||
AlwaysTrue,
|
||
InequalityImpossible,
|
||
}
|
||
|
||
fn is_cast_between_fixed_and_target<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> bool {
|
||
if let ExprKind::Cast(ref cast_exp, _) = expr.kind {
|
||
let precast_ty = cx.typeck_results().expr_ty(cast_exp);
|
||
let cast_ty = cx.typeck_results().expr_ty(expr);
|
||
|
||
return is_isize_or_usize(precast_ty) != is_isize_or_usize(cast_ty);
|
||
}
|
||
|
||
false
|
||
}
|
||
|
||
fn detect_absurd_comparison<'tcx>(
|
||
cx: &LateContext<'tcx>,
|
||
op: BinOpKind,
|
||
lhs: &'tcx Expr<'_>,
|
||
rhs: &'tcx Expr<'_>,
|
||
) -> Option<(ExtremeExpr<'tcx>, AbsurdComparisonResult)> {
|
||
use crate::types::AbsurdComparisonResult::{AlwaysFalse, AlwaysTrue, InequalityImpossible};
|
||
use crate::types::ExtremeType::{Maximum, Minimum};
|
||
use crate::utils::comparisons::{normalize_comparison, Rel};
|
||
|
||
// absurd comparison only makes sense on primitive types
|
||
// primitive types don't implement comparison operators with each other
|
||
if cx.typeck_results().expr_ty(lhs) != cx.typeck_results().expr_ty(rhs) {
|
||
return None;
|
||
}
|
||
|
||
// comparisons between fix sized types and target sized types are considered unanalyzable
|
||
if is_cast_between_fixed_and_target(cx, lhs) || is_cast_between_fixed_and_target(cx, rhs) {
|
||
return None;
|
||
}
|
||
|
||
let (rel, normalized_lhs, normalized_rhs) = normalize_comparison(op, lhs, rhs)?;
|
||
|
||
let lx = detect_extreme_expr(cx, normalized_lhs);
|
||
let rx = detect_extreme_expr(cx, normalized_rhs);
|
||
|
||
Some(match rel {
|
||
Rel::Lt => {
|
||
match (lx, rx) {
|
||
(Some(l @ ExtremeExpr { which: Maximum, .. }), _) => (l, AlwaysFalse), // max < x
|
||
(_, Some(r @ ExtremeExpr { which: Minimum, .. })) => (r, AlwaysFalse), // x < min
|
||
_ => return None,
|
||
}
|
||
},
|
||
Rel::Le => {
|
||
match (lx, rx) {
|
||
(Some(l @ ExtremeExpr { which: Minimum, .. }), _) => (l, AlwaysTrue), // min <= x
|
||
(Some(l @ ExtremeExpr { which: Maximum, .. }), _) => (l, InequalityImpossible), // max <= x
|
||
(_, Some(r @ ExtremeExpr { which: Minimum, .. })) => (r, InequalityImpossible), // x <= min
|
||
(_, Some(r @ ExtremeExpr { which: Maximum, .. })) => (r, AlwaysTrue), // x <= max
|
||
_ => return None,
|
||
}
|
||
},
|
||
Rel::Ne | Rel::Eq => return None,
|
||
})
|
||
}
|
||
|
||
fn detect_extreme_expr<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<ExtremeExpr<'tcx>> {
|
||
use crate::types::ExtremeType::{Maximum, Minimum};
|
||
|
||
let ty = cx.typeck_results().expr_ty(expr);
|
||
|
||
let cv = constant(cx, cx.typeck_results(), expr)?.0;
|
||
|
||
let which = match (ty.kind(), cv) {
|
||
(&ty::Bool, Constant::Bool(false)) | (&ty::Uint(_), Constant::Int(0)) => Minimum,
|
||
(&ty::Int(ity), Constant::Int(i)) if i == unsext(cx.tcx, i128::MIN >> (128 - int_bits(cx.tcx, ity)), ity) => {
|
||
Minimum
|
||
},
|
||
|
||
(&ty::Bool, Constant::Bool(true)) => Maximum,
|
||
(&ty::Int(ity), Constant::Int(i)) if i == unsext(cx.tcx, i128::MAX >> (128 - int_bits(cx.tcx, ity)), ity) => {
|
||
Maximum
|
||
},
|
||
(&ty::Uint(uty), Constant::Int(i)) if clip(cx.tcx, u128::MAX, uty) == i => Maximum,
|
||
|
||
_ => return None,
|
||
};
|
||
Some(ExtremeExpr { which, expr })
|
||
}
|
||
|
||
impl<'tcx> LateLintPass<'tcx> for AbsurdExtremeComparisons {
|
||
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
|
||
use crate::types::AbsurdComparisonResult::{AlwaysFalse, AlwaysTrue, InequalityImpossible};
|
||
use crate::types::ExtremeType::{Maximum, Minimum};
|
||
|
||
if let ExprKind::Binary(ref cmp, ref lhs, ref rhs) = expr.kind {
|
||
if let Some((culprit, result)) = detect_absurd_comparison(cx, cmp.node, lhs, rhs) {
|
||
if !expr.span.from_expansion() {
|
||
let msg = "this comparison involving the minimum or maximum element for this \
|
||
type contains a case that is always true or always false";
|
||
|
||
let conclusion = match result {
|
||
AlwaysFalse => "this comparison is always false".to_owned(),
|
||
AlwaysTrue => "this comparison is always true".to_owned(),
|
||
InequalityImpossible => format!(
|
||
"the case where the two sides are not equal never occurs, consider using `{} == {}` \
|
||
instead",
|
||
snippet(cx, lhs.span, "lhs"),
|
||
snippet(cx, rhs.span, "rhs")
|
||
),
|
||
};
|
||
|
||
let help = format!(
|
||
"because `{}` is the {} value for this type, {}",
|
||
snippet(cx, culprit.expr.span, "x"),
|
||
match culprit.which {
|
||
Minimum => "minimum",
|
||
Maximum => "maximum",
|
||
},
|
||
conclusion
|
||
);
|
||
|
||
span_lint_and_help(cx, ABSURD_EXTREME_COMPARISONS, expr.span, msg, None, &help);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
declare_clippy_lint! {
|
||
/// **What it does:** Checks for comparisons where the relation is always either
|
||
/// true or false, but where one side has been upcast so that the comparison is
|
||
/// necessary. Only integer types are checked.
|
||
///
|
||
/// **Why is this bad?** An expression like `let x : u8 = ...; (x as u32) > 300`
|
||
/// will mistakenly imply that it is possible for `x` to be outside the range of
|
||
/// `u8`.
|
||
///
|
||
/// **Known problems:**
|
||
/// https://github.com/rust-lang/rust-clippy/issues/886
|
||
///
|
||
/// **Example:**
|
||
/// ```rust
|
||
/// let x: u8 = 1;
|
||
/// (x as u32) > 300;
|
||
/// ```
|
||
pub INVALID_UPCAST_COMPARISONS,
|
||
pedantic,
|
||
"a comparison involving an upcast which is always true or false"
|
||
}
|
||
|
||
declare_lint_pass!(InvalidUpcastComparisons => [INVALID_UPCAST_COMPARISONS]);
|
||
|
||
#[derive(Copy, Clone, Debug, Eq)]
|
||
enum FullInt {
|
||
S(i128),
|
||
U(u128),
|
||
}
|
||
|
||
impl FullInt {
|
||
#[allow(clippy::cast_sign_loss)]
|
||
#[must_use]
|
||
fn cmp_s_u(s: i128, u: u128) -> Ordering {
|
||
if s < 0 {
|
||
Ordering::Less
|
||
} else if u > (i128::MAX as u128) {
|
||
Ordering::Greater
|
||
} else {
|
||
(s as u128).cmp(&u)
|
||
}
|
||
}
|
||
}
|
||
|
||
impl PartialEq for FullInt {
|
||
#[must_use]
|
||
fn eq(&self, other: &Self) -> bool {
|
||
self.partial_cmp(other).expect("`partial_cmp` only returns `Some(_)`") == Ordering::Equal
|
||
}
|
||
}
|
||
|
||
impl PartialOrd for FullInt {
|
||
#[must_use]
|
||
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
|
||
Some(match (self, other) {
|
||
(&Self::S(s), &Self::S(o)) => s.cmp(&o),
|
||
(&Self::U(s), &Self::U(o)) => s.cmp(&o),
|
||
(&Self::S(s), &Self::U(o)) => Self::cmp_s_u(s, o),
|
||
(&Self::U(s), &Self::S(o)) => Self::cmp_s_u(o, s).reverse(),
|
||
})
|
||
}
|
||
}
|
||
|
||
impl Ord for FullInt {
|
||
#[must_use]
|
||
fn cmp(&self, other: &Self) -> Ordering {
|
||
self.partial_cmp(other)
|
||
.expect("`partial_cmp` for FullInt can never return `None`")
|
||
}
|
||
}
|
||
|
||
fn numeric_cast_precast_bounds<'a>(cx: &LateContext<'_>, expr: &'a Expr<'_>) -> Option<(FullInt, FullInt)> {
|
||
if let ExprKind::Cast(ref cast_exp, _) = expr.kind {
|
||
let pre_cast_ty = cx.typeck_results().expr_ty(cast_exp);
|
||
let cast_ty = cx.typeck_results().expr_ty(expr);
|
||
// if it's a cast from i32 to u32 wrapping will invalidate all these checks
|
||
if cx.layout_of(pre_cast_ty).ok().map(|l| l.size) == cx.layout_of(cast_ty).ok().map(|l| l.size) {
|
||
return None;
|
||
}
|
||
match pre_cast_ty.kind() {
|
||
ty::Int(int_ty) => Some(match int_ty {
|
||
IntTy::I8 => (FullInt::S(i128::from(i8::MIN)), FullInt::S(i128::from(i8::MAX))),
|
||
IntTy::I16 => (FullInt::S(i128::from(i16::MIN)), FullInt::S(i128::from(i16::MAX))),
|
||
IntTy::I32 => (FullInt::S(i128::from(i32::MIN)), FullInt::S(i128::from(i32::MAX))),
|
||
IntTy::I64 => (FullInt::S(i128::from(i64::MIN)), FullInt::S(i128::from(i64::MAX))),
|
||
IntTy::I128 => (FullInt::S(i128::MIN), FullInt::S(i128::MAX)),
|
||
IntTy::Isize => (FullInt::S(isize::MIN as i128), FullInt::S(isize::MAX as i128)),
|
||
}),
|
||
ty::Uint(uint_ty) => Some(match uint_ty {
|
||
UintTy::U8 => (FullInt::U(u128::from(u8::MIN)), FullInt::U(u128::from(u8::MAX))),
|
||
UintTy::U16 => (FullInt::U(u128::from(u16::MIN)), FullInt::U(u128::from(u16::MAX))),
|
||
UintTy::U32 => (FullInt::U(u128::from(u32::MIN)), FullInt::U(u128::from(u32::MAX))),
|
||
UintTy::U64 => (FullInt::U(u128::from(u64::MIN)), FullInt::U(u128::from(u64::MAX))),
|
||
UintTy::U128 => (FullInt::U(u128::MIN), FullInt::U(u128::MAX)),
|
||
UintTy::Usize => (FullInt::U(usize::MIN as u128), FullInt::U(usize::MAX as u128)),
|
||
}),
|
||
_ => None,
|
||
}
|
||
} else {
|
||
None
|
||
}
|
||
}
|
||
|
||
fn node_as_const_fullint<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<FullInt> {
|
||
let val = constant(cx, cx.typeck_results(), expr)?.0;
|
||
if let Constant::Int(const_int) = val {
|
||
match *cx.typeck_results().expr_ty(expr).kind() {
|
||
ty::Int(ity) => Some(FullInt::S(sext(cx.tcx, const_int, ity))),
|
||
ty::Uint(_) => Some(FullInt::U(const_int)),
|
||
_ => None,
|
||
}
|
||
} else {
|
||
None
|
||
}
|
||
}
|
||
|
||
fn err_upcast_comparison(cx: &LateContext<'_>, span: Span, expr: &Expr<'_>, always: bool) {
|
||
if let ExprKind::Cast(ref cast_val, _) = expr.kind {
|
||
span_lint(
|
||
cx,
|
||
INVALID_UPCAST_COMPARISONS,
|
||
span,
|
||
&format!(
|
||
"because of the numeric bounds on `{}` prior to casting, this expression is always {}",
|
||
snippet(cx, cast_val.span, "the expression"),
|
||
if always { "true" } else { "false" },
|
||
),
|
||
);
|
||
}
|
||
}
|
||
|
||
fn upcast_comparison_bounds_err<'tcx>(
|
||
cx: &LateContext<'tcx>,
|
||
span: Span,
|
||
rel: comparisons::Rel,
|
||
lhs_bounds: Option<(FullInt, FullInt)>,
|
||
lhs: &'tcx Expr<'_>,
|
||
rhs: &'tcx Expr<'_>,
|
||
invert: bool,
|
||
) {
|
||
use crate::utils::comparisons::Rel;
|
||
|
||
if let Some((lb, ub)) = lhs_bounds {
|
||
if let Some(norm_rhs_val) = node_as_const_fullint(cx, rhs) {
|
||
if rel == Rel::Eq || rel == Rel::Ne {
|
||
if norm_rhs_val < lb || norm_rhs_val > ub {
|
||
err_upcast_comparison(cx, span, lhs, rel == Rel::Ne);
|
||
}
|
||
} else if match rel {
|
||
Rel::Lt => {
|
||
if invert {
|
||
norm_rhs_val < lb
|
||
} else {
|
||
ub < norm_rhs_val
|
||
}
|
||
},
|
||
Rel::Le => {
|
||
if invert {
|
||
norm_rhs_val <= lb
|
||
} else {
|
||
ub <= norm_rhs_val
|
||
}
|
||
},
|
||
Rel::Eq | Rel::Ne => unreachable!(),
|
||
} {
|
||
err_upcast_comparison(cx, span, lhs, true)
|
||
} else if match rel {
|
||
Rel::Lt => {
|
||
if invert {
|
||
norm_rhs_val >= ub
|
||
} else {
|
||
lb >= norm_rhs_val
|
||
}
|
||
},
|
||
Rel::Le => {
|
||
if invert {
|
||
norm_rhs_val > ub
|
||
} else {
|
||
lb > norm_rhs_val
|
||
}
|
||
},
|
||
Rel::Eq | Rel::Ne => unreachable!(),
|
||
} {
|
||
err_upcast_comparison(cx, span, lhs, false)
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<'tcx> LateLintPass<'tcx> for InvalidUpcastComparisons {
|
||
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
|
||
if let ExprKind::Binary(ref cmp, ref lhs, ref rhs) = expr.kind {
|
||
let normalized = comparisons::normalize_comparison(cmp.node, lhs, rhs);
|
||
let (rel, normalized_lhs, normalized_rhs) = if let Some(val) = normalized {
|
||
val
|
||
} else {
|
||
return;
|
||
};
|
||
|
||
let lhs_bounds = numeric_cast_precast_bounds(cx, normalized_lhs);
|
||
let rhs_bounds = numeric_cast_precast_bounds(cx, normalized_rhs);
|
||
|
||
upcast_comparison_bounds_err(cx, expr.span, rel, lhs_bounds, normalized_lhs, normalized_rhs, false);
|
||
upcast_comparison_bounds_err(cx, expr.span, rel, rhs_bounds, normalized_rhs, normalized_lhs, true);
|
||
}
|
||
}
|
||
}
|
||
|
||
declare_clippy_lint! {
|
||
/// **What it does:** Checks for public `impl` or `fn` missing generalization
|
||
/// over different hashers and implicitly defaulting to the default hashing
|
||
/// algorithm (`SipHash`).
|
||
///
|
||
/// **Why is this bad?** `HashMap` or `HashSet` with custom hashers cannot be
|
||
/// used with them.
|
||
///
|
||
/// **Known problems:** Suggestions for replacing constructors can contain
|
||
/// false-positives. Also applying suggestions can require modification of other
|
||
/// pieces of code, possibly including external crates.
|
||
///
|
||
/// **Example:**
|
||
/// ```rust
|
||
/// # use std::collections::HashMap;
|
||
/// # use std::hash::{Hash, BuildHasher};
|
||
/// # trait Serialize {};
|
||
/// impl<K: Hash + Eq, V> Serialize for HashMap<K, V> { }
|
||
///
|
||
/// pub fn foo(map: &mut HashMap<i32, i32>) { }
|
||
/// ```
|
||
/// could be rewritten as
|
||
/// ```rust
|
||
/// # use std::collections::HashMap;
|
||
/// # use std::hash::{Hash, BuildHasher};
|
||
/// # trait Serialize {};
|
||
/// impl<K: Hash + Eq, V, S: BuildHasher> Serialize for HashMap<K, V, S> { }
|
||
///
|
||
/// pub fn foo<S: BuildHasher>(map: &mut HashMap<i32, i32, S>) { }
|
||
/// ```
|
||
pub IMPLICIT_HASHER,
|
||
pedantic,
|
||
"missing generalization over different hashers"
|
||
}
|
||
|
||
declare_lint_pass!(ImplicitHasher => [IMPLICIT_HASHER]);
|
||
|
||
impl<'tcx> LateLintPass<'tcx> for ImplicitHasher {
|
||
#[allow(clippy::cast_possible_truncation, clippy::too_many_lines)]
|
||
fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
|
||
use rustc_span::BytePos;
|
||
|
||
fn suggestion<'tcx>(
|
||
cx: &LateContext<'tcx>,
|
||
diag: &mut DiagnosticBuilder<'_>,
|
||
generics_span: Span,
|
||
generics_suggestion_span: Span,
|
||
target: &ImplicitHasherType<'_>,
|
||
vis: ImplicitHasherConstructorVisitor<'_, '_, '_>,
|
||
) {
|
||
let generics_snip = snippet(cx, generics_span, "");
|
||
// trim `<` `>`
|
||
let generics_snip = if generics_snip.is_empty() {
|
||
""
|
||
} else {
|
||
&generics_snip[1..generics_snip.len() - 1]
|
||
};
|
||
|
||
multispan_sugg(
|
||
diag,
|
||
"consider adding a type parameter",
|
||
vec![
|
||
(
|
||
generics_suggestion_span,
|
||
format!(
|
||
"<{}{}S: ::std::hash::BuildHasher{}>",
|
||
generics_snip,
|
||
if generics_snip.is_empty() { "" } else { ", " },
|
||
if vis.suggestions.is_empty() {
|
||
""
|
||
} else {
|
||
// request users to add `Default` bound so that generic constructors can be used
|
||
" + Default"
|
||
},
|
||
),
|
||
),
|
||
(
|
||
target.span(),
|
||
format!("{}<{}, S>", target.type_name(), target.type_arguments(),),
|
||
),
|
||
],
|
||
);
|
||
|
||
if !vis.suggestions.is_empty() {
|
||
multispan_sugg(diag, "...and use generic constructor", vis.suggestions);
|
||
}
|
||
}
|
||
|
||
if !cx.access_levels.is_exported(item.hir_id()) {
|
||
return;
|
||
}
|
||
|
||
match item.kind {
|
||
ItemKind::Impl(ref impl_) => {
|
||
let mut vis = ImplicitHasherTypeVisitor::new(cx);
|
||
vis.visit_ty(impl_.self_ty);
|
||
|
||
for target in &vis.found {
|
||
if differing_macro_contexts(item.span, target.span()) {
|
||
return;
|
||
}
|
||
|
||
let generics_suggestion_span = impl_.generics.span.substitute_dummy({
|
||
let pos = snippet_opt(cx, item.span.until(target.span()))
|
||
.and_then(|snip| Some(item.span.lo() + BytePos(snip.find("impl")? as u32 + 4)));
|
||
if let Some(pos) = pos {
|
||
Span::new(pos, pos, item.span.data().ctxt)
|
||
} else {
|
||
return;
|
||
}
|
||
});
|
||
|
||
let mut ctr_vis = ImplicitHasherConstructorVisitor::new(cx, target);
|
||
for item in impl_.items.iter().map(|item| cx.tcx.hir().impl_item(item.id)) {
|
||
ctr_vis.visit_impl_item(item);
|
||
}
|
||
|
||
span_lint_and_then(
|
||
cx,
|
||
IMPLICIT_HASHER,
|
||
target.span(),
|
||
&format!(
|
||
"impl for `{}` should be generalized over different hashers",
|
||
target.type_name()
|
||
),
|
||
move |diag| {
|
||
suggestion(cx, diag, impl_.generics.span, generics_suggestion_span, target, ctr_vis);
|
||
},
|
||
);
|
||
}
|
||
},
|
||
ItemKind::Fn(ref sig, ref generics, body_id) => {
|
||
let body = cx.tcx.hir().body(body_id);
|
||
|
||
for ty in sig.decl.inputs {
|
||
let mut vis = ImplicitHasherTypeVisitor::new(cx);
|
||
vis.visit_ty(ty);
|
||
|
||
for target in &vis.found {
|
||
if in_external_macro(cx.sess(), generics.span) {
|
||
continue;
|
||
}
|
||
let generics_suggestion_span = generics.span.substitute_dummy({
|
||
let pos = snippet_opt(cx, item.span.until(body.params[0].pat.span))
|
||
.and_then(|snip| {
|
||
let i = snip.find("fn")?;
|
||
Some(item.span.lo() + BytePos((i + (&snip[i..]).find('(')?) as u32))
|
||
})
|
||
.expect("failed to create span for type parameters");
|
||
Span::new(pos, pos, item.span.data().ctxt)
|
||
});
|
||
|
||
let mut ctr_vis = ImplicitHasherConstructorVisitor::new(cx, target);
|
||
ctr_vis.visit_body(body);
|
||
|
||
span_lint_and_then(
|
||
cx,
|
||
IMPLICIT_HASHER,
|
||
target.span(),
|
||
&format!(
|
||
"parameter of type `{}` should be generalized over different hashers",
|
||
target.type_name()
|
||
),
|
||
move |diag| {
|
||
suggestion(cx, diag, generics.span, generics_suggestion_span, target, ctr_vis);
|
||
},
|
||
);
|
||
}
|
||
}
|
||
},
|
||
_ => {},
|
||
}
|
||
}
|
||
}
|
||
|
||
enum ImplicitHasherType<'tcx> {
|
||
HashMap(Span, Ty<'tcx>, Cow<'static, str>, Cow<'static, str>),
|
||
HashSet(Span, Ty<'tcx>, Cow<'static, str>),
|
||
}
|
||
|
||
impl<'tcx> ImplicitHasherType<'tcx> {
|
||
/// Checks that `ty` is a target type without a `BuildHasher`.
|
||
fn new(cx: &LateContext<'tcx>, hir_ty: &hir::Ty<'_>) -> Option<Self> {
|
||
if let TyKind::Path(QPath::Resolved(None, ref path)) = hir_ty.kind {
|
||
let params: Vec<_> = path
|
||
.segments
|
||
.last()
|
||
.as_ref()?
|
||
.args
|
||
.as_ref()?
|
||
.args
|
||
.iter()
|
||
.filter_map(|arg| match arg {
|
||
GenericArg::Type(ty) => Some(ty),
|
||
_ => None,
|
||
})
|
||
.collect();
|
||
let params_len = params.len();
|
||
|
||
let ty = hir_ty_to_ty(cx.tcx, hir_ty);
|
||
|
||
if is_type_diagnostic_item(cx, ty, sym::hashmap_type) && params_len == 2 {
|
||
Some(ImplicitHasherType::HashMap(
|
||
hir_ty.span,
|
||
ty,
|
||
snippet(cx, params[0].span, "K"),
|
||
snippet(cx, params[1].span, "V"),
|
||
))
|
||
} else if is_type_diagnostic_item(cx, ty, sym::hashset_type) && params_len == 1 {
|
||
Some(ImplicitHasherType::HashSet(
|
||
hir_ty.span,
|
||
ty,
|
||
snippet(cx, params[0].span, "T"),
|
||
))
|
||
} else {
|
||
None
|
||
}
|
||
} else {
|
||
None
|
||
}
|
||
}
|
||
|
||
fn type_name(&self) -> &'static str {
|
||
match *self {
|
||
ImplicitHasherType::HashMap(..) => "HashMap",
|
||
ImplicitHasherType::HashSet(..) => "HashSet",
|
||
}
|
||
}
|
||
|
||
fn type_arguments(&self) -> String {
|
||
match *self {
|
||
ImplicitHasherType::HashMap(.., ref k, ref v) => format!("{}, {}", k, v),
|
||
ImplicitHasherType::HashSet(.., ref t) => format!("{}", t),
|
||
}
|
||
}
|
||
|
||
fn ty(&self) -> Ty<'tcx> {
|
||
match *self {
|
||
ImplicitHasherType::HashMap(_, ty, ..) | ImplicitHasherType::HashSet(_, ty, ..) => ty,
|
||
}
|
||
}
|
||
|
||
fn span(&self) -> Span {
|
||
match *self {
|
||
ImplicitHasherType::HashMap(span, ..) | ImplicitHasherType::HashSet(span, ..) => span,
|
||
}
|
||
}
|
||
}
|
||
|
||
struct ImplicitHasherTypeVisitor<'a, 'tcx> {
|
||
cx: &'a LateContext<'tcx>,
|
||
found: Vec<ImplicitHasherType<'tcx>>,
|
||
}
|
||
|
||
impl<'a, 'tcx> ImplicitHasherTypeVisitor<'a, 'tcx> {
|
||
fn new(cx: &'a LateContext<'tcx>) -> Self {
|
||
Self { cx, found: vec![] }
|
||
}
|
||
}
|
||
|
||
impl<'a, 'tcx> Visitor<'tcx> for ImplicitHasherTypeVisitor<'a, 'tcx> {
|
||
type Map = Map<'tcx>;
|
||
|
||
fn visit_ty(&mut self, t: &'tcx hir::Ty<'_>) {
|
||
if let Some(target) = ImplicitHasherType::new(self.cx, t) {
|
||
self.found.push(target);
|
||
}
|
||
|
||
walk_ty(self, t);
|
||
}
|
||
|
||
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
|
||
NestedVisitorMap::None
|
||
}
|
||
}
|
||
|
||
/// Looks for default-hasher-dependent constructors like `HashMap::new`.
|
||
struct ImplicitHasherConstructorVisitor<'a, 'b, 'tcx> {
|
||
cx: &'a LateContext<'tcx>,
|
||
maybe_typeck_results: Option<&'tcx TypeckResults<'tcx>>,
|
||
target: &'b ImplicitHasherType<'tcx>,
|
||
suggestions: BTreeMap<Span, String>,
|
||
}
|
||
|
||
impl<'a, 'b, 'tcx> ImplicitHasherConstructorVisitor<'a, 'b, 'tcx> {
|
||
fn new(cx: &'a LateContext<'tcx>, target: &'b ImplicitHasherType<'tcx>) -> Self {
|
||
Self {
|
||
cx,
|
||
maybe_typeck_results: cx.maybe_typeck_results(),
|
||
target,
|
||
suggestions: BTreeMap::new(),
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<'a, 'b, 'tcx> Visitor<'tcx> for ImplicitHasherConstructorVisitor<'a, 'b, 'tcx> {
|
||
type Map = Map<'tcx>;
|
||
|
||
fn visit_body(&mut self, body: &'tcx Body<'_>) {
|
||
let old_maybe_typeck_results = self.maybe_typeck_results.replace(self.cx.tcx.typeck_body(body.id()));
|
||
walk_body(self, body);
|
||
self.maybe_typeck_results = old_maybe_typeck_results;
|
||
}
|
||
|
||
fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
|
||
if_chain! {
|
||
if let ExprKind::Call(ref fun, ref args) = e.kind;
|
||
if let ExprKind::Path(QPath::TypeRelative(ref ty, ref method)) = fun.kind;
|
||
if let TyKind::Path(QPath::Resolved(None, ty_path)) = ty.kind;
|
||
then {
|
||
if !TyS::same_type(self.target.ty(), self.maybe_typeck_results.unwrap().expr_ty(e)) {
|
||
return;
|
||
}
|
||
|
||
if match_path(ty_path, &paths::HASHMAP) {
|
||
if method.ident.name == sym::new {
|
||
self.suggestions
|
||
.insert(e.span, "HashMap::default()".to_string());
|
||
} else if method.ident.name == sym!(with_capacity) {
|
||
self.suggestions.insert(
|
||
e.span,
|
||
format!(
|
||
"HashMap::with_capacity_and_hasher({}, Default::default())",
|
||
snippet(self.cx, args[0].span, "capacity"),
|
||
),
|
||
);
|
||
}
|
||
} else if match_path(ty_path, &paths::HASHSET) {
|
||
if method.ident.name == sym::new {
|
||
self.suggestions
|
||
.insert(e.span, "HashSet::default()".to_string());
|
||
} else if method.ident.name == sym!(with_capacity) {
|
||
self.suggestions.insert(
|
||
e.span,
|
||
format!(
|
||
"HashSet::with_capacity_and_hasher({}, Default::default())",
|
||
snippet(self.cx, args[0].span, "capacity"),
|
||
),
|
||
);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
walk_expr(self, e);
|
||
}
|
||
|
||
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
|
||
NestedVisitorMap::OnlyBodies(self.cx.tcx.hir())
|
||
}
|
||
}
|