1976 lines
70 KiB
Rust
1976 lines
70 KiB
Rust
use crate::consts::{constant, miri_to_const, Constant};
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use crate::utils::sugg::Sugg;
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use crate::utils::visitors::LocalUsedVisitor;
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use crate::utils::{
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expr_block, get_parent_expr, implements_trait, in_macro, indent_of, is_allowed, is_expn_of, is_refutable,
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is_type_diagnostic_item, is_wild, match_qpath, match_type, meets_msrv, multispan_sugg, path_to_local,
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path_to_local_id, peel_hir_pat_refs, peel_mid_ty_refs, peel_n_hir_expr_refs, remove_blocks, snippet, snippet_block,
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snippet_opt, snippet_with_applicability, span_lint_and_help, span_lint_and_note, span_lint_and_sugg,
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span_lint_and_then, strip_pat_refs,
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};
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use crate::utils::{paths, search_same, SpanlessEq, SpanlessHash};
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use if_chain::if_chain;
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use rustc_ast::ast::LitKind;
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use rustc_data_structures::fx::{FxHashMap, FxHashSet};
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use rustc_errors::Applicability;
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use rustc_hir::def::CtorKind;
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use rustc_hir::{
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Arm, BindingAnnotation, Block, BorrowKind, Expr, ExprKind, Guard, HirId, Local, MatchSource, Mutability, Node, Pat,
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PatKind, QPath, RangeEnd,
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};
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use rustc_lint::{LateContext, LateLintPass, LintContext};
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use rustc_middle::lint::in_external_macro;
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use rustc_middle::ty::{self, Ty, TyS};
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use rustc_semver::RustcVersion;
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use rustc_session::{declare_tool_lint, impl_lint_pass};
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use rustc_span::source_map::{Span, Spanned};
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use rustc_span::sym;
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use std::cmp::Ordering;
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use std::collections::hash_map::Entry;
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use std::ops::Bound;
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declare_clippy_lint! {
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/// **What it does:** Checks for matches with a single arm where an `if let`
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/// will usually suffice.
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///
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/// **Why is this bad?** Just readability – `if let` nests less than a `match`.
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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 bar(stool: &str) {}
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/// # let x = Some("abc");
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/// // Bad
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/// match x {
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/// Some(ref foo) => bar(foo),
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/// _ => (),
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/// }
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///
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/// // Good
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/// if let Some(ref foo) = x {
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/// bar(foo);
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/// }
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/// ```
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pub SINGLE_MATCH,
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style,
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"a `match` statement with a single nontrivial arm (i.e., where the other arm is `_ => {}`) instead of `if let`"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for matches with two arms where an `if let else` will
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/// usually suffice.
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///
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/// **Why is this bad?** Just readability – `if let` nests less than a `match`.
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///
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/// **Known problems:** Personal style preferences may differ.
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///
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/// **Example:**
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///
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/// Using `match`:
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///
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/// ```rust
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/// # fn bar(foo: &usize) {}
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/// # let other_ref: usize = 1;
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/// # let x: Option<&usize> = Some(&1);
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/// match x {
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/// Some(ref foo) => bar(foo),
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/// _ => bar(&other_ref),
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/// }
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/// ```
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///
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/// Using `if let` with `else`:
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///
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/// ```rust
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/// # fn bar(foo: &usize) {}
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/// # let other_ref: usize = 1;
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/// # let x: Option<&usize> = Some(&1);
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/// if let Some(ref foo) = x {
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/// bar(foo);
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/// } else {
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/// bar(&other_ref);
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/// }
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/// ```
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pub SINGLE_MATCH_ELSE,
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pedantic,
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"a `match` statement with two arms where the second arm's pattern is a placeholder instead of a specific match pattern"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for matches where all arms match a reference,
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/// suggesting to remove the reference and deref the matched expression
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/// instead. It also checks for `if let &foo = bar` blocks.
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///
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/// **Why is this bad?** It just makes the code less readable. That reference
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/// destructuring adds nothing to the code.
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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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/// // Bad
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/// match x {
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/// &A(ref y) => foo(y),
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/// &B => bar(),
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/// _ => frob(&x),
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/// }
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///
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/// // Good
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/// match *x {
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/// A(ref y) => foo(y),
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/// B => bar(),
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/// _ => frob(x),
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/// }
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/// ```
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pub MATCH_REF_PATS,
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style,
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"a `match` or `if let` with all arms prefixed with `&` instead of deref-ing the match expression"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for matches where match expression is a `bool`. It
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/// suggests to replace the expression with an `if...else` block.
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///
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/// **Why is this bad?** It makes the code less readable.
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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 foo() {}
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/// # fn bar() {}
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/// let condition: bool = true;
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/// match condition {
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/// true => foo(),
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/// false => bar(),
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/// }
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/// ```
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/// Use if/else instead:
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/// ```rust
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/// # fn foo() {}
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/// # fn bar() {}
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/// let condition: bool = true;
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/// if condition {
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/// foo();
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/// } else {
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/// bar();
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/// }
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/// ```
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pub MATCH_BOOL,
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pedantic,
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"a `match` on a boolean expression instead of an `if..else` block"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for overlapping match arms.
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///
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/// **Why is this bad?** It is likely to be an error and if not, makes the code
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/// less obvious.
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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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/// let x = 5;
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/// match x {
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/// 1...10 => println!("1 ... 10"),
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/// 5...15 => println!("5 ... 15"),
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/// _ => (),
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/// }
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/// ```
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pub MATCH_OVERLAPPING_ARM,
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style,
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"a `match` with overlapping arms"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for arm which matches all errors with `Err(_)`
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/// and take drastic actions like `panic!`.
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///
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/// **Why is this bad?** It is generally a bad practice, similar to
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/// catching all exceptions in java with `catch(Exception)`
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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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/// let x: Result<i32, &str> = Ok(3);
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/// match x {
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/// Ok(_) => println!("ok"),
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/// Err(_) => panic!("err"),
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/// }
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/// ```
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pub MATCH_WILD_ERR_ARM,
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pedantic,
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"a `match` with `Err(_)` arm and take drastic actions"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for match which is used to add a reference to an
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/// `Option` value.
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///
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/// **Why is this bad?** Using `as_ref()` or `as_mut()` instead is shorter.
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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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/// let x: Option<()> = None;
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///
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/// // Bad
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/// let r: Option<&()> = match x {
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/// None => None,
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/// Some(ref v) => Some(v),
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/// };
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///
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/// // Good
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/// let r: Option<&()> = x.as_ref();
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/// ```
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pub MATCH_AS_REF,
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complexity,
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"a `match` on an Option value instead of using `as_ref()` or `as_mut`"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for wildcard enum matches using `_`.
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///
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/// **Why is this bad?** New enum variants added by library updates can be missed.
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///
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/// **Known problems:** Suggested replacements may be incorrect if guards exhaustively cover some
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/// variants, and also may not use correct path to enum if it's not present in the current scope.
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///
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/// **Example:**
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/// ```rust
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/// # enum Foo { A(usize), B(usize) }
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/// # let x = Foo::B(1);
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/// // Bad
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/// match x {
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/// Foo::A(_) => {},
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/// _ => {},
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/// }
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///
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/// // Good
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/// match x {
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/// Foo::A(_) => {},
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/// Foo::B(_) => {},
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/// }
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/// ```
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pub WILDCARD_ENUM_MATCH_ARM,
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restriction,
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"a wildcard enum match arm using `_`"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for wildcard enum matches for a single variant.
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///
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/// **Why is this bad?** New enum variants added by library updates can be missed.
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///
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/// **Known problems:** Suggested replacements may not use correct path to enum
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/// if it's not present in the current scope.
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///
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/// **Example:**
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///
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/// ```rust
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/// # enum Foo { A, B, C }
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/// # let x = Foo::B;
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/// // Bad
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/// match x {
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/// Foo::A => {},
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/// Foo::B => {},
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/// _ => {},
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/// }
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///
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/// // Good
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/// match x {
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/// Foo::A => {},
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/// Foo::B => {},
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/// Foo::C => {},
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/// }
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/// ```
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pub MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
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pedantic,
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"a wildcard enum match for a single variant"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for wildcard pattern used with others patterns in same match arm.
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///
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/// **Why is this bad?** Wildcard pattern already covers any other pattern as it will match anyway.
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/// It makes the code less readable, especially to spot wildcard pattern use in match arm.
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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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/// // Bad
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/// match "foo" {
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/// "a" => {},
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/// "bar" | _ => {},
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/// }
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///
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/// // Good
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/// match "foo" {
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/// "a" => {},
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/// _ => {},
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/// }
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/// ```
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pub WILDCARD_IN_OR_PATTERNS,
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complexity,
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"a wildcard pattern used with others patterns in same match arm"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for matches being used to destructure a single-variant enum
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/// or tuple struct where a `let` will suffice.
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///
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/// **Why is this bad?** Just readability – `let` doesn't nest, whereas a `match` does.
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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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/// enum Wrapper {
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/// Data(i32),
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/// }
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///
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/// let wrapper = Wrapper::Data(42);
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///
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/// let data = match wrapper {
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/// Wrapper::Data(i) => i,
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/// };
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/// ```
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///
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/// The correct use would be:
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/// ```rust
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/// enum Wrapper {
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/// Data(i32),
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/// }
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///
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/// let wrapper = Wrapper::Data(42);
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/// let Wrapper::Data(data) = wrapper;
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/// ```
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pub INFALLIBLE_DESTRUCTURING_MATCH,
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style,
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"a `match` statement with a single infallible arm instead of a `let`"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for useless match that binds to only one value.
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///
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/// **Why is this bad?** Readability and needless complexity.
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///
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/// **Known problems:** Suggested replacements may be incorrect when `match`
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/// is actually binding temporary value, bringing a 'dropped while borrowed' error.
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///
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/// **Example:**
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/// ```rust
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/// # let a = 1;
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/// # let b = 2;
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///
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/// // Bad
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/// match (a, b) {
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/// (c, d) => {
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/// // useless match
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/// }
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/// }
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///
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/// // Good
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/// let (c, d) = (a, b);
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/// ```
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pub MATCH_SINGLE_BINDING,
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complexity,
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"a match with a single binding instead of using `let` statement"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for unnecessary '..' pattern binding on struct when all fields are explicitly matched.
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///
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/// **Why is this bad?** Correctness and readability. It's like having a wildcard pattern after
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/// matching all enum variants explicitly.
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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 A { a: i32 }
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/// let a = A { a: 5 };
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///
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/// // Bad
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/// match a {
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/// A { a: 5, .. } => {},
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/// _ => {},
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/// }
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///
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/// // Good
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/// match a {
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/// A { a: 5 } => {},
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/// _ => {},
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/// }
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/// ```
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pub REST_PAT_IN_FULLY_BOUND_STRUCTS,
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restriction,
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"a match on a struct that binds all fields but still uses the wildcard pattern"
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}
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declare_clippy_lint! {
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/// **What it does:** Lint for redundant pattern matching over `Result`, `Option`,
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/// `std::task::Poll` or `std::net::IpAddr`
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///
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/// **Why is this bad?** It's more concise and clear to just use the proper
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/// utility 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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///
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/// ```rust
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/// # use std::task::Poll;
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/// # use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
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/// if let Ok(_) = Ok::<i32, i32>(42) {}
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/// if let Err(_) = Err::<i32, i32>(42) {}
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/// if let None = None::<()> {}
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/// if let Some(_) = Some(42) {}
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/// if let Poll::Pending = Poll::Pending::<()> {}
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/// if let Poll::Ready(_) = Poll::Ready(42) {}
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/// if let IpAddr::V4(_) = IpAddr::V4(Ipv4Addr::LOCALHOST) {}
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/// if let IpAddr::V6(_) = IpAddr::V6(Ipv6Addr::LOCALHOST) {}
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/// match Ok::<i32, i32>(42) {
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/// Ok(_) => true,
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/// Err(_) => false,
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/// };
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/// ```
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///
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/// The more idiomatic use would be:
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///
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/// ```rust
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/// # use std::task::Poll;
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/// # use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
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/// if Ok::<i32, i32>(42).is_ok() {}
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/// if Err::<i32, i32>(42).is_err() {}
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/// if None::<()>.is_none() {}
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/// if Some(42).is_some() {}
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/// if Poll::Pending::<()>.is_pending() {}
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/// if Poll::Ready(42).is_ready() {}
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/// if IpAddr::V4(Ipv4Addr::LOCALHOST).is_ipv4() {}
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/// if IpAddr::V6(Ipv6Addr::LOCALHOST).is_ipv6() {}
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/// Ok::<i32, i32>(42).is_ok();
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/// ```
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pub REDUNDANT_PATTERN_MATCHING,
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style,
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"use the proper utility function avoiding an `if let`"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for `match` or `if let` expressions producing a
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/// `bool` that could be written using `matches!`
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///
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/// **Why is this bad?** Readability and needless complexity.
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///
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/// **Known problems:** This lint falsely triggers, if there are arms with
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/// `cfg` attributes that remove an arm evaluating to `false`.
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///
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/// **Example:**
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/// ```rust
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/// let x = Some(5);
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///
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/// // Bad
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/// let a = match x {
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/// Some(0) => true,
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/// _ => false,
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/// };
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///
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/// let a = if let Some(0) = x {
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/// true
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/// } else {
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/// false
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/// };
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///
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/// // Good
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/// let a = matches!(x, Some(0));
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/// ```
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pub MATCH_LIKE_MATCHES_MACRO,
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style,
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"a match that could be written with the matches! macro"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for `match` with identical arm bodies.
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///
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/// **Why is this bad?** This is probably a copy & paste error. If arm bodies
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/// are the same on purpose, you can factor them
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/// [using `|`](https://doc.rust-lang.org/book/patterns.html#multiple-patterns).
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///
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/// **Known problems:** False positive possible with order dependent `match`
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/// (see issue
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/// [#860](https://github.com/rust-lang/rust-clippy/issues/860)).
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///
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/// **Example:**
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/// ```rust,ignore
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/// match foo {
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/// Bar => bar(),
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/// Quz => quz(),
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/// Baz => bar(), // <= oops
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/// }
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/// ```
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///
|
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/// This should probably be
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/// ```rust,ignore
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/// match foo {
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/// Bar => bar(),
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/// Quz => quz(),
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/// Baz => baz(), // <= fixed
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/// }
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/// ```
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///
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/// or if the original code was not a typo:
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/// ```rust,ignore
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/// match foo {
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/// Bar | Baz => bar(), // <= shows the intent better
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||
/// Quz => quz(),
|
||
/// }
|
||
/// ```
|
||
pub MATCH_SAME_ARMS,
|
||
pedantic,
|
||
"`match` with identical arm bodies"
|
||
}
|
||
|
||
#[derive(Default)]
|
||
pub struct Matches {
|
||
msrv: Option<RustcVersion>,
|
||
infallible_destructuring_match_linted: bool,
|
||
}
|
||
|
||
impl Matches {
|
||
#[must_use]
|
||
pub fn new(msrv: Option<RustcVersion>) -> Self {
|
||
Self {
|
||
msrv,
|
||
..Matches::default()
|
||
}
|
||
}
|
||
}
|
||
|
||
impl_lint_pass!(Matches => [
|
||
SINGLE_MATCH,
|
||
MATCH_REF_PATS,
|
||
MATCH_BOOL,
|
||
SINGLE_MATCH_ELSE,
|
||
MATCH_OVERLAPPING_ARM,
|
||
MATCH_WILD_ERR_ARM,
|
||
MATCH_AS_REF,
|
||
WILDCARD_ENUM_MATCH_ARM,
|
||
MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
|
||
WILDCARD_IN_OR_PATTERNS,
|
||
MATCH_SINGLE_BINDING,
|
||
INFALLIBLE_DESTRUCTURING_MATCH,
|
||
REST_PAT_IN_FULLY_BOUND_STRUCTS,
|
||
REDUNDANT_PATTERN_MATCHING,
|
||
MATCH_LIKE_MATCHES_MACRO,
|
||
MATCH_SAME_ARMS,
|
||
]);
|
||
|
||
const MATCH_LIKE_MATCHES_MACRO_MSRV: RustcVersion = RustcVersion::new(1, 42, 0);
|
||
|
||
impl<'tcx> LateLintPass<'tcx> for Matches {
|
||
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
|
||
if in_external_macro(cx.sess(), expr.span) || in_macro(expr.span) {
|
||
return;
|
||
}
|
||
|
||
redundant_pattern_match::check(cx, expr);
|
||
|
||
if meets_msrv(self.msrv.as_ref(), &MATCH_LIKE_MATCHES_MACRO_MSRV) {
|
||
if !check_match_like_matches(cx, expr) {
|
||
lint_match_arms(cx, expr);
|
||
}
|
||
} else {
|
||
lint_match_arms(cx, expr);
|
||
}
|
||
|
||
if let ExprKind::Match(ref ex, ref arms, MatchSource::Normal) = expr.kind {
|
||
check_single_match(cx, ex, arms, expr);
|
||
check_match_bool(cx, ex, arms, expr);
|
||
check_overlapping_arms(cx, ex, arms);
|
||
check_wild_err_arm(cx, ex, arms);
|
||
check_wild_enum_match(cx, ex, arms);
|
||
check_match_as_ref(cx, ex, arms, expr);
|
||
check_wild_in_or_pats(cx, arms);
|
||
|
||
if self.infallible_destructuring_match_linted {
|
||
self.infallible_destructuring_match_linted = false;
|
||
} else {
|
||
check_match_single_binding(cx, ex, arms, expr);
|
||
}
|
||
}
|
||
if let ExprKind::Match(ref ex, ref arms, _) = expr.kind {
|
||
check_match_ref_pats(cx, ex, arms, expr);
|
||
}
|
||
}
|
||
|
||
fn check_local(&mut self, cx: &LateContext<'tcx>, local: &'tcx Local<'_>) {
|
||
if_chain! {
|
||
if !in_external_macro(cx.sess(), local.span);
|
||
if !in_macro(local.span);
|
||
if let Some(ref expr) = local.init;
|
||
if let ExprKind::Match(ref target, ref arms, MatchSource::Normal) = expr.kind;
|
||
if arms.len() == 1 && arms[0].guard.is_none();
|
||
if let PatKind::TupleStruct(
|
||
QPath::Resolved(None, ref variant_name), ref args, _) = arms[0].pat.kind;
|
||
if args.len() == 1;
|
||
if let PatKind::Binding(_, arg, ..) = strip_pat_refs(&args[0]).kind;
|
||
let body = remove_blocks(&arms[0].body);
|
||
if path_to_local_id(body, arg);
|
||
|
||
then {
|
||
let mut applicability = Applicability::MachineApplicable;
|
||
self.infallible_destructuring_match_linted = true;
|
||
span_lint_and_sugg(
|
||
cx,
|
||
INFALLIBLE_DESTRUCTURING_MATCH,
|
||
local.span,
|
||
"you seem to be trying to use `match` to destructure a single infallible pattern. \
|
||
Consider using `let`",
|
||
"try this",
|
||
format!(
|
||
"let {}({}) = {};",
|
||
snippet_with_applicability(cx, variant_name.span, "..", &mut applicability),
|
||
snippet_with_applicability(cx, local.pat.span, "..", &mut applicability),
|
||
snippet_with_applicability(cx, target.span, "..", &mut applicability),
|
||
),
|
||
applicability,
|
||
);
|
||
}
|
||
}
|
||
}
|
||
|
||
fn check_pat(&mut self, cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>) {
|
||
if_chain! {
|
||
if !in_external_macro(cx.sess(), pat.span);
|
||
if !in_macro(pat.span);
|
||
if let PatKind::Struct(QPath::Resolved(_, ref path), fields, true) = pat.kind;
|
||
if let Some(def_id) = path.res.opt_def_id();
|
||
let ty = cx.tcx.type_of(def_id);
|
||
if let ty::Adt(def, _) = ty.kind();
|
||
if def.is_struct() || def.is_union();
|
||
if fields.len() == def.non_enum_variant().fields.len();
|
||
|
||
then {
|
||
span_lint_and_help(
|
||
cx,
|
||
REST_PAT_IN_FULLY_BOUND_STRUCTS,
|
||
pat.span,
|
||
"unnecessary use of `..` pattern in struct binding. All fields were already bound",
|
||
None,
|
||
"consider removing `..` from this binding",
|
||
);
|
||
}
|
||
}
|
||
}
|
||
|
||
extract_msrv_attr!(LateContext);
|
||
}
|
||
|
||
#[rustfmt::skip]
|
||
fn check_single_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
|
||
if arms.len() == 2 && arms[0].guard.is_none() && arms[1].guard.is_none() {
|
||
if in_macro(expr.span) {
|
||
// Don't lint match expressions present in
|
||
// macro_rules! block
|
||
return;
|
||
}
|
||
if let PatKind::Or(..) = arms[0].pat.kind {
|
||
// don't lint for or patterns for now, this makes
|
||
// the lint noisy in unnecessary situations
|
||
return;
|
||
}
|
||
let els = arms[1].body;
|
||
let els = if is_unit_expr(remove_blocks(els)) {
|
||
None
|
||
} else if let ExprKind::Block(Block { stmts, expr: block_expr, .. }, _) = els.kind {
|
||
if stmts.len() == 1 && block_expr.is_none() || stmts.is_empty() && block_expr.is_some() {
|
||
// single statement/expr "else" block, don't lint
|
||
return;
|
||
}
|
||
// block with 2+ statements or 1 expr and 1+ statement
|
||
Some(els)
|
||
} else {
|
||
// not a block, don't lint
|
||
return;
|
||
};
|
||
|
||
let ty = cx.typeck_results().expr_ty(ex);
|
||
if *ty.kind() != ty::Bool || is_allowed(cx, MATCH_BOOL, ex.hir_id) {
|
||
check_single_match_single_pattern(cx, ex, arms, expr, els);
|
||
check_single_match_opt_like(cx, ex, arms, expr, ty, els);
|
||
}
|
||
}
|
||
}
|
||
|
||
fn check_single_match_single_pattern(
|
||
cx: &LateContext<'_>,
|
||
ex: &Expr<'_>,
|
||
arms: &[Arm<'_>],
|
||
expr: &Expr<'_>,
|
||
els: Option<&Expr<'_>>,
|
||
) {
|
||
if is_wild(&arms[1].pat) {
|
||
report_single_match_single_pattern(cx, ex, arms, expr, els);
|
||
}
|
||
}
|
||
|
||
fn report_single_match_single_pattern(
|
||
cx: &LateContext<'_>,
|
||
ex: &Expr<'_>,
|
||
arms: &[Arm<'_>],
|
||
expr: &Expr<'_>,
|
||
els: Option<&Expr<'_>>,
|
||
) {
|
||
let lint = if els.is_some() { SINGLE_MATCH_ELSE } else { SINGLE_MATCH };
|
||
let els_str = els.map_or(String::new(), |els| {
|
||
format!(" else {}", expr_block(cx, els, None, "..", Some(expr.span)))
|
||
});
|
||
|
||
let (msg, sugg) = if_chain! {
|
||
let (pat, pat_ref_count) = peel_hir_pat_refs(arms[0].pat);
|
||
if let PatKind::Path(_) | PatKind::Lit(_) = pat.kind;
|
||
let (ty, ty_ref_count) = peel_mid_ty_refs(cx.typeck_results().expr_ty(ex));
|
||
if let Some(trait_id) = cx.tcx.lang_items().structural_peq_trait();
|
||
if ty.is_integral() || ty.is_char() || ty.is_str() || implements_trait(cx, ty, trait_id, &[]);
|
||
then {
|
||
// scrutinee derives PartialEq and the pattern is a constant.
|
||
let pat_ref_count = match pat.kind {
|
||
// string literals are already a reference.
|
||
PatKind::Lit(Expr { kind: ExprKind::Lit(lit), .. }) if lit.node.is_str() => pat_ref_count + 1,
|
||
_ => pat_ref_count,
|
||
};
|
||
// References are only implicitly added to the pattern, so no overflow here.
|
||
// e.g. will work: match &Some(_) { Some(_) => () }
|
||
// will not: match Some(_) { &Some(_) => () }
|
||
let ref_count_diff = ty_ref_count - pat_ref_count;
|
||
|
||
// Try to remove address of expressions first.
|
||
let (ex, removed) = peel_n_hir_expr_refs(ex, ref_count_diff);
|
||
let ref_count_diff = ref_count_diff - removed;
|
||
|
||
let msg = "you seem to be trying to use `match` for an equality check. Consider using `if`";
|
||
let sugg = format!(
|
||
"if {} == {}{} {}{}",
|
||
snippet(cx, ex.span, ".."),
|
||
// PartialEq for different reference counts may not exist.
|
||
"&".repeat(ref_count_diff),
|
||
snippet(cx, arms[0].pat.span, ".."),
|
||
expr_block(cx, &arms[0].body, None, "..", Some(expr.span)),
|
||
els_str,
|
||
);
|
||
(msg, sugg)
|
||
} else {
|
||
let msg = "you seem to be trying to use `match` for destructuring a single pattern. Consider using `if let`";
|
||
let sugg = format!(
|
||
"if let {} = {} {}{}",
|
||
snippet(cx, arms[0].pat.span, ".."),
|
||
snippet(cx, ex.span, ".."),
|
||
expr_block(cx, &arms[0].body, None, "..", Some(expr.span)),
|
||
els_str,
|
||
);
|
||
(msg, sugg)
|
||
}
|
||
};
|
||
|
||
span_lint_and_sugg(
|
||
cx,
|
||
lint,
|
||
expr.span,
|
||
msg,
|
||
"try this",
|
||
sugg,
|
||
Applicability::HasPlaceholders,
|
||
);
|
||
}
|
||
|
||
fn check_single_match_opt_like(
|
||
cx: &LateContext<'_>,
|
||
ex: &Expr<'_>,
|
||
arms: &[Arm<'_>],
|
||
expr: &Expr<'_>,
|
||
ty: Ty<'_>,
|
||
els: Option<&Expr<'_>>,
|
||
) {
|
||
// list of candidate `Enum`s we know will never get any more members
|
||
let candidates = &[
|
||
(&paths::COW, "Borrowed"),
|
||
(&paths::COW, "Cow::Borrowed"),
|
||
(&paths::COW, "Cow::Owned"),
|
||
(&paths::COW, "Owned"),
|
||
(&paths::OPTION, "None"),
|
||
(&paths::RESULT, "Err"),
|
||
(&paths::RESULT, "Ok"),
|
||
];
|
||
|
||
let path = match arms[1].pat.kind {
|
||
PatKind::TupleStruct(ref path, ref inner, _) => {
|
||
// Contains any non wildcard patterns (e.g., `Err(err)`)?
|
||
if !inner.iter().all(is_wild) {
|
||
return;
|
||
}
|
||
rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_qpath(path, false))
|
||
},
|
||
PatKind::Binding(BindingAnnotation::Unannotated, .., ident, None) => ident.to_string(),
|
||
PatKind::Path(ref path) => {
|
||
rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_qpath(path, false))
|
||
},
|
||
_ => return,
|
||
};
|
||
|
||
for &(ty_path, pat_path) in candidates {
|
||
if path == *pat_path && match_type(cx, ty, ty_path) {
|
||
report_single_match_single_pattern(cx, ex, arms, expr, els);
|
||
}
|
||
}
|
||
}
|
||
|
||
fn check_match_bool(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
|
||
// Type of expression is `bool`.
|
||
if *cx.typeck_results().expr_ty(ex).kind() == ty::Bool {
|
||
span_lint_and_then(
|
||
cx,
|
||
MATCH_BOOL,
|
||
expr.span,
|
||
"you seem to be trying to match on a boolean expression",
|
||
move |diag| {
|
||
if arms.len() == 2 {
|
||
// no guards
|
||
let exprs = if let PatKind::Lit(ref arm_bool) = arms[0].pat.kind {
|
||
if let ExprKind::Lit(ref lit) = arm_bool.kind {
|
||
match lit.node {
|
||
LitKind::Bool(true) => Some((&*arms[0].body, &*arms[1].body)),
|
||
LitKind::Bool(false) => Some((&*arms[1].body, &*arms[0].body)),
|
||
_ => None,
|
||
}
|
||
} else {
|
||
None
|
||
}
|
||
} else {
|
||
None
|
||
};
|
||
|
||
if let Some((true_expr, false_expr)) = exprs {
|
||
let sugg = match (is_unit_expr(true_expr), is_unit_expr(false_expr)) {
|
||
(false, false) => Some(format!(
|
||
"if {} {} else {}",
|
||
snippet(cx, ex.span, "b"),
|
||
expr_block(cx, true_expr, None, "..", Some(expr.span)),
|
||
expr_block(cx, false_expr, None, "..", Some(expr.span))
|
||
)),
|
||
(false, true) => Some(format!(
|
||
"if {} {}",
|
||
snippet(cx, ex.span, "b"),
|
||
expr_block(cx, true_expr, None, "..", Some(expr.span))
|
||
)),
|
||
(true, false) => {
|
||
let test = Sugg::hir(cx, ex, "..");
|
||
Some(format!(
|
||
"if {} {}",
|
||
!test,
|
||
expr_block(cx, false_expr, None, "..", Some(expr.span))
|
||
))
|
||
},
|
||
(true, true) => None,
|
||
};
|
||
|
||
if let Some(sugg) = sugg {
|
||
diag.span_suggestion(
|
||
expr.span,
|
||
"consider using an `if`/`else` expression",
|
||
sugg,
|
||
Applicability::HasPlaceholders,
|
||
);
|
||
}
|
||
}
|
||
}
|
||
},
|
||
);
|
||
}
|
||
}
|
||
|
||
fn check_overlapping_arms<'tcx>(cx: &LateContext<'tcx>, ex: &'tcx Expr<'_>, arms: &'tcx [Arm<'_>]) {
|
||
if arms.len() >= 2 && cx.typeck_results().expr_ty(ex).is_integral() {
|
||
let ranges = all_ranges(cx, arms, cx.typeck_results().expr_ty(ex));
|
||
let type_ranges = type_ranges(&ranges);
|
||
if !type_ranges.is_empty() {
|
||
if let Some((start, end)) = overlapping(&type_ranges) {
|
||
span_lint_and_note(
|
||
cx,
|
||
MATCH_OVERLAPPING_ARM,
|
||
start.span,
|
||
"some ranges overlap",
|
||
Some(end.span),
|
||
"overlaps with this",
|
||
);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
fn check_wild_err_arm<'tcx>(cx: &LateContext<'tcx>, ex: &Expr<'tcx>, arms: &[Arm<'tcx>]) {
|
||
let ex_ty = cx.typeck_results().expr_ty(ex).peel_refs();
|
||
if is_type_diagnostic_item(cx, ex_ty, sym::result_type) {
|
||
for arm in arms {
|
||
if let PatKind::TupleStruct(ref path, ref inner, _) = arm.pat.kind {
|
||
let path_str = rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_qpath(path, false));
|
||
if path_str == "Err" {
|
||
let mut matching_wild = inner.iter().any(is_wild);
|
||
let mut ident_bind_name = String::from("_");
|
||
if !matching_wild {
|
||
// Looking for unused bindings (i.e.: `_e`)
|
||
inner.iter().for_each(|pat| {
|
||
if let PatKind::Binding(_, id, ident, None) = pat.kind {
|
||
if ident.as_str().starts_with('_')
|
||
&& !LocalUsedVisitor::new(cx, id).check_expr(arm.body)
|
||
{
|
||
ident_bind_name = (&ident.name.as_str()).to_string();
|
||
matching_wild = true;
|
||
}
|
||
}
|
||
});
|
||
}
|
||
if_chain! {
|
||
if matching_wild;
|
||
if let ExprKind::Block(ref block, _) = arm.body.kind;
|
||
if is_panic_block(block);
|
||
then {
|
||
// `Err(_)` or `Err(_e)` arm with `panic!` found
|
||
span_lint_and_note(cx,
|
||
MATCH_WILD_ERR_ARM,
|
||
arm.pat.span,
|
||
&format!("`Err({})` matches all errors", &ident_bind_name),
|
||
None,
|
||
"match each error separately or use the error output, or use `.except(msg)` if the error case is unreachable",
|
||
);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
fn check_wild_enum_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>]) {
|
||
let ty = cx.typeck_results().expr_ty(ex);
|
||
if !ty.is_enum() {
|
||
// If there isn't a nice closed set of possible values that can be conveniently enumerated,
|
||
// don't complain about not enumerating the mall.
|
||
return;
|
||
}
|
||
|
||
// First pass - check for violation, but don't do much book-keeping because this is hopefully
|
||
// the uncommon case, and the book-keeping is slightly expensive.
|
||
let mut wildcard_span = None;
|
||
let mut wildcard_ident = None;
|
||
for arm in arms {
|
||
if let PatKind::Wild = arm.pat.kind {
|
||
wildcard_span = Some(arm.pat.span);
|
||
} else if let PatKind::Binding(_, _, ident, None) = arm.pat.kind {
|
||
wildcard_span = Some(arm.pat.span);
|
||
wildcard_ident = Some(ident);
|
||
}
|
||
}
|
||
|
||
if let Some(wildcard_span) = wildcard_span {
|
||
// Accumulate the variants which should be put in place of the wildcard because they're not
|
||
// already covered.
|
||
|
||
let mut missing_variants = vec![];
|
||
if let ty::Adt(def, _) = ty.kind() {
|
||
for variant in &def.variants {
|
||
missing_variants.push(variant);
|
||
}
|
||
}
|
||
|
||
for arm in arms {
|
||
if arm.guard.is_some() {
|
||
// Guards mean that this case probably isn't exhaustively covered. Technically
|
||
// this is incorrect, as we should really check whether each variant is exhaustively
|
||
// covered by the set of guards that cover it, but that's really hard to do.
|
||
continue;
|
||
}
|
||
if let PatKind::Path(ref path) = arm.pat.kind {
|
||
if let QPath::Resolved(_, p) = path {
|
||
missing_variants.retain(|e| e.ctor_def_id != Some(p.res.def_id()));
|
||
}
|
||
} else if let PatKind::TupleStruct(QPath::Resolved(_, p), ref patterns, ..) = arm.pat.kind {
|
||
// Some simple checks for exhaustive patterns.
|
||
// There is a room for improvements to detect more cases,
|
||
// but it can be more expensive to do so.
|
||
let is_pattern_exhaustive =
|
||
|pat: &&Pat<'_>| matches!(pat.kind, PatKind::Wild | PatKind::Binding(.., None));
|
||
if patterns.iter().all(is_pattern_exhaustive) {
|
||
missing_variants.retain(|e| e.ctor_def_id != Some(p.res.def_id()));
|
||
}
|
||
}
|
||
}
|
||
|
||
let mut suggestion: Vec<String> = missing_variants
|
||
.iter()
|
||
.map(|v| {
|
||
let suffix = match v.ctor_kind {
|
||
CtorKind::Fn => "(..)",
|
||
CtorKind::Const | CtorKind::Fictive => "",
|
||
};
|
||
let ident_str = if let Some(ident) = wildcard_ident {
|
||
format!("{} @ ", ident.name)
|
||
} else {
|
||
String::new()
|
||
};
|
||
// This path assumes that the enum type is imported into scope.
|
||
format!("{}{}{}", ident_str, cx.tcx.def_path_str(v.def_id), suffix)
|
||
})
|
||
.collect();
|
||
|
||
if suggestion.is_empty() {
|
||
return;
|
||
}
|
||
|
||
let mut message = "wildcard match will miss any future added variants";
|
||
|
||
if let ty::Adt(def, _) = ty.kind() {
|
||
if def.is_variant_list_non_exhaustive() {
|
||
message = "match on non-exhaustive enum doesn't explicitly match all known variants";
|
||
suggestion.push(String::from("_"));
|
||
}
|
||
}
|
||
|
||
if suggestion.len() == 1 {
|
||
// No need to check for non-exhaustive enum as in that case len would be greater than 1
|
||
span_lint_and_sugg(
|
||
cx,
|
||
MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
|
||
wildcard_span,
|
||
message,
|
||
"try this",
|
||
suggestion[0].clone(),
|
||
Applicability::MaybeIncorrect,
|
||
)
|
||
};
|
||
|
||
span_lint_and_sugg(
|
||
cx,
|
||
WILDCARD_ENUM_MATCH_ARM,
|
||
wildcard_span,
|
||
message,
|
||
"try this",
|
||
suggestion.join(" | "),
|
||
Applicability::MaybeIncorrect,
|
||
)
|
||
}
|
||
}
|
||
|
||
// If the block contains only a `panic!` macro (as expression or statement)
|
||
fn is_panic_block(block: &Block<'_>) -> bool {
|
||
match (&block.expr, block.stmts.len(), block.stmts.first()) {
|
||
(&Some(ref exp), 0, _) => {
|
||
is_expn_of(exp.span, "panic").is_some() && is_expn_of(exp.span, "unreachable").is_none()
|
||
},
|
||
(&None, 1, Some(stmt)) => {
|
||
is_expn_of(stmt.span, "panic").is_some() && is_expn_of(stmt.span, "unreachable").is_none()
|
||
},
|
||
_ => false,
|
||
}
|
||
}
|
||
|
||
fn check_match_ref_pats(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
|
||
if has_only_ref_pats(arms) {
|
||
let mut suggs = Vec::with_capacity(arms.len() + 1);
|
||
let (title, msg) = if let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, ref inner) = ex.kind {
|
||
let span = ex.span.source_callsite();
|
||
suggs.push((span, Sugg::hir_with_macro_callsite(cx, inner, "..").to_string()));
|
||
(
|
||
"you don't need to add `&` to both the expression and the patterns",
|
||
"try",
|
||
)
|
||
} else {
|
||
let span = ex.span.source_callsite();
|
||
suggs.push((span, Sugg::hir_with_macro_callsite(cx, ex, "..").deref().to_string()));
|
||
(
|
||
"you don't need to add `&` to all patterns",
|
||
"instead of prefixing all patterns with `&`, you can dereference the expression",
|
||
)
|
||
};
|
||
|
||
suggs.extend(arms.iter().filter_map(|a| {
|
||
if let PatKind::Ref(ref refp, _) = a.pat.kind {
|
||
Some((a.pat.span, snippet(cx, refp.span, "..").to_string()))
|
||
} else {
|
||
None
|
||
}
|
||
}));
|
||
|
||
span_lint_and_then(cx, MATCH_REF_PATS, expr.span, title, |diag| {
|
||
if !expr.span.from_expansion() {
|
||
multispan_sugg(diag, msg, suggs);
|
||
}
|
||
});
|
||
}
|
||
}
|
||
|
||
fn check_match_as_ref(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
|
||
if arms.len() == 2 && arms[0].guard.is_none() && arms[1].guard.is_none() {
|
||
let arm_ref: Option<BindingAnnotation> = if is_none_arm(&arms[0]) {
|
||
is_ref_some_arm(&arms[1])
|
||
} else if is_none_arm(&arms[1]) {
|
||
is_ref_some_arm(&arms[0])
|
||
} else {
|
||
None
|
||
};
|
||
if let Some(rb) = arm_ref {
|
||
let suggestion = if rb == BindingAnnotation::Ref {
|
||
"as_ref"
|
||
} else {
|
||
"as_mut"
|
||
};
|
||
|
||
let output_ty = cx.typeck_results().expr_ty(expr);
|
||
let input_ty = cx.typeck_results().expr_ty(ex);
|
||
|
||
let cast = if_chain! {
|
||
if let ty::Adt(_, substs) = input_ty.kind();
|
||
let input_ty = substs.type_at(0);
|
||
if let ty::Adt(_, substs) = output_ty.kind();
|
||
let output_ty = substs.type_at(0);
|
||
if let ty::Ref(_, output_ty, _) = *output_ty.kind();
|
||
if input_ty != output_ty;
|
||
then {
|
||
".map(|x| x as _)"
|
||
} else {
|
||
""
|
||
}
|
||
};
|
||
|
||
let mut applicability = Applicability::MachineApplicable;
|
||
span_lint_and_sugg(
|
||
cx,
|
||
MATCH_AS_REF,
|
||
expr.span,
|
||
&format!("use `{}()` instead", suggestion),
|
||
"try this",
|
||
format!(
|
||
"{}.{}(){}",
|
||
snippet_with_applicability(cx, ex.span, "_", &mut applicability),
|
||
suggestion,
|
||
cast,
|
||
),
|
||
applicability,
|
||
)
|
||
}
|
||
}
|
||
}
|
||
|
||
fn check_wild_in_or_pats(cx: &LateContext<'_>, arms: &[Arm<'_>]) {
|
||
for arm in arms {
|
||
if let PatKind::Or(ref fields) = arm.pat.kind {
|
||
// look for multiple fields in this arm that contains at least one Wild pattern
|
||
if fields.len() > 1 && fields.iter().any(is_wild) {
|
||
span_lint_and_help(
|
||
cx,
|
||
WILDCARD_IN_OR_PATTERNS,
|
||
arm.pat.span,
|
||
"wildcard pattern covers any other pattern as it will match anyway.",
|
||
None,
|
||
"Consider handling `_` separately.",
|
||
);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Lint a `match` or `if let .. { .. } else { .. }` expr that could be replaced by `matches!`
|
||
fn check_match_like_matches<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
|
||
if let ExprKind::Match(ex, arms, ref match_source) = &expr.kind {
|
||
match match_source {
|
||
MatchSource::Normal => find_matches_sugg(cx, ex, arms, expr, false),
|
||
MatchSource::IfLetDesugar { .. } => find_matches_sugg(cx, ex, arms, expr, true),
|
||
_ => false,
|
||
}
|
||
} else {
|
||
false
|
||
}
|
||
}
|
||
|
||
/// Lint a `match` or desugared `if let` for replacement by `matches!`
|
||
fn find_matches_sugg(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>, desugared: bool) -> bool {
|
||
if_chain! {
|
||
if arms.len() >= 2;
|
||
if cx.typeck_results().expr_ty(expr).is_bool();
|
||
if let Some((b1_arm, b0_arms)) = arms.split_last();
|
||
if let Some(b0) = find_bool_lit(&b0_arms[0].body.kind, desugared);
|
||
if let Some(b1) = find_bool_lit(&b1_arm.body.kind, desugared);
|
||
if is_wild(&b1_arm.pat);
|
||
if b0 != b1;
|
||
let if_guard = &b0_arms[0].guard;
|
||
if if_guard.is_none() || b0_arms.len() == 1;
|
||
if b0_arms[0].attrs.is_empty();
|
||
if b0_arms[1..].iter()
|
||
.all(|arm| {
|
||
find_bool_lit(&arm.body.kind, desugared).map_or(false, |b| b == b0) &&
|
||
arm.guard.is_none() && arm.attrs.is_empty()
|
||
});
|
||
then {
|
||
// The suggestion may be incorrect, because some arms can have `cfg` attributes
|
||
// evaluated into `false` and so such arms will be stripped before.
|
||
let mut applicability = Applicability::MaybeIncorrect;
|
||
let pat = {
|
||
use itertools::Itertools as _;
|
||
b0_arms.iter()
|
||
.map(|arm| snippet_with_applicability(cx, arm.pat.span, "..", &mut applicability))
|
||
.join(" | ")
|
||
};
|
||
let pat_and_guard = if let Some(Guard::If(g)) = if_guard {
|
||
format!("{} if {}", pat, snippet_with_applicability(cx, g.span, "..", &mut applicability))
|
||
} else {
|
||
pat
|
||
};
|
||
|
||
// strip potential borrows (#6503), but only if the type is a reference
|
||
let mut ex_new = ex;
|
||
if let ExprKind::AddrOf(BorrowKind::Ref, .., ex_inner) = ex.kind {
|
||
if let ty::Ref(..) = cx.typeck_results().expr_ty(&ex_inner).kind() {
|
||
ex_new = ex_inner;
|
||
}
|
||
};
|
||
span_lint_and_sugg(
|
||
cx,
|
||
MATCH_LIKE_MATCHES_MACRO,
|
||
expr.span,
|
||
&format!("{} expression looks like `matches!` macro", if desugared { "if let .. else" } else { "match" }),
|
||
"try this",
|
||
format!(
|
||
"{}matches!({}, {})",
|
||
if b0 { "" } else { "!" },
|
||
snippet_with_applicability(cx, ex_new.span, "..", &mut applicability),
|
||
pat_and_guard,
|
||
),
|
||
applicability,
|
||
);
|
||
true
|
||
} else {
|
||
false
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Extract a `bool` or `{ bool }`
|
||
fn find_bool_lit(ex: &ExprKind<'_>, desugared: bool) -> Option<bool> {
|
||
match ex {
|
||
ExprKind::Lit(Spanned {
|
||
node: LitKind::Bool(b), ..
|
||
}) => Some(*b),
|
||
ExprKind::Block(
|
||
rustc_hir::Block {
|
||
stmts: &[],
|
||
expr: Some(exp),
|
||
..
|
||
},
|
||
_,
|
||
) if desugared => {
|
||
if let ExprKind::Lit(Spanned {
|
||
node: LitKind::Bool(b), ..
|
||
}) = exp.kind
|
||
{
|
||
Some(b)
|
||
} else {
|
||
None
|
||
}
|
||
},
|
||
_ => None,
|
||
}
|
||
}
|
||
|
||
fn check_match_single_binding<'a>(cx: &LateContext<'a>, ex: &Expr<'a>, arms: &[Arm<'_>], expr: &Expr<'_>) {
|
||
if in_macro(expr.span) || arms.len() != 1 || is_refutable(cx, arms[0].pat) {
|
||
return;
|
||
}
|
||
|
||
// HACK:
|
||
// This is a hack to deal with arms that are excluded by macros like `#[cfg]`. It is only used here
|
||
// to prevent false positives as there is currently no better way to detect if code was excluded by
|
||
// a macro. See PR #6435
|
||
if_chain! {
|
||
if let Some(match_snippet) = snippet_opt(cx, expr.span);
|
||
if let Some(arm_snippet) = snippet_opt(cx, arms[0].span);
|
||
if let Some(ex_snippet) = snippet_opt(cx, ex.span);
|
||
let rest_snippet = match_snippet.replace(&arm_snippet, "").replace(&ex_snippet, "");
|
||
if rest_snippet.contains("=>");
|
||
then {
|
||
// The code it self contains another thick arrow "=>"
|
||
// -> Either another arm or a comment
|
||
return;
|
||
}
|
||
}
|
||
|
||
let matched_vars = ex.span;
|
||
let bind_names = arms[0].pat.span;
|
||
let match_body = remove_blocks(&arms[0].body);
|
||
let mut snippet_body = if match_body.span.from_expansion() {
|
||
Sugg::hir_with_macro_callsite(cx, match_body, "..").to_string()
|
||
} else {
|
||
snippet_block(cx, match_body.span, "..", Some(expr.span)).to_string()
|
||
};
|
||
|
||
// Do we need to add ';' to suggestion ?
|
||
match match_body.kind {
|
||
ExprKind::Block(block, _) => {
|
||
// macro + expr_ty(body) == ()
|
||
if block.span.from_expansion() && cx.typeck_results().expr_ty(&match_body).is_unit() {
|
||
snippet_body.push(';');
|
||
}
|
||
},
|
||
_ => {
|
||
// expr_ty(body) == ()
|
||
if cx.typeck_results().expr_ty(&match_body).is_unit() {
|
||
snippet_body.push(';');
|
||
}
|
||
},
|
||
}
|
||
|
||
let mut applicability = Applicability::MaybeIncorrect;
|
||
match arms[0].pat.kind {
|
||
PatKind::Binding(..) | PatKind::Tuple(_, _) | PatKind::Struct(..) => {
|
||
// If this match is in a local (`let`) stmt
|
||
let (target_span, sugg) = if let Some(parent_let_node) = opt_parent_let(cx, ex) {
|
||
(
|
||
parent_let_node.span,
|
||
format!(
|
||
"let {} = {};\n{}let {} = {};",
|
||
snippet_with_applicability(cx, bind_names, "..", &mut applicability),
|
||
snippet_with_applicability(cx, matched_vars, "..", &mut applicability),
|
||
" ".repeat(indent_of(cx, expr.span).unwrap_or(0)),
|
||
snippet_with_applicability(cx, parent_let_node.pat.span, "..", &mut applicability),
|
||
snippet_body
|
||
),
|
||
)
|
||
} else {
|
||
// If we are in closure, we need curly braces around suggestion
|
||
let mut indent = " ".repeat(indent_of(cx, ex.span).unwrap_or(0));
|
||
let (mut cbrace_start, mut cbrace_end) = ("".to_string(), "".to_string());
|
||
if let Some(parent_expr) = get_parent_expr(cx, expr) {
|
||
if let ExprKind::Closure(..) = parent_expr.kind {
|
||
cbrace_end = format!("\n{}}}", indent);
|
||
// Fix body indent due to the closure
|
||
indent = " ".repeat(indent_of(cx, bind_names).unwrap_or(0));
|
||
cbrace_start = format!("{{\n{}", indent);
|
||
}
|
||
};
|
||
(
|
||
expr.span,
|
||
format!(
|
||
"{}let {} = {};\n{}{}{}",
|
||
cbrace_start,
|
||
snippet_with_applicability(cx, bind_names, "..", &mut applicability),
|
||
snippet_with_applicability(cx, matched_vars, "..", &mut applicability),
|
||
indent,
|
||
snippet_body,
|
||
cbrace_end
|
||
),
|
||
)
|
||
};
|
||
span_lint_and_sugg(
|
||
cx,
|
||
MATCH_SINGLE_BINDING,
|
||
target_span,
|
||
"this match could be written as a `let` statement",
|
||
"consider using `let` statement",
|
||
sugg,
|
||
applicability,
|
||
);
|
||
},
|
||
PatKind::Wild => {
|
||
span_lint_and_sugg(
|
||
cx,
|
||
MATCH_SINGLE_BINDING,
|
||
expr.span,
|
||
"this match could be replaced by its body itself",
|
||
"consider using the match body instead",
|
||
snippet_body,
|
||
Applicability::MachineApplicable,
|
||
);
|
||
},
|
||
_ => (),
|
||
}
|
||
}
|
||
|
||
/// Returns true if the `ex` match expression is in a local (`let`) statement
|
||
fn opt_parent_let<'a>(cx: &LateContext<'a>, ex: &Expr<'a>) -> Option<&'a Local<'a>> {
|
||
if_chain! {
|
||
let map = &cx.tcx.hir();
|
||
if let Some(Node::Expr(parent_arm_expr)) = map.find(map.get_parent_node(ex.hir_id));
|
||
if let Some(Node::Local(parent_let_expr)) = map.find(map.get_parent_node(parent_arm_expr.hir_id));
|
||
then {
|
||
return Some(parent_let_expr);
|
||
}
|
||
}
|
||
None
|
||
}
|
||
|
||
/// Gets all arms that are unbounded `PatRange`s.
|
||
fn all_ranges<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>], ty: Ty<'tcx>) -> Vec<SpannedRange<Constant>> {
|
||
arms.iter()
|
||
.flat_map(|arm| {
|
||
if let Arm {
|
||
ref pat, guard: None, ..
|
||
} = *arm
|
||
{
|
||
if let PatKind::Range(ref lhs, ref rhs, range_end) = pat.kind {
|
||
let lhs = match lhs {
|
||
Some(lhs) => constant(cx, cx.typeck_results(), lhs)?.0,
|
||
None => miri_to_const(ty.numeric_min_val(cx.tcx)?)?,
|
||
};
|
||
let rhs = match rhs {
|
||
Some(rhs) => constant(cx, cx.typeck_results(), rhs)?.0,
|
||
None => miri_to_const(ty.numeric_max_val(cx.tcx)?)?,
|
||
};
|
||
let rhs = match range_end {
|
||
RangeEnd::Included => Bound::Included(rhs),
|
||
RangeEnd::Excluded => Bound::Excluded(rhs),
|
||
};
|
||
return Some(SpannedRange {
|
||
span: pat.span,
|
||
node: (lhs, rhs),
|
||
});
|
||
}
|
||
|
||
if let PatKind::Lit(ref value) = pat.kind {
|
||
let value = constant(cx, cx.typeck_results(), value)?.0;
|
||
return Some(SpannedRange {
|
||
span: pat.span,
|
||
node: (value.clone(), Bound::Included(value)),
|
||
});
|
||
}
|
||
}
|
||
None
|
||
})
|
||
.collect()
|
||
}
|
||
|
||
#[derive(Debug, Eq, PartialEq)]
|
||
pub struct SpannedRange<T> {
|
||
pub span: Span,
|
||
pub node: (T, Bound<T>),
|
||
}
|
||
|
||
type TypedRanges = Vec<SpannedRange<u128>>;
|
||
|
||
/// Gets all `Int` ranges or all `Uint` ranges. Mixed types are an error anyway
|
||
/// and other types than
|
||
/// `Uint` and `Int` probably don't make sense.
|
||
fn type_ranges(ranges: &[SpannedRange<Constant>]) -> TypedRanges {
|
||
ranges
|
||
.iter()
|
||
.filter_map(|range| match range.node {
|
||
(Constant::Int(start), Bound::Included(Constant::Int(end))) => Some(SpannedRange {
|
||
span: range.span,
|
||
node: (start, Bound::Included(end)),
|
||
}),
|
||
(Constant::Int(start), Bound::Excluded(Constant::Int(end))) => Some(SpannedRange {
|
||
span: range.span,
|
||
node: (start, Bound::Excluded(end)),
|
||
}),
|
||
(Constant::Int(start), Bound::Unbounded) => Some(SpannedRange {
|
||
span: range.span,
|
||
node: (start, Bound::Unbounded),
|
||
}),
|
||
_ => None,
|
||
})
|
||
.collect()
|
||
}
|
||
|
||
fn is_unit_expr(expr: &Expr<'_>) -> bool {
|
||
match expr.kind {
|
||
ExprKind::Tup(ref v) if v.is_empty() => true,
|
||
ExprKind::Block(ref b, _) if b.stmts.is_empty() && b.expr.is_none() => true,
|
||
_ => false,
|
||
}
|
||
}
|
||
|
||
// Checks if arm has the form `None => None`
|
||
fn is_none_arm(arm: &Arm<'_>) -> bool {
|
||
matches!(arm.pat.kind, PatKind::Path(ref path) if match_qpath(path, &paths::OPTION_NONE))
|
||
}
|
||
|
||
// Checks if arm has the form `Some(ref v) => Some(v)` (checks for `ref` and `ref mut`)
|
||
fn is_ref_some_arm(arm: &Arm<'_>) -> Option<BindingAnnotation> {
|
||
if_chain! {
|
||
if let PatKind::TupleStruct(ref path, ref pats, _) = arm.pat.kind;
|
||
if pats.len() == 1 && match_qpath(path, &paths::OPTION_SOME);
|
||
if let PatKind::Binding(rb, .., ident, _) = pats[0].kind;
|
||
if rb == BindingAnnotation::Ref || rb == BindingAnnotation::RefMut;
|
||
if let ExprKind::Call(ref e, ref args) = remove_blocks(&arm.body).kind;
|
||
if let ExprKind::Path(ref some_path) = e.kind;
|
||
if match_qpath(some_path, &paths::OPTION_SOME) && args.len() == 1;
|
||
if let ExprKind::Path(QPath::Resolved(_, ref path2)) = args[0].kind;
|
||
if path2.segments.len() == 1 && ident.name == path2.segments[0].ident.name;
|
||
then {
|
||
return Some(rb)
|
||
}
|
||
}
|
||
None
|
||
}
|
||
|
||
fn has_only_ref_pats(arms: &[Arm<'_>]) -> bool {
|
||
let mapped = arms
|
||
.iter()
|
||
.map(|a| {
|
||
match a.pat.kind {
|
||
PatKind::Ref(..) => Some(true), // &-patterns
|
||
PatKind::Wild => Some(false), // an "anything" wildcard is also fine
|
||
_ => None, // any other pattern is not fine
|
||
}
|
||
})
|
||
.collect::<Option<Vec<bool>>>();
|
||
// look for Some(v) where there's at least one true element
|
||
mapped.map_or(false, |v| v.iter().any(|el| *el))
|
||
}
|
||
|
||
pub fn overlapping<T>(ranges: &[SpannedRange<T>]) -> Option<(&SpannedRange<T>, &SpannedRange<T>)>
|
||
where
|
||
T: Copy + Ord,
|
||
{
|
||
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
|
||
enum Kind<'a, T> {
|
||
Start(T, &'a SpannedRange<T>),
|
||
End(Bound<T>, &'a SpannedRange<T>),
|
||
}
|
||
|
||
impl<'a, T: Copy> Kind<'a, T> {
|
||
fn range(&self) -> &'a SpannedRange<T> {
|
||
match *self {
|
||
Kind::Start(_, r) | Kind::End(_, r) => r,
|
||
}
|
||
}
|
||
|
||
fn value(self) -> Bound<T> {
|
||
match self {
|
||
Kind::Start(t, _) => Bound::Included(t),
|
||
Kind::End(t, _) => t,
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<'a, T: Copy + Ord> PartialOrd for Kind<'a, T> {
|
||
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
|
||
Some(self.cmp(other))
|
||
}
|
||
}
|
||
|
||
impl<'a, T: Copy + Ord> Ord for Kind<'a, T> {
|
||
fn cmp(&self, other: &Self) -> Ordering {
|
||
match (self.value(), other.value()) {
|
||
(Bound::Included(a), Bound::Included(b)) | (Bound::Excluded(a), Bound::Excluded(b)) => a.cmp(&b),
|
||
// Range patterns cannot be unbounded (yet)
|
||
(Bound::Unbounded, _) | (_, Bound::Unbounded) => unimplemented!(),
|
||
(Bound::Included(a), Bound::Excluded(b)) => match a.cmp(&b) {
|
||
Ordering::Equal => Ordering::Greater,
|
||
other => other,
|
||
},
|
||
(Bound::Excluded(a), Bound::Included(b)) => match a.cmp(&b) {
|
||
Ordering::Equal => Ordering::Less,
|
||
other => other,
|
||
},
|
||
}
|
||
}
|
||
}
|
||
|
||
let mut values = Vec::with_capacity(2 * ranges.len());
|
||
|
||
for r in ranges {
|
||
values.push(Kind::Start(r.node.0, r));
|
||
values.push(Kind::End(r.node.1, r));
|
||
}
|
||
|
||
values.sort();
|
||
|
||
for (a, b) in values.iter().zip(values.iter().skip(1)) {
|
||
match (a, b) {
|
||
(&Kind::Start(_, ra), &Kind::End(_, rb)) => {
|
||
if ra.node != rb.node {
|
||
return Some((ra, rb));
|
||
}
|
||
},
|
||
(&Kind::End(a, _), &Kind::Start(b, _)) if a != Bound::Included(b) => (),
|
||
_ => {
|
||
// skip if the range `a` is completely included into the range `b`
|
||
if let Ordering::Equal | Ordering::Less = a.cmp(&b) {
|
||
let kind_a = Kind::End(a.range().node.1, a.range());
|
||
let kind_b = Kind::End(b.range().node.1, b.range());
|
||
if let Ordering::Equal | Ordering::Greater = kind_a.cmp(&kind_b) {
|
||
return None;
|
||
}
|
||
}
|
||
return Some((a.range(), b.range()));
|
||
},
|
||
}
|
||
}
|
||
|
||
None
|
||
}
|
||
|
||
mod redundant_pattern_match {
|
||
use super::REDUNDANT_PATTERN_MATCHING;
|
||
use crate::utils::{match_qpath, match_trait_method, paths, snippet, span_lint_and_then};
|
||
use if_chain::if_chain;
|
||
use rustc_ast::ast::LitKind;
|
||
use rustc_errors::Applicability;
|
||
use rustc_hir::{Arm, Expr, ExprKind, MatchSource, PatKind, QPath};
|
||
use rustc_lint::LateContext;
|
||
use rustc_span::sym;
|
||
|
||
pub fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
|
||
if let ExprKind::Match(op, arms, ref match_source) = &expr.kind {
|
||
match match_source {
|
||
MatchSource::Normal => find_sugg_for_match(cx, expr, op, arms),
|
||
MatchSource::IfLetDesugar { .. } => find_sugg_for_if_let(cx, expr, op, arms, "if"),
|
||
MatchSource::WhileLetDesugar => find_sugg_for_if_let(cx, expr, op, arms, "while"),
|
||
_ => {},
|
||
}
|
||
}
|
||
}
|
||
|
||
fn find_sugg_for_if_let<'tcx>(
|
||
cx: &LateContext<'tcx>,
|
||
expr: &'tcx Expr<'_>,
|
||
op: &Expr<'_>,
|
||
arms: &[Arm<'_>],
|
||
keyword: &'static str,
|
||
) {
|
||
let good_method = match arms[0].pat.kind {
|
||
PatKind::TupleStruct(ref path, ref patterns, _) if patterns.len() == 1 => {
|
||
if let PatKind::Wild = patterns[0].kind {
|
||
if match_qpath(path, &paths::RESULT_OK) {
|
||
"is_ok()"
|
||
} else if match_qpath(path, &paths::RESULT_ERR) {
|
||
"is_err()"
|
||
} else if match_qpath(path, &paths::OPTION_SOME) {
|
||
"is_some()"
|
||
} else if match_qpath(path, &paths::POLL_READY) {
|
||
"is_ready()"
|
||
} else if match_qpath(path, &paths::IPADDR_V4) {
|
||
"is_ipv4()"
|
||
} else if match_qpath(path, &paths::IPADDR_V6) {
|
||
"is_ipv6()"
|
||
} else {
|
||
return;
|
||
}
|
||
} else {
|
||
return;
|
||
}
|
||
},
|
||
PatKind::Path(ref path) => {
|
||
if match_qpath(path, &paths::OPTION_NONE) {
|
||
"is_none()"
|
||
} else if match_qpath(path, &paths::POLL_PENDING) {
|
||
"is_pending()"
|
||
} else {
|
||
return;
|
||
}
|
||
},
|
||
_ => return,
|
||
};
|
||
|
||
// check that `while_let_on_iterator` lint does not trigger
|
||
if_chain! {
|
||
if keyword == "while";
|
||
if let ExprKind::MethodCall(method_path, _, _, _) = op.kind;
|
||
if method_path.ident.name == sym::next;
|
||
if match_trait_method(cx, op, &paths::ITERATOR);
|
||
then {
|
||
return;
|
||
}
|
||
}
|
||
|
||
let result_expr = match &op.kind {
|
||
ExprKind::AddrOf(_, _, borrowed) => borrowed,
|
||
_ => op,
|
||
};
|
||
span_lint_and_then(
|
||
cx,
|
||
REDUNDANT_PATTERN_MATCHING,
|
||
arms[0].pat.span,
|
||
&format!("redundant pattern matching, consider using `{}`", good_method),
|
||
|diag| {
|
||
// while let ... = ... { ... }
|
||
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||
let expr_span = expr.span;
|
||
|
||
// while let ... = ... { ... }
|
||
// ^^^
|
||
let op_span = result_expr.span.source_callsite();
|
||
|
||
// while let ... = ... { ... }
|
||
// ^^^^^^^^^^^^^^^^^^^
|
||
let span = expr_span.until(op_span.shrink_to_hi());
|
||
diag.span_suggestion(
|
||
span,
|
||
"try this",
|
||
format!("{} {}.{}", keyword, snippet(cx, op_span, "_"), good_method),
|
||
Applicability::MachineApplicable, // snippet
|
||
);
|
||
},
|
||
);
|
||
}
|
||
|
||
fn find_sugg_for_match<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, op: &Expr<'_>, arms: &[Arm<'_>]) {
|
||
if arms.len() == 2 {
|
||
let node_pair = (&arms[0].pat.kind, &arms[1].pat.kind);
|
||
|
||
let found_good_method = match node_pair {
|
||
(
|
||
PatKind::TupleStruct(ref path_left, ref patterns_left, _),
|
||
PatKind::TupleStruct(ref path_right, ref patterns_right, _),
|
||
) if patterns_left.len() == 1 && patterns_right.len() == 1 => {
|
||
if let (PatKind::Wild, PatKind::Wild) = (&patterns_left[0].kind, &patterns_right[0].kind) {
|
||
find_good_method_for_match(
|
||
arms,
|
||
path_left,
|
||
path_right,
|
||
&paths::RESULT_OK,
|
||
&paths::RESULT_ERR,
|
||
"is_ok()",
|
||
"is_err()",
|
||
)
|
||
.or_else(|| {
|
||
find_good_method_for_match(
|
||
arms,
|
||
path_left,
|
||
path_right,
|
||
&paths::IPADDR_V4,
|
||
&paths::IPADDR_V6,
|
||
"is_ipv4()",
|
||
"is_ipv6()",
|
||
)
|
||
})
|
||
} else {
|
||
None
|
||
}
|
||
},
|
||
(PatKind::TupleStruct(ref path_left, ref patterns, _), PatKind::Path(ref path_right))
|
||
| (PatKind::Path(ref path_left), PatKind::TupleStruct(ref path_right, ref patterns, _))
|
||
if patterns.len() == 1 =>
|
||
{
|
||
if let PatKind::Wild = patterns[0].kind {
|
||
find_good_method_for_match(
|
||
arms,
|
||
path_left,
|
||
path_right,
|
||
&paths::OPTION_SOME,
|
||
&paths::OPTION_NONE,
|
||
"is_some()",
|
||
"is_none()",
|
||
)
|
||
.or_else(|| {
|
||
find_good_method_for_match(
|
||
arms,
|
||
path_left,
|
||
path_right,
|
||
&paths::POLL_READY,
|
||
&paths::POLL_PENDING,
|
||
"is_ready()",
|
||
"is_pending()",
|
||
)
|
||
})
|
||
} else {
|
||
None
|
||
}
|
||
},
|
||
_ => None,
|
||
};
|
||
|
||
if let Some(good_method) = found_good_method {
|
||
let span = expr.span.to(op.span);
|
||
let result_expr = match &op.kind {
|
||
ExprKind::AddrOf(_, _, borrowed) => borrowed,
|
||
_ => op,
|
||
};
|
||
span_lint_and_then(
|
||
cx,
|
||
REDUNDANT_PATTERN_MATCHING,
|
||
expr.span,
|
||
&format!("redundant pattern matching, consider using `{}`", good_method),
|
||
|diag| {
|
||
diag.span_suggestion(
|
||
span,
|
||
"try this",
|
||
format!("{}.{}", snippet(cx, result_expr.span, "_"), good_method),
|
||
Applicability::MaybeIncorrect, // snippet
|
||
);
|
||
},
|
||
);
|
||
}
|
||
}
|
||
}
|
||
|
||
fn find_good_method_for_match<'a>(
|
||
arms: &[Arm<'_>],
|
||
path_left: &QPath<'_>,
|
||
path_right: &QPath<'_>,
|
||
expected_left: &[&str],
|
||
expected_right: &[&str],
|
||
should_be_left: &'a str,
|
||
should_be_right: &'a str,
|
||
) -> Option<&'a str> {
|
||
let body_node_pair = if match_qpath(path_left, expected_left) && match_qpath(path_right, expected_right) {
|
||
(&(*arms[0].body).kind, &(*arms[1].body).kind)
|
||
} else if match_qpath(path_right, expected_left) && match_qpath(path_left, expected_right) {
|
||
(&(*arms[1].body).kind, &(*arms[0].body).kind)
|
||
} else {
|
||
return None;
|
||
};
|
||
|
||
match body_node_pair {
|
||
(ExprKind::Lit(ref lit_left), ExprKind::Lit(ref lit_right)) => match (&lit_left.node, &lit_right.node) {
|
||
(LitKind::Bool(true), LitKind::Bool(false)) => Some(should_be_left),
|
||
(LitKind::Bool(false), LitKind::Bool(true)) => Some(should_be_right),
|
||
_ => None,
|
||
},
|
||
_ => None,
|
||
}
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn test_overlapping() {
|
||
use rustc_span::source_map::DUMMY_SP;
|
||
|
||
let sp = |s, e| SpannedRange {
|
||
span: DUMMY_SP,
|
||
node: (s, e),
|
||
};
|
||
|
||
assert_eq!(None, overlapping::<u8>(&[]));
|
||
assert_eq!(None, overlapping(&[sp(1, Bound::Included(4))]));
|
||
assert_eq!(
|
||
None,
|
||
overlapping(&[sp(1, Bound::Included(4)), sp(5, Bound::Included(6))])
|
||
);
|
||
assert_eq!(
|
||
None,
|
||
overlapping(&[
|
||
sp(1, Bound::Included(4)),
|
||
sp(5, Bound::Included(6)),
|
||
sp(10, Bound::Included(11))
|
||
],)
|
||
);
|
||
assert_eq!(
|
||
Some((&sp(1, Bound::Included(4)), &sp(3, Bound::Included(6)))),
|
||
overlapping(&[sp(1, Bound::Included(4)), sp(3, Bound::Included(6))])
|
||
);
|
||
assert_eq!(
|
||
Some((&sp(5, Bound::Included(6)), &sp(6, Bound::Included(11)))),
|
||
overlapping(&[
|
||
sp(1, Bound::Included(4)),
|
||
sp(5, Bound::Included(6)),
|
||
sp(6, Bound::Included(11))
|
||
],)
|
||
);
|
||
}
|
||
|
||
/// Implementation of `MATCH_SAME_ARMS`.
|
||
fn lint_match_arms<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) {
|
||
if let ExprKind::Match(_, ref arms, MatchSource::Normal) = expr.kind {
|
||
let hash = |&(_, arm): &(usize, &Arm<'_>)| -> u64 {
|
||
let mut h = SpanlessHash::new(cx);
|
||
h.hash_expr(&arm.body);
|
||
h.finish()
|
||
};
|
||
|
||
let eq = |&(lindex, lhs): &(usize, &Arm<'_>), &(rindex, rhs): &(usize, &Arm<'_>)| -> bool {
|
||
let min_index = usize::min(lindex, rindex);
|
||
let max_index = usize::max(lindex, rindex);
|
||
|
||
let mut local_map: FxHashMap<HirId, HirId> = FxHashMap::default();
|
||
let eq_fallback = |a: &Expr<'_>, b: &Expr<'_>| {
|
||
if_chain! {
|
||
if let Some(a_id) = path_to_local(a);
|
||
if let Some(b_id) = path_to_local(b);
|
||
let entry = match local_map.entry(a_id) {
|
||
Entry::Vacant(entry) => entry,
|
||
// check if using the same bindings as before
|
||
Entry::Occupied(entry) => return *entry.get() == b_id,
|
||
};
|
||
// the names technically don't have to match; this makes the lint more conservative
|
||
if cx.tcx.hir().name(a_id) == cx.tcx.hir().name(b_id);
|
||
if TyS::same_type(cx.typeck_results().expr_ty(a), cx.typeck_results().expr_ty(b));
|
||
if pat_contains_local(lhs.pat, a_id);
|
||
if pat_contains_local(rhs.pat, b_id);
|
||
then {
|
||
entry.insert(b_id);
|
||
true
|
||
} else {
|
||
false
|
||
}
|
||
}
|
||
};
|
||
// Arms with a guard are ignored, those can’t always be merged together
|
||
// This is also the case for arms in-between each there is an arm with a guard
|
||
(min_index..=max_index).all(|index| arms[index].guard.is_none())
|
||
&& SpanlessEq::new(cx)
|
||
.expr_fallback(eq_fallback)
|
||
.eq_expr(&lhs.body, &rhs.body)
|
||
// these checks could be removed to allow unused bindings
|
||
&& bindings_eq(lhs.pat, local_map.keys().copied().collect())
|
||
&& bindings_eq(rhs.pat, local_map.values().copied().collect())
|
||
};
|
||
|
||
let indexed_arms: Vec<(usize, &Arm<'_>)> = arms.iter().enumerate().collect();
|
||
for (&(_, i), &(_, j)) in search_same(&indexed_arms, hash, eq) {
|
||
span_lint_and_then(
|
||
cx,
|
||
MATCH_SAME_ARMS,
|
||
j.body.span,
|
||
"this `match` has identical arm bodies",
|
||
|diag| {
|
||
diag.span_note(i.body.span, "same as this");
|
||
|
||
// Note: this does not use `span_suggestion` on purpose:
|
||
// there is no clean way
|
||
// to remove the other arm. Building a span and suggest to replace it to ""
|
||
// makes an even more confusing error message. Also in order not to make up a
|
||
// span for the whole pattern, the suggestion is only shown when there is only
|
||
// one pattern. The user should know about `|` if they are already using it…
|
||
|
||
let lhs = snippet(cx, i.pat.span, "<pat1>");
|
||
let rhs = snippet(cx, j.pat.span, "<pat2>");
|
||
|
||
if let PatKind::Wild = j.pat.kind {
|
||
// if the last arm is _, then i could be integrated into _
|
||
// note that i.pat cannot be _, because that would mean that we're
|
||
// hiding all the subsequent arms, and rust won't compile
|
||
diag.span_note(
|
||
i.body.span,
|
||
&format!(
|
||
"`{}` has the same arm body as the `_` wildcard, consider removing it",
|
||
lhs
|
||
),
|
||
);
|
||
} else {
|
||
diag.span_help(i.pat.span, &format!("consider refactoring into `{} | {}`", lhs, rhs));
|
||
}
|
||
},
|
||
);
|
||
}
|
||
}
|
||
}
|
||
|
||
fn pat_contains_local(pat: &Pat<'_>, id: HirId) -> bool {
|
||
let mut result = false;
|
||
pat.walk_short(|p| {
|
||
result |= matches!(p.kind, PatKind::Binding(_, binding_id, ..) if binding_id == id);
|
||
!result
|
||
});
|
||
result
|
||
}
|
||
|
||
/// Returns true if all the bindings in the `Pat` are in `ids` and vice versa
|
||
fn bindings_eq(pat: &Pat<'_>, mut ids: FxHashSet<HirId>) -> bool {
|
||
let mut result = true;
|
||
pat.each_binding_or_first(&mut |_, id, _, _| result &= ids.remove(&id));
|
||
result && ids.is_empty()
|
||
}
|