mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-01 00:49:30 +00:00
835 lines
27 KiB
Rust
835 lines
27 KiB
Rust
use crate::consts::{constant, Constant};
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use crate::utils::paths;
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use crate::utils::sugg::Sugg;
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use crate::utils::{
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expr_block, in_macro, is_allowed, is_expn_of, match_qpath, match_type, multispan_sugg, remove_blocks, snippet,
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snippet_with_applicability, span_lint_and_sugg, span_lint_and_then, span_note_and_lint, walk_ptrs_ty,
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};
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use if_chain::if_chain;
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use rustc::hir::def::CtorKind;
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use rustc::hir::*;
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use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintContext, LintPass};
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use rustc::ty::{self, Ty, TyKind};
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use rustc::{declare_tool_lint, lint_array};
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use rustc_errors::Applicability;
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use std::cmp::Ordering;
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use std::collections::Bound;
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use std::ops::Deref;
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use syntax::ast::LitKind;
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use syntax::source_map::Span;
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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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/// 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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declare_clippy_lint! {
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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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/// **What it does:** Checks for matches with a 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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/// 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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/// 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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declare_clippy_lint! {
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pub SINGLE_MATCH_ELSE,
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pedantic,
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"a match statement with a 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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/// **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
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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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declare_clippy_lint! {
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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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/// **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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/// 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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/// 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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declare_clippy_lint! {
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pub MATCH_BOOL,
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style,
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"a match on a boolean expression instead of an `if..else` block"
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}
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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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declare_clippy_lint! {
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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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/// **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, just like
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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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declare_clippy_lint! {
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pub MATCH_WILD_ERR_ARM,
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style,
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"a match with `Err(_)` arm and take drastic actions"
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}
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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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/// 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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declare_clippy_lint! {
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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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/// **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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/// match x {
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/// A => {},
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/// _ => {},
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/// }
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/// ```
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declare_clippy_lint! {
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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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#[allow(missing_copy_implementations)]
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pub struct MatchPass;
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impl LintPass for MatchPass {
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fn get_lints(&self) -> LintArray {
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lint_array!(
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SINGLE_MATCH,
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MATCH_REF_PATS,
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MATCH_BOOL,
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SINGLE_MATCH_ELSE,
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MATCH_OVERLAPPING_ARM,
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MATCH_WILD_ERR_ARM,
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MATCH_AS_REF,
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WILDCARD_ENUM_MATCH_ARM
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)
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}
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fn name(&self) -> &'static str {
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"Matches"
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}
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}
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MatchPass {
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fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
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if in_external_macro(cx.sess(), expr.span) {
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return;
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}
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if let ExprKind::Match(ref ex, ref arms, MatchSource::Normal) = expr.node {
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check_single_match(cx, ex, arms, expr);
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check_match_bool(cx, ex, arms, expr);
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check_overlapping_arms(cx, ex, arms);
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check_wild_err_arm(cx, ex, arms);
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check_wild_enum_match(cx, ex, arms);
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check_match_as_ref(cx, ex, arms, expr);
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}
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if let ExprKind::Match(ref ex, ref arms, _) = expr.node {
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check_match_ref_pats(cx, ex, arms, expr);
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}
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}
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}
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#[rustfmt::skip]
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fn check_single_match(cx: &LateContext<'_, '_>, ex: &Expr, arms: &[Arm], expr: &Expr) {
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if arms.len() == 2 &&
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arms[0].pats.len() == 1 && arms[0].guard.is_none() &&
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arms[1].pats.len() == 1 && arms[1].guard.is_none() {
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let els = remove_blocks(&arms[1].body);
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let els = if is_unit_expr(els) {
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None
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} else if let ExprKind::Block(_, _) = els.node {
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// matches with blocks that contain statements are prettier as `if let + else`
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Some(els)
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} else {
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// allow match arms with just expressions
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return;
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};
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let ty = cx.tables.expr_ty(ex);
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if ty.sty != ty::Bool || is_allowed(cx, MATCH_BOOL, ex.id) {
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check_single_match_single_pattern(cx, ex, arms, expr, els);
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check_single_match_opt_like(cx, ex, arms, expr, ty, els);
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}
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}
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}
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fn check_single_match_single_pattern(
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cx: &LateContext<'_, '_>,
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ex: &Expr,
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arms: &[Arm],
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expr: &Expr,
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els: Option<&Expr>,
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) {
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if is_wild(&arms[1].pats[0]) {
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report_single_match_single_pattern(cx, ex, arms, expr, els);
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}
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}
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fn report_single_match_single_pattern(
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cx: &LateContext<'_, '_>,
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ex: &Expr,
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arms: &[Arm],
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expr: &Expr,
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els: Option<&Expr>,
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) {
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let lint = if els.is_some() { SINGLE_MATCH_ELSE } else { SINGLE_MATCH };
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let els_str = els.map_or(String::new(), |els| {
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format!(" else {}", expr_block(cx, els, None, ".."))
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});
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span_lint_and_sugg(
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cx,
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lint,
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expr.span,
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"you seem to be trying to use match for destructuring a single pattern. Consider using `if \
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let`",
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"try this",
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format!(
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"if let {} = {} {}{}",
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snippet(cx, arms[0].pats[0].span, ".."),
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snippet(cx, ex.span, ".."),
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expr_block(cx, &arms[0].body, None, ".."),
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els_str,
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),
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Applicability::HasPlaceholders,
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);
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}
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fn check_single_match_opt_like(
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cx: &LateContext<'_, '_>,
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ex: &Expr,
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arms: &[Arm],
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expr: &Expr,
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ty: Ty<'_>,
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els: Option<&Expr>,
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) {
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// list of candidate Enums we know will never get any more members
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let candidates = &[
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(&paths::COW, "Borrowed"),
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(&paths::COW, "Cow::Borrowed"),
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(&paths::COW, "Cow::Owned"),
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(&paths::COW, "Owned"),
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(&paths::OPTION, "None"),
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(&paths::RESULT, "Err"),
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(&paths::RESULT, "Ok"),
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];
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let path = match arms[1].pats[0].node {
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PatKind::TupleStruct(ref path, ref inner, _) => {
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// contains any non wildcard patterns? e.g. Err(err)
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if !inner.iter().all(is_wild) {
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return;
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}
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print::to_string(print::NO_ANN, |s| s.print_qpath(path, false))
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},
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PatKind::Binding(BindingAnnotation::Unannotated, .., ident, None) => ident.to_string(),
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PatKind::Path(ref path) => print::to_string(print::NO_ANN, |s| s.print_qpath(path, false)),
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_ => return,
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};
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for &(ty_path, pat_path) in candidates {
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if path == *pat_path && match_type(cx, ty, ty_path) {
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report_single_match_single_pattern(cx, ex, arms, expr, els);
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}
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}
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}
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fn check_match_bool(cx: &LateContext<'_, '_>, ex: &Expr, arms: &[Arm], expr: &Expr) {
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// type of expression == bool
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if cx.tables.expr_ty(ex).sty == ty::Bool {
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span_lint_and_then(
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cx,
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MATCH_BOOL,
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expr.span,
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"you seem to be trying to match on a boolean expression",
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move |db| {
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if arms.len() == 2 && arms[0].pats.len() == 1 {
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// no guards
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let exprs = if let PatKind::Lit(ref arm_bool) = arms[0].pats[0].node {
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if let ExprKind::Lit(ref lit) = arm_bool.node {
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match lit.node {
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LitKind::Bool(true) => Some((&*arms[0].body, &*arms[1].body)),
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LitKind::Bool(false) => Some((&*arms[1].body, &*arms[0].body)),
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_ => None,
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}
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} else {
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None
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}
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} else {
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None
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||
};
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if let Some((true_expr, false_expr)) = exprs {
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let sugg = match (is_unit_expr(true_expr), is_unit_expr(false_expr)) {
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(false, false) => Some(format!(
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"if {} {} else {}",
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snippet(cx, ex.span, "b"),
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expr_block(cx, true_expr, None, ".."),
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expr_block(cx, false_expr, None, "..")
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)),
|
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(false, true) => Some(format!(
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"if {} {}",
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snippet(cx, ex.span, "b"),
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expr_block(cx, true_expr, None, "..")
|
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)),
|
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(true, false) => {
|
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let test = Sugg::hir(cx, ex, "..");
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Some(format!("if {} {}", !test, expr_block(cx, false_expr, None, "..")))
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},
|
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(true, true) => None,
|
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};
|
||
|
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if let Some(sugg) = sugg {
|
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db.span_suggestion(
|
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expr.span,
|
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"consider using an if/else expression",
|
||
sugg,
|
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Applicability::HasPlaceholders,
|
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);
|
||
}
|
||
}
|
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}
|
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},
|
||
);
|
||
}
|
||
}
|
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|
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fn check_overlapping_arms<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ex: &'tcx Expr, arms: &'tcx [Arm]) {
|
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if arms.len() >= 2 && cx.tables.expr_ty(ex).is_integral() {
|
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let ranges = all_ranges(cx, arms);
|
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let type_ranges = type_ranges(&ranges);
|
||
if !type_ranges.is_empty() {
|
||
if let Some((start, end)) = overlapping(&type_ranges) {
|
||
span_note_and_lint(
|
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cx,
|
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MATCH_OVERLAPPING_ARM,
|
||
start.span,
|
||
"some ranges overlap",
|
||
end.span,
|
||
"overlaps with this",
|
||
);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
fn is_wild(pat: &impl std::ops::Deref<Target = Pat>) -> bool {
|
||
match pat.node {
|
||
PatKind::Wild => true,
|
||
_ => false,
|
||
}
|
||
}
|
||
|
||
fn check_wild_err_arm(cx: &LateContext<'_, '_>, ex: &Expr, arms: &[Arm]) {
|
||
let ex_ty = walk_ptrs_ty(cx.tables.expr_ty(ex));
|
||
if match_type(cx, ex_ty, &paths::RESULT) {
|
||
for arm in arms {
|
||
if let PatKind::TupleStruct(ref path, ref inner, _) = arm.pats[0].node {
|
||
let path_str = print::to_string(print::NO_ANN, |s| s.print_qpath(path, false));
|
||
if_chain! {
|
||
if path_str == "Err";
|
||
if inner.iter().any(is_wild);
|
||
if let ExprKind::Block(ref block, _) = arm.body.node;
|
||
if is_panic_block(block);
|
||
then {
|
||
// `Err(_)` arm with `panic!` found
|
||
span_note_and_lint(cx,
|
||
MATCH_WILD_ERR_ARM,
|
||
arm.pats[0].span,
|
||
"Err(_) will match all errors, maybe not a good idea",
|
||
arm.pats[0].span,
|
||
"to remove this warning, match each error separately \
|
||
or use unreachable macro");
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
fn check_wild_enum_match(cx: &LateContext<'_, '_>, ex: &Expr, arms: &[Arm]) {
|
||
let ty = cx.tables.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 {
|
||
for pat in &arm.pats {
|
||
if let PatKind::Wild = pat.node {
|
||
wildcard_span = Some(pat.span);
|
||
} else if let PatKind::Binding(_, _, ident, None) = pat.node {
|
||
wildcard_span = Some(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 TyKind::Adt(def, _) = ty.sty {
|
||
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;
|
||
}
|
||
for pat in &arm.pats {
|
||
if let PatKind::Path(ref path) = pat.deref().node {
|
||
if let QPath::Resolved(_, p) = path {
|
||
missing_variants.retain(|e| e.did != p.def.def_id());
|
||
}
|
||
} else if let PatKind::TupleStruct(ref path, ..) = pat.deref().node {
|
||
if let QPath::Resolved(_, p) = path {
|
||
missing_variants.retain(|e| e.did != p.def.def_id());
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
let 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.item_path_str(v.did), suffix)
|
||
})
|
||
.collect();
|
||
|
||
if suggestion.is_empty() {
|
||
return;
|
||
}
|
||
|
||
span_lint_and_sugg(
|
||
cx,
|
||
WILDCARD_ENUM_MATCH_ARM,
|
||
wildcard_span,
|
||
"wildcard match will miss any future added variants.",
|
||
"try this",
|
||
suggestion.join(" | "),
|
||
Applicability::MachineApplicable,
|
||
)
|
||
}
|
||
}
|
||
|
||
// 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::new();
|
||
let (title, msg) = if let ExprKind::AddrOf(Mutability::MutImmutable, ref inner) = ex.node {
|
||
suggs.push((ex.span, Sugg::hir(cx, inner, "..").to_string()));
|
||
(
|
||
"you don't need to add `&` to both the expression and the patterns",
|
||
"try",
|
||
)
|
||
} else {
|
||
suggs.push((ex.span, Sugg::hir(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().flat_map(|a| &a.pats).filter_map(|p| {
|
||
if let PatKind::Ref(ref refp, _) = p.node {
|
||
Some((p.span, snippet(cx, refp.span, "..").to_string()))
|
||
} else {
|
||
None
|
||
}
|
||
}));
|
||
|
||
span_lint_and_then(cx, MATCH_REF_PATS, expr.span, title, |db| {
|
||
if !in_macro(expr.span) {
|
||
multispan_sugg(db, msg.to_owned(), suggs);
|
||
}
|
||
});
|
||
}
|
||
}
|
||
|
||
fn check_match_as_ref(cx: &LateContext<'_, '_>, ex: &Expr, arms: &[Arm], expr: &Expr) {
|
||
if arms.len() == 2
|
||
&& arms[0].pats.len() == 1
|
||
&& arms[0].guard.is_none()
|
||
&& arms[1].pats.len() == 1
|
||
&& 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 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
|
||
),
|
||
applicability,
|
||
)
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Get all arms that are unbounded `PatRange`s.
|
||
fn all_ranges<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, arms: &'tcx [Arm]) -> Vec<SpannedRange<Constant>> {
|
||
arms.iter()
|
||
.flat_map(|arm| {
|
||
if let Arm {
|
||
ref pats, guard: None, ..
|
||
} = *arm
|
||
{
|
||
pats.iter()
|
||
} else {
|
||
[].iter()
|
||
}
|
||
.filter_map(|pat| {
|
||
if let PatKind::Range(ref lhs, ref rhs, ref range_end) = pat.node {
|
||
let lhs = constant(cx, cx.tables, lhs)?.0;
|
||
let rhs = constant(cx, cx.tables, rhs)?.0;
|
||
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.node {
|
||
let value = constant(cx, cx.tables, 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>>;
|
||
|
||
/// Get 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.node {
|
||
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 {
|
||
match arm.pats[0].node {
|
||
PatKind::Path(ref path) if match_qpath(path, &paths::OPTION_NONE) => true,
|
||
_ => false,
|
||
}
|
||
}
|
||
|
||
// 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.pats[0].node;
|
||
if pats.len() == 1 && match_qpath(path, &paths::OPTION_SOME);
|
||
if let PatKind::Binding(rb, .., ident, _) = pats[0].node;
|
||
if rb == BindingAnnotation::Ref || rb == BindingAnnotation::RefMut;
|
||
if let ExprKind::Call(ref e, ref args) = remove_blocks(&arm.body).node;
|
||
if let ExprKind::Path(ref some_path) = e.node;
|
||
if match_qpath(some_path, &paths::OPTION_SOME) && args.len() == 1;
|
||
if let ExprKind::Path(ref qpath) = args[0].node;
|
||
if let &QPath::Resolved(_, ref path2) = qpath;
|
||
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()
|
||
.flat_map(|a| &a.pats)
|
||
.map(|p| {
|
||
match p.node {
|
||
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: 'a> {
|
||
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) => (),
|
||
_ => return Some((a.range(), b.range())),
|
||
}
|
||
}
|
||
|
||
None
|
||
}
|