-use crate::consts::{constant, miri_to_const, Constant};
-use crate::utils::sugg::Sugg;
-use crate::utils::usage::is_unused;
-use crate::utils::{
- expr_block, get_arg_name, get_parent_expr, in_macro, indent_of, is_allowed, is_expn_of, is_refutable,
- is_type_diagnostic_item, is_wild, match_qpath, match_type, match_var, multispan_sugg, remove_blocks, snippet,
- snippet_block, snippet_with_applicability, span_lint_and_help, span_lint_and_note, span_lint_and_sugg,
- span_lint_and_then,
+use clippy_utils::consts::{constant, miri_to_const, Constant};
+use clippy_utils::diagnostics::{
+ multispan_sugg, span_lint_and_help, span_lint_and_note, span_lint_and_sugg, span_lint_and_then,
};
-use crate::utils::{paths, search_same, SpanlessEq, SpanlessHash};
+use clippy_utils::higher;
+use clippy_utils::source::{expr_block, indent_of, snippet, snippet_block, snippet_opt, snippet_with_applicability};
+use clippy_utils::sugg::Sugg;
+use clippy_utils::ty::{implements_trait, is_type_diagnostic_item, match_type, peel_mid_ty_refs};
+use clippy_utils::visitors::LocalUsedVisitor;
+use clippy_utils::{
+ get_parent_expr, in_macro, is_expn_of, is_lang_ctor, is_lint_allowed, is_refutable, is_wild, meets_msrv, msrvs,
+ path_to_local, path_to_local_id, peel_hir_pat_refs, peel_n_hir_expr_refs, recurse_or_patterns, remove_blocks,
+ strip_pat_refs,
+};
+use clippy_utils::{paths, search_same, SpanlessEq, SpanlessHash};
+use core::array;
+use core::iter::{once, ExactSizeIterator};
use if_chain::if_chain;
-use rustc_ast::ast::LitKind;
-use rustc_data_structures::fx::FxHashMap;
+use rustc_ast::ast::{Attribute, LitKind};
use rustc_errors::Applicability;
-use rustc_hir::def::CtorKind;
+use rustc_hir::def::{CtorKind, DefKind, Res};
+use rustc_hir::LangItem::{OptionNone, OptionSome};
use rustc_hir::{
- Arm, BindingAnnotation, Block, BorrowKind, Expr, ExprKind, Guard, Local, MatchSource, Mutability, Node, Pat,
- PatKind, QPath, RangeEnd,
+ self as hir, Arm, BindingAnnotation, Block, BorrowKind, Expr, ExprKind, Guard, HirId, Local, MatchSource,
+ Mutability, Node, Pat, PatKind, PathSegment, QPath, RangeEnd, TyKind,
};
+use rustc_hir::{HirIdMap, HirIdSet};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::lint::in_external_macro;
-use rustc_middle::ty::{self, Ty, TyS};
+use rustc_middle::ty::{self, Ty, TyS, VariantDef};
+use rustc_semver::RustcVersion;
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::source_map::{Span, Spanned};
-use rustc_span::Symbol;
+use rustc_span::sym;
use std::cmp::Ordering;
use std::collections::hash_map::Entry;
-use std::collections::Bound;
+use std::iter;
+use std::ops::Bound;
declare_clippy_lint! {
- /// **What it does:** Checks for matches with a single arm where an `if let`
+ /// ### What it does
+ /// Checks for matches with a single arm where an `if let`
/// will usually suffice.
///
- /// **Why is this bad?** Just readability – `if let` nests less than a `match`.
- ///
- /// **Known problems:** None.
+ /// ### Why is this bad?
+ /// Just readability – `if let` nests less than a `match`.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # fn bar(stool: &str) {}
/// # let x = Some("abc");
}
declare_clippy_lint! {
- /// **What it does:** Checks for matches with two arms where an `if let else` will
+ /// ### What it does
+ /// Checks for matches with two arms where an `if let else` will
/// usually suffice.
///
- /// **Why is this bad?** Just readability – `if let` nests less than a `match`.
- ///
- /// **Known problems:** Personal style preferences may differ.
+ /// ### Why is this bad?
+ /// Just readability – `if let` nests less than a `match`.
///
- /// **Example:**
+ /// ### Known problems
+ /// Personal style preferences may differ.
///
+ /// ### Example
/// Using `match`:
///
/// ```rust
}
declare_clippy_lint! {
- /// **What it does:** Checks for matches where all arms match a reference,
+ /// ### What it does
+ /// Checks for matches where all arms match a reference,
/// suggesting to remove the reference and deref the matched expression
/// instead. It also checks for `if let &foo = bar` blocks.
///
- /// **Why is this bad?** It just makes the code less readable. That reference
+ /// ### Why is this bad?
+ /// It just makes the code less readable. That reference
/// destructuring adds nothing to the code.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust,ignore
/// // Bad
/// match x {
}
declare_clippy_lint! {
- /// **What it does:** Checks for matches where match expression is a `bool`. It
+ /// ### What it does
+ /// Checks for matches where match expression is a `bool`. It
/// suggests to replace the expression with an `if...else` block.
///
- /// **Why is this bad?** It makes the code less readable.
- ///
- /// **Known problems:** None.
+ /// ### Why is this bad?
+ /// It makes the code less readable.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # fn foo() {}
/// # fn bar() {}
}
declare_clippy_lint! {
- /// **What it does:** Checks for overlapping match arms.
+ /// ### What it does
+ /// Checks for overlapping match arms.
///
- /// **Why is this bad?** It is likely to be an error and if not, makes the code
+ /// ### Why is this bad?
+ /// It is likely to be an error and if not, makes the code
/// less obvious.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let x = 5;
/// match x {
}
declare_clippy_lint! {
- /// **What it does:** Checks for arm which matches all errors with `Err(_)`
+ /// ### What it does
+ /// Checks for arm which matches all errors with `Err(_)`
/// and take drastic actions like `panic!`.
///
- /// **Why is this bad?** It is generally a bad practice, similar to
+ /// ### Why is this bad?
+ /// It is generally a bad practice, similar to
/// catching all exceptions in java with `catch(Exception)`
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let x: Result<i32, &str> = Ok(3);
/// match x {
}
declare_clippy_lint! {
- /// **What it does:** Checks for match which is used to add a reference to an
+ /// ### What it does
+ /// Checks for match which is used to add a reference to an
/// `Option` value.
///
- /// **Why is this bad?** Using `as_ref()` or `as_mut()` instead is shorter.
+ /// ### Why is this bad?
+ /// Using `as_ref()` or `as_mut()` instead is shorter.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let x: Option<()> = None;
///
}
declare_clippy_lint! {
- /// **What it does:** Checks for wildcard enum matches using `_`.
+ /// ### What it does
+ /// Checks for wildcard enum matches using `_`.
///
- /// **Why is this bad?** New enum variants added by library updates can be missed.
+ /// ### Why is this bad?
+ /// New enum variants added by library updates can be missed.
///
- /// **Known problems:** Suggested replacements may be incorrect if guards exhaustively cover some
+ /// ### Known problems
+ /// Suggested replacements may be incorrect if guards exhaustively cover some
/// variants, and also may not use correct path to enum if it's not present in the current scope.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # enum Foo { A(usize), B(usize) }
/// # let x = Foo::B(1);
}
declare_clippy_lint! {
- /// **What it does:** Checks for wildcard enum matches for a single variant.
+ /// ### What it does
+ /// Checks for wildcard enum matches for a single variant.
///
- /// **Why is this bad?** New enum variants added by library updates can be missed.
+ /// ### Why is this bad?
+ /// New enum variants added by library updates can be missed.
///
- /// **Known problems:** Suggested replacements may not use correct path to enum
+ /// ### Known problems
+ /// Suggested replacements may not use correct path to enum
/// if it's not present in the current scope.
///
- /// **Example:**
- ///
+ /// ### Example
/// ```rust
/// # enum Foo { A, B, C }
/// # let x = Foo::B;
}
declare_clippy_lint! {
- /// **What it does:** Checks for wildcard pattern used with others patterns in same match arm.
+ /// ### What it does
+ /// Checks for wildcard pattern used with others patterns in same match arm.
///
- /// **Why is this bad?** Wildcard pattern already covers any other pattern as it will match anyway.
+ /// ### Why is this bad?
+ /// Wildcard pattern already covers any other pattern as it will match anyway.
/// It makes the code less readable, especially to spot wildcard pattern use in match arm.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// // Bad
/// match "foo" {
}
declare_clippy_lint! {
- /// **What it does:** Checks for matches being used to destructure a single-variant enum
+ /// ### What it does
+ /// Checks for matches being used to destructure a single-variant enum
/// or tuple struct where a `let` will suffice.
///
- /// **Why is this bad?** Just readability – `let` doesn't nest, whereas a `match` does.
- ///
- /// **Known problems:** None.
+ /// ### Why is this bad?
+ /// Just readability – `let` doesn't nest, whereas a `match` does.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// enum Wrapper {
/// Data(i32),
}
declare_clippy_lint! {
- /// **What it does:** Checks for useless match that binds to only one value.
+ /// ### What it does
+ /// Checks for useless match that binds to only one value.
///
- /// **Why is this bad?** Readability and needless complexity.
+ /// ### Why is this bad?
+ /// Readability and needless complexity.
///
- /// **Known problems:** Suggested replacements may be incorrect when `match`
+ /// ### Known problems
+ /// Suggested replacements may be incorrect when `match`
/// is actually binding temporary value, bringing a 'dropped while borrowed' error.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # let a = 1;
/// # let b = 2;
}
declare_clippy_lint! {
- /// **What it does:** Checks for unnecessary '..' pattern binding on struct when all fields are explicitly matched.
+ /// ### What it does
+ /// Checks for unnecessary '..' pattern binding on struct when all fields are explicitly matched.
///
- /// **Why is this bad?** Correctness and readability. It's like having a wildcard pattern after
+ /// ### Why is this bad?
+ /// Correctness and readability. It's like having a wildcard pattern after
/// matching all enum variants explicitly.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # struct A { a: i32 }
/// let a = A { a: 5 };
}
declare_clippy_lint! {
- /// **What it does:** Lint for redundant pattern matching over `Result` or
- /// `Option`
+ /// ### What it does
+ /// Lint for redundant pattern matching over `Result`, `Option`,
+ /// `std::task::Poll` or `std::net::IpAddr`
///
- /// **Why is this bad?** It's more concise and clear to just use the proper
+ /// ### Why is this bad?
+ /// It's more concise and clear to just use the proper
/// utility function
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Known problems
+ /// This will change the drop order for the matched type. Both `if let` and
+ /// `while let` will drop the value at the end of the block, both `if` and `while` will drop the
+ /// value before entering the block. For most types this change will not matter, but for a few
+ /// types this will not be an acceptable change (e.g. locks). See the
+ /// [reference](https://doc.rust-lang.org/reference/destructors.html#drop-scopes) for more about
+ /// drop order.
///
+ /// ### Example
/// ```rust
+ /// # use std::task::Poll;
+ /// # use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
/// if let Ok(_) = Ok::<i32, i32>(42) {}
/// if let Err(_) = Err::<i32, i32>(42) {}
/// if let None = None::<()> {}
/// if let Some(_) = Some(42) {}
+ /// if let Poll::Pending = Poll::Pending::<()> {}
+ /// if let Poll::Ready(_) = Poll::Ready(42) {}
+ /// if let IpAddr::V4(_) = IpAddr::V4(Ipv4Addr::LOCALHOST) {}
+ /// if let IpAddr::V6(_) = IpAddr::V6(Ipv6Addr::LOCALHOST) {}
/// match Ok::<i32, i32>(42) {
/// Ok(_) => true,
/// Err(_) => false,
/// The more idiomatic use would be:
///
/// ```rust
+ /// # use std::task::Poll;
+ /// # use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
/// if Ok::<i32, i32>(42).is_ok() {}
/// if Err::<i32, i32>(42).is_err() {}
/// if None::<()>.is_none() {}
/// if Some(42).is_some() {}
+ /// if Poll::Pending::<()>.is_pending() {}
+ /// if Poll::Ready(42).is_ready() {}
+ /// if IpAddr::V4(Ipv4Addr::LOCALHOST).is_ipv4() {}
+ /// if IpAddr::V6(Ipv6Addr::LOCALHOST).is_ipv6() {}
/// Ok::<i32, i32>(42).is_ok();
/// ```
pub REDUNDANT_PATTERN_MATCHING,
}
declare_clippy_lint! {
- /// **What it does:** Checks for `match` or `if let` expressions producing a
+ /// ### What it does
+ /// Checks for `match` or `if let` expressions producing a
/// `bool` that could be written using `matches!`
///
- /// **Why is this bad?** Readability and needless complexity.
+ /// ### Why is this bad?
+ /// Readability and needless complexity.
///
- /// **Known problems:** None
+ /// ### Known problems
+ /// This lint falsely triggers, if there are arms with
+ /// `cfg` attributes that remove an arm evaluating to `false`.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let x = Some(5);
///
}
declare_clippy_lint! {
- /// **What it does:** Checks for `match` with identical arm bodies.
+ /// ### What it does
+ /// Checks for `match` with identical arm bodies.
///
- /// **Why is this bad?** This is probably a copy & paste error. If arm bodies
+ /// ### Why is this bad?
+ /// This is probably a copy & paste error. If arm bodies
/// are the same on purpose, you can factor them
/// [using `|`](https://doc.rust-lang.org/book/patterns.html#multiple-patterns).
///
- /// **Known problems:** False positive possible with order dependent `match`
+ /// ### Known problems
+ /// False positive possible with order dependent `match`
/// (see issue
/// [#860](https://github.com/rust-lang/rust-clippy/issues/860)).
///
- /// **Example:**
+ /// ### Example
/// ```rust,ignore
/// match foo {
/// Bar => bar(),
#[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,
}
redundant_pattern_match::check(cx, expr);
- if !check_match_like_matches(cx, expr) {
+
+ if meets_msrv(self.msrv.as_ref(), &msrvs::MATCHES_MACRO) {
+ 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 {
+ if let ExprKind::Match(ex, 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);
}
}
if let ExprKind::Match(ref ex, ref arms, _) = expr.kind {
- check_match_ref_pats(cx, ex, arms, expr);
+ check_match_ref_pats(cx, ex, arms.iter().map(|el| el.pat), expr);
+ }
+ if let Some(higher::IfLet { let_pat, let_expr, .. }) = higher::IfLet::hir(expr) {
+ check_match_ref_pats(cx, let_expr, once(let_pat), expr);
}
}
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 let Some(expr) = local.init;
+ if let ExprKind::Match(target, 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;
+ QPath::Resolved(None, variant_name), args, _) = arms[0].pat.kind;
if args.len() == 1;
- if let Some(arg) = get_arg_name(&args[0]);
- let body = remove_blocks(&arms[0].body);
- if match_var(body, arg);
+ 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;
if_chain! {
if !in_external_macro(cx.sess(), pat.span);
if !in_macro(pat.span);
- if let PatKind::Struct(ref qpath, fields, true) = pat.kind;
- if let QPath::Resolved(_, ref path) = qpath;
+ if let PatKind::Struct(QPath::Resolved(_, 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();
}
}
}
+
+ extract_msrv_attr!(LateContext);
}
#[rustfmt::skip]
if stmts.len() == 1 && block_expr.is_none() || stmts.is_empty() && block_expr.is_some() {
// single statement/expr "else" block, don't lint
return;
- } else {
- // block with 2+ statements or 1 expr and 1+ statement
- Some(els)
}
+ // block with 2+ statements or 1 expr and 1+ statement
+ Some(els)
} else {
// not a block, don't lint
- return;
+ return;
};
let ty = cx.typeck_results().expr_ty(ex);
- if *ty.kind() != ty::Bool || is_allowed(cx, MATCH_BOOL, ex.hir_id) {
+ if *ty.kind() != ty::Bool || is_lint_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);
}
expr: &Expr<'_>,
els: Option<&Expr<'_>>,
) {
- if is_wild(&arms[1].pat) {
+ if is_wild(arms[1].pat) {
report_single_match_single_pattern(cx, ex, arms, expr, els);
}
}
let els_str = els.map_or(String::new(), |els| {
format!(" else {}", expr_block(cx, els, None, "..", Some(expr.span)))
});
+
+ let (pat, pat_ref_count) = peel_hir_pat_refs(arms[0].pat);
+ let (msg, sugg) = if_chain! {
+ 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(spe_trait_id) = cx.tcx.lang_items().structural_peq_trait();
+ if let Some(pe_trait_id) = cx.tcx.lang_items().eq_trait();
+ if ty.is_integral() || ty.is_char() || ty.is_str()
+ || (implements_trait(cx, ty, spe_trait_id, &[])
+ && implements_trait(cx, ty, pe_trait_id, &[ty.into()]));
+ 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,
- "you seem to be trying to use match for destructuring a single pattern. Consider using `if \
- let`",
+ msg,
"try this",
- 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,
- ),
+ sugg,
Applicability::HasPlaceholders,
);
}
];
let path = match arms[1].pat.kind {
- PatKind::TupleStruct(ref path, ref inner, _) => {
+ PatKind::TupleStruct(ref path, inner, _) => {
// Contains any non wildcard patterns (e.g., `Err(err)`)?
if !inner.iter().all(is_wild) {
return;
move |diag| {
if arms.len() == 2 {
// no guards
- let exprs = if let PatKind::Lit(ref arm_bool) = arms[0].pat.kind {
+ let exprs = if let PatKind::Lit(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)),
}
}
-fn check_wild_err_arm(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>]) {
+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)) {
+ 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 {
+ if let PatKind::TupleStruct(ref path, 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(.., ident, None) = &pat.kind {
- if ident.as_str().starts_with('_') && is_unused(ident, arm.body) {
+ for pat in inner.iter() {
+ 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 let ExprKind::Block(block, _) = arm.body.kind;
if is_panic_block(block);
then {
// `Err(_)` or `Err(_e)` arm with `panic!` found
}
}
-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;
+enum CommonPrefixSearcher<'a> {
+ None,
+ Path(&'a [PathSegment<'a>]),
+ Mixed,
+}
+impl CommonPrefixSearcher<'a> {
+ fn with_path(&mut self, path: &'a [PathSegment<'a>]) {
+ match path {
+ [path @ .., _] => self.with_prefix(path),
+ [] => (),
+ }
}
+ fn with_prefix(&mut self, path: &'a [PathSegment<'a>]) {
+ match self {
+ Self::None => *self = Self::Path(path),
+ Self::Path(self_path)
+ if path
+ .iter()
+ .map(|p| p.ident.name)
+ .eq(self_path.iter().map(|p| p.ident.name)) => {},
+ Self::Path(_) => *self = Self::Mixed,
+ Self::Mixed => (),
+ }
+ }
+}
+
+fn is_hidden(cx: &LateContext<'_>, variant_def: &VariantDef) -> bool {
+ let attrs = cx.tcx.get_attrs(variant_def.def_id);
+ clippy_utils::attrs::is_doc_hidden(attrs) || clippy_utils::attrs::is_unstable(attrs)
+}
+
+#[allow(clippy::too_many_lines)]
+fn check_wild_enum_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>]) {
+ let ty = cx.typeck_results().expr_ty(ex).peel_refs();
+ let adt_def = match ty.kind() {
+ ty::Adt(adt_def, _)
+ if adt_def.is_enum()
+ && !(is_type_diagnostic_item(cx, ty, sym::option_type)
+ || is_type_diagnostic_item(cx, ty, sym::result_type)) =>
+ {
+ adt_def
+ },
+ _ => 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;
+ let mut has_non_wild = false;
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);
+ match peel_hir_pat_refs(arm.pat).0.kind {
+ PatKind::Wild => wildcard_span = Some(arm.pat.span),
+ PatKind::Binding(_, _, ident, None) => {
+ wildcard_span = Some(arm.pat.span);
+ wildcard_ident = Some(ident);
+ },
+ _ => has_non_wild = true,
}
}
+ let wildcard_span = match wildcard_span {
+ Some(x) if has_non_wild => x,
+ _ => return,
+ };
- 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.
+ // Accumulate the variants which should be put in place of the wildcard because they're not
+ // already covered.
+ let has_hidden = adt_def.variants.iter().any(|x| is_hidden(cx, x));
+ let mut missing_variants: Vec<_> = adt_def.variants.iter().filter(|x| !is_hidden(cx, x)).collect();
- let mut missing_variants = vec![];
- if let ty::Adt(def, _) = ty.kind() {
- for variant in &def.variants {
- missing_variants.push(variant);
+ let mut path_prefix = CommonPrefixSearcher::None;
+ for arm in arms {
+ // 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.
+ recurse_or_patterns(arm.pat, |pat| {
+ let path = match &peel_hir_pat_refs(pat).0.kind {
+ PatKind::Path(path) => {
+ #[allow(clippy::match_same_arms)]
+ let id = match cx.qpath_res(path, pat.hir_id) {
+ Res::Def(DefKind::Const | DefKind::ConstParam | DefKind::AnonConst, _) => return,
+ Res::Def(_, id) => id,
+ _ => return,
+ };
+ if arm.guard.is_none() {
+ missing_variants.retain(|e| e.ctor_def_id != Some(id));
+ }
+ path
+ },
+ PatKind::TupleStruct(path, patterns, ..) => {
+ if let Some(id) = cx.qpath_res(path, pat.hir_id).opt_def_id() {
+ if arm.guard.is_none() && patterns.iter().all(|p| !is_refutable(cx, p)) {
+ missing_variants.retain(|e| e.ctor_def_id != Some(id));
+ }
+ }
+ path
+ },
+ PatKind::Struct(path, patterns, ..) => {
+ if let Some(id) = cx.qpath_res(path, pat.hir_id).opt_def_id() {
+ if arm.guard.is_none() && patterns.iter().all(|p| !is_refutable(cx, p.pat)) {
+ missing_variants.retain(|e| e.def_id != id);
+ }
+ }
+ path
+ },
+ _ => return,
+ };
+ match path {
+ QPath::Resolved(_, path) => path_prefix.with_path(path.segments),
+ QPath::TypeRelative(
+ hir::Ty {
+ kind: TyKind::Path(QPath::Resolved(_, path)),
+ ..
+ },
+ _,
+ ) => path_prefix.with_prefix(path.segments),
+ _ => (),
}
- }
+ });
+ }
- 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(ref path, ref patterns, ..) = arm.pat.kind {
- if let QPath::Resolved(_, p) = path {
- // 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 format_suggestion = |variant: &VariantDef| {
+ format!(
+ "{}{}{}{}",
+ if let Some(ident) = wildcard_ident {
+ format!("{} @ ", ident.name)
+ } else {
+ String::new()
+ },
+ if let CommonPrefixSearcher::Path(path_prefix) = path_prefix {
+ let mut s = String::new();
+ for seg in path_prefix {
+ s.push_str(&seg.ident.as_str());
+ s.push_str("::");
}
+ s
+ } else {
+ let mut s = cx.tcx.def_path_str(adt_def.did);
+ s.push_str("::");
+ s
+ },
+ variant.ident.name,
+ match variant.ctor_kind {
+ CtorKind::Fn if variant.fields.len() == 1 => "(_)",
+ CtorKind::Fn => "(..)",
+ CtorKind::Const => "",
+ CtorKind::Fictive => "{ .. }",
}
- }
-
- 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("_"));
- }
- }
+ match missing_variants.as_slice() {
+ [] => (),
+ [x] if !adt_def.is_variant_list_non_exhaustive() && !has_hidden => span_lint_and_sugg(
+ cx,
+ MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
+ wildcard_span,
+ "wildcard matches only a single variant and will also match any future added variants",
+ "try this",
+ format_suggestion(x),
+ Applicability::MaybeIncorrect,
+ ),
+ variants => {
+ let mut suggestions: Vec<_> = variants.iter().copied().map(format_suggestion).collect();
+ let message = if adt_def.is_variant_list_non_exhaustive() || has_hidden {
+ suggestions.push("_".into());
+ "wildcard matches known variants and will also match future added variants"
+ } else {
+ "wildcard match will also match any future added variants"
+ };
- 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_ENUM_MATCH_ARM,
wildcard_span,
message,
"try this",
- suggestion[0].clone(),
+ suggestions.join(" | "),
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()
- },
+ (&Some(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()
},
}
}
-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
- }
- }));
+fn check_match_ref_pats<'a, 'b, I>(cx: &LateContext<'_>, ex: &Expr<'_>, pats: I, expr: &Expr<'_>)
+where
+ 'b: 'a,
+ I: Clone + Iterator<Item = &'a Pat<'b>>,
+{
+ if !has_only_ref_pats(pats.clone()) {
+ return;
+ }
- span_lint_and_then(cx, MATCH_REF_PATS, expr.span, title, |diag| {
- if !expr.span.from_expansion() {
- multispan_sugg(diag, msg, suggs);
- }
- });
+ let (first_sugg, msg, title);
+ let span = ex.span.source_callsite();
+ if let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, ref inner) = ex.kind {
+ first_sugg = once((span, Sugg::hir_with_macro_callsite(cx, inner, "..").to_string()));
+ msg = "try";
+ title = "you don't need to add `&` to both the expression and the patterns";
+ } else {
+ first_sugg = once((span, Sugg::hir_with_macro_callsite(cx, ex, "..").deref().to_string()));
+ msg = "instead of prefixing all patterns with `&`, you can dereference the expression";
+ title = "you don't need to add `&` to all patterns";
}
+
+ let remaining_suggs = pats.filter_map(|pat| {
+ if let PatKind::Ref(ref refp, _) = pat.kind {
+ Some((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, first_sugg.chain(remaining_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])
+ let arm_ref: Option<BindingAnnotation> = if is_none_arm(cx, &arms[0]) {
+ is_ref_some_arm(cx, &arms[1])
+ } else if is_none_arm(cx, &arms[1]) {
+ is_ref_some_arm(cx, &arms[0])
} else {
None
};
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 {
+ if let PatKind::Or(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.",
+ "wildcard pattern covers any other pattern as it will match anyway",
None,
- "Consider handling `_` separately.",
+ "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
+ if let Some(higher::IfLet {
+ let_pat,
+ let_expr,
+ if_then,
+ if_else: Some(if_else),
+ }) = higher::IfLet::hir(expr)
+ {
+ return find_matches_sugg(
+ cx,
+ let_expr,
+ array::IntoIter::new([(&[][..], Some(let_pat), if_then, None), (&[][..], None, if_else, None)]),
+ expr,
+ true,
+ );
+ }
+
+ if let ExprKind::Match(scrut, arms, MatchSource::Normal) = expr.kind {
+ return find_matches_sugg(
+ cx,
+ scrut,
+ arms.iter().map(|arm| {
+ (
+ cx.tcx.hir().attrs(arm.hir_id),
+ Some(arm.pat),
+ arm.body,
+ arm.guard.as_ref(),
+ )
+ }),
+ expr,
+ false,
+ );
}
+
+ 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 {
+/// Lint a `match` or `if let` for replacement by `matches!`
+fn find_matches_sugg<'a, 'b, I>(
+ cx: &LateContext<'_>,
+ ex: &Expr<'_>,
+ mut iter: I,
+ expr: &Expr<'_>,
+ is_if_let: bool,
+) -> bool
+where
+ 'b: 'a,
+ I: Clone
+ + DoubleEndedIterator
+ + ExactSizeIterator
+ + Iterator<
+ Item = (
+ &'a [Attribute],
+ Option<&'a Pat<'b>>,
+ &'a Expr<'b>,
+ Option<&'a Guard<'b>>,
+ ),
+ >,
+{
if_chain! {
- if arms.len() >= 2;
+ if iter.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 let Some((_, last_pat_opt, last_expr, _)) = iter.next_back();
+ let iter_without_last = iter.clone();
+ if let Some((first_attrs, _, first_expr, first_guard)) = iter.next();
+ if let Some(b0) = find_bool_lit(&first_expr.kind, is_if_let);
+ if let Some(b1) = find_bool_lit(&last_expr.kind, is_if_let);
if b0 != b1;
- let if_guard = &b0_arms[0].guard;
- if if_guard.is_none() || b0_arms.len() == 1;
- if b0_arms[1..].iter()
+ if first_guard.is_none() || iter.len() == 0;
+ if first_attrs.is_empty();
+ if iter
.all(|arm| {
- find_bool_lit(&arm.body.kind, desugared).map_or(false, |b| b == b0) &&
- arm.guard.is_none()
+ find_bool_lit(&arm.2.kind, is_if_let).map_or(false, |b| b == b0) && arm.3.is_none() && arm.0.is_empty()
});
then {
- let mut applicability = Applicability::MachineApplicable;
+ if let Some(ref last_pat) = last_pat_opt {
+ if !is_wild(last_pat) {
+ return false;
+ }
+ }
+
+ // 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))
+ iter_without_last
+ .filter_map(|arm| {
+ let pat_span = arm.1?.span;
+ Some(snippet_with_applicability(cx, pat_span, "..", &mut applicability))
+ })
.join(" | ")
};
- let pat_and_guard = if let Some(Guard::If(g)) = if_guard {
+ let pat_and_guard = if let Some(Guard::If(g)) = first_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" }),
+ &format!("{} expression looks like `matches!` macro", if is_if_let { "if let .. else" } else { "match" }),
"try this",
format!(
"{}matches!({}, {})",
if b0 { "" } else { "!" },
- snippet_with_applicability(cx, ex.span, "..", &mut applicability),
+ snippet_with_applicability(cx, ex_new.span, "..", &mut applicability),
pat_and_guard,
),
applicability,
}
/// Extract a `bool` or `{ bool }`
-fn find_bool_lit(ex: &ExprKind<'_>, desugared: bool) -> Option<bool> {
+fn find_bool_lit(ex: &ExprKind<'_>, is_if_let: bool) -> Option<bool> {
match ex {
ExprKind::Lit(Spanned {
node: LitKind::Bool(b), ..
..
},
_,
- ) if desugared => {
+ ) if is_if_let => {
if let ExprKind::Lit(Spanned {
node: LitKind::Bool(b), ..
}) = exp.kind
}
}
+#[allow(clippy::too_many_lines)]
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 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 {
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() {
+ 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() {
+ if cx.typeck_results().expr_ty(match_body).is_unit() {
snippet_body.push(';');
}
},
indent = " ".repeat(indent_of(cx, bind_names).unwrap_or(0));
cbrace_start = format!("{{\n{}", indent);
}
- };
+ }
+ // If the parent is already an arm, and the body is another match statement,
+ // we need curly braces around suggestion
+ let parent_node_id = cx.tcx.hir().get_parent_node(expr.hir_id);
+ if let Node::Arm(arm) = &cx.tcx.hir().get(parent_node_id) {
+ if let ExprKind::Match(..) = arm.body.kind {
+ cbrace_end = format!("\n{}}}", indent);
+ // Fix body indent due to the match
+ indent = " ".repeat(indent_of(cx, bind_names).unwrap_or(0));
+ cbrace_start = format!("{{\n{}", indent);
+ }
+ }
(
expr.span,
format!(
);
},
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,
- );
+ if ex.can_have_side_effects() {
+ let indent = " ".repeat(indent_of(cx, expr.span).unwrap_or(0));
+ let sugg = format!(
+ "{};\n{}{}",
+ snippet_with_applicability(cx, ex.span, "..", &mut applicability),
+ indent,
+ snippet_body
+ );
+ span_lint_and_sugg(
+ cx,
+ MATCH_SINGLE_BINDING,
+ expr.span,
+ "this match could be replaced by its scrutinee and body",
+ "consider using the scrutinee and body instead",
+ sugg,
+ applicability,
+ );
+ } else {
+ 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>> {
+ let map = &cx.tcx.hir();
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 {
/// 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
- {
+ .filter_map(|arm| {
+ if let Arm { 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,
});
}
- if let PatKind::Lit(ref value) = pat.kind {
+ if let PatKind::Lit(value) = pat.kind {
let value = constant(cx, cx.typeck_results(), value)?.0;
return Some(SpannedRange {
span: pat.span,
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,
+ ExprKind::Tup(v) if v.is_empty() => true,
+ ExprKind::Block(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))
+fn is_none_arm(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
+ matches!(arm.pat.kind, PatKind::Path(ref qpath) if is_lang_ctor(cx, qpath, OptionNone))
}
// 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> {
+fn is_ref_some_arm(cx: &LateContext<'_>, 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 let PatKind::TupleStruct(ref qpath, [first_pat, ..], _) = arm.pat.kind;
+ if is_lang_ctor(cx, qpath, OptionSome);
+ if let PatKind::Binding(rb, .., ident, _) = first_pat.kind;
if rb == BindingAnnotation::Ref || rb == BindingAnnotation::RefMut;
- if let ExprKind::Call(ref e, ref args) = remove_blocks(&arm.body).kind;
+ if let ExprKind::Call(e, 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(ref qpath) = args[0].kind;
- if let &QPath::Resolved(_, ref path2) = qpath;
+ if is_lang_ctor(cx, some_path, OptionSome) && args.len() == 1;
+ if let ExprKind::Path(QPath::Resolved(_, 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
+fn has_only_ref_pats<'a, 'b, I>(pats: I) -> bool
+where
+ 'b: 'a,
+ I: Iterator<Item = &'a Pat<'b>>,
+{
+ let mut at_least_one_is_true = false;
+ for opt in pats.map(|pat| match pat.kind {
+ PatKind::Ref(..) => Some(true), // &-patterns
+ PatKind::Wild => Some(false), // an "anything" wildcard is also fine
+ _ => None, // any other pattern is not fine
+ }) {
+ if let Some(inner) = opt {
+ if inner {
+ at_least_one_is_true = true;
}
- })
- .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))
+ } else {
+ return false;
+ }
+ }
+ at_least_one_is_true
}
pub fn overlapping<T>(ranges: &[SpannedRange<T>]) -> Option<(&SpannedRange<T>, &SpannedRange<T>)>
values.sort();
- for (a, b) in values.iter().zip(values.iter().skip(1)) {
+ for (a, b) in iter::zip(&values, values.iter().skip(1)) {
match (a, b) {
(&Kind::Start(_, ra), &Kind::End(_, rb)) => {
if ra.node != rb.node {
}
},
(&Kind::End(a, _), &Kind::Start(b, _)) if a != Bound::Included(b) => (),
- _ => return Some((a.range(), b.range())),
+ _ => {
+ // 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()));
+ },
}
}
mod redundant_pattern_match {
use super::REDUNDANT_PATTERN_MATCHING;
- use crate::utils::{match_qpath, match_trait_method, paths, snippet, span_lint_and_then};
+ use clippy_utils::diagnostics::span_lint_and_then;
+ use clippy_utils::higher;
+ use clippy_utils::source::{snippet, snippet_with_applicability};
+ use clippy_utils::ty::{implements_trait, is_type_diagnostic_item, is_type_lang_item, match_type};
+ use clippy_utils::{is_lang_ctor, is_qpath_def_path, is_trait_method, paths};
use if_chain::if_chain;
use rustc_ast::ast::LitKind;
+ use rustc_data_structures::fx::FxHashSet;
use rustc_errors::Applicability;
- use rustc_hir::{Arm, Expr, ExprKind, MatchSource, PatKind, QPath};
+ use rustc_hir::LangItem::{OptionNone, OptionSome, PollPending, PollReady, ResultErr, ResultOk};
+ use rustc_hir::{
+ intravisit::{walk_expr, ErasedMap, NestedVisitorMap, Visitor},
+ Arm, Block, Expr, ExprKind, LangItem, MatchSource, Node, Pat, PatKind, QPath,
+ };
use rustc_lint::LateContext;
+ use rustc_middle::ty::{self, subst::GenericArgKind, Ty};
+ 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"),
- _ => {},
+ if let Some(higher::IfLet {
+ if_else,
+ let_pat,
+ let_expr,
+ ..
+ }) = higher::IfLet::ast(cx, expr)
+ {
+ find_sugg_for_if_let(cx, expr, let_pat, let_expr, "if", if_else.is_some())
+ }
+ if let ExprKind::Match(op, arms, MatchSource::Normal) = &expr.kind {
+ find_sugg_for_match(cx, expr, op, arms)
+ }
+ if let Some(higher::WhileLet { let_pat, let_expr, .. }) = higher::WhileLet::hir(expr) {
+ find_sugg_for_if_let(cx, expr, let_pat, let_expr, "while", false)
+ }
+ }
+
+ /// Checks if the drop order for a type matters. Some std types implement drop solely to
+ /// deallocate memory. For these types, and composites containing them, changing the drop order
+ /// won't result in any observable side effects.
+ fn type_needs_ordered_drop(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
+ type_needs_ordered_drop_inner(cx, ty, &mut FxHashSet::default())
+ }
+
+ fn type_needs_ordered_drop_inner(cx: &LateContext<'tcx>, ty: Ty<'tcx>, seen: &mut FxHashSet<Ty<'tcx>>) -> bool {
+ if !seen.insert(ty) {
+ return false;
+ }
+ if !ty.needs_drop(cx.tcx, cx.param_env) {
+ false
+ } else if !cx
+ .tcx
+ .lang_items()
+ .drop_trait()
+ .map_or(false, |id| implements_trait(cx, ty, id, &[]))
+ {
+ // This type doesn't implement drop, so no side effects here.
+ // Check if any component type has any.
+ match ty.kind() {
+ ty::Tuple(_) => ty.tuple_fields().any(|ty| type_needs_ordered_drop_inner(cx, ty, seen)),
+ ty::Array(ty, _) => type_needs_ordered_drop_inner(cx, ty, seen),
+ ty::Adt(adt, subs) => adt
+ .all_fields()
+ .map(|f| f.ty(cx.tcx, subs))
+ .any(|ty| type_needs_ordered_drop_inner(cx, ty, seen)),
+ _ => true,
+ }
+ }
+ // Check for std types which implement drop, but only for memory allocation.
+ else if is_type_diagnostic_item(cx, ty, sym::vec_type)
+ || is_type_lang_item(cx, ty, LangItem::OwnedBox)
+ || is_type_diagnostic_item(cx, ty, sym::Rc)
+ || is_type_diagnostic_item(cx, ty, sym::Arc)
+ || is_type_diagnostic_item(cx, ty, sym::cstring_type)
+ || is_type_diagnostic_item(cx, ty, sym::BTreeMap)
+ || is_type_diagnostic_item(cx, ty, sym::LinkedList)
+ || match_type(cx, ty, &paths::WEAK_RC)
+ || match_type(cx, ty, &paths::WEAK_ARC)
+ {
+ // Check all of the generic arguments.
+ if let ty::Adt(_, subs) = ty.kind() {
+ subs.types().any(|ty| type_needs_ordered_drop_inner(cx, ty, seen))
+ } else {
+ true
+ }
+ } else {
+ true
+ }
+ }
+
+ // Extract the generic arguments out of a type
+ fn try_get_generic_ty(ty: Ty<'_>, index: usize) -> Option<Ty<'_>> {
+ if_chain! {
+ if let ty::Adt(_, subs) = ty.kind();
+ if let Some(sub) = subs.get(index);
+ if let GenericArgKind::Type(sub_ty) = sub.unpack();
+ then {
+ Some(sub_ty)
+ } else {
+ None
+ }
+ }
+ }
+
+ // Checks if there are any temporaries created in the given expression for which drop order
+ // matters.
+ fn temporaries_need_ordered_drop(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> bool {
+ struct V<'a, 'tcx> {
+ cx: &'a LateContext<'tcx>,
+ res: bool,
+ }
+ impl<'a, 'tcx> Visitor<'tcx> for V<'a, 'tcx> {
+ type Map = ErasedMap<'tcx>;
+ fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
+ NestedVisitorMap::None
+ }
+
+ fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
+ match expr.kind {
+ // Taking the reference of a value leaves a temporary
+ // e.g. In `&String::new()` the string is a temporary value.
+ // Remaining fields are temporary values
+ // e.g. In `(String::new(), 0).1` the string is a temporary value.
+ ExprKind::AddrOf(_, _, expr) | ExprKind::Field(expr, _) => {
+ if !matches!(expr.kind, ExprKind::Path(_)) {
+ if type_needs_ordered_drop(self.cx, self.cx.typeck_results().expr_ty(expr)) {
+ self.res = true;
+ } else {
+ self.visit_expr(expr);
+ }
+ }
+ },
+ // the base type is alway taken by reference.
+ // e.g. In `(vec![0])[0]` the vector is a temporary value.
+ ExprKind::Index(base, index) => {
+ if !matches!(base.kind, ExprKind::Path(_)) {
+ if type_needs_ordered_drop(self.cx, self.cx.typeck_results().expr_ty(base)) {
+ self.res = true;
+ } else {
+ self.visit_expr(base);
+ }
+ }
+ self.visit_expr(index);
+ },
+ // Method calls can take self by reference.
+ // e.g. In `String::new().len()` the string is a temporary value.
+ ExprKind::MethodCall(_, _, [self_arg, args @ ..], _) => {
+ if !matches!(self_arg.kind, ExprKind::Path(_)) {
+ let self_by_ref = self
+ .cx
+ .typeck_results()
+ .type_dependent_def_id(expr.hir_id)
+ .map_or(false, |id| self.cx.tcx.fn_sig(id).skip_binder().inputs()[0].is_ref());
+ if self_by_ref
+ && type_needs_ordered_drop(self.cx, self.cx.typeck_results().expr_ty(self_arg))
+ {
+ self.res = true;
+ } else {
+ self.visit_expr(self_arg);
+ }
+ }
+ args.iter().for_each(|arg| self.visit_expr(arg));
+ },
+ // Either explicitly drops values, or changes control flow.
+ ExprKind::DropTemps(_)
+ | ExprKind::Ret(_)
+ | ExprKind::Break(..)
+ | ExprKind::Yield(..)
+ | ExprKind::Block(Block { expr: None, .. }, _)
+ | ExprKind::Loop(..) => (),
+
+ // Only consider the final expression.
+ ExprKind::Block(Block { expr: Some(expr), .. }, _) => self.visit_expr(expr),
+
+ _ => walk_expr(self, expr),
+ }
}
}
+
+ let mut v = V { cx, res: false };
+ v.visit_expr(expr);
+ v.res
}
fn find_sugg_for_if_let<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx Expr<'_>,
- op: &Expr<'_>,
- arms: &[Arm<'_>],
+ let_pat: &Pat<'_>,
+ let_expr: &'tcx Expr<'_>,
keyword: &'static str,
+ has_else: bool,
) {
- 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()"
+ // also look inside refs
+ let mut kind = &let_pat.kind;
+ // if we have &None for example, peel it so we can detect "if let None = x"
+ if let PatKind::Ref(inner, _mutability) = kind {
+ kind = &inner.kind;
+ }
+ let op_ty = cx.typeck_results().expr_ty(let_expr);
+ // Determine which function should be used, and the type contained by the corresponding
+ // variant.
+ let (good_method, inner_ty) = match kind {
+ PatKind::TupleStruct(ref path, [sub_pat], _) => {
+ if let PatKind::Wild = sub_pat.kind {
+ if is_lang_ctor(cx, path, ResultOk) {
+ ("is_ok()", try_get_generic_ty(op_ty, 0).unwrap_or(op_ty))
+ } else if is_lang_ctor(cx, path, ResultErr) {
+ ("is_err()", try_get_generic_ty(op_ty, 1).unwrap_or(op_ty))
+ } else if is_lang_ctor(cx, path, OptionSome) {
+ ("is_some()", op_ty)
+ } else if is_lang_ctor(cx, path, PollReady) {
+ ("is_ready()", op_ty)
+ } else if is_qpath_def_path(cx, path, sub_pat.hir_id, &paths::IPADDR_V4) {
+ ("is_ipv4()", op_ty)
+ } else if is_qpath_def_path(cx, path, sub_pat.hir_id, &paths::IPADDR_V6) {
+ ("is_ipv6()", op_ty)
} else {
return;
}
return;
}
},
- PatKind::Path(ref path) if match_qpath(path, &paths::OPTION_NONE) => "is_none()",
+ PatKind::Path(ref path) => {
+ let method = if is_lang_ctor(cx, path, OptionNone) {
+ "is_none()"
+ } else if is_lang_ctor(cx, path, PollPending) {
+ "is_pending()"
+ } else {
+ return;
+ };
+ // `None` and `Pending` don't have an inner type.
+ (method, cx.tcx.types.unit)
+ },
_ => return,
};
+ // If this is the last expression in a block or there is an else clause then the whole
+ // type needs to be considered, not just the inner type of the branch being matched on.
+ // Note the last expression in a block is dropped after all local bindings.
+ let check_ty = if has_else
+ || (keyword == "if" && matches!(cx.tcx.hir().parent_iter(expr.hir_id).next(), Some((_, Node::Block(..)))))
+ {
+ op_ty
+ } else {
+ inner_ty
+ };
+
+ // All temporaries created in the scrutinee expression are dropped at the same time as the
+ // scrutinee would be, so they have to be considered as well.
+ // e.g. in `if let Some(x) = foo.lock().unwrap().baz.as_ref() { .. }` the lock will be held
+ // for the duration if body.
+ let needs_drop = type_needs_ordered_drop(cx, check_ty) || temporaries_need_ordered_drop(cx, let_expr);
+
// 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);
+ if let ExprKind::MethodCall(method_path, _, _, _) = let_expr.kind;
+ if method_path.ident.name == sym::next;
+ if is_trait_method(cx, let_expr, sym::Iterator);
then {
return;
}
}
- let result_expr = match &op.kind {
+ let result_expr = match &let_expr.kind {
ExprKind::AddrOf(_, _, borrowed) => borrowed,
- _ => op,
+ _ => let_expr,
};
span_lint_and_then(
cx,
REDUNDANT_PATTERN_MATCHING,
- arms[0].pat.span,
+ let_pat.span,
&format!("redundant pattern matching, consider using `{}`", good_method),
|diag| {
- // while let ... = ... { ... }
+ // if/while let ... = ... { ... }
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^
let expr_span = expr.span;
- // while let ... = ... { ... }
+ // if/while let ... = ... { ... }
// ^^^
let op_span = result_expr.span.source_callsite();
- // while let ... = ... { ... }
+ // if/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
- );
+
+ let mut app = if needs_drop {
+ Applicability::MaybeIncorrect
+ } else {
+ Applicability::MachineApplicable
+ };
+ let sugg = snippet_with_applicability(cx, op_span, "_", &mut app);
+
+ diag.span_suggestion(span, "try this", format!("{} {}.{}", keyword, sugg, good_method), app);
+
+ if needs_drop {
+ diag.note("this will change drop order of the result, as well as all temporaries");
+ diag.note("add `#[allow(clippy::redundant_pattern_matching)]` if this is important");
+ }
},
);
}
let found_good_method = match node_pair {
(
- PatKind::TupleStruct(ref path_left, ref patterns_left, _),
- PatKind::TupleStruct(ref path_right, ref patterns_right, _),
+ PatKind::TupleStruct(ref path_left, patterns_left, _),
+ PatKind::TupleStruct(ref path_right, 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(
+ cx,
arms,
path_left,
path_right,
"is_ok()",
"is_err()",
)
+ .or_else(|| {
+ find_good_method_for_match(
+ cx,
+ 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, _))
+ (PatKind::TupleStruct(ref path_left, patterns, _), PatKind::Path(ref path_right))
+ | (PatKind::Path(ref path_left), PatKind::TupleStruct(ref path_right, patterns, _))
if patterns.len() == 1 =>
{
if let PatKind::Wild = patterns[0].kind {
find_good_method_for_match(
+ cx,
arms,
path_left,
path_right,
"is_some()",
"is_none()",
)
+ .or_else(|| {
+ find_good_method_for_match(
+ cx,
+ arms,
+ path_left,
+ path_right,
+ &paths::POLL_READY,
+ &paths::POLL_PENDING,
+ "is_ready()",
+ "is_pending()",
+ )
+ })
} else {
None
}
}
}
+ #[allow(clippy::too_many_arguments)]
fn find_good_method_for_match<'a>(
+ cx: &LateContext<'_>,
arms: &[Arm<'_>],
path_left: &QPath<'_>,
path_right: &QPath<'_>,
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) {
+ let body_node_pair = if is_qpath_def_path(cx, path_left, arms[0].pat.hir_id, expected_left)
+ && is_qpath_def_path(cx, path_right, arms[1].pat.hir_id, expected_right)
+ {
(&(*arms[0].body).kind, &(*arms[1].body).kind)
- } else if match_qpath(path_right, expected_left) && match_qpath(path_left, expected_right) {
+ } else if is_qpath_def_path(cx, path_right, arms[1].pat.hir_id, expected_left)
+ && is_qpath_def_path(cx, path_left, arms[0].pat.hir_id, expected_right)
+ {
(&(*arms[1].body).kind, &(*arms[0].body).kind)
} else {
return None;
/// Implementation of `MATCH_SAME_ARMS`.
fn lint_match_arms<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) {
- fn same_bindings<'tcx>(lhs: &FxHashMap<Symbol, Ty<'tcx>>, rhs: &FxHashMap<Symbol, Ty<'tcx>>) -> bool {
- lhs.len() == rhs.len()
- && lhs
- .iter()
- .all(|(name, l_ty)| rhs.get(name).map_or(false, |r_ty| TyS::same_type(l_ty, r_ty)))
- }
-
- if let ExprKind::Match(_, ref arms, MatchSource::Normal) = expr.kind {
+ if let ExprKind::Match(_, arms, MatchSource::Normal) = expr.kind {
let hash = |&(_, arm): &(usize, &Arm<'_>)| -> u64 {
let mut h = SpanlessHash::new(cx);
- h.hash_expr(&arm.body);
+ h.hash_expr(arm.body);
h.finish()
};
let min_index = usize::min(lindex, rindex);
let max_index = usize::max(lindex, rindex);
+ let mut local_map: HirIdMap<HirId> = HirIdMap::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).eq_expr(&lhs.body, &rhs.body) &&
- // all patterns should have the same bindings
- same_bindings(&bindings(cx, &lhs.pat), &bindings(cx, &rhs.pat))
+ (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();
),
);
} else {
- diag.span_help(i.pat.span, &format!("consider refactoring into `{} | {}`", lhs, rhs));
+ diag.span_help(i.pat.span, &format!("consider refactoring into `{} | {}`", lhs, rhs,))
+ .help("...or consider changing the match arm bodies");
}
},
);
}
}
-/// Returns the list of bindings in a pattern.
-fn bindings<'tcx>(cx: &LateContext<'tcx>, pat: &Pat<'_>) -> FxHashMap<Symbol, Ty<'tcx>> {
- fn bindings_impl<'tcx>(cx: &LateContext<'tcx>, pat: &Pat<'_>, map: &mut FxHashMap<Symbol, Ty<'tcx>>) {
- match pat.kind {
- PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => bindings_impl(cx, pat, map),
- PatKind::TupleStruct(_, pats, _) => {
- for pat in pats {
- bindings_impl(cx, pat, map);
- }
- },
- PatKind::Binding(.., ident, ref as_pat) => {
- if let Entry::Vacant(v) = map.entry(ident.name) {
- v.insert(cx.typeck_results().pat_ty(pat));
- }
- if let Some(ref as_pat) = *as_pat {
- bindings_impl(cx, as_pat, map);
- }
- },
- PatKind::Or(fields) | PatKind::Tuple(fields, _) => {
- for pat in fields {
- bindings_impl(cx, pat, map);
- }
- },
- PatKind::Struct(_, fields, _) => {
- for pat in fields {
- bindings_impl(cx, &pat.pat, map);
- }
- },
- PatKind::Slice(lhs, ref mid, rhs) => {
- for pat in lhs {
- bindings_impl(cx, pat, map);
- }
- if let Some(ref mid) = *mid {
- bindings_impl(cx, mid, map);
- }
- for pat in rhs {
- bindings_impl(cx, pat, map);
- }
- },
- PatKind::Lit(..) | PatKind::Range(..) | PatKind::Wild | PatKind::Path(..) => (),
- }
- }
-
- let mut result = FxHashMap::default();
- bindings_impl(cx, pat, &mut result);
+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: HirIdSet) -> bool {
+ let mut result = true;
+ pat.each_binding_or_first(&mut |_, id, _, _| result &= ids.remove(&id));
+ result && ids.is_empty()
+}
projects / rust.git / blobdiff