use crate::consts::{constant, miri_to_const, Constant};
-use crate::utils::paths;
-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, walk_ptrs_ty,
+use clippy_utils::diagnostics::{
+ multispan_sugg, span_lint_and_help, span_lint_and_note, span_lint_and_sugg, span_lint_and_then,
};
+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_allowed, is_expn_of, is_refutable, is_wild, match_qpath, meets_msrv, 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 if_chain::if_chain;
use rustc_ast::ast::LitKind;
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_errors::Applicability;
-use rustc_hir::def::CtorKind;
+use rustc_hir::def::{CtorKind, DefKind, Res};
use rustc_hir::{
- Arm, BindingAnnotation, Block, BorrowKind, Expr, ExprKind, 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_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::lint::in_external_macro;
-use rustc_middle::ty::{self, Ty};
+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;
+use rustc_span::source_map::{Span, Spanned};
+use rustc_span::sym;
use std::cmp::Ordering;
-use std::collections::Bound;
+use std::collections::hash_map::Entry;
+use std::iter;
+use std::ops::Bound;
declare_clippy_lint! {
/// **What it does:** Checks for matches with a single arm where an `if let`
/// ```rust
/// # fn bar(stool: &str) {}
/// # let x = Some("abc");
+ /// // Bad
/// match x {
/// Some(ref foo) => bar(foo),
/// _ => (),
/// }
+ ///
+ /// // Good
+ /// if let Some(ref foo) = x {
+ /// bar(foo);
+ /// }
/// ```
pub SINGLE_MATCH,
style,
///
/// **Example:**
/// ```rust,ignore
+ /// // Bad
/// match x {
/// &A(ref y) => foo(y),
/// &B => bar(),
/// _ => frob(&x),
/// }
+ ///
+ /// // Good
+ /// match *x {
+ /// A(ref y) => foo(y),
+ /// B => bar(),
+ /// _ => frob(x),
+ /// }
/// ```
pub MATCH_REF_PATS,
style,
/// **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, just like
+ /// **Why is this bad?** It is generally a bad practice, similar to
/// catching all exceptions in java with `catch(Exception)`
///
/// **Known problems:** None.
/// }
/// ```
pub MATCH_WILD_ERR_ARM,
- style,
+ pedantic,
"a `match` with `Err(_)` arm and take drastic actions"
}
/// **Example:**
/// ```rust
/// let x: Option<()> = None;
+ ///
+ /// // Bad
/// let r: Option<&()> = match x {
/// None => None,
/// Some(ref v) => Some(v),
/// };
+ ///
+ /// // Good
+ /// let r: Option<&()> = x.as_ref();
/// ```
pub MATCH_AS_REF,
complexity,
/// ```rust
/// # enum Foo { A(usize), B(usize) }
/// # let x = Foo::B(1);
+ /// // Bad
/// match x {
- /// A => {},
+ /// Foo::A(_) => {},
/// _ => {},
/// }
+ ///
+ /// // Good
+ /// match x {
+ /// Foo::A(_) => {},
+ /// Foo::B(_) => {},
+ /// }
/// ```
pub WILDCARD_ENUM_MATCH_ARM,
restriction,
"a wildcard enum match arm using `_`"
}
+declare_clippy_lint! {
+ /// **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.
+ ///
+ /// **Known problems:** Suggested replacements may not use correct path to enum
+ /// if it's not present in the current scope.
+ ///
+ /// **Example:**
+ ///
+ /// ```rust
+ /// # enum Foo { A, B, C }
+ /// # let x = Foo::B;
+ /// // Bad
+ /// match x {
+ /// Foo::A => {},
+ /// Foo::B => {},
+ /// _ => {},
+ /// }
+ ///
+ /// // Good
+ /// match x {
+ /// Foo::A => {},
+ /// Foo::B => {},
+ /// Foo::C => {},
+ /// }
+ /// ```
+ pub MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
+ pedantic,
+ "a wildcard enum match for a single variant"
+}
+
declare_clippy_lint! {
/// **What it does:** Checks for wildcard pattern used with others patterns in same match arm.
///
///
/// **Example:**
/// ```rust
+ /// // Bad
/// match "foo" {
/// "a" => {},
/// "bar" | _ => {},
/// }
+ ///
+ /// // Good
+ /// match "foo" {
+ /// "a" => {},
+ /// _ => {},
+ /// }
/// ```
pub WILDCARD_IN_OR_PATTERNS,
complexity,
"a match on a struct that binds all fields but still uses the wildcard pattern"
}
+declare_clippy_lint! {
+ /// **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
+ /// utility function
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **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,
+ style,
+ "use the proper utility function avoiding an `if let`"
+}
+
+declare_clippy_lint! {
+ /// **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.
+ ///
+ /// **Known problems:** This lint falsely triggers, if there are arms with
+ /// `cfg` attributes that remove an arm evaluating to `false`.
+ ///
+ /// **Example:**
+ /// ```rust
+ /// let x = Some(5);
+ ///
+ /// // Bad
+ /// let a = match x {
+ /// Some(0) => true,
+ /// _ => false,
+ /// };
+ ///
+ /// let a = if let Some(0) = x {
+ /// true
+ /// } else {
+ /// false
+ /// };
+ ///
+ /// // Good
+ /// let a = matches!(x, Some(0));
+ /// ```
+ pub MATCH_LIKE_MATCHES_MACRO,
+ style,
+ "a match that could be written with the matches! macro"
+}
+
+declare_clippy_lint! {
+ /// **What it does:** Checks for `match` with identical 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`
+ /// (see issue
+ /// [#860](https://github.com/rust-lang/rust-clippy/issues/860)).
+ ///
+ /// **Example:**
+ /// ```rust,ignore
+ /// match foo {
+ /// Bar => bar(),
+ /// Quz => quz(),
+ /// Baz => bar(), // <= oops
+ /// }
+ /// ```
+ ///
+ /// This should probably be
+ /// ```rust,ignore
+ /// match foo {
+ /// Bar => bar(),
+ /// Quz => quz(),
+ /// Baz => baz(), // <= fixed
+ /// }
+ /// ```
+ ///
+ /// or if the original code was not a typo:
+ /// ```rust,ignore
+ /// match foo {
+ /// Bar | Baz => bar(), // <= shows the intent better
+ /// Quz => quz(),
+ /// }
+ /// ```
+ pub MATCH_SAME_ARMS,
+ pedantic,
+ "`match` with identical arm bodies"
+}
+
#[derive(Default)]
pub struct Matches {
+ msrv: Option<RustcVersion>,
infallible_destructuring_match_linted: bool,
}
+impl Matches {
+ #[must_use]
+ pub fn new(msrv: Option<RustcVersion>) -> Self {
+ Self {
+ msrv,
+ ..Matches::default()
+ }
+ }
+}
+
impl_lint_pass!(Matches => [
SINGLE_MATCH,
MATCH_REF_PATS,
MATCH_WILD_ERR_ARM,
MATCH_AS_REF,
WILDCARD_ENUM_MATCH_ARM,
+ MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
WILDCARD_IN_OR_PATTERNS,
MATCH_SINGLE_BINDING,
INFALLIBLE_DESTRUCTURING_MATCH,
- REST_PAT_IN_FULLY_BOUND_STRUCTS
+ REST_PAT_IN_FULLY_BOUND_STRUCTS,
+ REDUNDANT_PATTERN_MATCHING,
+ MATCH_LIKE_MATCHES_MACRO,
+ MATCH_SAME_ARMS,
]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Matches {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
- if in_external_macro(cx.sess(), expr.span) {
+const MATCH_LIKE_MATCHES_MACRO_MSRV: RustcVersion = RustcVersion::new(1, 42, 0);
+
+impl<'tcx> LateLintPass<'tcx> for Matches {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+ if in_external_macro(cx.sess(), expr.span) || in_macro(expr.span) {
return;
}
+
+ redundant_pattern_match::check(cx, expr);
+
+ if meets_msrv(self.msrv.as_ref(), &MATCH_LIKE_MATCHES_MACRO_MSRV) {
+ if !check_match_like_matches(cx, expr) {
+ lint_match_arms(cx, expr);
+ }
+ } else {
+ lint_match_arms(cx, expr);
+ }
+
if let ExprKind::Match(ref ex, ref arms, MatchSource::Normal) = expr.kind {
check_single_match(cx, ex, arms, expr);
check_match_bool(cx, ex, arms, expr);
}
}
- fn check_local(&mut self, cx: &LateContext<'a, 'tcx>, local: &'tcx Local<'_>) {
+ fn check_local(&mut self, cx: &LateContext<'tcx>, local: &'tcx Local<'_>) {
if_chain! {
if !in_external_macro(cx.sess(), local.span);
if !in_macro(local.span);
if let PatKind::TupleStruct(
QPath::Resolved(None, ref variant_name), ref args, _) = arms[0].pat.kind;
if args.len() == 1;
- if let Some(arg) = get_arg_name(&args[0]);
+ if let PatKind::Binding(_, arg, ..) = strip_pat_refs(&args[0]).kind;
let body = remove_blocks(&arms[0].body);
- if match_var(body, arg);
+ if path_to_local_id(body, arg);
then {
let mut applicability = Applicability::MachineApplicable;
}
}
- fn check_pat(&mut self, cx: &LateContext<'a, 'tcx>, pat: &'tcx Pat<'_>) {
+ fn check_pat(&mut self, cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>) {
if_chain! {
if !in_external_macro(cx.sess(), pat.span);
if !in_macro(pat.span);
- if let PatKind::Struct(ref qpath, fields, true) = pat.kind;
- if let QPath::Resolved(_, ref path) = qpath;
+ if let PatKind::Struct(QPath::Resolved(_, ref path), fields, true) = pat.kind;
if let Some(def_id) = path.res.opt_def_id();
let ty = cx.tcx.type_of(def_id);
- if let ty::Adt(def, _) = ty.kind;
+ if let ty::Adt(def, _) = ty.kind();
if def.is_struct() || def.is_union();
if fields.len() == def.non_enum_variant().fields.len();
}
}
}
+
+ extract_msrv_attr!(LateContext);
}
#[rustfmt::skip]
-fn check_single_match(cx: &LateContext<'_, '_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
+fn check_single_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
if arms.len() == 2 && arms[0].guard.is_none() && arms[1].guard.is_none() {
if in_macro(expr.span) {
// Don't lint match expressions present in
// the lint noisy in unnecessary situations
return;
}
- let els = remove_blocks(&arms[1].body);
- let els = if is_unit_expr(els) {
+ let els = arms[1].body;
+ let els = if is_unit_expr(remove_blocks(els)) {
None
- } else if let ExprKind::Block(_, _) = els.kind {
- // matches with blocks that contain statements are prettier as `if let + else`
+ } else if let ExprKind::Block(Block { stmts, expr: block_expr, .. }, _) = els.kind {
+ if stmts.len() == 1 && block_expr.is_none() || stmts.is_empty() && block_expr.is_some() {
+ // single statement/expr "else" block, don't lint
+ return;
+ }
+ // block with 2+ statements or 1 expr and 1+ statement
Some(els)
} else {
- // allow match arms with just expressions
+ // not a block, don't lint
return;
};
- let ty = cx.tables.expr_ty(ex);
- if ty.kind != ty::Bool || is_allowed(cx, MATCH_BOOL, ex.hir_id) {
+
+ let ty = cx.typeck_results().expr_ty(ex);
+ if *ty.kind() != ty::Bool || is_allowed(cx, MATCH_BOOL, ex.hir_id) {
check_single_match_single_pattern(cx, ex, arms, expr, els);
check_single_match_opt_like(cx, ex, arms, expr, ty, els);
}
}
fn check_single_match_single_pattern(
- cx: &LateContext<'_, '_>,
+ cx: &LateContext<'_>,
ex: &Expr<'_>,
arms: &[Arm<'_>],
expr: &Expr<'_>,
}
fn report_single_match_single_pattern(
- cx: &LateContext<'_, '_>,
+ cx: &LateContext<'_>,
ex: &Expr<'_>,
arms: &[Arm<'_>],
expr: &Expr<'_>,
let els_str = els.map_or(String::new(), |els| {
format!(" else {}", expr_block(cx, els, None, "..", Some(expr.span)))
});
+
+ let (msg, sugg) = if_chain! {
+ let (pat, pat_ref_count) = peel_hir_pat_refs(arms[0].pat);
+ if let PatKind::Path(_) | PatKind::Lit(_) = pat.kind;
+ let (ty, ty_ref_count) = peel_mid_ty_refs(cx.typeck_results().expr_ty(ex));
+ if let Some(trait_id) = cx.tcx.lang_items().structural_peq_trait();
+ if ty.is_integral() || ty.is_char() || ty.is_str() || implements_trait(cx, ty, trait_id, &[]);
+ then {
+ // scrutinee derives PartialEq and the pattern is a constant.
+ let pat_ref_count = match pat.kind {
+ // string literals are already a reference.
+ PatKind::Lit(Expr { kind: ExprKind::Lit(lit), .. }) if lit.node.is_str() => pat_ref_count + 1,
+ _ => pat_ref_count,
+ };
+ // References are only implicitly added to the pattern, so no overflow here.
+ // e.g. will work: match &Some(_) { Some(_) => () }
+ // will not: match Some(_) { &Some(_) => () }
+ let ref_count_diff = ty_ref_count - pat_ref_count;
+
+ // Try to remove address of expressions first.
+ let (ex, removed) = peel_n_hir_expr_refs(ex, ref_count_diff);
+ let ref_count_diff = ref_count_diff - removed;
+
+ let msg = "you seem to be trying to use `match` for an equality check. Consider using `if`";
+ let sugg = format!(
+ "if {} == {}{} {}{}",
+ snippet(cx, ex.span, ".."),
+ // PartialEq for different reference counts may not exist.
+ "&".repeat(ref_count_diff),
+ snippet(cx, arms[0].pat.span, ".."),
+ expr_block(cx, &arms[0].body, None, "..", Some(expr.span)),
+ els_str,
+ );
+ (msg, sugg)
+ } else {
+ let msg = "you seem to be trying to use `match` for destructuring a single pattern. Consider using `if let`";
+ let sugg = format!(
+ "if let {} = {} {}{}",
+ snippet(cx, arms[0].pat.span, ".."),
+ snippet(cx, ex.span, ".."),
+ expr_block(cx, &arms[0].body, None, "..", Some(expr.span)),
+ els_str,
+ );
+ (msg, sugg)
+ }
+ };
+
span_lint_and_sugg(
cx,
lint,
expr.span,
- "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,
);
}
fn check_single_match_opt_like(
- cx: &LateContext<'_, '_>,
+ cx: &LateContext<'_>,
ex: &Expr<'_>,
arms: &[Arm<'_>],
expr: &Expr<'_>,
}
}
-fn check_match_bool(cx: &LateContext<'_, '_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
+fn check_match_bool(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
// Type of expression is `bool`.
- if cx.tables.expr_ty(ex).kind == ty::Bool {
+ if *cx.typeck_results().expr_ty(ex).kind() == ty::Bool {
span_lint_and_then(
cx,
MATCH_BOOL,
}
}
-fn check_overlapping_arms<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ex: &'tcx Expr<'_>, arms: &'tcx [Arm<'_>]) {
- if arms.len() >= 2 && cx.tables.expr_ty(ex).is_integral() {
- let ranges = all_ranges(cx, arms, cx.tables.expr_ty(ex));
+fn check_overlapping_arms<'tcx>(cx: &LateContext<'tcx>, ex: &'tcx Expr<'_>, arms: &'tcx [Arm<'_>]) {
+ if arms.len() >= 2 && cx.typeck_results().expr_ty(ex).is_integral() {
+ let ranges = all_ranges(cx, arms, cx.typeck_results().expr_ty(ex));
let type_ranges = type_ranges(&ranges);
if !type_ranges.is_empty() {
if let Some((start, end)) = overlapping(&type_ranges) {
}
}
-fn check_wild_err_arm(cx: &LateContext<'_, '_>, ex: &Expr<'_>, arms: &[Arm<'_>]) {
- let ex_ty = walk_ptrs_ty(cx.tables.expr_ty(ex));
- if is_type_diagnostic_item(cx, ex_ty, sym!(result_type)) {
+fn check_wild_err_arm<'tcx>(cx: &LateContext<'tcx>, ex: &Expr<'tcx>, arms: &[Arm<'tcx>]) {
+ let ex_ty = cx.typeck_results().expr_ty(ex).peel_refs();
+ if is_type_diagnostic_item(cx, ex_ty, sym::result_type) {
for arm in arms {
if let PatKind::TupleStruct(ref path, ref inner, _) = arm.pat.kind {
let path_str = rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_qpath(path, false));
if !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) {
+ 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;
}
arm.pat.span,
&format!("`Err({})` matches all errors", &ident_bind_name),
None,
- "match each error separately or use the error output",
+ "match each error separately or use the error output, or use `.except(msg)` if the error case is unreachable",
);
}
}
}
}
-fn check_wild_enum_match(cx: &LateContext<'_, '_>, ex: &Expr<'_>, arms: &[Arm<'_>]) {
- let ty = cx.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;
+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 => (),
+ }
+ }
+}
+
+#[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 mut missing_variants: Vec<_> = adt_def.variants.iter().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 arm.guard.is_none() && patterns.iter().all(|p| !is_refutable(cx, p)) {
+ let id = cx.qpath_res(path, pat.hir_id).def_id();
+ missing_variants.retain(|e| e.ctor_def_id != Some(id));
+ }
+ path
+ },
+ PatKind::Struct(path, patterns, ..) => {
+ if arm.guard.is_none() && patterns.iter().all(|p| !is_refutable(cx, p.pat)) {
+ let id = cx.qpath_res(path, pat.hir_id).def_id();
+ 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, ..) = arm.pat.kind {
- if let QPath::Resolved(_, p) = path {
- 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("_"));
- }
- }
+ )
+ };
- span_lint_and_sugg(
+ match missing_variants.as_slice() {
+ [] => (),
+ [x] if !adt_def.is_variant_list_non_exhaustive() => span_lint_and_sugg(
cx,
- WILDCARD_ENUM_MATCH_ARM,
+ MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
wildcard_span,
- message,
+ "wildcard matches only a single variant and will also match any future added variants",
"try this",
- suggestion.join(" | "),
- Applicability::MachineApplicable,
- )
- }
+ format_suggestion(x),
+ Applicability::MaybeIncorrect,
+ ),
+ variants => {
+ let mut suggestions: Vec<_> = variants.iter().cloned().map(format_suggestion).collect();
+ let message = if adt_def.is_variant_list_non_exhaustive() {
+ suggestions.push("_".into());
+ "wildcard matches known variants and will also match future added variants"
+ } else {
+ "wildcard match will also match any future added variants"
+ };
+
+ span_lint_and_sugg(
+ cx,
+ WILDCARD_ENUM_MATCH_ARM,
+ wildcard_span,
+ message,
+ "try this",
+ suggestions.join(" | "),
+ Applicability::MaybeIncorrect,
+ )
+ },
+ };
}
// If the block contains only a `panic!` macro (as expression or statement)
}
}
-fn check_match_ref_pats(cx: &LateContext<'_, '_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
+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 {
}
}
-fn check_match_as_ref(cx: &LateContext<'_, '_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
+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])
"as_mut"
};
- let output_ty = cx.tables.expr_ty(expr);
- let input_ty = cx.tables.expr_ty(ex);
+ let output_ty = cx.typeck_results().expr_ty(expr);
+ let input_ty = cx.typeck_results().expr_ty(ex);
let cast = if_chain! {
- if let ty::Adt(_, substs) = input_ty.kind;
+ if let ty::Adt(_, substs) = input_ty.kind();
let input_ty = substs.type_at(0);
- if let ty::Adt(_, substs) = output_ty.kind;
+ if let ty::Adt(_, substs) = output_ty.kind();
let output_ty = substs.type_at(0);
- if let ty::Ref(_, output_ty, _) = output_ty.kind;
+ if let ty::Ref(_, output_ty, _) = *output_ty.kind();
if input_ty != output_ty;
then {
".map(|x| x as _)"
}
}
-fn check_wild_in_or_pats(cx: &LateContext<'_, '_>, arms: &[Arm<'_>]) {
+fn check_wild_in_or_pats(cx: &LateContext<'_>, arms: &[Arm<'_>]) {
for arm in arms {
if let PatKind::Or(ref fields) = arm.pat.kind {
// look for multiple fields in this arm that contains at least one Wild pattern
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",
);
}
}
}
}
-fn check_match_single_binding<'a>(cx: &LateContext<'_, 'a>, ex: &Expr<'a>, arms: &[Arm<'_>], expr: &Expr<'_>) {
+/// Lint a `match` or `if let .. { .. } else { .. }` expr that could be replaced by `matches!`
+fn check_match_like_matches<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
+ if let ExprKind::Match(ex, arms, ref match_source) = &expr.kind {
+ match match_source {
+ MatchSource::Normal => find_matches_sugg(cx, ex, arms, expr, false),
+ MatchSource::IfLetDesugar { .. } => find_matches_sugg(cx, ex, arms, expr, true),
+ _ => false,
+ }
+ } else {
+ false
+ }
+}
+
+/// Lint a `match` or desugared `if let` for replacement by `matches!`
+fn find_matches_sugg(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>, desugared: bool) -> bool {
+ if_chain! {
+ if arms.len() >= 2;
+ if cx.typeck_results().expr_ty(expr).is_bool();
+ if let Some((b1_arm, b0_arms)) = arms.split_last();
+ if let Some(b0) = find_bool_lit(&b0_arms[0].body.kind, desugared);
+ if let Some(b1) = find_bool_lit(&b1_arm.body.kind, desugared);
+ if is_wild(&b1_arm.pat);
+ if b0 != b1;
+ let if_guard = &b0_arms[0].guard;
+ if if_guard.is_none() || b0_arms.len() == 1;
+ if cx.tcx.hir().attrs(b0_arms[0].hir_id).is_empty();
+ if b0_arms[1..].iter()
+ .all(|arm| {
+ find_bool_lit(&arm.body.kind, desugared).map_or(false, |b| b == b0) &&
+ arm.guard.is_none() && cx.tcx.hir().attrs(arm.hir_id).is_empty()
+ });
+ then {
+ // The suggestion may be incorrect, because some arms can have `cfg` attributes
+ // evaluated into `false` and so such arms will be stripped before.
+ let mut applicability = Applicability::MaybeIncorrect;
+ let pat = {
+ use itertools::Itertools as _;
+ b0_arms.iter()
+ .map(|arm| snippet_with_applicability(cx, arm.pat.span, "..", &mut applicability))
+ .join(" | ")
+ };
+ let pat_and_guard = if let Some(Guard::If(g)) = if_guard {
+ format!("{} if {}", pat, snippet_with_applicability(cx, g.span, "..", &mut applicability))
+ } else {
+ pat
+ };
+
+ // strip potential borrows (#6503), but only if the type is a reference
+ let mut ex_new = ex;
+ if let ExprKind::AddrOf(BorrowKind::Ref, .., ex_inner) = ex.kind {
+ if let ty::Ref(..) = cx.typeck_results().expr_ty(&ex_inner).kind() {
+ ex_new = ex_inner;
+ }
+ };
+ span_lint_and_sugg(
+ cx,
+ MATCH_LIKE_MATCHES_MACRO,
+ expr.span,
+ &format!("{} expression looks like `matches!` macro", if desugared { "if let .. else" } else { "match" }),
+ "try this",
+ format!(
+ "{}matches!({}, {})",
+ if b0 { "" } else { "!" },
+ snippet_with_applicability(cx, ex_new.span, "..", &mut applicability),
+ pat_and_guard,
+ ),
+ applicability,
+ );
+ true
+ } else {
+ false
+ }
+ }
+}
+
+/// Extract a `bool` or `{ bool }`
+fn find_bool_lit(ex: &ExprKind<'_>, desugared: bool) -> Option<bool> {
+ match ex {
+ ExprKind::Lit(Spanned {
+ node: LitKind::Bool(b), ..
+ }) => Some(*b),
+ ExprKind::Block(
+ rustc_hir::Block {
+ stmts: &[],
+ expr: Some(exp),
+ ..
+ },
+ _,
+ ) if desugared => {
+ if let ExprKind::Lit(Spanned {
+ node: LitKind::Bool(b), ..
+ }) = exp.kind
+ {
+ Some(b)
+ } else {
+ None
+ }
+ },
+ _ => None,
+ }
+}
+
+#[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);
match match_body.kind {
ExprKind::Block(block, _) => {
// macro + expr_ty(body) == ()
- if block.span.from_expansion() && cx.tables.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.tables.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!(
}
/// 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>> {
+fn opt_parent_let<'a>(cx: &LateContext<'a>, ex: &Expr<'a>) -> Option<&'a Local<'a>> {
if_chain! {
let map = &cx.tcx.hir();
if let Some(Node::Expr(parent_arm_expr)) = map.find(map.get_parent_node(ex.hir_id));
}
/// Gets all arms that are unbounded `PatRange`s.
-fn all_ranges<'a, 'tcx>(
- cx: &LateContext<'a, 'tcx>,
- arms: &'tcx [Arm<'_>],
- ty: Ty<'tcx>,
-) -> Vec<SpannedRange<Constant>> {
+fn all_ranges<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>], ty: Ty<'tcx>) -> Vec<SpannedRange<Constant>> {
arms.iter()
.flat_map(|arm| {
if let Arm {
{
if let PatKind::Range(ref lhs, ref rhs, range_end) = pat.kind {
let lhs = match lhs {
- Some(lhs) => constant(cx, cx.tables, lhs)?.0,
+ Some(lhs) => constant(cx, cx.typeck_results(), lhs)?.0,
None => miri_to_const(ty.numeric_min_val(cx.tcx)?)?,
};
let rhs = match rhs {
- Some(rhs) => constant(cx, cx.tables, rhs)?.0,
+ Some(rhs) => constant(cx, cx.typeck_results(), rhs)?.0,
None => miri_to_const(ty.numeric_max_val(cx.tcx)?)?,
};
let rhs = match range_end {
}
if let PatKind::Lit(ref value) = pat.kind {
- let value = constant(cx, cx.tables, value)?.0;
+ let value = constant(cx, cx.typeck_results(), value)?.0;
return Some(SpannedRange {
span: pat.span,
node: (value.clone(), Bound::Included(value)),
// Checks if arm has the form `None => None`
fn is_none_arm(arm: &Arm<'_>) -> bool {
- match arm.pat.kind {
- PatKind::Path(ref path) if match_qpath(path, &paths::OPTION_NONE) => true,
- _ => false,
- }
+ matches!(arm.pat.kind, PatKind::Path(ref path) if match_qpath(path, &paths::OPTION_NONE))
}
// Checks if arm has the form `Some(ref v) => Some(v)` (checks for `ref` and `ref mut`)
if let ExprKind::Call(ref e, ref args) = remove_blocks(&arm.body).kind;
if let ExprKind::Path(ref some_path) = e.kind;
if match_qpath(some_path, &paths::OPTION_SOME) && args.len() == 1;
- if let ExprKind::Path(ref qpath) = args[0].kind;
- if let &QPath::Resolved(_, ref path2) = qpath;
+ if let ExprKind::Path(QPath::Resolved(_, ref path2)) = args[0].kind;
if path2.segments.len() == 1 && ident.name == path2.segments[0].ident.name;
then {
return Some(rb)
values.sort();
- for (a, b) in values.iter().zip(values.iter().skip(1)) {
+ for (a, b) in iter::zip(&values, &values[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()));
+ },
}
}
None
}
+mod redundant_pattern_match {
+ use super::REDUNDANT_PATTERN_MATCHING;
+ use clippy_utils::diagnostics::span_lint_and_then;
+ use clippy_utils::source::snippet;
+ use clippy_utils::{is_trait_method, match_qpath, paths};
+ use if_chain::if_chain;
+ use rustc_ast::ast::LitKind;
+ use rustc_errors::Applicability;
+ use rustc_hir::{Arm, Expr, ExprKind, MatchSource, PatKind, QPath};
+ use rustc_lint::LateContext;
+ use rustc_span::sym;
+
+ pub fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+ if let ExprKind::Match(op, arms, ref match_source) = &expr.kind {
+ match match_source {
+ MatchSource::Normal => find_sugg_for_match(cx, expr, op, arms),
+ MatchSource::IfLetDesugar { .. } => find_sugg_for_if_let(cx, expr, op, arms, "if"),
+ MatchSource::WhileLetDesugar => find_sugg_for_if_let(cx, expr, op, arms, "while"),
+ _ => {},
+ }
+ }
+ }
+
+ fn find_sugg_for_if_let<'tcx>(
+ cx: &LateContext<'tcx>,
+ expr: &'tcx Expr<'_>,
+ op: &Expr<'_>,
+ arms: &[Arm<'_>],
+ keyword: &'static str,
+ ) {
+ let good_method = match arms[0].pat.kind {
+ PatKind::TupleStruct(ref path, ref patterns, _) if patterns.len() == 1 => {
+ if let PatKind::Wild = patterns[0].kind {
+ if match_qpath(path, &paths::RESULT_OK) {
+ "is_ok()"
+ } else if match_qpath(path, &paths::RESULT_ERR) {
+ "is_err()"
+ } else if match_qpath(path, &paths::OPTION_SOME) {
+ "is_some()"
+ } else if match_qpath(path, &paths::POLL_READY) {
+ "is_ready()"
+ } else if match_qpath(path, &paths::IPADDR_V4) {
+ "is_ipv4()"
+ } else if match_qpath(path, &paths::IPADDR_V6) {
+ "is_ipv6()"
+ } else {
+ return;
+ }
+ } else {
+ return;
+ }
+ },
+ PatKind::Path(ref path) => {
+ if match_qpath(path, &paths::OPTION_NONE) {
+ "is_none()"
+ } else if match_qpath(path, &paths::POLL_PENDING) {
+ "is_pending()"
+ } else {
+ return;
+ }
+ },
+ _ => return,
+ };
+
+ // check that `while_let_on_iterator` lint does not trigger
+ if_chain! {
+ if keyword == "while";
+ if let ExprKind::MethodCall(method_path, _, _, _) = op.kind;
+ if method_path.ident.name == sym::next;
+ if is_trait_method(cx, op, sym::Iterator);
+ then {
+ return;
+ }
+ }
+
+ let result_expr = match &op.kind {
+ ExprKind::AddrOf(_, _, borrowed) => borrowed,
+ _ => op,
+ };
+ span_lint_and_then(
+ cx,
+ REDUNDANT_PATTERN_MATCHING,
+ arms[0].pat.span,
+ &format!("redundant pattern matching, consider using `{}`", good_method),
+ |diag| {
+ // while let ... = ... { ... }
+ // ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ let expr_span = expr.span;
+
+ // while let ... = ... { ... }
+ // ^^^
+ let op_span = result_expr.span.source_callsite();
+
+ // while let ... = ... { ... }
+ // ^^^^^^^^^^^^^^^^^^^
+ let span = expr_span.until(op_span.shrink_to_hi());
+ diag.span_suggestion(
+ span,
+ "try this",
+ format!("{} {}.{}", keyword, snippet(cx, op_span, "_"), good_method),
+ Applicability::MachineApplicable, // snippet
+ );
+ },
+ );
+ }
+
+ fn find_sugg_for_match<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, op: &Expr<'_>, arms: &[Arm<'_>]) {
+ if arms.len() == 2 {
+ let node_pair = (&arms[0].pat.kind, &arms[1].pat.kind);
+
+ let found_good_method = match node_pair {
+ (
+ PatKind::TupleStruct(ref path_left, ref patterns_left, _),
+ PatKind::TupleStruct(ref path_right, ref patterns_right, _),
+ ) if patterns_left.len() == 1 && patterns_right.len() == 1 => {
+ if let (PatKind::Wild, PatKind::Wild) = (&patterns_left[0].kind, &patterns_right[0].kind) {
+ find_good_method_for_match(
+ arms,
+ path_left,
+ path_right,
+ &paths::RESULT_OK,
+ &paths::RESULT_ERR,
+ "is_ok()",
+ "is_err()",
+ )
+ .or_else(|| {
+ find_good_method_for_match(
+ arms,
+ path_left,
+ path_right,
+ &paths::IPADDR_V4,
+ &paths::IPADDR_V6,
+ "is_ipv4()",
+ "is_ipv6()",
+ )
+ })
+ } else {
+ None
+ }
+ },
+ (PatKind::TupleStruct(ref path_left, ref patterns, _), PatKind::Path(ref path_right))
+ | (PatKind::Path(ref path_left), PatKind::TupleStruct(ref path_right, ref patterns, _))
+ if patterns.len() == 1 =>
+ {
+ if let PatKind::Wild = patterns[0].kind {
+ find_good_method_for_match(
+ arms,
+ path_left,
+ path_right,
+ &paths::OPTION_SOME,
+ &paths::OPTION_NONE,
+ "is_some()",
+ "is_none()",
+ )
+ .or_else(|| {
+ find_good_method_for_match(
+ arms,
+ path_left,
+ path_right,
+ &paths::POLL_READY,
+ &paths::POLL_PENDING,
+ "is_ready()",
+ "is_pending()",
+ )
+ })
+ } else {
+ None
+ }
+ },
+ _ => None,
+ };
+
+ if let Some(good_method) = found_good_method {
+ let span = expr.span.to(op.span);
+ let result_expr = match &op.kind {
+ ExprKind::AddrOf(_, _, borrowed) => borrowed,
+ _ => op,
+ };
+ span_lint_and_then(
+ cx,
+ REDUNDANT_PATTERN_MATCHING,
+ expr.span,
+ &format!("redundant pattern matching, consider using `{}`", good_method),
+ |diag| {
+ diag.span_suggestion(
+ span,
+ "try this",
+ format!("{}.{}", snippet(cx, result_expr.span, "_"), good_method),
+ Applicability::MaybeIncorrect, // snippet
+ );
+ },
+ );
+ }
+ }
+ }
+
+ fn find_good_method_for_match<'a>(
+ arms: &[Arm<'_>],
+ path_left: &QPath<'_>,
+ path_right: &QPath<'_>,
+ expected_left: &[&str],
+ expected_right: &[&str],
+ should_be_left: &'a str,
+ should_be_right: &'a str,
+ ) -> Option<&'a str> {
+ let body_node_pair = if match_qpath(path_left, expected_left) && match_qpath(path_right, expected_right) {
+ (&(*arms[0].body).kind, &(*arms[1].body).kind)
+ } else if match_qpath(path_right, expected_left) && match_qpath(path_left, expected_right) {
+ (&(*arms[1].body).kind, &(*arms[0].body).kind)
+ } else {
+ return None;
+ };
+
+ match body_node_pair {
+ (ExprKind::Lit(ref lit_left), ExprKind::Lit(ref lit_right)) => match (&lit_left.node, &lit_right.node) {
+ (LitKind::Bool(true), LitKind::Bool(false)) => Some(should_be_left),
+ (LitKind::Bool(false), LitKind::Bool(true)) => Some(should_be_right),
+ _ => None,
+ },
+ _ => None,
+ }
+ }
+}
+
#[test]
fn test_overlapping() {
use rustc_span::source_map::DUMMY_SP;
],)
);
}
+
+/// Implementation of `MATCH_SAME_ARMS`.
+fn lint_match_arms<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) {
+ if let ExprKind::Match(_, ref arms, MatchSource::Normal) = expr.kind {
+ let hash = |&(_, arm): &(usize, &Arm<'_>)| -> u64 {
+ let mut h = SpanlessHash::new(cx);
+ h.hash_expr(&arm.body);
+ h.finish()
+ };
+
+ let eq = |&(lindex, lhs): &(usize, &Arm<'_>), &(rindex, rhs): &(usize, &Arm<'_>)| -> bool {
+ let min_index = usize::min(lindex, rindex);
+ let max_index = usize::max(lindex, rindex);
+
+ let mut local_map: FxHashMap<HirId, HirId> = FxHashMap::default();
+ let eq_fallback = |a: &Expr<'_>, b: &Expr<'_>| {
+ if_chain! {
+ if let Some(a_id) = path_to_local(a);
+ if let Some(b_id) = path_to_local(b);
+ let entry = match local_map.entry(a_id) {
+ Entry::Vacant(entry) => entry,
+ // check if using the same bindings as before
+ Entry::Occupied(entry) => return *entry.get() == b_id,
+ };
+ // the names technically don't have to match; this makes the lint more conservative
+ if cx.tcx.hir().name(a_id) == cx.tcx.hir().name(b_id);
+ if TyS::same_type(cx.typeck_results().expr_ty(a), cx.typeck_results().expr_ty(b));
+ if pat_contains_local(lhs.pat, a_id);
+ if pat_contains_local(rhs.pat, b_id);
+ then {
+ entry.insert(b_id);
+ true
+ } else {
+ false
+ }
+ }
+ };
+ // Arms with a guard are ignored, those can’t always be merged together
+ // This is also the case for arms in-between each there is an arm with a guard
+ (min_index..=max_index).all(|index| arms[index].guard.is_none())
+ && SpanlessEq::new(cx)
+ .expr_fallback(eq_fallback)
+ .eq_expr(&lhs.body, &rhs.body)
+ // these checks could be removed to allow unused bindings
+ && bindings_eq(lhs.pat, local_map.keys().copied().collect())
+ && bindings_eq(rhs.pat, local_map.values().copied().collect())
+ };
+
+ let indexed_arms: Vec<(usize, &Arm<'_>)> = arms.iter().enumerate().collect();
+ for (&(_, i), &(_, j)) in search_same(&indexed_arms, hash, eq) {
+ span_lint_and_then(
+ cx,
+ MATCH_SAME_ARMS,
+ j.body.span,
+ "this `match` has identical arm bodies",
+ |diag| {
+ diag.span_note(i.body.span, "same as this");
+
+ // Note: this does not use `span_suggestion` on purpose:
+ // there is no clean way
+ // to remove the other arm. Building a span and suggest to replace it to ""
+ // makes an even more confusing error message. Also in order not to make up a
+ // span for the whole pattern, the suggestion is only shown when there is only
+ // one pattern. The user should know about `|` if they are already using it…
+
+ let lhs = snippet(cx, i.pat.span, "<pat1>");
+ let rhs = snippet(cx, j.pat.span, "<pat2>");
+
+ if let PatKind::Wild = j.pat.kind {
+ // if the last arm is _, then i could be integrated into _
+ // note that i.pat cannot be _, because that would mean that we're
+ // hiding all the subsequent arms, and rust won't compile
+ diag.span_note(
+ i.body.span,
+ &format!(
+ "`{}` has the same arm body as the `_` wildcard, consider removing it",
+ lhs
+ ),
+ );
+ } else {
+ diag.span_help(i.pat.span, &format!("consider refactoring into `{} | {}`", lhs, rhs));
+ }
+ },
+ );
+ }
+ }
+}
+
+fn pat_contains_local(pat: &Pat<'_>, id: HirId) -> bool {
+ let mut result = false;
+ pat.walk_short(|p| {
+ result |= matches!(p.kind, PatKind::Binding(_, binding_id, ..) if binding_id == id);
+ !result
+ });
+ result
+}
+
+/// Returns true if all the bindings in the `Pat` are in `ids` and vice versa
+fn bindings_eq(pat: &Pat<'_>, mut ids: FxHashSet<HirId>) -> bool {
+ let mut result = true;
+ pat.each_binding_or_first(&mut |_, id, _, _| result &= ids.remove(&id));
+ result && ids.is_empty()
+}
projects / rust.git / blobdiff