mod match_like_matches;
mod match_same_arms;
+mod redundant_pattern_match;
declare_clippy_lint! {
/// ### What it does
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::sugg::Sugg;
- use clippy_utils::ty::{implements_trait, is_type_diagnostic_item, is_type_lang_item, match_type};
- use clippy_utils::{higher, match_def_path};
- use clippy_utils::{is_lang_ctor, 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::LangItem::{OptionNone, PollPending};
- use rustc_hir::{
- intravisit::{walk_expr, Visitor},
- Arm, Block, Expr, ExprKind, LangItem, MatchSource, Node, Pat, PatKind, QPath, UnOp,
- };
- use rustc_lint::LateContext;
- use rustc_middle::ty::{self, subst::GenericArgKind, DefIdTree, Ty};
- use rustc_span::sym;
-
- pub fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
- if let Some(higher::IfLet {
- if_else,
- let_pat,
- let_expr,
- ..
- }) = higher::IfLet::hir(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<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
- type_needs_ordered_drop_inner(cx, ty, &mut FxHashSet::default())
- }
-
- fn type_needs_ordered_drop_inner<'tcx>(
- 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)
- || 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<'tcx>(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> {
- 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<'_>,
- let_pat: &Pat<'_>,
- let_expr: &'tcx Expr<'_>,
- keyword: &'static str,
- has_else: bool,
- ) {
- // also look inside refs
- // if we have &None for example, peel it so we can detect "if let None = x"
- let check_pat = match let_pat.kind {
- PatKind::Ref(inner, _mutability) => inner,
- _ => let_pat,
- };
- 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 check_pat.kind {
- PatKind::TupleStruct(ref qpath, [sub_pat], _) => {
- if let PatKind::Wild = sub_pat.kind {
- let res = cx.typeck_results().qpath_res(qpath, check_pat.hir_id);
- let Some(id) = res.opt_def_id().and_then(|ctor_id| cx.tcx.parent(ctor_id)) else { return };
- let lang_items = cx.tcx.lang_items();
- if Some(id) == lang_items.result_ok_variant() {
- ("is_ok()", try_get_generic_ty(op_ty, 0).unwrap_or(op_ty))
- } else if Some(id) == lang_items.result_err_variant() {
- ("is_err()", try_get_generic_ty(op_ty, 1).unwrap_or(op_ty))
- } else if Some(id) == lang_items.option_some_variant() {
- ("is_some()", op_ty)
- } else if Some(id) == lang_items.poll_ready_variant() {
- ("is_ready()", op_ty)
- } else if match_def_path(cx, id, &paths::IPADDR_V4) {
- ("is_ipv4()", op_ty)
- } else if match_def_path(cx, id, &paths::IPADDR_V6) {
- ("is_ipv6()", op_ty)
- } else {
- return;
- }
- } else {
- return;
- }
- },
- 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, _, _) = 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 &let_expr.kind {
- ExprKind::AddrOf(_, _, borrowed) => borrowed,
- ExprKind::Unary(UnOp::Deref, deref) => deref,
- _ => let_expr,
- };
-
- span_lint_and_then(
- cx,
- REDUNDANT_PATTERN_MATCHING,
- let_pat.span,
- &format!("redundant pattern matching, consider using `{}`", good_method),
- |diag| {
- // if/while let ... = ... { ... }
- // ^^^^^^^^^^^^^^^^^^^^^^^^^^^
- let expr_span = expr.span;
-
- // if/while let ... = ... { ... }
- // ^^^
- let op_span = result_expr.span.source_callsite();
-
- // if/while let ... = ... { ... }
- // ^^^^^^^^^^^^^^^^^^^
- let span = expr_span.until(op_span.shrink_to_hi());
-
- let app = if needs_drop {
- Applicability::MaybeIncorrect
- } else {
- Applicability::MachineApplicable
- };
-
- let sugg = Sugg::hir_with_macro_callsite(cx, result_expr, "_")
- .maybe_par()
- .to_string();
-
- 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");
- }
- },
- );
- }
-
- 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, 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,
- &paths::RESULT_OK,
- &paths::RESULT_ERR,
- "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, 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,
- &paths::OPTION_SOME,
- &paths::OPTION_NONE,
- "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
- }
- },
- _ => 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
- );
- },
- );
- }
- }
- }
-
- #[allow(clippy::too_many_arguments)]
- fn find_good_method_for_match<'a>(
- cx: &LateContext<'_>,
- 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 left_id = cx
- .typeck_results()
- .qpath_res(path_left, arms[0].pat.hir_id)
- .opt_def_id()?;
- let right_id = cx
- .typeck_results()
- .qpath_res(path_right, arms[1].pat.hir_id)
- .opt_def_id()?;
- let body_node_pair =
- if match_def_path(cx, left_id, expected_left) && match_def_path(cx, right_id, expected_right) {
- (&(*arms[0].body).kind, &(*arms[1].body).kind)
- } else if match_def_path(cx, right_id, expected_left) && match_def_path(cx, right_id, 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;
--- /dev/null
+use super::REDUNDANT_PATTERN_MATCHING;
+use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::source::snippet;
+use clippy_utils::sugg::Sugg;
+use clippy_utils::ty::{implements_trait, is_type_diagnostic_item, is_type_lang_item, match_type};
+use clippy_utils::{higher, match_def_path};
+use clippy_utils::{is_lang_ctor, 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::LangItem::{OptionNone, PollPending};
+use rustc_hir::{
+ intravisit::{walk_expr, Visitor},
+ Arm, Block, Expr, ExprKind, LangItem, MatchSource, Node, Pat, PatKind, QPath, UnOp,
+};
+use rustc_lint::LateContext;
+use rustc_middle::ty::{self, subst::GenericArgKind, DefIdTree, Ty};
+use rustc_span::sym;
+
+pub fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+ if let Some(higher::IfLet {
+ if_else,
+ let_pat,
+ let_expr,
+ ..
+ }) = higher::IfLet::hir(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<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
+ type_needs_ordered_drop_inner(cx, ty, &mut FxHashSet::default())
+}
+
+fn type_needs_ordered_drop_inner<'tcx>(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)
+ || 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<'tcx>(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> {
+ 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<'_>,
+ let_pat: &Pat<'_>,
+ let_expr: &'tcx Expr<'_>,
+ keyword: &'static str,
+ has_else: bool,
+) {
+ // also look inside refs
+ // if we have &None for example, peel it so we can detect "if let None = x"
+ let check_pat = match let_pat.kind {
+ PatKind::Ref(inner, _mutability) => inner,
+ _ => let_pat,
+ };
+ 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 check_pat.kind {
+ PatKind::TupleStruct(ref qpath, [sub_pat], _) => {
+ if let PatKind::Wild = sub_pat.kind {
+ let res = cx.typeck_results().qpath_res(qpath, check_pat.hir_id);
+ let Some(id) = res.opt_def_id().and_then(|ctor_id| cx.tcx.parent(ctor_id)) else { return };
+ let lang_items = cx.tcx.lang_items();
+ if Some(id) == lang_items.result_ok_variant() {
+ ("is_ok()", try_get_generic_ty(op_ty, 0).unwrap_or(op_ty))
+ } else if Some(id) == lang_items.result_err_variant() {
+ ("is_err()", try_get_generic_ty(op_ty, 1).unwrap_or(op_ty))
+ } else if Some(id) == lang_items.option_some_variant() {
+ ("is_some()", op_ty)
+ } else if Some(id) == lang_items.poll_ready_variant() {
+ ("is_ready()", op_ty)
+ } else if match_def_path(cx, id, &paths::IPADDR_V4) {
+ ("is_ipv4()", op_ty)
+ } else if match_def_path(cx, id, &paths::IPADDR_V6) {
+ ("is_ipv6()", op_ty)
+ } else {
+ return;
+ }
+ } else {
+ return;
+ }
+ },
+ 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, _, _) = 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 &let_expr.kind {
+ ExprKind::AddrOf(_, _, borrowed) => borrowed,
+ ExprKind::Unary(UnOp::Deref, deref) => deref,
+ _ => let_expr,
+ };
+
+ span_lint_and_then(
+ cx,
+ REDUNDANT_PATTERN_MATCHING,
+ let_pat.span,
+ &format!("redundant pattern matching, consider using `{}`", good_method),
+ |diag| {
+ // if/while let ... = ... { ... }
+ // ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ let expr_span = expr.span;
+
+ // if/while let ... = ... { ... }
+ // ^^^
+ let op_span = result_expr.span.source_callsite();
+
+ // if/while let ... = ... { ... }
+ // ^^^^^^^^^^^^^^^^^^^
+ let span = expr_span.until(op_span.shrink_to_hi());
+
+ let app = if needs_drop {
+ Applicability::MaybeIncorrect
+ } else {
+ Applicability::MachineApplicable
+ };
+
+ let sugg = Sugg::hir_with_macro_callsite(cx, result_expr, "_")
+ .maybe_par()
+ .to_string();
+
+ 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");
+ }
+ },
+ );
+}
+
+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, 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,
+ &paths::RESULT_OK,
+ &paths::RESULT_ERR,
+ "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, 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,
+ &paths::OPTION_SOME,
+ &paths::OPTION_NONE,
+ "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
+ }
+ },
+ _ => 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
+ );
+ },
+ );
+ }
+ }
+}
+
+#[allow(clippy::too_many_arguments)]
+fn find_good_method_for_match<'a>(
+ cx: &LateContext<'_>,
+ 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 left_id = cx
+ .typeck_results()
+ .qpath_res(path_left, arms[0].pat.hir_id)
+ .opt_def_id()?;
+ let right_id = cx
+ .typeck_results()
+ .qpath_res(path_right, arms[1].pat.hir_id)
+ .opt_def_id()?;
+ let body_node_pair = if match_def_path(cx, left_id, expected_left) && match_def_path(cx, right_id, expected_right) {
+ (&(*arms[0].body).kind, &(*arms[1].body).kind)
+ } else if match_def_path(cx, right_id, expected_left) && match_def_path(cx, right_id, 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,
+ }
+}
projects / rust.git / commitdiff