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,
+ get_parent_expr, in_macro, is_allowed, is_expn_of, is_lang_ctor, 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 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, DefKind, Res};
+use rustc_hir::LangItem::{OptionNone, OptionSome};
use rustc_hir::{
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, VariantDef};
use rustc_span::sym;
use std::cmp::Ordering;
use std::collections::hash_map::Entry;
+use std::iter;
use std::ops::Bound;
declare_clippy_lint! {
/// **Why is this bad?** It's more concise and clear to just use the proper
/// utility function
///
- /// **Known problems:** None.
+ /// **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:**
///
MATCH_SAME_ARMS,
]);
-const MATCH_LIKE_MATCHES_MACRO_MSRV: RustcVersion = RustcVersion::new(1, 42, 0);
-
impl<'tcx> LateLintPass<'tcx> for Matches {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if in_external_macro(cx.sess(), expr.span) || in_macro(expr.span) {
redundant_pattern_match::check(cx, expr);
- if meets_msrv(self.msrv.as_ref(), &MATCH_LIKE_MATCHES_MACRO_MSRV) {
+ if meets_msrv(self.msrv.as_ref(), &msrvs::MATCHES_MACRO) {
if !check_match_like_matches(cx, expr) {
lint_match_arms(cx, expr);
}
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);
check_match_single_binding(cx, ex, arms, expr);
}
}
- if let ExprKind::Match(ref ex, ref arms, _) = expr.kind {
+ if let ExprKind::Match(ex, arms, _) = expr.kind {
check_match_ref_pats(cx, ex, arms, 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 PatKind::Binding(_, arg, ..) = strip_pat_refs(&args[0]).kind;
- let body = remove_blocks(&arms[0].body);
+ 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 {
if_chain! {
if !in_external_macro(cx.sess(), pat.span);
if !in_macro(pat.span);
- if let PatKind::Struct(QPath::Resolved(_, ref path), fields, true) = pat.kind;
+ if let 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();
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! {
- 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, &[]);
+ 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 {
// 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)),
+ expr_block(cx, arms[0].body, None, "..", Some(expr.span)),
els_str,
);
(msg, sugg)
"if let {} = {} {}{}",
snippet(cx, arms[0].pat.span, ".."),
snippet(cx, ex.span, ".."),
- expr_block(cx, &arms[0].body, None, "..", Some(expr.span)),
+ expr_block(cx, arms[0].body, None, "..", Some(expr.span)),
els_str,
);
(msg, sugg)
];
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)),
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 {
+ 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| {
+ 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)
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 is_doc_hidden(cx: &LateContext<'_>, variant_def: &VariantDef) -> bool {
+ let attrs = cx.tcx.get_attrs(variant_def.def_id);
+ clippy_utils::attrs::is_doc_hidden(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();
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));
+ 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 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);
+ 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
},
match missing_variants.as_slice() {
[] => (),
- [x] if !adt_def.is_variant_list_non_exhaustive() => span_lint_and_sugg(
+ [x] if !adt_def.is_variant_list_non_exhaustive() && !is_doc_hidden(cx, x) => span_lint_and_sugg(
cx,
MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
wildcard_span,
Applicability::MaybeIncorrect,
),
variants => {
- let mut suggestions: Vec<_> = variants.iter().cloned().map(format_suggestion).collect();
+ let mut suggestions: Vec<_> = variants.iter().copied().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"
// 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 (title, msg) = if let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner) = ex.kind {
let span = ex.span.source_callsite();
suggs.push((span, Sugg::hir_with_macro_callsite(cx, inner, "..").to_string()));
(
};
suggs.extend(arms.iter().filter_map(|a| {
- if let PatKind::Ref(ref refp, _) = a.pat.kind {
+ if let PatKind::Ref(refp, _) = a.pat.kind {
Some((a.pat.span, snippet(cx, refp.span, "..").to_string()))
} else {
None
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
};
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(
// 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() {
+ if let ty::Ref(..) = cx.typeck_results().expr_ty(ex_inner).kind() {
ex_new = ex_inner;
}
};
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(';');
}
},
/// 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::TupleStruct(ref qpath, pats, _) = arm.pat.kind;
+ if is_lang_ctor(cx, qpath, OptionSome);
if let PatKind::Binding(rb, .., ident, _) = pats[0].kind;
if rb == BindingAnnotation::Ref || rb == BindingAnnotation::RefMut;
- if let ExprKind::Call(ref e, ref args) = remove_blocks(&arm.body).kind;
+ if let ExprKind::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(QPath::Resolved(_, ref path2)) = args[0].kind;
+ 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)
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) => (),
_ => {
// skip if the range `a` is completely included into the range `b`
- if let Ordering::Equal | Ordering::Less = a.cmp(&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) {
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 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_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, 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"),
+ MatchSource::IfLetDesugar { contains_else_clause } => {
+ find_sugg_for_if_let(cx, expr, op, &arms[0], "if", *contains_else_clause)
+ },
+ MatchSource::WhileLetDesugar => find_sugg_for_if_let(cx, expr, op, &arms[0], "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 {
+ 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(cx, ty)),
+ ty::Array(ty, _) => type_needs_ordered_drop(cx, ty),
+ ty::Adt(adt, subs) => adt
+ .all_fields()
+ .map(|f| f.ty(cx.tcx, subs))
+ .any(|ty| type_needs_ordered_drop(cx, ty)),
+ _ => 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)
+ || match_type(cx, ty, &paths::BTREEMAP)
+ || match_type(cx, ty, &paths::LINKED_LIST)
+ || 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(cx, ty))
+ } 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<'_>],
+ op: &'tcx Expr<'tcx>,
+ arm: &Arm<'_>,
keyword: &'static str,
+ has_else: bool,
) {
// also look inside refs
- let mut kind = &arms[0].pat.kind;
+ let mut kind = &arm.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 good_method = match 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()"
+ let op_ty = cx.typeck_results().expr_ty(op);
+ // 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;
}
}
},
PatKind::Path(ref path) => {
- if match_qpath(path, &paths::OPTION_NONE) {
+ let method = if is_lang_ctor(cx, path, OptionNone) {
"is_none()"
- } else if match_qpath(path, &paths::POLL_PENDING) {
+ } 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, op);
+
// check that `while_let_on_iterator` lint does not trigger
if_chain! {
if keyword == "while";
span_lint_and_then(
cx,
REDUNDANT_PATTERN_MATCHING,
- arms[0].pat.span,
+ arm.pat.span,
&format!("redundant pattern matching, consider using `{}`", good_method),
|diag| {
// while let ... = ... { ... }
// 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,
)
.or_else(|| {
find_good_method_for_match(
+ cx,
arms,
path_left,
path_right,
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,
)
.or_else(|| {
find_good_method_for_match(
+ cx,
arms,
path_left,
path_right,
}
}
+ #[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<'_>) {
- 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: FxHashMap<HirId, HirId> = FxHashMap::default();
+ 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);
(min_index..=max_index).all(|index| arms[index].guard.is_none())
&& SpanlessEq::new(cx)
.expr_fallback(eq_fallback)
- .eq_expr(&lhs.body, &rhs.body)
+ .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())
}
/// 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 {
+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