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-rw-r--r--src/tools/clippy/clippy_lints/src/dereference.rs714
1 files changed, 525 insertions, 189 deletions
diff --git a/src/tools/clippy/clippy_lints/src/dereference.rs b/src/tools/clippy/clippy_lints/src/dereference.rs
index 514661589..88e28018e 100644
--- a/src/tools/clippy/clippy_lints/src/dereference.rs
+++ b/src/tools/clippy/clippy_lints/src/dereference.rs
@@ -1,24 +1,34 @@
use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_hir_and_then};
use clippy_utils::source::{snippet_with_applicability, snippet_with_context};
use clippy_utils::sugg::has_enclosing_paren;
-use clippy_utils::ty::{expr_sig, peel_mid_ty_refs, variant_of_res};
-use clippy_utils::{get_parent_expr, is_lint_allowed, path_to_local, walk_to_expr_usage};
+use clippy_utils::ty::{expr_sig, is_copy, peel_mid_ty_refs, ty_sig, variant_of_res};
+use clippy_utils::{
+ fn_def_id, get_parent_expr, get_parent_expr_for_hir, is_lint_allowed, meets_msrv, msrvs, path_to_local,
+ walk_to_expr_usage,
+};
use rustc_ast::util::parser::{PREC_POSTFIX, PREC_PREFIX};
use rustc_data_structures::fx::FxIndexMap;
use rustc_errors::Applicability;
use rustc_hir::intravisit::{walk_ty, Visitor};
use rustc_hir::{
- self as hir, BindingAnnotation, Body, BodyId, BorrowKind, Closure, Expr, ExprKind, FnRetTy, GenericArg, HirId,
- ImplItem, ImplItemKind, Item, ItemKind, Local, MatchSource, Mutability, Node, Pat, PatKind, Path, QPath, TraitItem,
- TraitItemKind, TyKind, UnOp,
+ self as hir, def_id::DefId, BindingAnnotation, Body, BodyId, BorrowKind, Closure, Expr, ExprKind, FnRetTy,
+ GenericArg, HirId, ImplItem, ImplItemKind, Item, ItemKind, Local, MatchSource, Mutability, Node, Pat, PatKind,
+ Path, QPath, TraitItem, TraitItemKind, TyKind, UnOp,
};
+use rustc_index::bit_set::BitSet;
use rustc_infer::infer::TyCtxtInferExt;
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability};
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitable, TypeckResults};
+use rustc_middle::ty::{
+ self, subst::Subst, Binder, BoundVariableKind, EarlyBinder, FnSig, GenericArgKind, List, ParamTy, PredicateKind,
+ ProjectionPredicate, Ty, TyCtxt, TypeVisitable, TypeckResults,
+};
+use rustc_semver::RustcVersion;
use rustc_session::{declare_tool_lint, impl_lint_pass};
-use rustc_span::{symbol::sym, Span, Symbol};
-use rustc_trait_selection::infer::InferCtxtExt;
+use rustc_span::{symbol::sym, Span, Symbol, DUMMY_SP};
+use rustc_trait_selection::infer::InferCtxtExt as _;
+use rustc_trait_selection::traits::{query::evaluate_obligation::InferCtxtExt as _, Obligation, ObligationCause};
+use std::collections::VecDeque;
declare_clippy_lint! {
/// ### What it does
@@ -127,7 +137,7 @@ declare_clippy_lint! {
/// ```
#[clippy::version = "1.60.0"]
pub EXPLICIT_AUTO_DEREF,
- nursery,
+ complexity,
"dereferencing when the compiler would automatically dereference"
}
@@ -151,6 +161,7 @@ pub struct Dereferencing {
/// been finished. Note we can't lint at the end of every body as they can be nested within each
/// other.
current_body: Option<BodyId>,
+
/// The list of locals currently being checked by the lint.
/// If the value is `None`, then the binding has been seen as a ref pattern, but is not linted.
/// This is needed for or patterns where one of the branches can be linted, but another can not
@@ -158,6 +169,19 @@ pub struct Dereferencing {
///
/// e.g. `m!(x) | Foo::Bar(ref x)`
ref_locals: FxIndexMap<HirId, Option<RefPat>>,
+
+ // `IntoIterator` for arrays requires Rust 1.53.
+ msrv: Option<RustcVersion>,
+}
+
+impl Dereferencing {
+ #[must_use]
+ pub fn new(msrv: Option<RustcVersion>) -> Self {
+ Self {
+ msrv,
+ ..Dereferencing::default()
+ }
+ }
}
struct StateData {
@@ -170,6 +194,7 @@ struct StateData {
struct DerefedBorrow {
count: usize,
msg: &'static str,
+ snip_expr: Option<HirId>,
}
enum State {
@@ -183,24 +208,24 @@ enum State {
},
DerefedBorrow(DerefedBorrow),
ExplicitDeref {
- // Span and id of the top-level deref expression if the parent expression is a borrow.
- deref_span_id: Option<(Span, HirId)>,
+ mutability: Option<Mutability>,
},
ExplicitDerefField {
name: Symbol,
},
Reborrow {
- deref_span: Span,
- deref_hir_id: HirId,
+ mutability: Mutability,
+ },
+ Borrow {
+ mutability: Mutability,
},
- Borrow,
}
// A reference operation considered by this lint pass
enum RefOp {
Method(Mutability),
Deref,
- AddrOf,
+ AddrOf(Mutability),
}
struct RefPat {
@@ -250,7 +275,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
match (self.state.take(), kind) {
(None, kind) => {
let expr_ty = typeck.expr_ty(expr);
- let (position, adjustments) = walk_parents(cx, expr);
+ let (position, adjustments) = walk_parents(cx, expr, self.msrv);
match kind {
RefOp::Deref => {
@@ -263,7 +288,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
));
} else if position.is_deref_stable() {
self.state = Some((
- State::ExplicitDeref { deref_span_id: None },
+ State::ExplicitDeref { mutability: None },
StateData { span: expr.span, hir_id: expr.hir_id, position },
));
}
@@ -289,7 +314,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
},
));
},
- RefOp::AddrOf => {
+ RefOp::AddrOf(mutability) => {
// Find the number of times the borrow is auto-derefed.
let mut iter = adjustments.iter();
let mut deref_count = 0usize;
@@ -331,20 +356,23 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
let deref_msg =
"this expression creates a reference which is immediately dereferenced by the compiler";
let borrow_msg = "this expression borrows a value the compiler would automatically borrow";
+ let impl_msg = "the borrowed expression implements the required traits";
- let (required_refs, msg) = if position.can_auto_borrow() {
- (1, if deref_count == 1 { borrow_msg } else { deref_msg })
+ let (required_refs, msg, snip_expr) = if position.can_auto_borrow() {
+ (1, if deref_count == 1 { borrow_msg } else { deref_msg }, None)
+ } else if let Position::ImplArg(hir_id) = position {
+ (0, impl_msg, Some(hir_id))
} else if let Some(&Adjust::Borrow(AutoBorrow::Ref(_, mutability))) =
next_adjust.map(|a| &a.kind)
{
if matches!(mutability, AutoBorrowMutability::Mut { .. }) && !position.is_reborrow_stable()
{
- (3, deref_msg)
+ (3, deref_msg, None)
} else {
- (2, deref_msg)
+ (2, deref_msg, None)
}
} else {
- (2, deref_msg)
+ (2, deref_msg, None)
};
if deref_count >= required_refs {
@@ -354,12 +382,17 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
// can't be removed without breaking the code. See earlier comment.
count: deref_count - required_refs,
msg,
+ snip_expr,
}),
StateData { span: expr.span, hir_id: expr.hir_id, position },
));
- } else if position.is_deref_stable() {
+ } else if position.is_deref_stable()
+ // Auto-deref doesn't combine with other adjustments
+ && next_adjust.map_or(true, |a| matches!(a.kind, Adjust::Deref(_) | Adjust::Borrow(_)))
+ && iter.all(|a| matches!(a.kind, Adjust::Deref(_) | Adjust::Borrow(_)))
+ {
self.state = Some((
- State::Borrow,
+ State::Borrow { mutability },
StateData {
span: expr.span,
hir_id: expr.hir_id,
@@ -395,7 +428,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
data,
));
},
- (Some((State::DerefedBorrow(state), data)), RefOp::AddrOf) if state.count != 0 => {
+ (Some((State::DerefedBorrow(state), data)), RefOp::AddrOf(_)) if state.count != 0 => {
self.state = Some((
State::DerefedBorrow(DerefedBorrow {
count: state.count - 1,
@@ -404,12 +437,12 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
data,
));
},
- (Some((State::DerefedBorrow(state), data)), RefOp::AddrOf) => {
+ (Some((State::DerefedBorrow(state), data)), RefOp::AddrOf(mutability)) => {
let position = data.position;
report(cx, expr, State::DerefedBorrow(state), data);
if position.is_deref_stable() {
self.state = Some((
- State::Borrow,
+ State::Borrow { mutability },
StateData {
span: expr.span,
hir_id: expr.hir_id,
@@ -430,43 +463,28 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
));
} else if position.is_deref_stable() {
self.state = Some((
- State::ExplicitDeref { deref_span_id: None },
+ State::ExplicitDeref { mutability: None },
StateData { span: expr.span, hir_id: expr.hir_id, position },
));
}
},
- (Some((State::Borrow, data)), RefOp::Deref) => {
+ (Some((State::Borrow { mutability }, data)), RefOp::Deref) => {
if typeck.expr_ty(sub_expr).is_ref() {
- self.state = Some((
- State::Reborrow {
- deref_span: expr.span,
- deref_hir_id: expr.hir_id,
- },
- data,
- ));
+ self.state = Some((State::Reborrow { mutability }, data));
} else {
self.state = Some((
State::ExplicitDeref {
- deref_span_id: Some((expr.span, expr.hir_id)),
+ mutability: Some(mutability),
},
data,
));
}
},
- (
- Some((
- State::Reborrow {
- deref_span,
- deref_hir_id,
- },
- data,
- )),
- RefOp::Deref,
- ) => {
+ (Some((State::Reborrow { mutability }, data)), RefOp::Deref) => {
self.state = Some((
State::ExplicitDeref {
- deref_span_id: Some((deref_span, deref_hir_id)),
+ mutability: Some(mutability),
},
data,
));
@@ -485,7 +503,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
}
fn check_pat(&mut self, cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>) {
- if let PatKind::Binding(BindingAnnotation::Ref, id, name, _) = pat.kind {
+ if let PatKind::Binding(BindingAnnotation::REF, id, name, _) = pat.kind {
if let Some(opt_prev_pat) = self.ref_locals.get_mut(&id) {
// This binding id has been seen before. Add this pattern to the list of changes.
if let Some(prev_pat) = opt_prev_pat {
@@ -521,7 +539,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
spans: vec![pat.span],
app,
replacements: vec![(pat.span, snip.into())],
- hir_id: pat.hir_id
+ hir_id: pat.hir_id,
}),
);
}
@@ -553,6 +571,8 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
self.current_body = None;
}
}
+
+ extract_msrv_attr!(LateContext);
}
fn try_parse_ref_op<'tcx>(
@@ -561,7 +581,7 @@ fn try_parse_ref_op<'tcx>(
expr: &'tcx Expr<'_>,
) -> Option<(RefOp, &'tcx Expr<'tcx>)> {
let (def_id, arg) = match expr.kind {
- ExprKind::MethodCall(_, [arg], _) => (typeck.type_dependent_def_id(expr.hir_id)?, arg),
+ ExprKind::MethodCall(_, arg, [], _) => (typeck.type_dependent_def_id(expr.hir_id)?, arg),
ExprKind::Call(
Expr {
kind: ExprKind::Path(path),
@@ -573,7 +593,7 @@ fn try_parse_ref_op<'tcx>(
ExprKind::Unary(UnOp::Deref, sub_expr) if !typeck.expr_ty(sub_expr).is_unsafe_ptr() => {
return Some((RefOp::Deref, sub_expr));
},
- ExprKind::AddrOf(BorrowKind::Ref, _, sub_expr) => return Some((RefOp::AddrOf, sub_expr)),
+ ExprKind::AddrOf(BorrowKind::Ref, mutability, sub_expr) => return Some((RefOp::AddrOf(mutability), sub_expr)),
_ => return None,
};
if tcx.is_diagnostic_item(sym::deref_method, def_id) {
@@ -605,22 +625,26 @@ enum Position {
/// The method is defined on a reference type. e.g. `impl Foo for &T`
MethodReceiverRefImpl,
Callee,
+ ImplArg(HirId),
FieldAccess(Symbol),
Postfix,
Deref,
/// Any other location which will trigger auto-deref to a specific time.
- DerefStable(i8),
+ /// Contains the precedence of the parent expression and whether the target type is sized.
+ DerefStable(i8, bool),
/// Any other location which will trigger auto-reborrowing.
+ /// Contains the precedence of the parent expression.
ReborrowStable(i8),
+ /// Contains the precedence of the parent expression.
Other(i8),
}
impl Position {
fn is_deref_stable(self) -> bool {
- matches!(self, Self::DerefStable(_))
+ matches!(self, Self::DerefStable(..))
}
fn is_reborrow_stable(self) -> bool {
- matches!(self, Self::DerefStable(_) | Self::ReborrowStable(_))
+ matches!(self, Self::DerefStable(..) | Self::ReborrowStable(_))
}
fn can_auto_borrow(self) -> bool {
@@ -628,7 +652,7 @@ impl Position {
}
fn lint_explicit_deref(self) -> bool {
- matches!(self, Self::Other(_) | Self::DerefStable(_) | Self::ReborrowStable(_))
+ matches!(self, Self::Other(_) | Self::DerefStable(..) | Self::ReborrowStable(_))
}
fn precedence(self) -> i8 {
@@ -638,8 +662,8 @@ impl Position {
| Self::Callee
| Self::FieldAccess(_)
| Self::Postfix => PREC_POSTFIX,
- Self::Deref => PREC_PREFIX,
- Self::DerefStable(p) | Self::ReborrowStable(p) | Self::Other(p) => p,
+ Self::ImplArg(_) | Self::Deref => PREC_PREFIX,
+ Self::DerefStable(p, _) | Self::ReborrowStable(p) | Self::Other(p) => p,
}
}
}
@@ -647,8 +671,12 @@ impl Position {
/// Walks up the parent expressions attempting to determine both how stable the auto-deref result
/// is, and which adjustments will be applied to it. Note this will not consider auto-borrow
/// locations as those follow different rules.
-#[allow(clippy::too_many_lines)]
-fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (Position, &'tcx [Adjustment<'tcx>]) {
+#[expect(clippy::too_many_lines)]
+fn walk_parents<'tcx>(
+ cx: &LateContext<'tcx>,
+ e: &'tcx Expr<'_>,
+ msrv: Option<RustcVersion>,
+) -> (Position, &'tcx [Adjustment<'tcx>]) {
let mut adjustments = [].as_slice();
let mut precedence = 0i8;
let ctxt = e.span.ctxt();
@@ -659,7 +687,7 @@ fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (Position, &
}
match parent {
Node::Local(Local { ty: Some(ty), span, .. }) if span.ctxt() == ctxt => {
- Some(binding_ty_auto_deref_stability(ty, precedence))
+ Some(binding_ty_auto_deref_stability(cx, ty, precedence, List::empty()))
},
Node::Item(&Item {
kind: ItemKind::Static(..) | ItemKind::Const(..),
@@ -680,11 +708,7 @@ fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (Position, &
..
}) if span.ctxt() == ctxt => {
let ty = cx.tcx.type_of(def_id);
- Some(if ty.is_ref() {
- Position::DerefStable(precedence)
- } else {
- Position::Other(precedence)
- })
+ Some(ty_auto_deref_stability(cx, ty, precedence).position_for_result(cx))
},
Node::Item(&Item {
@@ -705,45 +729,51 @@ fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (Position, &
span,
..
}) if span.ctxt() == ctxt => {
- let output = cx.tcx.fn_sig(def_id.to_def_id()).skip_binder().output();
- Some(if !output.is_ref() {
- Position::Other(precedence)
- } else if output.has_placeholders() || output.has_opaque_types() {
- Position::ReborrowStable(precedence)
- } else {
- Position::DerefStable(precedence)
- })
+ let output = cx
+ .tcx
+ .erase_late_bound_regions(cx.tcx.fn_sig(def_id.to_def_id()).output());
+ Some(ty_auto_deref_stability(cx, output, precedence).position_for_result(cx))
+ },
+
+ Node::ExprField(field) if field.span.ctxt() == ctxt => match get_parent_expr_for_hir(cx, field.hir_id) {
+ Some(Expr {
+ hir_id,
+ kind: ExprKind::Struct(path, ..),
+ ..
+ }) => variant_of_res(cx, cx.qpath_res(path, *hir_id))
+ .and_then(|variant| variant.fields.iter().find(|f| f.name == field.ident.name))
+ .map(|field_def| {
+ ty_auto_deref_stability(cx, cx.tcx.type_of(field_def.did), precedence).position_for_arg()
+ }),
+ _ => None,
},
Node::Expr(parent) if parent.span.ctxt() == ctxt => match parent.kind {
ExprKind::Ret(_) => {
let owner_id = cx.tcx.hir().body_owner(cx.enclosing_body.unwrap());
Some(
- if let Node::Expr(Expr {
- kind: ExprKind::Closure(&Closure { fn_decl, .. }),
- ..
- }) = cx.tcx.hir().get(owner_id)
+ if let Node::Expr(
+ closure_expr @ Expr {
+ kind: ExprKind::Closure(closure),
+ ..
+ },
+ ) = cx.tcx.hir().get(owner_id)
{
- match fn_decl.output {
- FnRetTy::Return(ty) => binding_ty_auto_deref_stability(ty, precedence),
- FnRetTy::DefaultReturn(_) => Position::Other(precedence),
- }
+ closure_result_position(cx, closure, cx.typeck_results().expr_ty(closure_expr), precedence)
} else {
let output = cx
.tcx
- .fn_sig(cx.tcx.hir().local_def_id(owner_id))
- .skip_binder()
- .output();
- if !output.is_ref() {
- Position::Other(precedence)
- } else if output.has_placeholders() || output.has_opaque_types() {
- Position::ReborrowStable(precedence)
- } else {
- Position::DerefStable(precedence)
- }
+ .erase_late_bound_regions(cx.tcx.fn_sig(cx.tcx.hir().local_def_id(owner_id)).output());
+ ty_auto_deref_stability(cx, output, precedence).position_for_result(cx)
},
)
},
+ ExprKind::Closure(closure) => Some(closure_result_position(
+ cx,
+ closure,
+ cx.typeck_results().expr_ty(parent),
+ precedence,
+ )),
ExprKind::Call(func, _) if func.hir_id == child_id => {
(child_id == e.hir_id).then_some(Position::Callee)
},
@@ -751,65 +781,72 @@ fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (Position, &
.iter()
.position(|arg| arg.hir_id == child_id)
.zip(expr_sig(cx, func))
- .and_then(|(i, sig)| sig.input_with_hir(i))
- .map(|(hir_ty, ty)| match hir_ty {
- // Type inference for closures can depend on how they're called. Only go by the explicit
- // types here.
- Some(ty) => binding_ty_auto_deref_stability(ty, precedence),
- None => param_auto_deref_stability(ty.skip_binder(), precedence),
+ .and_then(|(i, sig)| {
+ sig.input_with_hir(i).map(|(hir_ty, ty)| match hir_ty {
+ // Type inference for closures can depend on how they're called. Only go by the explicit
+ // types here.
+ Some(hir_ty) => binding_ty_auto_deref_stability(cx, hir_ty, precedence, ty.bound_vars()),
+ None => {
+ if let ty::Param(param_ty) = ty.skip_binder().kind() {
+ needless_borrow_impl_arg_position(cx, parent, i, *param_ty, e, precedence, msrv)
+ } else {
+ ty_auto_deref_stability(cx, cx.tcx.erase_late_bound_regions(ty), precedence)
+ .position_for_arg()
+ }
+ },
+ })
}),
- ExprKind::MethodCall(_, args, _) => {
+ ExprKind::MethodCall(_, receiver, args, _) => {
let id = cx.typeck_results().type_dependent_def_id(parent.hir_id).unwrap();
- args.iter().position(|arg| arg.hir_id == child_id).map(|i| {
- if i == 0 {
- // Check for calls to trait methods where the trait is implemented on a reference.
- // Two cases need to be handled:
- // * `self` methods on `&T` will never have auto-borrow
- // * `&self` methods on `&T` can have auto-borrow, but `&self` methods on `T` will take
- // priority.
- if e.hir_id != child_id {
- Position::ReborrowStable(precedence)
- } else if let Some(trait_id) = cx.tcx.trait_of_item(id)
- && let arg_ty = cx.tcx.erase_regions(cx.typeck_results().expr_ty_adjusted(e))
- && let ty::Ref(_, sub_ty, _) = *arg_ty.kind()
- && let subs = match cx
- .typeck_results()
- .node_substs_opt(parent.hir_id)
- .and_then(|subs| subs.get(1..))
- {
- Some(subs) => cx.tcx.mk_substs(subs.iter().copied()),
- None => cx.tcx.mk_substs([].iter()),
- } && let impl_ty = if cx.tcx.fn_sig(id).skip_binder().inputs()[0].is_ref() {
- // Trait methods taking `&self`
- sub_ty
- } else {
- // Trait methods taking `self`
- arg_ty
- } && impl_ty.is_ref()
- && cx.tcx.infer_ctxt().enter(|infcx|
- infcx
- .type_implements_trait(trait_id, impl_ty, subs, cx.param_env)
- .must_apply_modulo_regions()
- )
+ if receiver.hir_id == child_id {
+ // Check for calls to trait methods where the trait is implemented on a reference.
+ // Two cases need to be handled:
+ // * `self` methods on `&T` will never have auto-borrow
+ // * `&self` methods on `&T` can have auto-borrow, but `&self` methods on `T` will take
+ // priority.
+ if e.hir_id != child_id {
+ return Some(Position::ReborrowStable(precedence))
+ } else if let Some(trait_id) = cx.tcx.trait_of_item(id)
+ && let arg_ty = cx.tcx.erase_regions(cx.typeck_results().expr_ty_adjusted(e))
+ && let ty::Ref(_, sub_ty, _) = *arg_ty.kind()
+ && let subs = match cx
+ .typeck_results()
+ .node_substs_opt(parent.hir_id)
+ .and_then(|subs| subs.get(1..))
{
- Position::MethodReceiverRefImpl
+ Some(subs) => cx.tcx.mk_substs(subs.iter().copied()),
+ None => cx.tcx.mk_substs(std::iter::empty::<ty::subst::GenericArg<'_>>()),
+ } && let impl_ty = if cx.tcx.fn_sig(id).skip_binder().inputs()[0].is_ref() {
+ // Trait methods taking `&self`
+ sub_ty
} else {
- Position::MethodReceiver
- }
+ // Trait methods taking `self`
+ arg_ty
+ } && impl_ty.is_ref()
+ && cx.tcx.infer_ctxt().enter(|infcx|
+ infcx
+ .type_implements_trait(trait_id, impl_ty, subs, cx.param_env)
+ .must_apply_modulo_regions()
+ )
+ {
+ return Some(Position::MethodReceiverRefImpl)
+ }
+ return Some(Position::MethodReceiver);
+ }
+ args.iter().position(|arg| arg.hir_id == child_id).map(|i| {
+ let ty = cx.tcx.fn_sig(id).skip_binder().inputs()[i + 1];
+ if let ty::Param(param_ty) = ty.kind() {
+ needless_borrow_impl_arg_position(cx, parent, i + 1, *param_ty, e, precedence, msrv)
} else {
- param_auto_deref_stability(cx.tcx.fn_sig(id).skip_binder().inputs()[i], precedence)
+ ty_auto_deref_stability(
+ cx,
+ cx.tcx.erase_late_bound_regions(cx.tcx.fn_sig(id).input(i + 1)),
+ precedence,
+ )
+ .position_for_arg()
}
})
},
- ExprKind::Struct(path, fields, _) => {
- let variant = variant_of_res(cx, cx.qpath_res(path, parent.hir_id));
- fields
- .iter()
- .find(|f| f.expr.hir_id == child_id)
- .zip(variant)
- .and_then(|(field, variant)| variant.fields.iter().find(|f| f.name == field.ident.name))
- .map(|field| param_auto_deref_stability(cx.tcx.type_of(field.did), precedence))
- },
ExprKind::Field(child, name) if child.hir_id == e.hir_id => Some(Position::FieldAccess(name.name)),
ExprKind::Unary(UnOp::Deref, child) if child.hir_id == e.hir_id => Some(Position::Deref),
ExprKind::Match(child, _, MatchSource::TryDesugar | MatchSource::AwaitDesugar)
@@ -831,6 +868,26 @@ fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (Position, &
(position, adjustments)
}
+fn closure_result_position<'tcx>(
+ cx: &LateContext<'tcx>,
+ closure: &'tcx Closure<'_>,
+ ty: Ty<'tcx>,
+ precedence: i8,
+) -> Position {
+ match closure.fn_decl.output {
+ FnRetTy::Return(hir_ty) => {
+ if let Some(sig) = ty_sig(cx, ty)
+ && let Some(output) = sig.output()
+ {
+ binding_ty_auto_deref_stability(cx, hir_ty, precedence, output.bound_vars())
+ } else {
+ Position::Other(precedence)
+ }
+ },
+ FnRetTy::DefaultReturn(_) => Position::Other(precedence),
+ }
+}
+
// Checks the stability of auto-deref when assigned to a binding with the given explicit type.
//
// e.g.
@@ -840,7 +897,12 @@ fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (Position, &
//
// Here `y1` and `y2` would resolve to different types, so the type `&Box<_>` is not stable when
// switching to auto-dereferencing.
-fn binding_ty_auto_deref_stability(ty: &hir::Ty<'_>, precedence: i8) -> Position {
+fn binding_ty_auto_deref_stability<'tcx>(
+ cx: &LateContext<'tcx>,
+ ty: &'tcx hir::Ty<'_>,
+ precedence: i8,
+ binder_args: &'tcx List<BoundVariableKind>,
+) -> Position {
let TyKind::Rptr(_, ty) = &ty.kind else {
return Position::Other(precedence);
};
@@ -870,21 +932,33 @@ fn binding_ty_auto_deref_stability(ty: &hir::Ty<'_>, precedence: i8) -> Position
{
Position::ReborrowStable(precedence)
} else {
- Position::DerefStable(precedence)
+ Position::DerefStable(
+ precedence,
+ cx.tcx
+ .erase_late_bound_regions(Binder::bind_with_vars(
+ cx.typeck_results().node_type(ty.ty.hir_id),
+ binder_args,
+ ))
+ .is_sized(cx.tcx.at(DUMMY_SP), cx.param_env.without_caller_bounds()),
+ )
}
},
- TyKind::Slice(_)
- | TyKind::Array(..)
- | TyKind::BareFn(_)
- | TyKind::Never
+ TyKind::Slice(_) => Position::DerefStable(precedence, false),
+ TyKind::Array(..) | TyKind::Ptr(_) | TyKind::BareFn(_) => Position::DerefStable(precedence, true),
+ TyKind::Never
| TyKind::Tup(_)
- | TyKind::Ptr(_)
- | TyKind::TraitObject(..)
- | TyKind::Path(_) => Position::DerefStable(precedence),
- TyKind::OpaqueDef(..)
- | TyKind::Infer
- | TyKind::Typeof(..)
- | TyKind::Err => Position::ReborrowStable(precedence),
+ | TyKind::Path(_) => Position::DerefStable(
+ precedence,
+ cx.tcx
+ .erase_late_bound_regions(Binder::bind_with_vars(
+ cx.typeck_results().node_type(ty.ty.hir_id),
+ binder_args,
+ ))
+ .is_sized(cx.tcx.at(DUMMY_SP), cx.param_env.without_caller_bounds()),
+ ),
+ TyKind::OpaqueDef(..) | TyKind::Infer | TyKind::Typeof(..) | TyKind::TraitObject(..) | TyKind::Err => {
+ Position::ReborrowStable(precedence)
+ },
};
}
}
@@ -920,10 +994,238 @@ fn ty_contains_infer(ty: &hir::Ty<'_>) -> bool {
v.0
}
+// Checks whether:
+// * child is an expression of the form `&e` in an argument position requiring an `impl Trait`
+// * `e`'s type implements `Trait` and is copyable
+// If the conditions are met, returns `Some(Position::ImplArg(..))`; otherwise, returns `None`.
+// The "is copyable" condition is to avoid the case where removing the `&` means `e` would have to
+// be moved, but it cannot be.
+fn needless_borrow_impl_arg_position<'tcx>(
+ cx: &LateContext<'tcx>,
+ parent: &Expr<'tcx>,
+ arg_index: usize,
+ param_ty: ParamTy,
+ mut expr: &Expr<'tcx>,
+ precedence: i8,
+ msrv: Option<RustcVersion>,
+) -> Position {
+ let destruct_trait_def_id = cx.tcx.lang_items().destruct_trait();
+ let sized_trait_def_id = cx.tcx.lang_items().sized_trait();
+
+ let Some(callee_def_id) = fn_def_id(cx, parent) else { return Position::Other(precedence) };
+ let fn_sig = cx.tcx.fn_sig(callee_def_id).skip_binder();
+ let substs_with_expr_ty = cx
+ .typeck_results()
+ .node_substs(if let ExprKind::Call(callee, _) = parent.kind {
+ callee.hir_id
+ } else {
+ parent.hir_id
+ });
+
+ let predicates = cx.tcx.param_env(callee_def_id).caller_bounds();
+ let projection_predicates = predicates
+ .iter()
+ .filter_map(|predicate| {
+ if let PredicateKind::Projection(projection_predicate) = predicate.kind().skip_binder() {
+ Some(projection_predicate)
+ } else {
+ None
+ }
+ })
+ .collect::<Vec<_>>();
+
+ let mut trait_with_ref_mut_self_method = false;
+
+ // If no traits were found, or only the `Destruct`, `Sized`, or `Any` traits were found, return.
+ if predicates
+ .iter()
+ .filter_map(|predicate| {
+ if let PredicateKind::Trait(trait_predicate) = predicate.kind().skip_binder()
+ && trait_predicate.trait_ref.self_ty() == param_ty.to_ty(cx.tcx)
+ {
+ Some(trait_predicate.trait_ref.def_id)
+ } else {
+ None
+ }
+ })
+ .inspect(|trait_def_id| {
+ trait_with_ref_mut_self_method |= has_ref_mut_self_method(cx, *trait_def_id);
+ })
+ .all(|trait_def_id| {
+ Some(trait_def_id) == destruct_trait_def_id
+ || Some(trait_def_id) == sized_trait_def_id
+ || cx.tcx.is_diagnostic_item(sym::Any, trait_def_id)
+ })
+ {
+ return Position::Other(precedence);
+ }
+
+ // `substs_with_referent_ty` can be constructed outside of `check_referent` because the same
+ // elements are modified each time `check_referent` is called.
+ let mut substs_with_referent_ty = substs_with_expr_ty.to_vec();
+
+ let mut check_referent = |referent| {
+ let referent_ty = cx.typeck_results().expr_ty(referent);
+
+ if !is_copy(cx, referent_ty) {
+ return false;
+ }
+
+ // https://github.com/rust-lang/rust-clippy/pull/9136#pullrequestreview-1037379321
+ if trait_with_ref_mut_self_method && !matches!(referent_ty.kind(), ty::Ref(_, _, Mutability::Mut)) {
+ return false;
+ }
+
+ if !replace_types(
+ cx,
+ param_ty,
+ referent_ty,
+ fn_sig,
+ arg_index,
+ &projection_predicates,
+ &mut substs_with_referent_ty,
+ ) {
+ return false;
+ }
+
+ predicates.iter().all(|predicate| {
+ if let PredicateKind::Trait(trait_predicate) = predicate.kind().skip_binder()
+ && cx.tcx.is_diagnostic_item(sym::IntoIterator, trait_predicate.trait_ref.def_id)
+ && let ty::Param(param_ty) = trait_predicate.self_ty().kind()
+ && let GenericArgKind::Type(ty) = substs_with_referent_ty[param_ty.index as usize].unpack()
+ && ty.is_array()
+ && !meets_msrv(msrv, msrvs::ARRAY_INTO_ITERATOR)
+ {
+ return false;
+ }
+
+ let predicate = EarlyBinder(predicate).subst(cx.tcx, &substs_with_referent_ty);
+ let obligation = Obligation::new(ObligationCause::dummy(), cx.param_env, predicate);
+ cx.tcx
+ .infer_ctxt()
+ .enter(|infcx| infcx.predicate_must_hold_modulo_regions(&obligation))
+ })
+ };
+
+ let mut needless_borrow = false;
+ while let ExprKind::AddrOf(_, _, referent) = expr.kind {
+ if !check_referent(referent) {
+ break;
+ }
+ expr = referent;
+ needless_borrow = true;
+ }
+
+ if needless_borrow {
+ Position::ImplArg(expr.hir_id)
+ } else {
+ Position::Other(precedence)
+ }
+}
+
+fn has_ref_mut_self_method(cx: &LateContext<'_>, trait_def_id: DefId) -> bool {
+ cx.tcx
+ .associated_items(trait_def_id)
+ .in_definition_order()
+ .any(|assoc_item| {
+ if assoc_item.fn_has_self_parameter {
+ let self_ty = cx.tcx.fn_sig(assoc_item.def_id).skip_binder().inputs()[0];
+ matches!(self_ty.kind(), ty::Ref(_, _, Mutability::Mut))
+ } else {
+ false
+ }
+ })
+}
+
+// Iteratively replaces `param_ty` with `new_ty` in `substs`, and similarly for each resulting
+// projected type that is a type parameter. Returns `false` if replacing the types would have an
+// effect on the function signature beyond substituting `new_ty` for `param_ty`.
+// See: https://github.com/rust-lang/rust-clippy/pull/9136#discussion_r927212757
+fn replace_types<'tcx>(
+ cx: &LateContext<'tcx>,
+ param_ty: ParamTy,
+ new_ty: Ty<'tcx>,
+ fn_sig: FnSig<'tcx>,
+ arg_index: usize,
+ projection_predicates: &[ProjectionPredicate<'tcx>],
+ substs: &mut [ty::GenericArg<'tcx>],
+) -> bool {
+ let mut replaced = BitSet::new_empty(substs.len());
+
+ let mut deque = VecDeque::with_capacity(substs.len());
+ deque.push_back((param_ty, new_ty));
+
+ while let Some((param_ty, new_ty)) = deque.pop_front() {
+ // If `replaced.is_empty()`, then `param_ty` and `new_ty` are those initially passed in.
+ if !fn_sig
+ .inputs_and_output
+ .iter()
+ .enumerate()
+ .all(|(i, ty)| (replaced.is_empty() && i == arg_index) || !ty.contains(param_ty.to_ty(cx.tcx)))
+ {
+ return false;
+ }
+
+ substs[param_ty.index as usize] = ty::GenericArg::from(new_ty);
+
+ // The `replaced.insert(...)` check provides some protection against infinite loops.
+ if replaced.insert(param_ty.index) {
+ for projection_predicate in projection_predicates {
+ if projection_predicate.projection_ty.self_ty() == param_ty.to_ty(cx.tcx)
+ && let Some(term_ty) = projection_predicate.term.ty()
+ && let ty::Param(term_param_ty) = term_ty.kind()
+ {
+ let item_def_id = projection_predicate.projection_ty.item_def_id;
+ let assoc_item = cx.tcx.associated_item(item_def_id);
+ let projection = cx.tcx
+ .mk_projection(assoc_item.def_id, cx.tcx.mk_substs_trait(new_ty, &[]));
+
+ if let Ok(projected_ty) = cx.tcx.try_normalize_erasing_regions(cx.param_env, projection)
+ && substs[term_param_ty.index as usize] != ty::GenericArg::from(projected_ty)
+ {
+ deque.push_back((*term_param_ty, projected_ty));
+ }
+ }
+ }
+ }
+ }
+
+ true
+}
+
+struct TyPosition<'tcx> {
+ position: Position,
+ ty: Option<Ty<'tcx>>,
+}
+impl From<Position> for TyPosition<'_> {
+ fn from(position: Position) -> Self {
+ Self { position, ty: None }
+ }
+}
+impl<'tcx> TyPosition<'tcx> {
+ fn new_deref_stable_for_result(precedence: i8, ty: Ty<'tcx>) -> Self {
+ Self {
+ position: Position::ReborrowStable(precedence),
+ ty: Some(ty),
+ }
+ }
+ fn position_for_result(self, cx: &LateContext<'tcx>) -> Position {
+ match (self.position, self.ty) {
+ (Position::ReborrowStable(precedence), Some(ty)) => {
+ Position::DerefStable(precedence, ty.is_sized(cx.tcx.at(DUMMY_SP), cx.param_env))
+ },
+ (position, _) => position,
+ }
+ }
+ fn position_for_arg(self) -> Position {
+ self.position
+ }
+}
+
// Checks whether a type is stable when switching to auto dereferencing,
-fn param_auto_deref_stability(ty: Ty<'_>, precedence: i8) -> Position {
+fn ty_auto_deref_stability<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, precedence: i8) -> TyPosition<'tcx> {
let ty::Ref(_, mut ty, _) = *ty.kind() else {
- return Position::Other(precedence);
+ return Position::Other(precedence).into();
};
loop {
@@ -932,35 +1234,38 @@ fn param_auto_deref_stability(ty: Ty<'_>, precedence: i8) -> Position {
ty = ref_ty;
continue;
},
- ty::Infer(_)
- | ty::Error(_)
- | ty::Param(_)
- | ty::Bound(..)
- | ty::Opaque(..)
- | ty::Placeholder(_)
- | ty::Dynamic(..) => Position::ReborrowStable(precedence),
- ty::Adt(..) if ty.has_placeholders() || ty.has_param_types_or_consts() => {
- Position::ReborrowStable(precedence)
+ ty::Param(_) => TyPosition::new_deref_stable_for_result(precedence, ty),
+ ty::Infer(_) | ty::Error(_) | ty::Bound(..) | ty::Opaque(..) | ty::Placeholder(_) | ty::Dynamic(..) => {
+ Position::ReborrowStable(precedence).into()
},
- ty::Adt(..)
- | ty::Bool
+ ty::Adt(..) if ty.has_placeholders() || ty.has_opaque_types() => {
+ Position::ReborrowStable(precedence).into()
+ },
+ ty::Adt(_, substs) if substs.has_param_types_or_consts() => {
+ TyPosition::new_deref_stable_for_result(precedence, ty)
+ },
+ ty::Bool
| ty::Char
| ty::Int(_)
| ty::Uint(_)
- | ty::Float(_)
- | ty::Foreign(_)
- | ty::Str
| ty::Array(..)
- | ty::Slice(..)
+ | ty::Float(_)
| ty::RawPtr(..)
+ | ty::FnPtr(_) => Position::DerefStable(precedence, true).into(),
+ ty::Str | ty::Slice(..) => Position::DerefStable(precedence, false).into(),
+ ty::Adt(..)
+ | ty::Foreign(_)
| ty::FnDef(..)
- | ty::FnPtr(_)
- | ty::Closure(..)
| ty::Generator(..)
| ty::GeneratorWitness(..)
+ | ty::Closure(..)
| ty::Never
| ty::Tuple(_)
- | ty::Projection(_) => Position::DerefStable(precedence),
+ | ty::Projection(_) => Position::DerefStable(
+ precedence,
+ ty.is_sized(cx.tcx.at(DUMMY_SP), cx.param_env.without_caller_bounds()),
+ )
+ .into(),
};
}
}
@@ -1026,7 +1331,8 @@ fn report<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, state: State, data
},
State::DerefedBorrow(state) => {
let mut app = Applicability::MachineApplicable;
- let (snip, snip_is_macro) = snippet_with_context(cx, expr.span, data.span.ctxt(), "..", &mut app);
+ let snip_expr = state.snip_expr.map_or(expr, |hir_id| cx.tcx.hir().expect_expr(hir_id));
+ let (snip, snip_is_macro) = snippet_with_context(cx, snip_expr.span, data.span.ctxt(), "..", &mut app);
span_lint_hir_and_then(cx, NEEDLESS_BORROW, data.hir_id, data.span, state.msg, |diag| {
let calls_field = matches!(expr.kind, ExprKind::Field(..)) && matches!(data.position, Position::Callee);
let sugg = if !snip_is_macro
@@ -1040,34 +1346,64 @@ fn report<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, state: State, data
diag.span_suggestion(data.span, "change this to", sugg, app);
});
},
- State::ExplicitDeref { deref_span_id } => {
- let (span, hir_id, precedence) = if let Some((span, hir_id)) = deref_span_id
+ State::ExplicitDeref { mutability } => {
+ if matches!(
+ expr.kind,
+ ExprKind::Block(..)
+ | ExprKind::ConstBlock(_)
+ | ExprKind::If(..)
+ | ExprKind::Loop(..)
+ | ExprKind::Match(..)
+ ) && matches!(data.position, Position::DerefStable(_, true))
+ {
+ // Rustc bug: auto deref doesn't work on block expression when targeting sized types.
+ return;
+ }
+
+ let (prefix, precedence) = if let Some(mutability) = mutability
&& !cx.typeck_results().expr_ty(expr).is_ref()
{
- (span, hir_id, PREC_PREFIX)
+ let prefix = match mutability {
+ Mutability::Not => "&",
+ Mutability::Mut => "&mut ",
+ };
+ (prefix, 0)
} else {
- (data.span, data.hir_id, data.position.precedence())
+ ("", data.position.precedence())
};
span_lint_hir_and_then(
cx,
EXPLICIT_AUTO_DEREF,
- hir_id,
- span,
+ data.hir_id,
+ data.span,
"deref which would be done by auto-deref",
|diag| {
let mut app = Applicability::MachineApplicable;
- let (snip, snip_is_macro) = snippet_with_context(cx, expr.span, span.ctxt(), "..", &mut app);
+ let (snip, snip_is_macro) = snippet_with_context(cx, expr.span, data.span.ctxt(), "..", &mut app);
let sugg =
if !snip_is_macro && expr.precedence().order() < precedence && !has_enclosing_paren(&snip) {
- format!("({})", snip)
+ format!("{}({})", prefix, snip)
} else {
- snip.into()
+ format!("{}{}", prefix, snip)
};
- diag.span_suggestion(span, "try this", sugg, app);
+ diag.span_suggestion(data.span, "try this", sugg, app);
},
);
},
State::ExplicitDerefField { .. } => {
+ if matches!(
+ expr.kind,
+ ExprKind::Block(..)
+ | ExprKind::ConstBlock(_)
+ | ExprKind::If(..)
+ | ExprKind::Loop(..)
+ | ExprKind::Match(..)
+ ) && matches!(data.position, Position::DerefStable(_, true))
+ {
+ // Rustc bug: auto deref doesn't work on block expression when targeting sized types.
+ return;
+ }
+
span_lint_hir_and_then(
cx,
EXPLICIT_AUTO_DEREF,
@@ -1081,7 +1417,7 @@ fn report<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, state: State, data
},
);
},
- State::Borrow | State::Reborrow { .. } => (),
+ State::Borrow { .. } | State::Reborrow { .. } => (),
}
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-24 08:39:08 +0000