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Note when a a move/borrow error is caused by a deref coercion 

Fixes #73268

When a deref coercion occurs, we may end up with a move error if the
base value has been partially moved out of. However, we do not indicate
anywhere that a deref coercion is occuring, resulting in an error
message with a confusing span.

This PR adds an explicit note to move errors when a deref coercion is
involved. We mention the name of the type that the deref-coercion
resolved to, as well as the `Deref::Target` associated type being used.
This commit is contained in:
Aaron Hill 2020-07-25 07:04:13 -04:00
parent a1947b3f9e
commit d18b4bb7a7
No known key found for this signature in database
GPG Key ID: B4087E510E98B164
23 changed files with 250 additions and 54 deletions
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4
compiler/rustc_middle/src/ty/adjustment.rs
View File

@ -4,6 +4,7 @@ use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_hir::lang_items::LangItem;
use rustc_macros::HashStable;
use rustc_span::Span;
#[derive(Clone, Copy, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
pub enum PointerCast {
@ -113,6 +114,9 @@ pub enum Adjust<'tcx> {
pub struct OverloadedDeref<'tcx> {
pub region: ty::Region<'tcx>,
pub mutbl: hir::Mutability,
/// The `Span` associated with the field access or method call
/// that triggered this overloaded deref.
pub span: Span,
}
impl<'tcx> OverloadedDeref<'tcx> {

7
compiler/rustc_middle/src/ty/structural_impls.rs
View File

@ -606,8 +606,11 @@ impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> {
type Lifted = ty::adjustment::OverloadedDeref<'tcx>;
fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
tcx.lift(&self.region)
.map(|region| ty::adjustment::OverloadedDeref { region, mutbl: self.mutbl })
tcx.lift(&self.region).map(|region| ty::adjustment::OverloadedDeref {
region,
mutbl: self.mutbl,
span: self.span,
})
}
}

27
compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs
View File

@ -66,7 +66,10 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
let span = use_spans.args_or_use();
let move_site_vec = self.get_moved_indexes(location, mpi);
debug!("report_use_of_moved_or_uninitialized: move_site_vec={:?}", move_site_vec);
debug!(
"report_use_of_moved_or_uninitialized: move_site_vec={:?} use_spans={:?}",
move_site_vec, use_spans
);
let move_out_indices: Vec<_> =
move_site_vec.iter().map(|move_site| move_site.moi).collect();
@ -229,6 +232,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
);
}
}
// Deref::deref takes &self, which cannot cause a move
FnSelfUseKind::DerefCoercion { .. } => unreachable!(),
}
} else {
err.span_label(
@ -355,6 +360,20 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
self.note_type_does_not_implement_copy(&mut err, &note_msg, ty, span, partial_str);
}
if let UseSpans::FnSelfUse {
kind: FnSelfUseKind::DerefCoercion { deref_target, deref_target_ty },
..
} = use_spans
{
err.note(&format!(
"{} occurs due to deref coercion to `{}`",
desired_action.as_noun(),
deref_target_ty
));
err.span_note(deref_target, "deref defined here");
}
if let Some((_, mut old_err)) =
self.move_error_reported.insert(move_out_indices, (used_place, err))
{
@ -945,7 +964,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
name: &str,
borrow: &BorrowData<'tcx>,
drop_span: Span,
borrow_spans: UseSpans,
borrow_spans: UseSpans<'tcx>,
explanation: BorrowExplanation,
) -> DiagnosticBuilder<'cx> {
debug!(
@ -1146,7 +1165,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
location: Location,
borrow: &BorrowData<'tcx>,
drop_span: Span,
borrow_spans: UseSpans,
borrow_spans: UseSpans<'tcx>,
proper_span: Span,
explanation: BorrowExplanation,
) -> DiagnosticBuilder<'cx> {
@ -1274,7 +1293,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
fn report_escaping_closure_capture(
&mut self,
use_span: UseSpans,
use_span: UseSpans<'tcx>,
var_span: Span,
fr_name: &RegionName,
category: ConstraintCategory,

2
compiler/rustc_mir/src/borrow_check/diagnostics/explain_borrow.rs
View File

@ -501,7 +501,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
fn later_use_kind(
&self,
borrow: &BorrowData<'tcx>,
use_spans: UseSpans,
use_spans: UseSpans<'tcx>,
location: Location,
) -> (LaterUseKind, Span) {
match use_spans {

73
compiler/rustc_mir/src/borrow_check/diagnostics/mod.rs
View File

@ -11,7 +11,7 @@ use rustc_middle::mir::{
PlaceRef, ProjectionElem, Rvalue, Statement, StatementKind, Terminator, TerminatorKind,
};
use rustc_middle::ty::print::Print;
use rustc_middle::ty::{self, DefIdTree, Ty, TyCtxt};
use rustc_middle::ty::{self, DefIdTree, Instance, Ty, TyCtxt};
use rustc_span::{
hygiene::{DesugaringKind, ForLoopLoc},
symbol::sym,
@ -538,7 +538,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
/// The span(s) associated to a use of a place.
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub(super) enum UseSpans {
pub(super) enum UseSpans<'tcx> {
/// The access is caused by capturing a variable for a closure.
ClosureUse {
/// This is true if the captured variable was from a generator.
@ -558,7 +558,7 @@ pub(super) enum UseSpans {
fn_call_span: Span,
/// The definition span of the method being called
fn_span: Span,
kind: FnSelfUseKind,
kind: FnSelfUseKind<'tcx>,
},
/// This access is caused by a `match` or `if let` pattern.
PatUse(Span),
@ -567,22 +567,32 @@ pub(super) enum UseSpans {
}
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub(super) enum FnSelfUseKind {
pub(super) enum FnSelfUseKind<'tcx> {
/// A normal method call of the form `receiver.foo(a, b, c)`
Normal { self_arg: Ident, implicit_into_iter: bool },
/// A call to `FnOnce::call_once`, desugared from `my_closure(a, b, c)`
FnOnceCall,
/// A call to an operator trait, desuraged from operator syntax (e.g. `a << b`)
Operator { self_arg: Ident },
DerefCoercion {
/// The `Span` of the `Target` associated type
/// in the `Deref` impl we are using.
deref_target: Span,
/// The type `T::Deref` we are dereferencing to
deref_target_ty: Ty<'tcx>,
},
}
impl UseSpans {
impl UseSpans<'_> {
pub(super) fn args_or_use(self) -> Span {
match self {
UseSpans::ClosureUse { args_span: span, .. }
| UseSpans::PatUse(span)
| UseSpans::FnSelfUse { var_span: span, .. }
| UseSpans::OtherUse(span) => span,
UseSpans::FnSelfUse {
fn_call_span, kind: FnSelfUseKind::DerefCoercion { .. }, ..
} => fn_call_span,
UseSpans::FnSelfUse { var_span, .. } => var_span,
}
}
@ -590,8 +600,11 @@ impl UseSpans {
match self {
UseSpans::ClosureUse { var_span: span, .. }
| UseSpans::PatUse(span)
| UseSpans::FnSelfUse { var_span: span, .. }
| UseSpans::OtherUse(span) => span,
UseSpans::FnSelfUse {
fn_call_span, kind: FnSelfUseKind::DerefCoercion { .. }, ..
} => fn_call_span,
UseSpans::FnSelfUse { var_span, .. } => var_span,
}
}
@ -754,7 +767,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
&self,
moved_place: PlaceRef<'tcx>, // Could also be an upvar.
location: Location,
) -> UseSpans {
) -> UseSpans<'tcx> {
use self::UseSpans::*;
let stmt = match self.body[location.block].statements.get(location.statement_index) {
@ -809,36 +822,64 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
kind: TerminatorKind::Call { fn_span, from_hir_call, .. }, ..
}) = &self.body[location.block].terminator
{
let method_did = if let Some(method_did) =
let (method_did, method_substs) = if let Some(info) =
crate::util::find_self_call(self.infcx.tcx, &self.body, target_temp, location.block)
{
method_did
info
} else {
return normal_ret;
};
let tcx = self.infcx.tcx;
let parent = tcx.parent(method_did);
let is_fn_once = parent == tcx.lang_items().fn_once_trait();
let is_operator = !from_hir_call
&& parent.map_or(false, |p| tcx.lang_items().group(LangItemGroup::Op).contains(&p));
let is_deref = !from_hir_call && tcx.is_diagnostic_item(sym::deref_method, method_did);
let fn_call_span = *fn_span;
let self_arg = tcx.fn_arg_names(method_did)[0];
debug!(
"terminator = {:?} from_hir_call={:?}",
self.body[location.block].terminator, from_hir_call
);
// Check for a 'special' use of 'self' -
// an FnOnce call, an operator (e.g. `<<`), or a
// deref coercion.
let kind = if is_fn_once {
FnSelfUseKind::FnOnceCall
Some(FnSelfUseKind::FnOnceCall)
} else if is_operator {
FnSelfUseKind::Operator { self_arg }
Some(FnSelfUseKind::Operator { self_arg })
} else if is_deref {
let deref_target =
tcx.get_diagnostic_item(sym::deref_target).and_then(|deref_target| {
Instance::resolve(tcx, self.param_env, deref_target, method_substs)
.transpose()
});
if let Some(Ok(instance)) = deref_target {
let deref_target_ty = instance.ty(tcx, self.param_env);
Some(FnSelfUseKind::DerefCoercion {
deref_target: tcx.def_span(instance.def_id()),
deref_target_ty,
})
} else {
None
}
} else {
None
};
let kind = kind.unwrap_or_else(|| {
// This isn't a 'special' use of `self`
debug!("move_spans: method_did={:?}, fn_call_span={:?}", method_did, fn_call_span);
let implicit_into_iter = matches!(
fn_call_span.desugaring_kind(),
Some(DesugaringKind::ForLoop(ForLoopLoc::IntoIter))
);
FnSelfUseKind::Normal { self_arg, implicit_into_iter }
};
});
return FnSelfUse {
var_span: stmt.source_info.span,
@ -859,7 +900,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
/// and its usage of the local assigned at `location`.
/// This is done by searching in statements succeeding `location`
/// and originating from `maybe_closure_span`.
pub(super) fn borrow_spans(&self, use_span: Span, location: Location) -> UseSpans {
pub(super) fn borrow_spans(&self, use_span: Span, location: Location) -> UseSpans<'tcx> {
use self::UseSpans::*;
debug!("borrow_spans: use_span={:?} location={:?}", use_span, location);
@ -963,7 +1004,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
/// Helper to retrieve span(s) of given borrow from the current MIR
/// representation
pub(super) fn retrieve_borrow_spans(&self, borrow: &BorrowData<'_>) -> UseSpans {
pub(super) fn retrieve_borrow_spans(&self, borrow: &BorrowData<'_>) -> UseSpans<'tcx> {
let span = self.body.source_info(borrow.reserve_location).span;
self.borrow_spans(span, borrow.reserve_location)
}

6
compiler/rustc_mir/src/borrow_check/diagnostics/move_errors.rs
View File

@ -47,7 +47,7 @@ enum GroupedMoveError<'tcx> {
// Everything that isn't from pattern matching.
OtherIllegalMove {
original_path: Place<'tcx>,
use_spans: UseSpans,
use_spans: UseSpans<'tcx>,
kind: IllegalMoveOriginKind<'tcx>,
},
}
@ -222,7 +222,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
let (mut err, err_span) = {
let (span, use_spans, original_path, kind): (
Span,
Option<UseSpans>,
Option<UseSpans<'tcx>>,
Place<'tcx>,
&IllegalMoveOriginKind<'_>,
) = match error {
@ -291,7 +291,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
move_place: Place<'tcx>,
deref_target_place: Place<'tcx>,
span: Span,
use_spans: Option<UseSpans>,
use_spans: Option<UseSpans<'tcx>>,
) -> DiagnosticBuilder<'a> {
// Inspect the type of the content behind the
// borrow to provide feedback about why this

5
compiler/rustc_mir/src/borrow_check/mod.rs
View File

@ -17,7 +17,7 @@ use rustc_middle::mir::{AggregateKind, BasicBlock, BorrowCheckResult, BorrowKind
use rustc_middle::mir::{Field, ProjectionElem, Promoted, Rvalue, Statement, StatementKind};
use rustc_middle::mir::{InlineAsmOperand, Terminator, TerminatorKind};
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::{self, InstanceDef, RegionVid, TyCtxt};
use rustc_middle::ty::{self, InstanceDef, ParamEnv, RegionVid, TyCtxt};
use rustc_session::lint::builtin::{MUTABLE_BORROW_RESERVATION_CONFLICT, UNUSED_MUT};
use rustc_span::{Span, Symbol, DUMMY_SP};
@ -287,6 +287,7 @@ fn do_mir_borrowck<'a, 'tcx>(
if let Err((move_data, move_errors)) = move_data_results {
let mut promoted_mbcx = MirBorrowckCtxt {
infcx,
param_env,
body: promoted_body,
mir_def_id: def.did,
move_data: &move_data,
@ -320,6 +321,7 @@ fn do_mir_borrowck<'a, 'tcx>(
let mut mbcx = MirBorrowckCtxt {
infcx,
param_env,
body,
mir_def_id: def.did,
move_data: &mdpe.move_data,
@ -473,6 +475,7 @@ fn do_mir_borrowck<'a, 'tcx>(
crate struct MirBorrowckCtxt<'cx, 'tcx> {
crate infcx: &'cx InferCtxt<'cx, 'tcx>,
param_env: ParamEnv<'tcx>,
body: &'cx Body<'tcx>,
mir_def_id: LocalDefId,
move_data: &'cx MoveData<'tcx>,

2
compiler/rustc_mir/src/transform/check_const_item_mutation.rs
View File

@ -101,7 +101,7 @@ impl<'a, 'tcx> Visitor<'tcx> for ConstMutationChecker<'a, 'tcx> {
.note("each usage of a `const` item creates a new temporary")
.note("the mutable reference will refer to this temporary, not the original `const` item");
if let Some(method_did) = method_did {
if let Some((method_did, _substs)) = method_did {
lint.span_note(self.tcx.def_span(method_did), "mutable reference created due to call to this method");
}

13
compiler/rustc_mir/src/util/find_self_call.rs
View File

@ -1,30 +1,31 @@
use rustc_middle::mir::*;
use rustc_middle::ty::subst::SubstsRef;
use rustc_middle::ty::{self, TyCtxt};
use rustc_span::def_id::DefId;
/// Checks if the specified `local` is used as the `self` prameter of a method call
/// in the provided `BasicBlock`. If it is, then the `DefId` of the called method is
/// returned.
pub fn find_self_call(
tcx: TyCtxt<'_>,
body: &Body<'_>,
pub fn find_self_call<'tcx>(
tcx: TyCtxt<'tcx>,
body: &Body<'tcx>,
local: Local,
block: BasicBlock,
) -> Option<DefId> {
) -> Option<(DefId, SubstsRef<'tcx>)> {
debug!("find_self_call(local={:?}): terminator={:?}", local, &body[block].terminator);
if let Some(Terminator { kind: TerminatorKind::Call { func, args, .. }, .. }) =
&body[block].terminator
{
debug!("find_self_call: func={:?}", func);
if let Operand::Constant(box Constant { literal: ty::Const { ty, .. }, .. }) = func {
if let ty::FnDef(def_id, _) = *ty.kind() {
if let ty::FnDef(def_id, substs) = *ty.kind() {
if let Some(ty::AssocItem { fn_has_self_parameter: true, .. }) =
tcx.opt_associated_item(def_id)
{
debug!("find_self_call: args={:?}", args);
if let [Operand::Move(self_place) | Operand::Copy(self_place), ..] = **args {
if self_place.as_local() == Some(local) {
return Some(def_id);
return Some((def_id, substs));
}
}
}

29
compiler/rustc_mir_build/src/thir/cx/expr.rs
View File

@ -117,7 +117,14 @@ fn apply_adjustment<'a, 'tcx>(
},
};
overloaded_place(cx, hir_expr, adjustment.target, Some(call), vec![expr.to_ref()])
overloaded_place(
cx,
hir_expr,
adjustment.target,
Some(call),
vec![expr.to_ref()],
deref.span,
)
}
Adjust::Borrow(AutoBorrow::Ref(_, m)) => {
ExprKind::Borrow { borrow_kind: m.to_borrow_kind(), arg: expr.to_ref() }
@ -277,7 +284,14 @@ fn make_mirror_unadjusted<'a, 'tcx>(
hir::ExprKind::Index(ref lhs, ref index) => {
if cx.typeck_results().is_method_call(expr) {
overloaded_place(cx, expr, expr_ty, None, vec![lhs.to_ref(), index.to_ref()])
overloaded_place(
cx,
expr,
expr_ty,
None,
vec![lhs.to_ref(), index.to_ref()],
expr.span,
)
} else {
ExprKind::Index { lhs: lhs.to_ref(), index: index.to_ref() }
}
@ -285,7 +299,7 @@ fn make_mirror_unadjusted<'a, 'tcx>(
hir::ExprKind::Unary(hir::UnOp::UnDeref, ref arg) => {
if cx.typeck_results().is_method_call(expr) {
overloaded_place(cx, expr, expr_ty, None, vec![arg.to_ref()])
overloaded_place(cx, expr, expr_ty, None, vec![arg.to_ref()], expr.span)
} else {
ExprKind::Deref { arg: arg.to_ref() }
}
@ -1025,6 +1039,7 @@ fn overloaded_place<'a, 'tcx>(
place_ty: Ty<'tcx>,
overloaded_callee: Option<(DefId, SubstsRef<'tcx>)>,
args: Vec<ExprRef<'tcx>>,
span: Span,
) -> ExprKind<'tcx> {
// For an overloaded *x or x[y] expression of type T, the method
// call returns an &T and we must add the deref so that the types
@ -1040,24 +1055,24 @@ fn overloaded_place<'a, 'tcx>(
// `Deref(Mut)::Deref(_mut)` and `Index(Mut)::index(_mut)`.
let (region, mutbl) = match *recv_ty.kind() {
ty::Ref(region, _, mutbl) => (region, mutbl),
_ => span_bug!(expr.span, "overloaded_place: receiver is not a reference"),
_ => span_bug!(span, "overloaded_place: receiver is not a reference"),
};
let ref_ty = cx.tcx.mk_ref(region, ty::TypeAndMut { ty: place_ty, mutbl });
// construct the complete expression `foo()` for the overloaded call,
// which will yield the &T type
let temp_lifetime = cx.region_scope_tree.temporary_scope(expr.hir_id.local_id);
let fun = method_callee(cx, expr, expr.span, overloaded_callee);
let fun = method_callee(cx, expr, span, overloaded_callee);
let ref_expr = Expr {
temp_lifetime,
ty: ref_ty,
span: expr.span,
span,
kind: ExprKind::Call {
ty: fun.ty,
fun: fun.to_ref(),
args,
from_hir_call: false,
fn_span: expr.span,
fn_span: span,
},
};

2
compiler/rustc_span/src/symbol.rs
View File

@ -416,7 +416,9 @@ symbols! {
deny,
deprecated,
deref,
deref_method,
deref_mut,
deref_target,
derive,
diagnostic,
direct,

7
compiler/rustc_trait_selection/src/autoderef.rs
View File

@ -27,6 +27,7 @@ pub struct Autoderef<'a, 'tcx> {
// Meta infos:
infcx: &'a InferCtxt<'a, 'tcx>,
span: Span,
overloaded_span: Span,
body_id: hir::HirId,
param_env: ty::ParamEnv<'tcx>,
@ -98,10 +99,12 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
body_id: hir::HirId,
span: Span,
base_ty: Ty<'tcx>,
overloaded_span: Span,
) -> Autoderef<'a, 'tcx> {
Autoderef {
infcx,
span,
overloaded_span,
body_id,
param_env,
state: AutoderefSnapshot {
@ -190,6 +193,10 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
self.span
}
pub fn overloaded_span(&self) -> Span {
self.overloaded_span
}
pub fn reached_recursion_limit(&self) -> bool {
self.state.reached_recursion_limit
}

2
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View File

@ -483,7 +483,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
};
if let ty::Ref(region, base_ty, mutbl) = *real_ty.kind() {
let mut autoderef = Autoderef::new(self, param_env, body_id, span, base_ty);
let mut autoderef = Autoderef::new(self, param_env, body_id, span, base_ty, span);
if let Some(steps) = autoderef.find_map(|(ty, steps)| {
// Re-add the `&`
let ty = self.tcx.mk_ref(region, TypeAndMut { ty, mutbl });

19
compiler/rustc_typeck/src/check/autoderef.rs
View File

@ -12,7 +12,18 @@ use std::iter;
impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
pub fn autoderef(&'a self, span: Span, base_ty: Ty<'tcx>) -> Autoderef<'a, 'tcx> {
Autoderef::new(self, self.param_env, self.body_id, span, base_ty)
Autoderef::new(self, self.param_env, self.body_id, span, base_ty, span)
}
/// Like `autoderef`, but provides a custom `Span` to use for calls to
/// an overloaded `Deref` operator
pub fn autoderef_overloaded_span(
&'a self,
span: Span,
base_ty: Ty<'tcx>,
overloaded_span: Span,
) -> Autoderef<'a, 'tcx> {
Autoderef::new(self, self.param_env, self.body_id, span, base_ty, overloaded_span)
}
pub fn try_overloaded_deref(
@ -44,7 +55,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
|InferOk { value: method, obligations: o }| {
obligations.extend(o);
if let ty::Ref(region, _, mutbl) = *method.sig.output().kind() {
Some(OverloadedDeref { region, mutbl })
Some(OverloadedDeref {
region,
mutbl,
span: autoderef.overloaded_span(),
})
} else {
None
}

3
compiler/rustc_typeck/src/check/method/confirm.rs
View File

@ -137,7 +137,8 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
) -> Ty<'tcx> {
// Commit the autoderefs by calling `autoderef` again, but this
// time writing the results into the various typeck results.
let mut autoderef = self.autoderef(self.span, unadjusted_self_ty);
let mut autoderef =
self.autoderef_overloaded_span(self.span, unadjusted_self_ty, self.call_expr.span);
let (_, n) = match autoderef.nth(pick.autoderefs) {
Some(n) => n,
None => {

7
compiler/rustc_typeck/src/check/method/probe.rs
View File

@ -446,9 +446,10 @@ fn method_autoderef_steps<'tcx>(
tcx.infer_ctxt().enter_with_canonical(DUMMY_SP, &goal, |ref infcx, goal, inference_vars| {
let ParamEnvAnd { param_env, value: self_ty } = goal;
let mut autoderef = Autoderef::new(infcx, param_env, hir::CRATE_HIR_ID, DUMMY_SP, self_ty)
.include_raw_pointers()
.silence_errors();
let mut autoderef =
Autoderef::new(infcx, param_env, hir::CRATE_HIR_ID, DUMMY_SP, self_ty, DUMMY_SP)
.include_raw_pointers()
.silence_errors();
let mut reached_raw_pointer = false;
let mut steps: Vec<_> = autoderef
.by_ref()

2
compiler/rustc_typeck/src/check/place_op.rs
View File

@ -242,7 +242,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
) {
let method = self.register_infer_ok_obligations(ok);
if let ty::Ref(region, _, mutbl) = *method.sig.output().kind() {
*deref = OverloadedDeref { region, mutbl };
*deref = OverloadedDeref { region, mutbl, span: deref.span };
}
// If this is a union field, also throw an error for `DerefMut` of `ManuallyDrop` (see RFC 2514).
// This helps avoid accidental drops.

2
library/core/src/ops/deref.rs
View File

@ -63,11 +63,13 @@
pub trait Deref {
/// The resulting type after dereferencing.
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_diagnostic_item = "deref_target"]
type Target: ?Sized;
/// Dereferences the value.
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_diagnostic_item = "deref_method"]
fn deref(&self) -> &Self::Target;
}

2
src/test/ui/lint/lint-unconditional-recursion.stderr
View File

@ -149,7 +149,7 @@ error: function cannot return without recursing
LL | fn deref(&self) -> &Baz {
| ^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing
LL | self.as_ref()
| ---- recursive call site
| ------------- recursive call site
|
= help: a `loop` may express intention better if this is on purpose

33
src/test/ui/moves/move-deref-coercion.rs Normal file
View File

@ -0,0 +1,33 @@
use std::ops::Deref;
struct NotCopy {
inner: bool
}
impl NotCopy {
fn inner_method(&self) {}
}
struct Foo {
first: NotCopy,
second: NotCopy
}
impl Deref for Foo {
type Target = NotCopy;
fn deref(&self) -> &NotCopy {
&self.second
}
}
fn use_field(val: Foo) {
let _val = val.first;
val.inner; //~ ERROR borrow of
}
fn use_method(val: Foo) {
let _val = val.first;
val.inner_method(); //~ ERROR borrow of
}
fn main() {}

35
src/test/ui/moves/move-deref-coercion.stderr Normal file
View File

@ -0,0 +1,35 @@
error[E0382]: borrow of partially moved value: `val`
--> $DIR/move-deref-coercion.rs:25:5
|
LL | let _val = val.first;
| --------- value partially moved here
LL | val.inner;
| ^^^^^^^^^ value borrowed here after partial move
|
= note: partial move occurs because `val.first` has type `NotCopy`, which does not implement the `Copy` trait
= note: borrow occurs due to deref coercion to `NotCopy`
note: deref defined here
--> $DIR/move-deref-coercion.rs:17:5
|
LL | type Target = NotCopy;
| ^^^^^^^^^^^^^^^^^^^^^^
error[E0382]: borrow of partially moved value: `val`
--> $DIR/move-deref-coercion.rs:30:5
|
LL | let _val = val.first;
| --------- value partially moved here
LL | val.inner_method();
| ^^^^^^^^^^^^^^^^^^ value borrowed here after partial move
|
= note: partial move occurs because `val.first` has type `NotCopy`, which does not implement the `Copy` trait
= note: borrow occurs due to deref coercion to `NotCopy`
note: deref defined here
--> $DIR/move-deref-coercion.rs:17:5
|
LL | type Target = NotCopy;
| ^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0382`.

11
src/test/ui/no-capture-arc.stderr
View File

@ -1,5 +1,5 @@
error[E0382]: borrow of moved value: `arc_v`
--> $DIR/no-capture-arc.rs:14:18
--> $DIR/no-capture-arc.rs:14:16
|
LL | let arc_v = Arc::new(v);
| ----- move occurs because `arc_v` has type `Arc<Vec<i32>>`, which does not implement the `Copy` trait
@ -10,7 +10,14 @@ LL | assert_eq!((*arc_v)[3], 4);
| ----- variable moved due to use in closure
...
LL | assert_eq!((*arc_v)[2], 3);
| ^^^^^ value borrowed here after move
| ^^^^^^^^ value borrowed here after move
|
= note: borrow occurs due to deref coercion to `Vec<i32>`
note: deref defined here
--> $SRC_DIR/alloc/src/sync.rs:LL:COL
|
LL | type Target = T;
| ^^^^^^^^^^^^^^^^
error: aborting due to previous error

11
src/test/ui/no-reuse-move-arc.stderr
View File

@ -1,5 +1,5 @@
error[E0382]: borrow of moved value: `arc_v`
--> $DIR/no-reuse-move-arc.rs:12:18
--> $DIR/no-reuse-move-arc.rs:12:16
|
LL | let arc_v = Arc::new(v);
| ----- move occurs because `arc_v` has type `Arc<Vec<i32>>`, which does not implement the `Copy` trait
@ -10,7 +10,14 @@ LL | assert_eq!((*arc_v)[3], 4);
| ----- variable moved due to use in closure
...
LL | assert_eq!((*arc_v)[2], 3);
| ^^^^^ value borrowed here after move
| ^^^^^^^^ value borrowed here after move
|
= note: borrow occurs due to deref coercion to `Vec<i32>`
note: deref defined here
--> $SRC_DIR/alloc/src/sync.rs:LL:COL
|
LL | type Target = T;
| ^^^^^^^^^^^^^^^^
error: aborting due to previous error