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Auto merge of #106095 - estebank:pin-mut-reborrow, r=compiler-errors

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Suggest `Pin::as_mut` when encountering borrow error

Fix #65409 for `Pin<&mut T>`.
This commit is contained in:
bors 2022-12-27 07:31:42 +00:00
commit 0ca50032ce
17 changed files with 205 additions and 23 deletions
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14
compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
View file

@ -194,7 +194,13 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
if !seen_spans.contains(&move_span) {
if !closure {
self.suggest_ref_or_clone(mpi, move_span, &mut err, &mut in_pattern);
self.suggest_ref_or_clone(
mpi,
move_span,
&mut err,
&mut in_pattern,
move_spans,
);
}
self.explain_captures(
@ -312,6 +318,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
move_span: Span,
err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>,
in_pattern: &mut bool,
move_spans: UseSpans<'_>,
) {
struct ExpressionFinder<'hir> {
expr_span: Span,
@ -440,6 +447,11 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
) = call_expr.kind
{
// Do not suggest `.clone()` in a `for` loop, we already suggest borrowing.
} else if let UseSpans::FnSelfUse {
kind: CallKind::Normal { .. },
..
} = move_spans {
// We already suggest cloning for these cases in `explain_captures`.
} else {
self.suggest_cloning(err, ty, move_span);
}

55
compiler/rustc_borrowck/src/diagnostics/mod.rs
View file

@ -6,7 +6,7 @@ use rustc_errors::{Applicability, Diagnostic};
use rustc_hir as hir;
use rustc_hir::def::{CtorKind, Namespace};
use rustc_hir::GeneratorKind;
use rustc_infer::infer::TyCtxtInferExt;
use rustc_infer::infer::{LateBoundRegionConversionTime, TyCtxtInferExt};
use rustc_middle::mir::tcx::PlaceTy;
use rustc_middle::mir::{
AggregateKind, Constant, FakeReadCause, Field, Local, LocalInfo, LocalKind, Location, Operand,
@ -18,7 +18,10 @@ use rustc_mir_dataflow::move_paths::{InitLocation, LookupResult};
use rustc_span::def_id::LocalDefId;
use rustc_span::{symbol::sym, Span, Symbol, DUMMY_SP};
use rustc_target::abi::VariantIdx;
use rustc_trait_selection::traits::type_known_to_meet_bound_modulo_regions;
use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
use rustc_trait_selection::traits::{
type_known_to_meet_bound_modulo_regions, Obligation, ObligationCause,
};
use super::borrow_set::BorrowData;
use super::MirBorrowckCtxt;
@ -1066,18 +1069,16 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
}
CallKind::Normal { self_arg, desugaring, method_did } => {
let self_arg = self_arg.unwrap();
let tcx = self.infcx.tcx;
if let Some((CallDesugaringKind::ForLoopIntoIter, _)) = desugaring {
let ty = moved_place.ty(self.body, self.infcx.tcx).ty;
let suggest = match self.infcx.tcx.get_diagnostic_item(sym::IntoIterator) {
let ty = moved_place.ty(self.body, tcx).ty;
let suggest = match tcx.get_diagnostic_item(sym::IntoIterator) {
Some(def_id) => {
let infcx = self.infcx.tcx.infer_ctxt().build();
type_known_to_meet_bound_modulo_regions(
&infcx,
self.param_env,
infcx.tcx.mk_imm_ref(
infcx.tcx.lifetimes.re_erased,
infcx.tcx.erase_regions(ty),
),
tcx.mk_imm_ref(tcx.lifetimes.re_erased, tcx.erase_regions(ty)),
def_id,
DUMMY_SP,
)
@ -1133,8 +1134,44 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
place_name, partially_str, loop_message
),
);
let infcx = tcx.infer_ctxt().build();
let ty = tcx.erase_regions(moved_place.ty(self.body, tcx).ty);
if let ty::Adt(def, substs) = ty.kind()
&& Some(def.did()) == tcx.lang_items().pin_type()
&& let ty::Ref(_, _, hir::Mutability::Mut) = substs.type_at(0).kind()
&& let self_ty = infcx.replace_bound_vars_with_fresh_vars(
fn_call_span,
LateBoundRegionConversionTime::FnCall,
tcx.fn_sig(method_did).input(0),
)
&& infcx.can_eq(self.param_env, ty, self_ty).is_ok()
{
err.span_suggestion_verbose(
fn_call_span.shrink_to_lo(),
"consider reborrowing the `Pin` instead of moving it",
"as_mut().".to_string(),
Applicability::MaybeIncorrect,
);
}
if let Some(clone_trait) = tcx.lang_items().clone_trait()
&& let trait_ref = tcx.mk_trait_ref(clone_trait, [ty])
&& let o = Obligation::new(
tcx,
ObligationCause::dummy(),
self.param_env,
ty::Binder::dummy(trait_ref),
)
&& infcx.predicate_must_hold_modulo_regions(&o)
{
err.span_suggestion_verbose(
fn_call_span.shrink_to_lo(),
"you can `clone` the value and consume it, but this might not be \
your desired behavior",
"clone().".to_string(),
Applicability::MaybeIncorrect,
);
}
}
let tcx = self.infcx.tcx;
// Avoid pointing to the same function in multiple different
// error messages.
if span != DUMMY_SP && self.fn_self_span_reported.insert(self_arg.span) {