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Rollup merge of rust-lang#89734 - estebank:issue-72312, r=nikomatsakis
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Point at capture points for non-`'static` reference crossing a `yield` point

```
error[E0759]: `self` has an anonymous lifetime `'_` but it needs to satisfy a `'static` lifetime requirement
  --> $DIR/issue-72312.rs:10:24
   |
LL |     pub async fn start(&self) {
   |                        ^^^^^ this data with an anonymous lifetime `'_`...
...
LL |         require_static(async move {
   |         -------------- ...is required to live as long as `'static` here...
LL |             &self;
   |             ----- ...and is captured here
   |
note: `'static` lifetime requirement introduced by this trait bound
  --> $DIR/issue-72312.rs:2:22
   |
LL | fn require_static<T: 'static>(val: T) -> T {
   |                      ^^^^^^^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0759`.
```

Fix rust-lang#72312.
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@matthiaskrgr
matthiaskrgr committed Dec 11, 2021
2 parents b6d96a1 + d2d9eb3 commit d9df1a8
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Showing 37 changed files with 466 additions and 133 deletions.
1 change: 1 addition & 0 deletions compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -368,6 +368,7 @@ fn try_extract_error_from_fulfill_cx<'tcx>(
error_region,
cause.clone(),
placeholder_region,
vec![],
),
),
(Some(error_region), _) => NiceRegionError::new(
Expand Down
3 changes: 2 additions & 1 deletion compiler/rustc_infer/src/infer/error_reporting/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -384,6 +384,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
sub_r,
sup_origin,
sup_r,
_,
) => {
if sub_r.is_placeholder() {
self.report_placeholder_failure(sub_origin, sub_r, sup_r).emit();
Expand Down Expand Up @@ -464,7 +465,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
errors.sort_by_key(|u| match *u {
RegionResolutionError::ConcreteFailure(ref sro, _, _) => sro.span(),
RegionResolutionError::GenericBoundFailure(ref sro, _, _) => sro.span(),
RegionResolutionError::SubSupConflict(_, ref rvo, _, _, _, _) => rvo.span(),
RegionResolutionError::SubSupConflict(_, ref rvo, _, _, _, _, _) => rvo.span(),
RegionResolutionError::UpperBoundUniverseConflict(_, ref rvo, _, _, _) => rvo.span(),
});
errors
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -67,7 +67,7 @@ impl<'cx, 'tcx> NiceRegionError<'cx, 'tcx> {
pub fn regions(&self) -> Option<(Span, ty::Region<'tcx>, ty::Region<'tcx>)> {
match (&self.error, self.regions) {
(Some(ConcreteFailure(origin, sub, sup)), None) => Some((origin.span(), sub, sup)),
(Some(SubSupConflict(_, _, origin, sub, _, sup)), None) => {
(Some(SubSupConflict(_, _, origin, sub, _, sup, _)), None) => {
Some((origin.span(), sub, sup))
}
(None, Some((span, sub, sup))) => Some((span, sub, sup)),
Expand Down
4 changes: 4 additions & 0 deletions compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@ impl NiceRegionError<'me, 'tcx> {
sub_placeholder @ ty::RePlaceholder(_),
_,
sup_placeholder @ ty::RePlaceholder(_),
_,
)) => self.try_report_trait_placeholder_mismatch(
Some(self.tcx().mk_region(ty::ReVar(*vid))),
cause,
Expand All @@ -49,6 +50,7 @@ impl NiceRegionError<'me, 'tcx> {
sub_placeholder @ ty::RePlaceholder(_),
_,
_,
_,
)) => self.try_report_trait_placeholder_mismatch(
Some(self.tcx().mk_region(ty::ReVar(*vid))),
cause,
Expand All @@ -64,6 +66,7 @@ impl NiceRegionError<'me, 'tcx> {
_,
_,
sup_placeholder @ ty::RePlaceholder(_),
_,
)) => self.try_report_trait_placeholder_mismatch(
Some(self.tcx().mk_region(ty::ReVar(*vid))),
cause,
Expand All @@ -79,6 +82,7 @@ impl NiceRegionError<'me, 'tcx> {
_,
SubregionOrigin::Subtype(box TypeTrace { cause, values }),
sup_placeholder @ ty::RePlaceholder(_),
_,
)) => self.try_report_trait_placeholder_mismatch(
Some(self.tcx().mk_region(ty::ReVar(*vid))),
cause,
Expand Down
139 changes: 93 additions & 46 deletions compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,8 @@ use rustc_hir::def_id::DefId;
use rustc_hir::intravisit::{walk_ty, ErasedMap, NestedVisitorMap, Visitor};
use rustc_hir::{self as hir, GenericBound, Item, ItemKind, Lifetime, LifetimeName, Node, TyKind};
use rustc_middle::ty::{
self, AssocItemContainer, RegionKind, Ty, TyCtxt, TypeFoldable, TypeVisitor,
self, AssocItemContainer, RegionKind, StaticLifetimeVisitor, Ty, TyCtxt, TypeFoldable,
TypeVisitor,
};
use rustc_span::symbol::Ident;
use rustc_span::{MultiSpan, Span};
Expand All @@ -23,16 +24,17 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
pub(super) fn try_report_static_impl_trait(&self) -> Option<ErrorReported> {
debug!("try_report_static_impl_trait(error={:?})", self.error);
let tcx = self.tcx();
let (var_origin, sub_origin, sub_r, sup_origin, sup_r) = match self.error.as_ref()? {
let (var_origin, sub_origin, sub_r, sup_origin, sup_r, spans) = match self.error.as_ref()? {
RegionResolutionError::SubSupConflict(
_,
var_origin,
sub_origin,
sub_r,
sup_origin,
sup_r,
spans,
) if **sub_r == RegionKind::ReStatic => {
(var_origin, sub_origin, sub_r, sup_origin, sup_r)
(var_origin, sub_origin, sub_r, sup_origin, sup_r, spans)
}
RegionResolutionError::ConcreteFailure(
SubregionOrigin::Subtype(box TypeTrace { cause, .. }),
Expand Down Expand Up @@ -74,7 +76,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
err.span_label(
cause.span,
&format!(
"...is captured and required to live as long as `'static` here \
"...is used and required to live as long as `'static` here \
because of an implicit lifetime bound on the {}",
match ctxt.assoc_item.container {
AssocItemContainer::TraitContainer(id) =>
Expand Down Expand Up @@ -123,56 +125,101 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
param_name,
lifetime,
);
err.span_label(param.param_ty_span, &format!("this data with {}...", lifetime));
debug!("try_report_static_impl_trait: param_info={:?}", param);

// We try to make the output have fewer overlapping spans if possible.
if (sp == sup_origin.span() || !return_sp.overlaps(sup_origin.span()))
&& sup_origin.span() != return_sp
{
// FIXME: account for `async fn` like in `async-await/issues/issue-62097.rs`

// Customize the spans and labels depending on their relative order so
// that split sentences flow correctly.
if sup_origin.span().overlaps(return_sp) && sp == sup_origin.span() {
// Avoid the following:
//
// error: cannot infer an appropriate lifetime
// --> $DIR/must_outlive_least_region_or_bound.rs:18:50
// |
// LL | fn foo(x: &i32) -> Box<dyn Debug> { Box::new(x) }
// | ---- ---------^-
let (mention_influencer, influencer_point) =
if sup_origin.span().overlaps(param.param_ty_span) {
// Account for `async fn` like in `async-await/issues/issue-62097.rs`.
// The desugaring of `async `fn`s causes `sup_origin` and `param` to point at the same
// place (but with different `ctxt`, hence `overlaps` instead of `==` above).
//
// and instead show:
// This avoids the following:
//
// error: cannot infer an appropriate lifetime
// --> $DIR/must_outlive_least_region_or_bound.rs:18:50
// |
// LL | fn foo(x: &i32) -> Box<dyn Debug> { Box::new(x) }
// | ---- ^
err.span_label(
sup_origin.span(),
"...is captured here, requiring it to live as long as `'static`",
);
// LL | pub async fn run_dummy_fn(&self) {
// | ^^^^^
// | |
// | this data with an anonymous lifetime `'_`...
// | ...is captured here...
(false, sup_origin.span())
} else {
err.span_label(sup_origin.span(), "...is captured here...");
if return_sp < sup_origin.span() {
err.span_note(
return_sp,
"...and is required to live as long as `'static` here",
(!sup_origin.span().overlaps(return_sp), param.param_ty_span)
};
err.span_label(influencer_point, &format!("this data with {}...", lifetime));

debug!("try_report_static_impl_trait: param_info={:?}", param);

let mut spans = spans.clone();

if mention_influencer {
spans.push(sup_origin.span());
}
// We dedup the spans *ignoring* expansion context.
spans.sort();
spans.dedup_by_key(|span| (span.lo(), span.hi()));

// We try to make the output have fewer overlapping spans if possible.
let require_msg = if spans.is_empty() {
"...is used and required to live as long as `'static` here"
} else {
"...and is required to live as long as `'static` here"
};
let require_span =
if sup_origin.span().overlaps(return_sp) { sup_origin.span() } else { return_sp };

for span in &spans {
err.span_label(*span, "...is used here...");
}

if spans.iter().any(|sp| sp.overlaps(return_sp) || *sp > return_sp) {
// If any of the "captured here" labels appears on the same line or after
// `require_span`, we put it on a note to ensure the text flows by appearing
// always at the end.
err.span_note(require_span, require_msg);
} else {
// We don't need a note, it's already at the end, it can be shown as a `span_label`.
err.span_label(require_span, require_msg);
}

if let SubregionOrigin::RelateParamBound(_, _, Some(bound)) = sub_origin {
err.span_note(*bound, "`'static` lifetime requirement introduced by this bound");
}
if let SubregionOrigin::Subtype(box TypeTrace { cause, .. }) = sub_origin {
if let ObligationCauseCode::ReturnValue(hir_id)
| ObligationCauseCode::BlockTailExpression(hir_id) = &cause.code
{
let parent_id = tcx.hir().get_parent_item(*hir_id);
if let Some(fn_decl) = tcx.hir().fn_decl_by_hir_id(parent_id) {
let mut span: MultiSpan = fn_decl.output.span().into();
let mut add_label = true;
if let hir::FnRetTy::Return(ty) = fn_decl.output {
let mut v = StaticLifetimeVisitor(vec![], tcx.hir());
v.visit_ty(ty);
if !v.0.is_empty() {
span = v.0.clone().into();
for sp in v.0 {
span.push_span_label(
sp,
"`'static` requirement introduced here".to_string(),
);
}
add_label = false;
}
}
if add_label {
span.push_span_label(
fn_decl.output.span(),
"requirement introduced by this return type".to_string(),
);
}
span.push_span_label(
cause.span,
"because of this returned expression".to_string(),
);
} else {
err.span_label(
return_sp,
"...and is required to live as long as `'static` here",
err.span_note(
span,
"`'static` lifetime requirement introduced by the return type",
);
}
}
} else {
err.span_label(
return_sp,
"...is captured and required to live as long as `'static` here",
);
}

let fn_returns = tcx.return_type_impl_or_dyn_traits(anon_reg_sup.def_id);
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
_sub,
sup_origin,
_sup,
_,
) = error.clone()
{
if let (&Subtype(ref sup_trace), &Subtype(ref sub_trace)) = (&sup_origin, &sub_origin) {
Expand Down
30 changes: 29 additions & 1 deletion compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_middle::ty::{ReEarlyBound, ReEmpty, ReErased, ReFree, ReStatic};
use rustc_middle::ty::{ReLateBound, RePlaceholder, ReVar};
use rustc_middle::ty::{Region, RegionVid};
use rustc_span::Span;
use std::fmt;

/// This function performs lexical region resolution given a complete
Expand Down Expand Up @@ -96,6 +97,7 @@ pub enum RegionResolutionError<'tcx> {
Region<'tcx>,
SubregionOrigin<'tcx>,
Region<'tcx>,
Vec<Span>, // All the influences on a given value that didn't meet its constraints.
),

/// Indicates a `'b: 'a` constraint where `'a` is in a universe that
Expand Down Expand Up @@ -567,7 +569,30 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
// if this rule starts to create problems we'll
// have to revisit this portion of the code and
// think hard about it. =) -- nikomatsakis
self.collect_error_for_expanding_node(graph, &mut dup_vec, node_vid, errors);

// Obtain the spans for all the places that can
// influence the constraints on this value for
// richer diagnostics in `static_impl_trait`.
let influences: Vec<Span> = self
.data
.constraints
.iter()
.filter_map(|(constraint, origin)| match (constraint, origin) {
(
Constraint::VarSubVar(_, sup),
SubregionOrigin::DataBorrowed(_, sp),
) if sup == &node_vid => Some(*sp),
_ => None,
})
.collect();

self.collect_error_for_expanding_node(
graph,
&mut dup_vec,
node_vid,
errors,
influences,
);
}
}
}
Expand Down Expand Up @@ -621,6 +646,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
dup_vec: &mut IndexVec<RegionVid, Option<RegionVid>>,
node_idx: RegionVid,
errors: &mut Vec<RegionResolutionError<'tcx>>,
influences: Vec<Span>,
) {
// Errors in expanding nodes result from a lower-bound that is
// not contained by an upper-bound.
Expand Down Expand Up @@ -667,13 +693,15 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
sup: {:?}",
origin, node_idx, lower_bound.region, upper_bound.region
);

errors.push(RegionResolutionError::SubSupConflict(
node_idx,
origin,
lower_bound.origin.clone(),
lower_bound.region,
upper_bound.origin.clone(),
upper_bound.region,
influences,
));
return;
}
Expand Down
36 changes: 2 additions & 34 deletions compiler/rustc_middle/src/ty/context.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1481,40 +1481,8 @@ impl<'tcx> TyCtxt<'tcx> {
scope_def_id: LocalDefId,
) -> Vec<&'tcx hir::Ty<'tcx>> {
let hir_id = self.hir().local_def_id_to_hir_id(scope_def_id);
let hir_output = match self.hir().get(hir_id) {
Node::Item(hir::Item {
kind:
ItemKind::Fn(
hir::FnSig {
decl: hir::FnDecl { output: hir::FnRetTy::Return(ty), .. },
..
},
..,
),
..
})
| Node::ImplItem(hir::ImplItem {
kind:
hir::ImplItemKind::Fn(
hir::FnSig {
decl: hir::FnDecl { output: hir::FnRetTy::Return(ty), .. },
..
},
_,
),
..
})
| Node::TraitItem(hir::TraitItem {
kind:
hir::TraitItemKind::Fn(
hir::FnSig {
decl: hir::FnDecl { output: hir::FnRetTy::Return(ty), .. },
..
},
_,
),
..
}) => ty,
let hir_output = match self.hir().fn_decl_by_hir_id(hir_id) {
Some(hir::FnDecl { output: hir::FnRetTy::Return(ty), .. }) => ty,
_ => return vec![],
};

Expand Down
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