From e025306fa050ac593bff366eb1c9bff7bfd00b1d Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Sat, 22 Oct 2022 02:48:36 +0000
Subject: [PATCH] Don't ICE on regions from anonymous_lifetime_in_impl_trait
---
.../src/diagnostics/region_name.rs | 100 ++++++++++++++++--
.../ui/borrowck/anonymous-region-in-apit.rs | 12 +++
.../borrowck/anonymous-region-in-apit.stderr | 16 +++
3 files changed, 120 insertions(+), 8 deletions(-)
create mode 100644 src/test/ui/borrowck/anonymous-region-in-apit.rs
create mode 100644 src/test/ui/borrowck/anonymous-region-in-apit.stderr
diff --git a/compiler/rustc_borrowck/src/diagnostics/region_name.rs b/compiler/rustc_borrowck/src/diagnostics/region_name.rs
index 4d251cf7ac752..c044dbaba47e2 100644
--- a/compiler/rustc_borrowck/src/diagnostics/region_name.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/region_name.rs
@@ -251,7 +251,8 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
.or_else(|| self.give_name_if_anonymous_region_appears_in_upvars(fr))
.or_else(|| self.give_name_if_anonymous_region_appears_in_output(fr))
.or_else(|| self.give_name_if_anonymous_region_appears_in_yield_ty(fr))
- .or_else(|| self.give_name_if_anonymous_region_appears_in_impl_signature(fr));
+ .or_else(|| self.give_name_if_anonymous_region_appears_in_impl_signature(fr))
+ .or_else(|| self.give_name_if_anonymous_region_appears_in_arg_position_impl_trait(fr));
if let Some(ref value) = value {
self.region_names.try_borrow_mut().unwrap().insert(fr, value.clone());
@@ -869,13 +870,8 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
return None;
}
- let mut found = false;
- tcx.fold_regions(tcx.type_of(region_parent), |r: ty::Region<'tcx>, _| {
- if *r == ty::ReEarlyBound(region) {
- found = true;
- }
- r
- });
+ let found = tcx
+ .any_free_region_meets(&tcx.type_of(region_parent), |r| *r == ty::ReEarlyBound(region));
Some(RegionName {
name: self.synthesize_region_name(),
@@ -888,4 +884,92 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
),
})
}
+
+ fn give_name_if_anonymous_region_appears_in_arg_position_impl_trait(
+ &self,
+ fr: RegionVid,
+ ) -> Option<RegionName> {
+ let ty::ReEarlyBound(region) = *self.to_error_region(fr)? else {
+ return None;
+ };
+ if region.has_name() {
+ return None;
+ };
+
+ let predicates = self
+ .infcx
+ .tcx
+ .predicates_of(self.body.source.def_id())
+ .instantiate_identity(self.infcx.tcx)
+ .predicates;
+
+ if let Some(upvar_index) = self
+ .regioncx
+ .universal_regions()
+ .defining_ty
+ .upvar_tys()
+ .position(|ty| self.any_param_predicate_mentions(&predicates, ty, region))
+ {
+ let (upvar_name, upvar_span) = self.regioncx.get_upvar_name_and_span_for_region(
+ self.infcx.tcx,
+ &self.upvars,
+ upvar_index,
+ );
+ let region_name = self.synthesize_region_name();
+
+ Some(RegionName {
+ name: region_name,
+ source: RegionNameSource::AnonRegionFromUpvar(upvar_span, upvar_name),
+ })
+ } else if let Some(arg_index) = self
+ .regioncx
+ .universal_regions()
+ .unnormalized_input_tys
+ .iter()
+ .position(|ty| self.any_param_predicate_mentions(&predicates, *ty, region))
+ {
+ let (arg_name, arg_span) = self.regioncx.get_argument_name_and_span_for_region(
+ self.body,
+ &self.local_names,
+ arg_index,
+ );
+ let region_name = self.synthesize_region_name();
+
+ Some(RegionName {
+ name: region_name,
+ source: RegionNameSource::AnonRegionFromArgument(
+ RegionNameHighlight::CannotMatchHirTy(arg_span, arg_name?.to_string()),
+ ),
+ })
+ } else {
+ None
+ }
+ }
+
+ fn any_param_predicate_mentions(
+ &self,
+ predicates: &[ty::Predicate<'tcx>],
+ ty: Ty<'tcx>,
+ region: ty::EarlyBoundRegion,
+ ) -> bool {
+ let tcx = self.infcx.tcx;
+ ty.walk().any(|arg| {
+ if let ty::GenericArgKind::Type(ty) = arg.unpack()
+ && let ty::Param(_) = ty.kind()
+ {
+ predicates.iter().any(|pred| {
+ match pred.kind().skip_binder() {
+ ty::PredicateKind::Trait(data) if data.self_ty() == ty => {}
+ ty::PredicateKind::Projection(data) if data.projection_ty.self_ty() == ty => {}
+ _ => return false,
+ }
+ tcx.any_free_region_meets(pred, |r| {
+ *r == ty::ReEarlyBound(region)
+ })
+ })
+ } else {
+ false
+ }
+ })
+ }
}
diff --git a/src/test/ui/borrowck/anonymous-region-in-apit.rs b/src/test/ui/borrowck/anonymous-region-in-apit.rs
new file mode 100644
index 0000000000000..7799a7cb151de
--- /dev/null
+++ b/src/test/ui/borrowck/anonymous-region-in-apit.rs
@@ -0,0 +1,12 @@
+#![feature(anonymous_lifetime_in_impl_trait)]
+
+trait Foo<T> {
+ fn bar(self, baz: T);
+}
+
+fn qux(foo: impl Foo<&str>) {
+ |baz: &str| foo.bar(baz);
+ //~^ ERROR borrowed data escapes outside of closure
+}
+
+fn main() {}
diff --git a/src/test/ui/borrowck/anonymous-region-in-apit.stderr b/src/test/ui/borrowck/anonymous-region-in-apit.stderr
new file mode 100644
index 0000000000000..9e100f8ac3c50
--- /dev/null
+++ b/src/test/ui/borrowck/anonymous-region-in-apit.stderr
@@ -0,0 +1,16 @@
+error[E0521]: borrowed data escapes outside of closure
+ --> $DIR/anonymous-region-in-apit.rs:8:17
+ |
+LL | fn qux(foo: impl Foo<&str>) {
+ | --- lifetime `'2` appears in the type of `foo`
+LL | |baz: &str| foo.bar(baz);
+ | --- - ^^^^^^^^^^^^
+ | | | |
+ | | | `baz` escapes the closure body here
+ | | | argument requires that `'1` must outlive `'2`
+ | | let's call the lifetime of this reference `'1`
+ | `baz` is a reference that is only valid in the closure body
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0521`.