From 6dcff4e9f6badd8b7daf24c52d80dd6b89d12f4a Mon Sep 17 00:00:00 2001
From: Esteban Kuber <esteban@kuber.com.ar>
Date: Thu, 14 Oct 2021 17:57:39 +0000
Subject: [PATCH] Use the "nice E0277 errors"[1] for `!Send` `impl Future` from
foreign crate
Partly address #78543 by making the error quieter.
We don't have access to the `typeck` tables from foreign crates, so we
used to completely skip the new code when checking foreign crates. Now,
we carry on and don't provide as nice output (we don't clarify *what* is
making the `Future: !Send`), but at least we no longer emit a sea of
derived obligations in the output.
[1]: https://blog.rust-lang.org/inside-rust/2019/10/11/AsyncAwait-Not-Send-Error-Improvements.html
---
.../src/traits/error_reporting/suggestions.rs | 147 +++++++++---------
src/test/ui/async-await/issues/issue-67893.rs | 2 +-
.../ui/async-await/issues/issue-67893.stderr | 15 +-
3 files changed, 73 insertions(+), 91 deletions(-)
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 970fb304879..4c7c112f260 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -151,7 +151,7 @@ pub trait InferCtxtExt<'tcx> {
outer_generator: Option<DefId>,
trait_ref: ty::TraitRef<'tcx>,
target_ty: Ty<'tcx>,
- typeck_results: &ty::TypeckResults<'tcx>,
+ typeck_results: Option<&ty::TypeckResults<'tcx>>,
obligation: &PredicateObligation<'tcx>,
next_code: Option<&ObligationCauseCode<'tcx>>,
);
@@ -1463,11 +1463,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
}
// Only continue if a generator was found.
- debug!(
- "maybe_note_obligation_cause_for_async_await: generator={:?} trait_ref={:?} \
- target_ty={:?}",
- generator, trait_ref, target_ty
- );
+ debug!(?generator, ?trait_ref, ?target_ty, "maybe_note_obligation_cause_for_async_await");
let (generator_did, trait_ref, target_ty) = match (generator, trait_ref, target_ty) {
(Some(generator_did), Some(trait_ref), Some(target_ty)) => {
(generator_did, trait_ref, target_ty)
@@ -1477,14 +1473,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
let span = self.tcx.def_span(generator_did);
- // Do not ICE on closure typeck (#66868).
- if !generator_did.is_local() {
- return false;
- }
-
- // Get the typeck results from the infcx if the generator is the function we are
- // currently type-checking; otherwise, get them by performing a query.
- // This is needed to avoid cycles.
let in_progress_typeck_results = self.in_progress_typeck_results.map(|t| t.borrow());
let generator_did_root = self.tcx.closure_base_def_id(generator_did);
debug!(
@@ -1495,14 +1483,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
in_progress_typeck_results.as_ref().map(|t| t.hir_owner),
span
);
- let query_typeck_results;
- let typeck_results: &TypeckResults<'tcx> = match &in_progress_typeck_results {
- Some(t) if t.hir_owner.to_def_id() == generator_did_root => t,
- _ => {
- query_typeck_results = self.tcx.typeck(generator_did.expect_local());
- &query_typeck_results
- }
- };
let generator_body = generator_did
.as_local()
@@ -1545,51 +1525,59 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
let mut interior_or_upvar_span = None;
let mut interior_extra_info = None;
- if let Some(upvars) = self.tcx.upvars_mentioned(generator_did) {
- interior_or_upvar_span = upvars.iter().find_map(|(upvar_id, upvar)| {
- let upvar_ty = typeck_results.node_type(*upvar_id);
- let upvar_ty = self.resolve_vars_if_possible(upvar_ty);
- if ty_matches(ty::Binder::dummy(upvar_ty)) {
- Some(GeneratorInteriorOrUpvar::Upvar(upvar.span))
- } else {
- None
- }
- });
+ // Get the typeck results from the infcx if the generator is the function we are currently
+ // type-checking; otherwise, get them by performing a query. This is needed to avoid
+ // cycles. If we can't use resolved types because the generator comes from another crate,
+ // we still provide a targeted error but without all the relevant spans.
+ let query_typeck_results;
+ let typeck_results: Option<&TypeckResults<'tcx>> = match &in_progress_typeck_results {
+ Some(t) if t.hir_owner.to_def_id() == generator_did_root => Some(&t),
+ _ if generator_did.is_local() => {
+ query_typeck_results = self.tcx.typeck(generator_did.expect_local());
+ Some(&query_typeck_results)
+ }
+ _ => None, // Do not ICE on closure typeck (#66868).
};
+ if let Some(typeck_results) = typeck_results {
+ if let Some(upvars) = self.tcx.upvars_mentioned(generator_did) {
+ interior_or_upvar_span = upvars.iter().find_map(|(upvar_id, upvar)| {
+ let upvar_ty = typeck_results.node_type(*upvar_id);
+ let upvar_ty = self.resolve_vars_if_possible(upvar_ty);
+ if ty_matches(ty::Binder::dummy(upvar_ty)) {
+ Some(GeneratorInteriorOrUpvar::Upvar(upvar.span))
+ } else {
+ None
+ }
+ });
+ };
- // The generator interior types share the same binders
- if let Some(cause) =
- typeck_results.generator_interior_types.as_ref().skip_binder().iter().find(
- |ty::GeneratorInteriorTypeCause { ty, .. }| {
- ty_matches(typeck_results.generator_interior_types.rebind(ty))
- },
- )
- {
- // Check to see if any awaited expressions have the target type.
- let from_awaited_ty = visitor
- .awaits
- .into_iter()
- .map(|id| hir.expect_expr(id))
- .find(|await_expr| {
- let ty = typeck_results.expr_ty_adjusted(&await_expr);
- debug!(
- "maybe_note_obligation_cause_for_async_await: await_expr={:?}",
- await_expr
- );
- ty_matches(ty::Binder::dummy(ty))
- })
- .map(|expr| expr.span);
- let ty::GeneratorInteriorTypeCause { span, scope_span, yield_span, expr, .. } = cause;
+ // The generator interior types share the same binders
+ if let Some(cause) =
+ typeck_results.generator_interior_types.as_ref().skip_binder().iter().find(
+ |ty::GeneratorInteriorTypeCause { ty, .. }| {
+ ty_matches(typeck_results.generator_interior_types.rebind(ty))
+ },
+ )
+ {
+ // Check to see if any awaited expressions have the target type.
+ let from_awaited_ty = visitor
+ .awaits
+ .into_iter()
+ .map(|id| hir.expect_expr(id))
+ .find(|await_expr| {
+ ty_matches(ty::Binder::dummy(typeck_results.expr_ty_adjusted(&await_expr)))
+ })
+ .map(|expr| expr.span);
+ let ty::GeneratorInteriorTypeCause { span, scope_span, yield_span, expr, .. } =
+ cause;
- interior_or_upvar_span = Some(GeneratorInteriorOrUpvar::Interior(*span));
- interior_extra_info = Some((*scope_span, *yield_span, *expr, from_awaited_ty));
- };
+ interior_or_upvar_span = Some(GeneratorInteriorOrUpvar::Interior(*span));
+ interior_extra_info = Some((*scope_span, *yield_span, *expr, from_awaited_ty));
+ };
+ } else {
+ interior_or_upvar_span = Some(GeneratorInteriorOrUpvar::Interior(span));
+ }
- debug!(
- "maybe_note_obligation_cause_for_async_await: interior_or_upvar={:?} \
- generator_interior_types={:?}",
- interior_or_upvar_span, typeck_results.generator_interior_types
- );
if let Some(interior_or_upvar_span) = interior_or_upvar_span {
self.note_obligation_cause_for_async_await(
err,
@@ -1620,7 +1608,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
outer_generator: Option<DefId>,
trait_ref: ty::TraitRef<'tcx>,
target_ty: Ty<'tcx>,
- typeck_results: &ty::TypeckResults<'tcx>,
+ typeck_results: Option<&ty::TypeckResults<'tcx>>,
obligation: &PredicateObligation<'tcx>,
next_code: Option<&ObligationCauseCode<'tcx>>,
) {
@@ -1831,7 +1819,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
// Look at the last interior type to get a span for the `.await`.
debug!(
"note_obligation_cause_for_async_await generator_interior_types: {:#?}",
- typeck_results.generator_interior_types
+ typeck_results.as_ref().map(|t| &t.generator_interior_types)
);
explain_yield(interior_span, yield_span, scope_span);
}
@@ -1852,10 +1840,14 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
// ^^^^^^^ a temporary `&T` created inside this method call due to `&self`
// ```
//
- let is_region_borrow = typeck_results
- .expr_adjustments(expr)
- .iter()
- .any(|adj| adj.is_region_borrow());
+ let is_region_borrow = if let Some(typeck_results) = typeck_results {
+ typeck_results
+ .expr_adjustments(expr)
+ .iter()
+ .any(|adj| adj.is_region_borrow())
+ } else {
+ false
+ };
// ```rust
// struct Foo(*const u8);
@@ -1868,15 +1860,16 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
DefKind::Fn | DefKind::Ctor(..) => target_ty.is_unsafe_ptr(),
_ => false,
};
-
- if (typeck_results.is_method_call(e) && is_region_borrow)
- || is_raw_borrow_inside_fn_like_call
- {
- err.span_help(
- parent_span,
- "consider moving this into a `let` \
+ if let Some(typeck_results) = typeck_results {
+ if (typeck_results.is_method_call(e) && is_region_borrow)
+ || is_raw_borrow_inside_fn_like_call
+ {
+ err.span_help(
+ parent_span,
+ "consider moving this into a `let` \
binding to create a shorter lived borrow",
- );
+ );
+ }
}
}
}
diff --git a/src/test/ui/async-await/issues/issue-67893.rs b/src/test/ui/async-await/issues/issue-67893.rs
index f34ce8081ca..8b53408d758 100644
--- a/src/test/ui/async-await/issues/issue-67893.rs
+++ b/src/test/ui/async-await/issues/issue-67893.rs
@@ -7,5 +7,5 @@ fn g(_: impl Send) {}
fn main() {
g(issue_67893::run())
- //~^ ERROR: `MutexGuard<'_, ()>` cannot be sent between threads safely
+ //~^ ERROR generator cannot be sent between threads safely
}
diff --git a/src/test/ui/async-await/issues/issue-67893.stderr b/src/test/ui/async-await/issues/issue-67893.stderr
index c4b55e6ec20..7321a38c021 100644
--- a/src/test/ui/async-await/issues/issue-67893.stderr
+++ b/src/test/ui/async-await/issues/issue-67893.stderr
@@ -1,20 +1,10 @@
-error[E0277]: `MutexGuard<'_, ()>` cannot be sent between threads safely
+error: generator cannot be sent between threads safely
--> $DIR/issue-67893.rs:9:5
|
LL | g(issue_67893::run())
- | ^ `MutexGuard<'_, ()>` cannot be sent between threads safely
- |
- ::: $DIR/auxiliary/issue_67893.rs:7:20
- |
-LL | pub async fn run() {
- | - within this `impl Future`
+ | ^ generator is not `Send`
|
= help: within `impl Future`, the trait `Send` is not implemented for `MutexGuard<'_, ()>`
- = note: required because it appears within the type `for<'r, 's, 't0, 't1, 't2, 't3> {ResumeTy, Arc<Mutex<()>>, &'r Mutex<()>, Result<MutexGuard<'s, ()>, PoisonError<MutexGuard<'t0, ()>>>, &'t1 MutexGuard<'t2, ()>, MutexGuard<'t3, ()>, (), impl Future}`
- = note: required because it appears within the type `[static generator@run::{closure#0}]`
- = note: required because it appears within the type `from_generator::GenFuture<[static generator@run::{closure#0}]>`
- = note: required because it appears within the type `impl Future`
- = note: required because it appears within the type `impl Future`
note: required by a bound in `g`
--> $DIR/issue-67893.rs:6:14
|
@@ -23,4 +13,3 @@ LL | fn g(_: impl Send) {}
error: aborting due to previous error
-For more information about this error, try `rustc --explain E0277`.