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Auto merge of #81055 - matthewjasper:non-fatal-overflow, r=nikomatsakis

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Make hitting the recursion limit in projection non-fatal

This change was originally made in #80246 to avoid future (effectively) infinite loop bugs in projections,
but wundergraph relies on rustc recovering here.

cc #80953

r? `@nikomatsakis`
This commit is contained in:
bors 2021-01-28 18:57:10 +00:00
commit c0b64d97be
4 changed files with 63 additions and 13 deletions
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11
compiler/rustc_trait_selection/src/traits/project.rs
View File

@ -736,14 +736,9 @@ fn project_type<'cx, 'tcx>(
if !selcx.tcx().sess.recursion_limit().value_within_limit(obligation.recursion_depth) {
debug!("project: overflow!");
match selcx.query_mode() {
super::TraitQueryMode::Standard => {
selcx.infcx().report_overflow_error(&obligation, true);
}
super::TraitQueryMode::Canonical => {
return Err(ProjectionTyError::TraitSelectionError(SelectionError::Overflow));
}
}
// This should really be an immediate error, but some existing code
// relies on being able to recover from this.
return Err(ProjectionTyError::TraitSelectionError(SelectionError::Overflow));
}
let obligation_trait_ref = &obligation.predicate.trait_ref(selcx.tcx());

4
compiler/rustc_trait_selection/src/traits/select/mod.rs
View File

@ -291,10 +291,6 @@ pub fn tcx(&self) -> TyCtxt<'tcx> {
self.infcx.tcx
}
pub(super) fn query_mode(&self) -> TraitQueryMode {
self.query_mode
}
///////////////////////////////////////////////////////////////////////////
// Selection
//

58
src/test/ui/associated-types/project-recursion-limit-non-fatal.rs Normal file
View File

@ -0,0 +1,58 @@
// Regression test for #80953. Hitting the recursion limit in projection
// is non-fatal. The above code, minimised from wundergraph shows a case
// where this is relied on.
// check-pass
struct AlternateTable {}
struct AlternateQuery {}
pub trait Query {}
pub trait AsQuery {
type Query;
}
impl<T: Query> AsQuery for T {
type Query = Self;
}
impl AsQuery for AlternateTable {
type Query = AlternateQuery;
}
pub trait Table: AsQuery {
type PrimaryKey;
}
impl Table for AlternateTable {
type PrimaryKey = ();
}
pub trait FilterDsl<Predicate> {
type Output;
}
pub type Filter<Source, Predicate> = <Source as FilterDsl<Predicate>>::Output;
impl<T, Predicate> FilterDsl<Predicate> for T
where
T: Table,
T::Query: FilterDsl<Predicate>,
{
type Output = Filter<T::Query, Predicate>;
}
impl<Predicate> FilterDsl<Predicate> for AlternateQuery {
type Output = &'static str;
}
pub trait HandleDelete {
type Filter;
}
impl<T> HandleDelete for T
where
T: Table,
T::Query: FilterDsl<T::PrimaryKey>,
Filter<T::Query, T::PrimaryKey>: ,
{
type Filter = Filter<T::Query, T::PrimaryKey>;
}
fn main() {
let x: <AlternateTable as HandleDelete>::Filter = "Hello, world";
println!("{}", x);
}

3
src/test/ui/issues/issue-23122-2.stderr
View File

@ -1,10 +1,11 @@
error[E0275]: overflow evaluating the requirement `<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<T as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next`
error[E0275]: overflow evaluating the requirement `<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<T as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next: Sized`
--> $DIR/issue-23122-2.rs:9:5
|
LL | type Next = <GetNext<T::Next> as Next>::Next;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`issue_23122_2`)
= note: required because of the requirements on the impl of `Next` for `GetNext<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<T as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next>`
error: aborting due to previous error