diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs index f087afa20ba..39efff211ad 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs @@ -22,6 +22,7 @@ use rustc_errors::{ MultiSpan, Style, }; use rustc_hir as hir; +use rustc_hir::def::Namespace; use rustc_hir::def_id::DefId; use rustc_hir::intravisit::Visitor; use rustc_hir::GenericParam; @@ -34,6 +35,7 @@ use rustc_middle::traits::select::OverflowError; use rustc_middle::ty::abstract_const::NotConstEvaluatable; use rustc_middle::ty::error::ExpectedFound; use rustc_middle::ty::fold::{TypeFolder, TypeSuperFoldable}; +use rustc_middle::ty::print::{FmtPrinter, Print}; use rustc_middle::ty::{ self, SubtypePredicate, ToPolyTraitRef, ToPredicate, TraitRef, Ty, TyCtxt, TypeFoldable, TypeVisitable, @@ -109,7 +111,10 @@ pub trait TypeErrCtxtExt<'tcx> { suggest_increasing_limit: bool, ) -> ! where - T: fmt::Display + TypeFoldable<'tcx>; + T: fmt::Display + + TypeFoldable<'tcx> + + Print<'tcx, FmtPrinter<'tcx, 'tcx>, Output = FmtPrinter<'tcx, 'tcx>>, + >>::Error: std::fmt::Debug; fn suggest_new_overflow_limit(&self, err: &mut Diagnostic); @@ -468,15 +473,31 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { suggest_increasing_limit: bool, ) -> ! where - T: fmt::Display + TypeFoldable<'tcx>, + T: fmt::Display + + TypeFoldable<'tcx> + + Print<'tcx, FmtPrinter<'tcx, 'tcx>, Output = FmtPrinter<'tcx, 'tcx>>, + >>::Error: std::fmt::Debug, { let predicate = self.resolve_vars_if_possible(obligation.predicate.clone()); + let mut pred_str = predicate.to_string(); + if pred_str.len() > 50 { + // We don't need to save the type to a file, we will be talking about this type already + // in a separate note when we explain the obligation, so it will be available that way. + pred_str = predicate + .print(FmtPrinter::new_with_limit( + self.tcx, + Namespace::TypeNS, + rustc_session::Limit(6), + )) + .unwrap() + .into_buffer(); + } let mut err = struct_span_err!( self.tcx.sess, obligation.cause.span, E0275, "overflow evaluating the requirement `{}`", - predicate + pred_str, ); if suggest_increasing_limit { diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs index c369c5de52b..c9966fc4363 100644 --- a/compiler/rustc_trait_selection/src/traits/select/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs @@ -42,6 +42,7 @@ use rustc_middle::mir::interpret::ErrorHandled; use rustc_middle::ty::abstract_const::NotConstEvaluatable; use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams}; use rustc_middle::ty::fold::BottomUpFolder; +use rustc_middle::ty::print::{FmtPrinter, Print}; use rustc_middle::ty::relate::TypeRelation; use rustc_middle::ty::SubstsRef; use rustc_middle::ty::{self, EarlyBinder, PolyProjectionPredicate, ToPolyTraitRef, ToPredicate}; @@ -1081,11 +1082,17 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { it.for_each(|o| o.recursion_depth = cmp::max(min_depth, o.recursion_depth) + 1); } - fn check_recursion_depth>( + fn check_recursion_depth( &self, depth: usize, error_obligation: &Obligation<'tcx, T>, - ) -> Result<(), OverflowError> { + ) -> Result<(), OverflowError> + where + T: fmt::Display + + TypeFoldable<'tcx> + + Print<'tcx, FmtPrinter<'tcx, 'tcx>, Output = FmtPrinter<'tcx, 'tcx>>, + >>::Error: std::fmt::Debug, + { if !self.infcx.tcx.recursion_limit().value_within_limit(depth) { match self.query_mode { TraitQueryMode::Standard => { @@ -1109,11 +1116,17 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { /// The weird return type of this function allows it to be used with the `try` (`?`) /// operator within certain functions. #[inline(always)] - fn check_recursion_limit, V: Display + TypeFoldable<'tcx>>( + fn check_recursion_limit, V>( &self, obligation: &Obligation<'tcx, T>, error_obligation: &Obligation<'tcx, V>, - ) -> Result<(), OverflowError> { + ) -> Result<(), OverflowError> + where + V: fmt::Display + + TypeFoldable<'tcx> + + Print<'tcx, FmtPrinter<'tcx, 'tcx>, Output = FmtPrinter<'tcx, 'tcx>>, + >>::Error: std::fmt::Debug, + { self.check_recursion_depth(obligation.recursion_depth, error_obligation) } diff --git a/src/test/ui/error-codes/E0275.stderr b/src/test/ui/error-codes/E0275.stderr index 0cb54f29666..49a4d984af9 100644 --- a/src/test/ui/error-codes/E0275.stderr +++ b/src/test/ui/error-codes/E0275.stderr @@ -1,4 +1,4 @@ -error[E0275]: overflow evaluating the requirement `Bar>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>: Foo` +error[E0275]: overflow evaluating the requirement `Bar>>>>>>: Foo` --> $DIR/E0275.rs:6:33 | LL | impl Foo for T where Bar: Foo {} diff --git a/src/test/ui/issues/issue-20413.stderr b/src/test/ui/issues/issue-20413.stderr index dbaaf7a7746..91509ceace8 100644 --- a/src/test/ui/issues/issue-20413.stderr +++ b/src/test/ui/issues/issue-20413.stderr @@ -7,7 +7,7 @@ LL | struct NoData; = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData` = help: if you intended `T` to be a const parameter, use `const T: usize` instead -error[E0275]: overflow evaluating the requirement `NoData>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>: Foo` +error[E0275]: overflow evaluating the requirement `NoData>>>>>>: Foo` --> $DIR/issue-20413.rs:9:36 | LL | impl Foo for T where NoData: Foo { @@ -23,7 +23,7 @@ LL | impl Foo for T where NoData: Foo { = note: 127 redundant requirements hidden = note: required for `NoData` to implement `Foo` -error[E0275]: overflow evaluating the requirement `EvenLessData>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>: Baz` +error[E0275]: overflow evaluating the requirement `EvenLessData>>>>>>: Baz` --> $DIR/issue-20413.rs:28:42 | LL | impl Bar for T where EvenLessData: Baz { @@ -45,7 +45,7 @@ LL | impl Baz for T where AlmostNoData: Bar { = note: 126 redundant requirements hidden = note: required for `EvenLessData` to implement `Baz` -error[E0275]: overflow evaluating the requirement `AlmostNoData>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>: Bar` +error[E0275]: overflow evaluating the requirement `AlmostNoData>>>>>>: Bar` --> $DIR/issue-20413.rs:35:42 | LL | impl Baz for T where AlmostNoData: Bar {