diff --git a/compiler/rustc_trait_selection/src/solve/assembly.rs b/compiler/rustc_trait_selection/src/solve/assembly.rs index 126ec60b3d6..841169ac78d 100644 --- a/compiler/rustc_trait_selection/src/solve/assembly.rs +++ b/compiler/rustc_trait_selection/src/solve/assembly.rs @@ -90,18 +90,22 @@ pub(super) trait GoalKind<'tcx>: TypeFoldable<'tcx> + Copy + Eq { fn trait_def_id(self, tcx: TyCtxt<'tcx>) -> DefId; + // Consider a clause, which consists of a "assumption" and some "requirements", + // to satisfy a goal. If the requirements hold, then attempt to satisfy our + // goal by equating it with the assumption. + fn consider_implied_clause( + ecx: &mut EvalCtxt<'_, 'tcx>, + goal: Goal<'tcx, Self>, + assumption: ty::Predicate<'tcx>, + requirements: impl IntoIterator>>, + ) -> QueryResult<'tcx>; + fn consider_impl_candidate( ecx: &mut EvalCtxt<'_, 'tcx>, goal: Goal<'tcx, Self>, impl_def_id: DefId, ) -> QueryResult<'tcx>; - fn consider_assumption( - ecx: &mut EvalCtxt<'_, 'tcx>, - goal: Goal<'tcx, Self>, - assumption: ty::Predicate<'tcx>, - ) -> QueryResult<'tcx>; - // A type implements an `auto trait` if its components do as well. These components // are given by built-in rules from [`instantiate_constituent_tys_for_auto_trait`]. fn consider_auto_trait_candidate( @@ -355,7 +359,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { candidates: &mut Vec>, ) { for (i, assumption) in goal.param_env.caller_bounds().iter().enumerate() { - match G::consider_assumption(self, goal, assumption) { + match G::consider_implied_clause(self, goal, assumption, []) { Ok(result) => { candidates.push(Candidate { source: CandidateSource::ParamEnv(i), result }) } @@ -402,7 +406,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { for assumption in self.tcx().item_bounds(alias_ty.def_id).subst(self.tcx(), alias_ty.substs) { - match G::consider_assumption(self, goal, assumption) { + match G::consider_implied_clause(self, goal, assumption, []) { Ok(result) => { candidates.push(Candidate { source: CandidateSource::AliasBound, result }) } @@ -452,7 +456,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { for assumption in elaborate_predicates(tcx, bounds.iter().map(|bound| bound.with_self_ty(tcx, self_ty))) { - match G::consider_assumption(self, goal, assumption.predicate) { + match G::consider_implied_clause(self, goal, assumption.predicate, []) { Ok(result) => { candidates.push(Candidate { source: CandidateSource::BuiltinImpl, result }) } diff --git a/compiler/rustc_trait_selection/src/solve/project_goals.rs b/compiler/rustc_trait_selection/src/solve/project_goals.rs index 883342148f4..48153b465b7 100644 --- a/compiler/rustc_trait_selection/src/solve/project_goals.rs +++ b/compiler/rustc_trait_selection/src/solve/project_goals.rs @@ -168,6 +168,37 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { self.trait_def_id(tcx) } + fn consider_implied_clause( + ecx: &mut EvalCtxt<'_, 'tcx>, + goal: Goal<'tcx, Self>, + assumption: ty::Predicate<'tcx>, + requirements: impl IntoIterator>>, + ) -> QueryResult<'tcx> { + if let Some(poly_projection_pred) = assumption.to_opt_poly_projection_pred() + && poly_projection_pred.projection_def_id() == goal.predicate.def_id() + { + ecx.infcx.probe(|_| { + let assumption_projection_pred = + ecx.infcx.instantiate_binder_with_infer(poly_projection_pred); + let mut nested_goals = ecx.infcx.eq( + goal.param_env, + goal.predicate.projection_ty, + assumption_projection_pred.projection_ty, + )?; + nested_goals.extend(requirements); + let subst_certainty = ecx.evaluate_all(nested_goals)?; + + ecx.eq_term_and_make_canonical_response( + goal, + subst_certainty, + assumption_projection_pred.term, + ) + }) + } else { + Err(NoSolution) + } + } + fn consider_impl_candidate( ecx: &mut EvalCtxt<'_, 'tcx>, goal: Goal<'tcx, ProjectionPredicate<'tcx>>, @@ -260,35 +291,6 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { }) } - fn consider_assumption( - ecx: &mut EvalCtxt<'_, 'tcx>, - goal: Goal<'tcx, Self>, - assumption: ty::Predicate<'tcx>, - ) -> QueryResult<'tcx> { - if let Some(poly_projection_pred) = assumption.to_opt_poly_projection_pred() - && poly_projection_pred.projection_def_id() == goal.predicate.def_id() - { - ecx.infcx.probe(|_| { - let assumption_projection_pred = - ecx.infcx.instantiate_binder_with_infer(poly_projection_pred); - let nested_goals = ecx.infcx.eq( - goal.param_env, - goal.predicate.projection_ty, - assumption_projection_pred.projection_ty, - )?; - let subst_certainty = ecx.evaluate_all(nested_goals)?; - - ecx.eq_term_and_make_canonical_response( - goal, - subst_certainty, - assumption_projection_pred.term, - ) - }) - } else { - Err(NoSolution) - } - } - fn consider_auto_trait_candidate( _ecx: &mut EvalCtxt<'_, 'tcx>, goal: Goal<'tcx, Self>, @@ -329,25 +331,28 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { goal: Goal<'tcx, Self>, goal_kind: ty::ClosureKind, ) -> QueryResult<'tcx> { - if let Some(tupled_inputs_and_output) = - structural_traits::extract_tupled_inputs_and_output_from_callable( - ecx.tcx(), - goal.predicate.self_ty(), - goal_kind, - )? - { - let pred = tupled_inputs_and_output - .map_bound(|(inputs, output)| ty::ProjectionPredicate { - projection_ty: ecx - .tcx() - .mk_alias_ty(goal.predicate.def_id(), [goal.predicate.self_ty(), inputs]), - term: output.into(), - }) - .to_predicate(ecx.tcx()); - Self::consider_assumption(ecx, goal, pred) - } else { - ecx.make_canonical_response(Certainty::AMBIGUOUS) - } + let tcx = ecx.tcx(); + let Some(tupled_inputs_and_output) = + structural_traits::extract_tupled_inputs_and_output_from_callable( + tcx, + goal.predicate.self_ty(), + goal_kind, + )? else { + return ecx.make_canonical_response(Certainty::AMBIGUOUS); + }; + let output_is_sized_pred = tupled_inputs_and_output + .map_bound(|(_, output)| tcx.at(DUMMY_SP).mk_trait_ref(LangItem::Sized, [output])); + + let pred = tupled_inputs_and_output + .map_bound(|(inputs, output)| ty::ProjectionPredicate { + projection_ty: tcx + .mk_alias_ty(goal.predicate.def_id(), [goal.predicate.self_ty(), inputs]), + term: output.into(), + }) + .to_predicate(tcx); + // A built-in `Fn` impl only holds if the output is sized. + // (FIXME: technically we only need to check this if the type is a fn ptr...) + Self::consider_implied_clause(ecx, goal, pred, [goal.with(tcx, output_is_sized_pred)]) } fn consider_builtin_tuple_candidate( @@ -466,7 +471,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { let term = substs.as_generator().return_ty().into(); - Self::consider_assumption( + Self::consider_implied_clause( ecx, goal, ty::Binder::dummy(ty::ProjectionPredicate { @@ -474,6 +479,9 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { term, }) .to_predicate(tcx), + // Technically, we need to check that the future type is Sized, + // but that's already proven by the generator being WF. + [], ) } @@ -503,7 +511,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { bug!("unexpected associated item `<{self_ty} as Generator>::{name}`") }; - Self::consider_assumption( + Self::consider_implied_clause( ecx, goal, ty::Binder::dummy(ty::ProjectionPredicate { @@ -513,6 +521,9 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { term, }) .to_predicate(tcx), + // Technically, we need to check that the future type is Sized, + // but that's already proven by the generator being WF. + [], ) } diff --git a/compiler/rustc_trait_selection/src/solve/trait_goals.rs b/compiler/rustc_trait_selection/src/solve/trait_goals.rs index d12e5f797fb..f2f25ef850a 100644 --- a/compiler/rustc_trait_selection/src/solve/trait_goals.rs +++ b/compiler/rustc_trait_selection/src/solve/trait_goals.rs @@ -6,6 +6,7 @@ use super::assembly; use super::infcx_ext::InferCtxtExt; use super::{CanonicalResponse, Certainty, EvalCtxt, Goal, QueryResult}; use rustc_hir::def_id::DefId; +use rustc_hir::LangItem; use rustc_infer::infer::InferCtxt; use rustc_infer::traits::query::NoSolution; use rustc_infer::traits::util::supertraits; @@ -61,10 +62,11 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> { }) } - fn consider_assumption( + fn consider_implied_clause( ecx: &mut EvalCtxt<'_, 'tcx>, goal: Goal<'tcx, Self>, assumption: ty::Predicate<'tcx>, + requirements: impl IntoIterator>>, ) -> QueryResult<'tcx> { if let Some(poly_trait_pred) = assumption.to_opt_poly_trait_pred() && poly_trait_pred.def_id() == goal.predicate.def_id() @@ -73,11 +75,12 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> { ecx.infcx.probe(|_| { let assumption_trait_pred = ecx.infcx.instantiate_binder_with_infer(poly_trait_pred); - let nested_goals = ecx.infcx.eq( + let mut nested_goals = ecx.infcx.eq( goal.param_env, goal.predicate.trait_ref, assumption_trait_pred.trait_ref, )?; + nested_goals.extend(requirements); ecx.evaluate_all_and_make_canonical_response(nested_goals) }) } else { @@ -173,23 +176,26 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> { goal: Goal<'tcx, Self>, goal_kind: ty::ClosureKind, ) -> QueryResult<'tcx> { - if let Some(tupled_inputs_and_output) = + let tcx = ecx.tcx(); + let Some(tupled_inputs_and_output) = structural_traits::extract_tupled_inputs_and_output_from_callable( - ecx.tcx(), + tcx, goal.predicate.self_ty(), goal_kind, - )? - { - let pred = tupled_inputs_and_output - .map_bound(|(inputs, _)| { - ecx.tcx() - .mk_trait_ref(goal.predicate.def_id(), [goal.predicate.self_ty(), inputs]) - }) - .to_predicate(ecx.tcx()); - Self::consider_assumption(ecx, goal, pred) - } else { - ecx.make_canonical_response(Certainty::AMBIGUOUS) - } + )? else { + return ecx.make_canonical_response(Certainty::AMBIGUOUS); + }; + let output_is_sized_pred = tupled_inputs_and_output + .map_bound(|(_, output)| tcx.at(DUMMY_SP).mk_trait_ref(LangItem::Sized, [output])); + + let pred = tupled_inputs_and_output + .map_bound(|(inputs, _)| { + tcx.mk_trait_ref(goal.predicate.def_id(), [goal.predicate.self_ty(), inputs]) + }) + .to_predicate(tcx); + // A built-in `Fn` impl only holds if the output is sized. + // (FIXME: technically we only need to check this if the type is a fn ptr...) + Self::consider_implied_clause(ecx, goal, pred, [goal.with(tcx, output_is_sized_pred)]) } fn consider_builtin_tuple_candidate( @@ -225,6 +231,8 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> { } // Async generator unconditionally implement `Future` + // Technically, we need to check that the future output type is Sized, + // but that's already proven by the generator being WF. ecx.make_canonical_response(Certainty::Yes) } @@ -244,13 +252,16 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> { } let generator = substs.as_generator(); - Self::consider_assumption( + Self::consider_implied_clause( ecx, goal, ty::Binder::dummy( tcx.mk_trait_ref(goal.predicate.def_id(), [self_ty, generator.resume_ty()]), ) .to_predicate(tcx), + // Technically, we need to check that the generator types are Sized, + // but that's already proven by the generator being WF. + [], ) } diff --git a/tests/ui/traits/new-solver/builtin-fn-must-return-sized.rs b/tests/ui/traits/new-solver/builtin-fn-must-return-sized.rs new file mode 100644 index 00000000000..ba473653ecf --- /dev/null +++ b/tests/ui/traits/new-solver/builtin-fn-must-return-sized.rs @@ -0,0 +1,17 @@ +// compile-flags: -Ztrait-solver=next + +#![feature(fn_traits)] +#![feature(unboxed_closures)] +#![feature(tuple_trait)] + +use std::ops::Fn; +use std::marker::Tuple; + +fn foo, T: Tuple>(f: Option, t: T) { + let y = (f.unwrap()).call(t); +} + +fn main() { + foo:: str, _>(None, ()); + //~^ expected a `Fn<_>` closure, found `fn() -> str` +} diff --git a/tests/ui/traits/new-solver/builtin-fn-must-return-sized.stderr b/tests/ui/traits/new-solver/builtin-fn-must-return-sized.stderr new file mode 100644 index 00000000000..f7551739b13 --- /dev/null +++ b/tests/ui/traits/new-solver/builtin-fn-must-return-sized.stderr @@ -0,0 +1,18 @@ +error[E0277]: expected a `Fn<_>` closure, found `fn() -> str` + --> $DIR/builtin-fn-must-return-sized.rs:15:27 + | +LL | foo:: str, _>(None, ()); + | --------------------- ^^^^ expected an `Fn<_>` closure, found `fn() -> str` + | | + | required by a bound introduced by this call + | + = help: the trait `Fn<_>` is not implemented for `fn() -> str` +note: required by a bound in `foo` + --> $DIR/builtin-fn-must-return-sized.rs:10:11 + | +LL | fn foo, T: Tuple>(f: Option, t: T) { + | ^^^^^ required by this bound in `foo` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0277`.