diff --git a/compiler/rustc_trait_selection/src/traits/wf.rs b/compiler/rustc_trait_selection/src/traits/wf.rs index f26310665f9fa..7331f128753db 100644 --- a/compiler/rustc_trait_selection/src/traits/wf.rs +++ b/compiler/rustc_trait_selection/src/traits/wf.rs @@ -518,6 +518,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> { /// Pushes all the predicates needed to validate that `ty` is WF into `out`. #[instrument(level = "debug", skip(self))] fn compute(&mut self, arg: GenericArg<'tcx>) { + let tcx = self.tcx(); let mut walker = arg.walk(); let param_env = self.param_env; let depth = self.recursion_depth; @@ -542,7 +543,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> { )); let cause = self.cause(traits::WellFormed(None)); self.out.push(traits::Obligation::with_depth( - self.tcx(), + tcx, cause, self.recursion_depth, self.param_env, @@ -554,7 +555,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> { let cause = self.cause(traits::WellFormed(None)); self.out.push(traits::Obligation::with_depth( - self.tcx(), + tcx, cause, self.recursion_depth, self.param_env, @@ -576,7 +577,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> { )); let cause = self.cause(traits::WellFormed(None)); self.out.push(traits::Obligation::with_depth( - self.tcx(), + tcx, cause, self.recursion_depth, self.param_env, @@ -661,6 +662,16 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> { } ty::FnDef(did, args) => { + // HACK: Check the return type of function definitions for + // well-formedness to mostly fix #84533. This is still not + // perfect and there may be ways to abuse the fact that we + // ignore requirements with escaping bound vars. That's a + // more general issue however. + // + // FIXME(eddyb) add the type to `walker` instead of recursing. + let fn_sig = tcx.fn_sig(did).instantiate(tcx, args); + self.compute(fn_sig.output().skip_binder().into()); + let obligations = self.nominal_obligations(did, args); self.out.extend(obligations); } @@ -670,7 +681,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> { if !r.has_escaping_bound_vars() && !rty.has_escaping_bound_vars() { let cause = self.cause(traits::ReferenceOutlivesReferent(ty)); self.out.push(traits::Obligation::with_depth( - self.tcx(), + tcx, cause, depth, param_env, @@ -745,7 +756,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> { // All of the requirements on type parameters // have already been checked for `impl Trait` in // return position. We do need to check type-alias-impl-trait though. - if self.tcx().is_type_alias_impl_trait(def_id) { + if tcx.is_type_alias_impl_trait(def_id) { let obligations = self.nominal_obligations(def_id, args); self.out.extend(obligations); } @@ -767,12 +778,12 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> { // obligations that don't refer to Self and // checking those - let defer_to_coercion = self.tcx().features().object_safe_for_dispatch; + let defer_to_coercion = tcx.features().object_safe_for_dispatch; if !defer_to_coercion { let cause = self.cause(traits::WellFormed(None)); let component_traits = data.auto_traits().chain(data.principal_def_id()); - let tcx = self.tcx(); + let tcx = tcx; self.out.extend(component_traits.map(|did| { traits::Obligation::with_depth( tcx, @@ -800,7 +811,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> { ty::Infer(_) => { let cause = self.cause(traits::WellFormed(None)); self.out.push(traits::Obligation::with_depth( - self.tcx(), + tcx, cause, self.recursion_depth, param_env, diff --git a/tests/ui/fn/fn-item-lifetime-bounds.rs b/tests/ui/fn/fn-item-lifetime-bounds.rs deleted file mode 100644 index 68a1d0ce9b0b2..0000000000000 --- a/tests/ui/fn/fn-item-lifetime-bounds.rs +++ /dev/null @@ -1,37 +0,0 @@ -// check-pass -// known-bug: #84533 - -// Should fail. Lifetimes are checked correctly when `foo` is called, but NOT -// when only the lifetime parameters are instantiated. - -use std::marker::PhantomData; - -#[allow(dead_code)] -fn foo<'b, 'a>() -> PhantomData<&'b &'a ()> { - PhantomData -} - -#[allow(dead_code)] -#[allow(path_statements)] -fn caller<'b, 'a>() { - foo::<'b, 'a>; -} - -// In contrast to above, below code correctly does NOT compile. -// fn caller<'b, 'a>() { -// foo::<'b, 'a>(); -// } - -// error: lifetime may not live long enough -// --> src/main.rs:22:5 -// | -// 21 | fn caller<'b, 'a>() { -// | -- -- lifetime `'a` defined here -// | | -// | lifetime `'b` defined here -// 22 | foo::<'b, 'a>(); -// | ^^^^^^^^^^^^^^^ requires that `'a` must outlive `'b` -// | -// = help: consider adding the following bound: `'a: 'b` - -fn main() {} diff --git a/tests/ui/wf/wf-fn-def-check-sig-1.rs b/tests/ui/wf/wf-fn-def-check-sig-1.rs new file mode 100644 index 0000000000000..621d1ac3fc1be --- /dev/null +++ b/tests/ui/wf/wf-fn-def-check-sig-1.rs @@ -0,0 +1,44 @@ +// Regression test for #84533. + +use std::marker::PhantomData; + +fn foo<'b, 'a>() -> PhantomData<&'b &'a ()> { + PhantomData +} + +fn extend_lifetime<'a, 'b, T: ?Sized>(x: &'a T) -> &'b T { + let f = foo::<'b, 'a>; + //~^ ERROR lifetime may not live long enough + f.baz(x) +} + +trait Foo<'a, 'b, T: ?Sized> { + fn baz(self, s: &'a T) -> &'b T; +} +impl<'a, 'b, R, F, T: ?Sized> Foo<'a, 'b, T> for F +where + F: Fn() -> R, + R: ProofForConversion<'a, 'b, T>, +{ + fn baz(self, s: &'a T) -> &'b T { + self().convert(s) + } +} + +trait ProofForConversion<'a, 'b, T: ?Sized> { + fn convert(self, s: &'a T) -> &'b T; +} +impl<'a, 'b, T: ?Sized> ProofForConversion<'a, 'b, T> for PhantomData<&'b &'a ()> { + fn convert(self, s: &'a T) -> &'b T { + s + } +} + +fn main() { + let d; + { + let x = "Hello World".to_string(); + d = extend_lifetime(&x); + } + println!("{}", d); +} diff --git a/tests/ui/wf/wf-fn-def-check-sig-1.stderr b/tests/ui/wf/wf-fn-def-check-sig-1.stderr new file mode 100644 index 0000000000000..9501d6de8b528 --- /dev/null +++ b/tests/ui/wf/wf-fn-def-check-sig-1.stderr @@ -0,0 +1,14 @@ +error: lifetime may not live long enough + --> $DIR/wf-fn-def-check-sig-1.rs:10:13 + | +LL | fn extend_lifetime<'a, 'b, T: ?Sized>(x: &'a T) -> &'b T { + | -- -- lifetime `'b` defined here + | | + | lifetime `'a` defined here +LL | let f = foo::<'b, 'a>; + | ^^^^^^^^^^^^^ requires that `'a` must outlive `'b` + | + = help: consider adding the following bound: `'a: 'b` + +error: aborting due to previous error + diff --git a/tests/ui/wf/wf-fn-def-check-sig-2.rs b/tests/ui/wf/wf-fn-def-check-sig-2.rs new file mode 100644 index 0000000000000..51740dca8e9be --- /dev/null +++ b/tests/ui/wf/wf-fn-def-check-sig-2.rs @@ -0,0 +1,44 @@ +// Regression test for #84533 involving higher-ranked regions +// in the return type. +use std::marker::PhantomData; + +fn foo<'c, 'b, 'a>(_: &'c ()) -> (&'c (), PhantomData<&'b &'a ()>) { + (&(), PhantomData) +} + +fn extend_lifetime<'a, 'b, T: ?Sized>(x: &'a T) -> &'b T { + let f = foo; + f.baz(x) + //~^ ERROR lifetime may not live long enough +} + +trait Foo<'a, 'b, T: ?Sized> { + fn baz(self, s: &'a T) -> &'b T; +} +impl<'a, 'b, R, F, T: ?Sized> Foo<'a, 'b, T> for F +where + F: for<'c> Fn(&'c ()) -> (&'c (), R), + R: ProofForConversion<'a, 'b, T>, +{ + fn baz(self, s: &'a T) -> &'b T { + self(&()).1.convert(s) + } +} + +trait ProofForConversion<'a, 'b, T: ?Sized> { + fn convert(self, s: &'a T) -> &'b T; +} +impl<'a, 'b, T: ?Sized> ProofForConversion<'a, 'b, T> for PhantomData<&'b &'a ()> { + fn convert(self, s: &'a T) -> &'b T { + s + } +} + +fn main() { + let d; + { + let x = "Hello World".to_string(); + d = extend_lifetime(&x); + } + println!("{}", d); +} diff --git a/tests/ui/wf/wf-fn-def-check-sig-2.stderr b/tests/ui/wf/wf-fn-def-check-sig-2.stderr new file mode 100644 index 0000000000000..70c0fd32e1bd2 --- /dev/null +++ b/tests/ui/wf/wf-fn-def-check-sig-2.stderr @@ -0,0 +1,15 @@ +error: lifetime may not live long enough + --> $DIR/wf-fn-def-check-sig-2.rs:11:5 + | +LL | fn extend_lifetime<'a, 'b, T: ?Sized>(x: &'a T) -> &'b T { + | -- -- lifetime `'b` defined here + | | + | lifetime `'a` defined here +LL | let f = foo; +LL | f.baz(x) + | ^^^^^^^^ function was supposed to return data with lifetime `'b` but it is returning data with lifetime `'a` + | + = help: consider adding the following bound: `'a: 'b` + +error: aborting due to previous error +