From ce9d8678ca9d25c603dfc655a5f955bee4a0a9fe Mon Sep 17 00:00:00 2001 From: lcnr Date: Mon, 14 Apr 2025 10:37:51 +0200 Subject: [PATCH 1/3] do not leak auto traits in item bounds --- .../src/solve/trait_goals.rs | 32 ++++++++++++++---- .../avoid-query-cycle-via-item-bound.rs | 33 +++++++++++++++++++ tests/ui/impl-trait/in-trait/refine-cycle.rs | 3 ++ 3 files changed, 61 insertions(+), 7 deletions(-) create mode 100644 tests/ui/impl-trait/auto-trait-leakage/avoid-query-cycle-via-item-bound.rs diff --git a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs index d42c9980f4633..3adfac3d42926 100644 --- a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs +++ b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs @@ -164,6 +164,7 @@ where ecx: &mut EvalCtxt<'_, D>, goal: Goal, ) -> Result, NoSolution> { + let cx = ecx.cx(); if goal.predicate.polarity != ty::PredicatePolarity::Positive { return Err(NoSolution); } @@ -174,20 +175,37 @@ where // Only consider auto impls of unsafe traits when there are no unsafe // fields. - if ecx.cx().trait_is_unsafe(goal.predicate.def_id()) + if cx.trait_is_unsafe(goal.predicate.def_id()) && goal.predicate.self_ty().has_unsafe_fields() { return Err(NoSolution); } - // We only look into opaque types during analysis for opaque types - // outside of their defining scope. Doing so for opaques in the - // defining scope may require calling `typeck` on the same item we're - // currently type checking, which will result in a fatal cycle that - // ideally we want to avoid, since we can make progress on this goal - // via an alias bound or a locally-inferred hidden type instead. + // We leak the implemented auto traits of opaques outside of their defining scope. + // This depends on `typeck` of the defining scope of that opaque, which may result in + // fatal query cycles. + // + // We only get to this point if we're outside of the defining scope as we'd otherwise + // be able to normalize the opaque type. We may also cycle in case `typeck` of a defining + // scope relies on the current context, e.g. either because it also leaks auto trait + // bounds of opaques defined in the current context or by evaluating the current item. + // + // To avoid this we don't try to leak auto trait bounds if they can also be proven via + // item bounds of the opaque. These bounds are always applicable as auto traits must not + // have any generic parameters. They would also get preferred over the impl candidate + // when merging candidates anyways. + // + // See tests/ui/impl-trait/auto-trait-leakage/avoid-query-cycle-via-item-bound.rs. if let ty::Alias(ty::Opaque, opaque_ty) = goal.predicate.self_ty().kind() { debug_assert!(ecx.opaque_type_is_rigid(opaque_ty.def_id)); + for item_bound in cx.item_self_bounds(opaque_ty.def_id).skip_binder() { + if item_bound + .as_trait_clause() + .is_some_and(|b| b.def_id() == goal.predicate.def_id()) + { + return Err(NoSolution); + } + } } ecx.probe_and_evaluate_goal_for_constituent_tys( diff --git a/tests/ui/impl-trait/auto-trait-leakage/avoid-query-cycle-via-item-bound.rs b/tests/ui/impl-trait/auto-trait-leakage/avoid-query-cycle-via-item-bound.rs new file mode 100644 index 0000000000000..7f366fdcabd28 --- /dev/null +++ b/tests/ui/impl-trait/auto-trait-leakage/avoid-query-cycle-via-item-bound.rs @@ -0,0 +1,33 @@ +//@ check-pass +//@ revisions: current next +//@[next] compile-flags: -Znext-solver +//@ ignore-compare-mode-next-solver (explicit revisions) + +// When proving auto trait bounds, make sure that we depend on auto trait +// leakage if we can also prove it via an item bound. +fn is_send(_: T) {} + +fn direct() -> impl Send { + is_send(check(false)); // leaks auto traits, depends on `check` + 1u16 +} + +trait Indir: Send {} +impl Indir for u32 {} +fn indir() -> impl Indir { + is_send(check(false)); // leaks auto traits, depends on `check` + 1u32 +} + +fn check(b: bool) -> impl Sized { + if b { + // must not leak auto traits, as we otherwise get a query cycle. + is_send(direct()); + is_send(indir()); + } + 1u64 +} + +fn main() { + check(true); +} diff --git a/tests/ui/impl-trait/in-trait/refine-cycle.rs b/tests/ui/impl-trait/in-trait/refine-cycle.rs index 78d672a7ed60a..d97f9821347ef 100644 --- a/tests/ui/impl-trait/in-trait/refine-cycle.rs +++ b/tests/ui/impl-trait/in-trait/refine-cycle.rs @@ -1,4 +1,7 @@ //@ check-pass +//@ revisions: current next +//@[next] compile-flags: -Znext-solver +//@ ignore-compare-mode-next-solver (explicit revisions) // Make sure that refinement checking doesn't cause a cycle in `Instance::resolve` // which calls `compare_impl_item`. From 2e79f7cd6102ac7faa4938f61f056e26b08249a9 Mon Sep 17 00:00:00 2001 From: lcnr Date: Mon, 14 Apr 2025 10:38:16 +0200 Subject: [PATCH 2/3] move tests --- .../impl-trait/{ => auto-trait-leakage}/auto-trait-coherence.rs | 0 .../{ => auto-trait-leakage}/auto-trait-coherence.stderr | 0 .../{ => auto-trait-leakage}/auto-trait-contains-err.rs | 0 .../{ => auto-trait-leakage}/auto-trait-contains-err.stderr | 0 .../impl-trait/{ => auto-trait-leakage}/auto-trait-leak-rpass.rs | 0 tests/ui/impl-trait/{ => auto-trait-leakage}/auto-trait-leak.rs | 0 .../ui/impl-trait/{ => auto-trait-leakage}/auto-trait-leak.stderr | 0 tests/ui/impl-trait/{ => auto-trait-leakage}/auto-trait-leak2.rs | 0 .../impl-trait/{ => auto-trait-leakage}/auto-trait-leak2.stderr | 0 9 files changed, 0 insertions(+), 0 deletions(-) rename tests/ui/impl-trait/{ => auto-trait-leakage}/auto-trait-coherence.rs (100%) rename tests/ui/impl-trait/{ => auto-trait-leakage}/auto-trait-coherence.stderr (100%) rename tests/ui/impl-trait/{ => auto-trait-leakage}/auto-trait-contains-err.rs (100%) rename tests/ui/impl-trait/{ => auto-trait-leakage}/auto-trait-contains-err.stderr (100%) rename tests/ui/impl-trait/{ => auto-trait-leakage}/auto-trait-leak-rpass.rs (100%) rename tests/ui/impl-trait/{ => auto-trait-leakage}/auto-trait-leak.rs (100%) rename tests/ui/impl-trait/{ => auto-trait-leakage}/auto-trait-leak.stderr (100%) rename tests/ui/impl-trait/{ => auto-trait-leakage}/auto-trait-leak2.rs (100%) rename tests/ui/impl-trait/{ => auto-trait-leakage}/auto-trait-leak2.stderr (100%) diff --git a/tests/ui/impl-trait/auto-trait-coherence.rs b/tests/ui/impl-trait/auto-trait-leakage/auto-trait-coherence.rs similarity index 100% rename from tests/ui/impl-trait/auto-trait-coherence.rs rename to tests/ui/impl-trait/auto-trait-leakage/auto-trait-coherence.rs diff --git a/tests/ui/impl-trait/auto-trait-coherence.stderr b/tests/ui/impl-trait/auto-trait-leakage/auto-trait-coherence.stderr similarity index 100% rename from tests/ui/impl-trait/auto-trait-coherence.stderr rename to tests/ui/impl-trait/auto-trait-leakage/auto-trait-coherence.stderr diff --git a/tests/ui/impl-trait/auto-trait-contains-err.rs b/tests/ui/impl-trait/auto-trait-leakage/auto-trait-contains-err.rs similarity index 100% rename from tests/ui/impl-trait/auto-trait-contains-err.rs rename to tests/ui/impl-trait/auto-trait-leakage/auto-trait-contains-err.rs diff --git a/tests/ui/impl-trait/auto-trait-contains-err.stderr b/tests/ui/impl-trait/auto-trait-leakage/auto-trait-contains-err.stderr similarity index 100% rename from tests/ui/impl-trait/auto-trait-contains-err.stderr rename to tests/ui/impl-trait/auto-trait-leakage/auto-trait-contains-err.stderr diff --git a/tests/ui/impl-trait/auto-trait-leak-rpass.rs b/tests/ui/impl-trait/auto-trait-leakage/auto-trait-leak-rpass.rs similarity index 100% rename from tests/ui/impl-trait/auto-trait-leak-rpass.rs rename to tests/ui/impl-trait/auto-trait-leakage/auto-trait-leak-rpass.rs diff --git a/tests/ui/impl-trait/auto-trait-leak.rs b/tests/ui/impl-trait/auto-trait-leakage/auto-trait-leak.rs similarity index 100% rename from tests/ui/impl-trait/auto-trait-leak.rs rename to tests/ui/impl-trait/auto-trait-leakage/auto-trait-leak.rs diff --git a/tests/ui/impl-trait/auto-trait-leak.stderr b/tests/ui/impl-trait/auto-trait-leakage/auto-trait-leak.stderr similarity index 100% rename from tests/ui/impl-trait/auto-trait-leak.stderr rename to tests/ui/impl-trait/auto-trait-leakage/auto-trait-leak.stderr diff --git a/tests/ui/impl-trait/auto-trait-leak2.rs b/tests/ui/impl-trait/auto-trait-leakage/auto-trait-leak2.rs similarity index 100% rename from tests/ui/impl-trait/auto-trait-leak2.rs rename to tests/ui/impl-trait/auto-trait-leakage/auto-trait-leak2.rs diff --git a/tests/ui/impl-trait/auto-trait-leak2.stderr b/tests/ui/impl-trait/auto-trait-leakage/auto-trait-leak2.stderr similarity index 100% rename from tests/ui/impl-trait/auto-trait-leak2.stderr rename to tests/ui/impl-trait/auto-trait-leakage/auto-trait-leak2.stderr From 836ea25b4d42d307a75e98ec0c703dbc8bcdab79 Mon Sep 17 00:00:00 2001 From: lcnr Date: Mon, 14 Apr 2025 11:02:36 +0200 Subject: [PATCH 3/3] add RPITIT tests: method compat auto trait leakage --- ...atability-via-leakage-cycle.current.stderr | 58 +++++++++ ...ompatability-via-leakage-cycle.next.stderr | 122 ++++++++++++++++++ .../method-compatability-via-leakage-cycle.rs | 30 +++++ .../method-compatability-via-leakage.rs | 14 ++ 4 files changed, 224 insertions(+) create mode 100644 tests/ui/impl-trait/in-trait/method-compatability-via-leakage-cycle.current.stderr create mode 100644 tests/ui/impl-trait/in-trait/method-compatability-via-leakage-cycle.next.stderr create mode 100644 tests/ui/impl-trait/in-trait/method-compatability-via-leakage-cycle.rs create mode 100644 tests/ui/impl-trait/in-trait/method-compatability-via-leakage.rs diff --git a/tests/ui/impl-trait/in-trait/method-compatability-via-leakage-cycle.current.stderr b/tests/ui/impl-trait/in-trait/method-compatability-via-leakage-cycle.current.stderr new file mode 100644 index 0000000000000..bf598d6270940 --- /dev/null +++ b/tests/ui/impl-trait/in-trait/method-compatability-via-leakage-cycle.current.stderr @@ -0,0 +1,58 @@ +error[E0391]: cycle detected when computing type of `::{anon_assoc#0}` + --> $DIR/method-compatability-via-leakage-cycle.rs:21:24 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^ + | +note: ...which requires comparing an impl and trait method signature, inferring any hidden `impl Trait` types in the process... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:24 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^ + = note: ...which requires evaluating trait selection obligation `::foo::{opaque#0}: core::marker::Send`... +note: ...which requires computing type of opaque `::foo::{opaque#0}`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:24 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^ +note: ...which requires borrow-checking `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires promoting constants in MIR for `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires checking if `::foo` contains FFI-unwind calls... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires building MIR for `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires match-checking `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires type-checking `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + = note: ...which again requires computing type of `::{anon_assoc#0}`, completing the cycle +note: cycle used when checking that `` is well-formed + --> $DIR/method-compatability-via-leakage-cycle.rs:17:1 + | +LL | impl Trait for u32 { + | ^^^^^^^^^^^^^^^^^^ + = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information + +error: aborting due to 1 previous error + +For more information about this error, try `rustc --explain E0391`. diff --git a/tests/ui/impl-trait/in-trait/method-compatability-via-leakage-cycle.next.stderr b/tests/ui/impl-trait/in-trait/method-compatability-via-leakage-cycle.next.stderr new file mode 100644 index 0000000000000..6bec5bbc06323 --- /dev/null +++ b/tests/ui/impl-trait/in-trait/method-compatability-via-leakage-cycle.next.stderr @@ -0,0 +1,122 @@ +error[E0391]: cycle detected when computing type of `::{anon_assoc#0}` + --> $DIR/method-compatability-via-leakage-cycle.rs:21:24 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^ + | +note: ...which requires comparing an impl and trait method signature, inferring any hidden `impl Trait` types in the process... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires computing type of `::foo::{opaque#0}`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:24 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^ +note: ...which requires computing type of opaque `::foo::{opaque#0}`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:24 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^ +note: ...which requires borrow-checking `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires promoting constants in MIR for `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires checking if `::foo` contains FFI-unwind calls... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires building MIR for `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires match-checking `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires type-checking `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + = note: ...which again requires computing type of `::{anon_assoc#0}`, completing the cycle +note: cycle used when checking that `` is well-formed + --> $DIR/method-compatability-via-leakage-cycle.rs:17:1 + | +LL | impl Trait for u32 { + | ^^^^^^^^^^^^^^^^^^ + = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information + +error[E0391]: cycle detected when computing type of `::{anon_assoc#0}` + --> $DIR/method-compatability-via-leakage-cycle.rs:21:24 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^ + | +note: ...which requires comparing an impl and trait method signature, inferring any hidden `impl Trait` types in the process... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires computing type of `::foo::{opaque#0}`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:24 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^ +note: ...which requires computing type of opaque `::foo::{opaque#0}`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:24 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^ +note: ...which requires borrow-checking `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires promoting constants in MIR for `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires checking if `::foo` contains FFI-unwind calls... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires building MIR for `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires match-checking `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: ...which requires type-checking `::foo`... + --> $DIR/method-compatability-via-leakage-cycle.rs:21:5 + | +LL | fn foo(b: bool) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + = note: ...which again requires computing type of `::{anon_assoc#0}`, completing the cycle +note: cycle used when checking that `` is well-formed + --> $DIR/method-compatability-via-leakage-cycle.rs:17:1 + | +LL | impl Trait for u32 { + | ^^^^^^^^^^^^^^^^^^ + = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information + = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no` + +error: aborting due to 2 previous errors + +For more information about this error, try `rustc --explain E0391`. diff --git a/tests/ui/impl-trait/in-trait/method-compatability-via-leakage-cycle.rs b/tests/ui/impl-trait/in-trait/method-compatability-via-leakage-cycle.rs new file mode 100644 index 0000000000000..917820dc2b8b0 --- /dev/null +++ b/tests/ui/impl-trait/in-trait/method-compatability-via-leakage-cycle.rs @@ -0,0 +1,30 @@ +//@ revisions: current next +//@[next] compile-flags: -Znext-solver +//@ ignore-compare-mode-next-solver (explicit revisions) +//@ known-bug: #139788 + +// Recursively using the trait method inside of an impl in case checking +// method compatability relies on opaque type leakage currently causes a +// cycle error. + +trait Trait { + // desugars to + // type Assoc: Sized + Send; + // fn foo(b: bool) -> Self::Assoc; + fn foo(b: bool) -> impl Sized + Send; +} + +impl Trait for u32 { + // desugars to + // type Assoc = impl_rpit::; + // fn foo(b: bool) -> Self::Assoc { .. } + fn foo(b: bool) -> impl Sized { + if b { + u32::foo(false) + } else { + 1u32 + } + } +} + +fn main() {} diff --git a/tests/ui/impl-trait/in-trait/method-compatability-via-leakage.rs b/tests/ui/impl-trait/in-trait/method-compatability-via-leakage.rs new file mode 100644 index 0000000000000..249ec0728c1a0 --- /dev/null +++ b/tests/ui/impl-trait/in-trait/method-compatability-via-leakage.rs @@ -0,0 +1,14 @@ +//@ check-pass +//@ revisions: current next +//@[next] compile-flags: -Znext-solver +//@ ignore-compare-mode-next-solver (explicit revisions) + +trait Trait { + fn foo() -> impl Sized + Send; +} + +impl Trait for u32 { + fn foo() -> impl Sized {} +} + +fn main() {}