From b8396d10c42cf758bcf901019181a0d47e56ed19 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Fri, 6 Oct 2023 20:27:30 +0000
Subject: [PATCH] Always make inductive cycles as ambig during typeck
---
.../src/traits/select/mod.rs | 2 +-
tests/ui/marker_trait_attr/unsound-overlap.rs | 1 +
.../marker_trait_attr/unsound-overlap.stderr | 21 +++++++++++--
tests/ui/specialization/issue-39448.rs | 3 +-
tests/ui/specialization/issue-39448.stderr | 31 +++++++------------
tests/ui/specialization/issue-39618.rs | 3 +-
tests/ui/specialization/issue-39618.stderr | 20 ++++++++++--
7 files changed, 53 insertions(+), 28 deletions(-)
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 1894fbba302..81b66523688 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -236,7 +236,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
freshener: infcx.freshener(),
intercrate_ambiguity_causes: None,
query_mode: TraitQueryMode::Standard,
- treat_inductive_cycle: TreatInductiveCycleAs::Recur,
+ treat_inductive_cycle: TreatInductiveCycleAs::Ambig,
}
}
diff --git a/tests/ui/marker_trait_attr/unsound-overlap.rs b/tests/ui/marker_trait_attr/unsound-overlap.rs
index 2e5101b822c..2ce26b610f6 100644
--- a/tests/ui/marker_trait_attr/unsound-overlap.rs
+++ b/tests/ui/marker_trait_attr/unsound-overlap.rs
@@ -8,6 +8,7 @@ trait B {}
impl<T: A> B for T {}
impl<T: B> A for T {}
impl A for &str {}
+//~^ ERROR type annotations needed: cannot satisfy `&str: A`
impl<T: A + B> A for (T,) {}
trait TraitWithAssoc {
type Assoc;
diff --git a/tests/ui/marker_trait_attr/unsound-overlap.stderr b/tests/ui/marker_trait_attr/unsound-overlap.stderr
index 5e58f5227ed..13498fa4b22 100644
--- a/tests/ui/marker_trait_attr/unsound-overlap.stderr
+++ b/tests/ui/marker_trait_attr/unsound-overlap.stderr
@@ -1,5 +1,19 @@
+error[E0283]: type annotations needed: cannot satisfy `&str: A`
+ --> $DIR/unsound-overlap.rs:10:12
+ |
+LL | impl A for &str {}
+ | ^^^^
+ |
+note: multiple `impl`s satisfying `&str: A` found
+ --> $DIR/unsound-overlap.rs:9:1
+ |
+LL | impl<T: B> A for T {}
+ | ^^^^^^^^^^^^^^^^^^
+LL | impl A for &str {}
+ | ^^^^^^^^^^^^^^^
+
error[E0119]: conflicting implementations of trait `TraitWithAssoc` for type `((&str,),)`
- --> $DIR/unsound-overlap.rs:20:1
+ --> $DIR/unsound-overlap.rs:21:1
|
LL | impl<T: A> TraitWithAssoc for T {
| ------------------------------- first implementation here
@@ -7,6 +21,7 @@ LL | impl<T: A> TraitWithAssoc for T {
LL | impl TraitWithAssoc for ((&str,),) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `((&str,),)`
-error: aborting due to 1 previous error
+error: aborting due to 2 previous errors
-For more information about this error, try `rustc --explain E0119`.
+Some errors have detailed explanations: E0119, E0283.
+For more information about an error, try `rustc --explain E0119`.
diff --git a/tests/ui/specialization/issue-39448.rs b/tests/ui/specialization/issue-39448.rs
index a15c4bd6b7f..1c8843d983a 100644
--- a/tests/ui/specialization/issue-39448.rs
+++ b/tests/ui/specialization/issue-39448.rs
@@ -22,6 +22,7 @@ trait FromA<T> {
}
impl<T: A, U: A + FromA<T>> FromA<T> for U {
+ //~^ ERROR cycle detected when computing whether impls specialize one another
default fn from(x: T) -> Self {
ToA::to(x)
}
@@ -42,7 +43,7 @@ where
#[allow(dead_code)]
fn foo<T: A, U: A>(x: T, y: U) -> U {
- x.foo(y.to()).to() //~ ERROR overflow evaluating the requirement
+ x.foo(y.to()).to()
}
fn main() {
diff --git a/tests/ui/specialization/issue-39448.stderr b/tests/ui/specialization/issue-39448.stderr
index dc5db4f4285..e2c5f8c4846 100644
--- a/tests/ui/specialization/issue-39448.stderr
+++ b/tests/ui/specialization/issue-39448.stderr
@@ -8,28 +8,21 @@ LL | #![feature(specialization)]
= help: consider using `min_specialization` instead, which is more stable and complete
= note: `#[warn(incomplete_features)]` on by default
-error[E0275]: overflow evaluating the requirement `T: FromA<U>`
- --> $DIR/issue-39448.rs:45:13
- |
-LL | x.foo(y.to()).to()
- | ^^
- |
-note: required for `T` to implement `FromA<U>`
- --> $DIR/issue-39448.rs:24:29
+error[E0391]: cycle detected when computing whether impls specialize one another
+ --> $DIR/issue-39448.rs:24:1
|
LL | impl<T: A, U: A + FromA<T>> FromA<T> for U {
- | -------- ^^^^^^^^ ^
- | |
- | unsatisfied trait bound introduced here
-note: required for `U` to implement `ToA<T>`
- --> $DIR/issue-39448.rs:34:12
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
-LL | impl<T, U> ToA<U> for T
- | ^^^^^^ ^
-LL | where
-LL | U: FromA<T>,
- | -------- unsatisfied trait bound introduced here
+ = note: ...which requires evaluating trait selection obligation `u16: FromA<u8>`...
+ = note: ...which again requires computing whether impls specialize one another, completing the cycle
+note: cycle used when building specialization graph of trait `FromA`
+ --> $DIR/issue-39448.rs:20:1
+ |
+LL | trait FromA<T> {
+ | ^^^^^^^^^^^^^^
+ = 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; 1 warning emitted
-For more information about this error, try `rustc --explain E0275`.
+For more information about this error, try `rustc --explain E0391`.
diff --git a/tests/ui/specialization/issue-39618.rs b/tests/ui/specialization/issue-39618.rs
index 5b9b012e665..14a6fcf572e 100644
--- a/tests/ui/specialization/issue-39618.rs
+++ b/tests/ui/specialization/issue-39618.rs
@@ -2,8 +2,6 @@
// FIXME(JohnTitor): Centril pointed out this looks suspicions, we should revisit here.
// More context: https://github.com/rust-lang/rust/pull/69192#discussion_r379846796
-//@ check-pass
-
#![feature(specialization)] //~ WARN the feature `specialization` is incomplete
trait Foo {
@@ -19,6 +17,7 @@ impl<T> Bar for T where T: Foo {
}
impl<T> Foo for T where T: Bar {
+ //~^ ERROR cycle detected when computing whether impls specialize one another
fn foo(&self) {}
}
diff --git a/tests/ui/specialization/issue-39618.stderr b/tests/ui/specialization/issue-39618.stderr
index 19de60c7c17..756162ce92c 100644
--- a/tests/ui/specialization/issue-39618.stderr
+++ b/tests/ui/specialization/issue-39618.stderr
@@ -1,5 +1,5 @@
warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
- --> $DIR/issue-39618.rs:7:12
+ --> $DIR/issue-39618.rs:5:12
|
LL | #![feature(specialization)]
| ^^^^^^^^^^^^^^
@@ -8,5 +8,21 @@ LL | #![feature(specialization)]
= help: consider using `min_specialization` instead, which is more stable and complete
= note: `#[warn(incomplete_features)]` on by default
-warning: 1 warning emitted
+error[E0391]: cycle detected when computing whether impls specialize one another
+ --> $DIR/issue-39618.rs:19:1
+ |
+LL | impl<T> Foo for T where T: Bar {
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ |
+ = note: ...which requires evaluating trait selection obligation `u64: Bar`...
+ = note: ...which again requires computing whether impls specialize one another, completing the cycle
+note: cycle used when building specialization graph of trait `Foo`
+ --> $DIR/issue-39618.rs:7:1
+ |
+LL | trait Foo {
+ | ^^^^^^^^^
+ = 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; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0391`.