Provide more context on recursive `impl` evaluation overflow #119389

estebank · 2023-12-28T19:09:16Z

When an associated type Self::Assoc is part of a where clause, we end up unable to evaluate the requirement and emit a E0275.

We now point at the associated type if specified in the impl. If so, we also suggest using that type instead of Self::Assoc. Otherwise, we explain that these are not allowed.

error[E0275]: overflow evaluating the requirement `<(T,) as Grault>::A == _`
  --> $DIR/impl-wf-cycle-1.rs:15:1
   |
LL | / impl<T: Grault> Grault for (T,)
LL | |
LL | | where
LL | |     Self::A: Baz,
LL | |     Self::B: Fiz,
   | |_________________^
LL |   {
LL |       type A = ();
   |       ------ associated type `<(T,) as Grault>::A` is specified here
   |
note: required for `(T,)` to implement `Grault`
  --> $DIR/impl-wf-cycle-1.rs:15:17
   |
LL | impl<T: Grault> Grault for (T,)
   |                 ^^^^^^     ^^^^
...
LL |     Self::A: Baz,
   |              --- unsatisfied trait bound introduced here
   = note: 1 redundant requirement hidden
   = note: required for `(T,)` to implement `Grault`
help: associated type for the current `impl` cannot be restricted in `where` clauses, remove this bound
   |
LL -     Self::A: Baz,
   |

error[E0275]: overflow evaluating the requirement `<T as B>::Type == <T as B>::Type`
  --> $DIR/impl-wf-cycle-3.rs:7:1
   |
LL | / impl<T> B for T
LL | | where
LL | |     T: A<Self::Type>,
   | |_____________________^
LL |   {
LL |       type Type = bool;
   |       --------- associated type `<T as B>::Type` is specified here
   |
note: required for `T` to implement `B`
  --> $DIR/impl-wf-cycle-3.rs:7:9
   |
LL | impl<T> B for T
   |         ^     ^
LL | where
LL |     T: A<Self::Type>,
   |        ------------- unsatisfied trait bound introduced here
help: replace the associated type with the type specified in this `impl`
   |
LL |     T: A<bool>,
   |          ~~~~

error[E0275]: overflow evaluating the requirement `<T as Filter>::ToMatch == <T as Filter>::ToMatch`
  --> $DIR/impl-wf-cycle-4.rs:5:1
   |
LL | / impl<T> Filter for T
LL | | where
LL | |     T: Fn(Self::ToMatch),
   | |_________________________^
   |
note: required for `T` to implement `Filter`
  --> $DIR/impl-wf-cycle-4.rs:5:9
   |
LL | impl<T> Filter for T
   |         ^^^^^^     ^
LL | where
LL |     T: Fn(Self::ToMatch),
   |        ----------------- unsatisfied trait bound introduced here
note: associated types for the current `impl` cannot be restricted in `where` clauses
  --> $DIR/impl-wf-cycle-4.rs:7:11
   |
LL |     T: Fn(Self::ToMatch),
   |           ^^^^^^^^^^^^^

Fix #116925

rustbot · 2023-12-28T19:09:25Z

r? @petrochenkov

(rustbot has picked a reviewer for you, use r? to override)

bors · 2023-12-28T23:49:01Z

☔ The latest upstream changes (presumably #119174) made this pull request unmergeable. Please resolve the merge conflicts.

petrochenkov · 2023-12-29T00:14:30Z

r? compiler
I'm overloaded with reviews.

bors · 2024-01-05T19:29:59Z

☔ The latest upstream changes (presumably #119621) made this pull request unmergeable. Please resolve the merge conflicts.

TaKO8Ki

I left some suggestions. Other than them, r=me

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

TaKO8Ki · 2024-01-12T04:36:37Z

@rustbot author

When an associated type `Self::Assoc` is part of a `where` clause, we end up unable to evaluate the requirement and emit a E0275. We now point at the associated type if specified in the `impl`. If so, we also suggest using that type instead of `Self::Assoc`. Otherwise, we explain that these are not allowed. ``` error[E0275]: overflow evaluating the requirement `<(T,) as Grault>::A == _` --> $DIR/impl-wf-cycle-1.rs:15:1 | LL | / impl<T: Grault> Grault for (T,) LL | | LL | | where LL | | Self::A: Baz, LL | | Self::B: Fiz, | |_________________^ LL | { LL | type A = (); | ------ associated type `<(T,) as Grault>::A` is specified here | note: required for `(T,)` to implement `Grault` --> $DIR/impl-wf-cycle-1.rs:15:17 | LL | impl<T: Grault> Grault for (T,) | ^^^^^^ ^^^^ ... LL | Self::A: Baz, | --- unsatisfied trait bound introduced here = note: 1 redundant requirement hidden = note: required for `(T,)` to implement `Grault` help: associated type for the current `impl` cannot be restricted in `where` clauses, remove this bound | LL - Self::A: Baz, LL + , | ``` ``` error[E0275]: overflow evaluating the requirement `<T as B>::Type == <T as B>::Type` --> $DIR/impl-wf-cycle-3.rs:7:1 | LL | / impl<T> B for T LL | | where LL | | T: A<Self::Type>, | |_____________________^ LL | { LL | type Type = bool; | --------- associated type `<T as B>::Type` is specified here | note: required for `T` to implement `B` --> $DIR/impl-wf-cycle-3.rs:7:9 | LL | impl<T> B for T | ^ ^ LL | where LL | T: A<Self::Type>, | ------------- unsatisfied trait bound introduced here help: replace the associated type with the type specified in this `impl` | LL | T: A<bool>, | ~~~~ ``` ``` error[E0275]: overflow evaluating the requirement `<T as Filter>::ToMatch == <T as Filter>::ToMatch` --> $DIR/impl-wf-cycle-4.rs:5:1 | LL | / impl<T> Filter for T LL | | where LL | | T: Fn(Self::ToMatch), | |_________________________^ | note: required for `T` to implement `Filter` --> $DIR/impl-wf-cycle-4.rs:5:9 | LL | impl<T> Filter for T | ^^^^^^ ^ LL | where LL | T: Fn(Self::ToMatch), | ----------------- unsatisfied trait bound introduced here note: associated types for the current `impl` cannot be restricted in `where` clauses --> $DIR/impl-wf-cycle-4.rs:7:11 | LL | T: Fn(Self::ToMatch), | ^^^^^^^^^^^^^ ``` Fix rust-lang#116925

estebank · 2024-01-22T17:53:13Z

@rustbot review

TaKO8Ki · 2024-01-24T06:38:20Z

@bors r+ rollup

bors · 2024-01-24T06:38:22Z

📌 Commit 29bdf9e has been approved by TaKO8Ki

It is now in the queue for this repository.

Provide more context on recursive `impl` evaluation overflow When an associated type `Self::Assoc` is part of a `where` clause, we end up unable to evaluate the requirement and emit a E0275. We now point at the associated type if specified in the `impl`. If so, we also suggest using that type instead of `Self::Assoc`. Otherwise, we explain that these are not allowed. ``` error[E0275]: overflow evaluating the requirement `<(T,) as Grault>::A == _` --> $DIR/impl-wf-cycle-1.rs:15:1 | LL | / impl<T: Grault> Grault for (T,) LL | | LL | | where LL | | Self::A: Baz, LL | | Self::B: Fiz, | |_________________^ LL | { LL | type A = (); | ------ associated type `<(T,) as Grault>::A` is specified here | note: required for `(T,)` to implement `Grault` --> $DIR/impl-wf-cycle-1.rs:15:17 | LL | impl<T: Grault> Grault for (T,) | ^^^^^^ ^^^^ ... LL | Self::A: Baz, | --- unsatisfied trait bound introduced here = note: 1 redundant requirement hidden = note: required for `(T,)` to implement `Grault` help: associated type for the current `impl` cannot be restricted in `where` clauses, remove this bound | LL - Self::A: Baz, | ``` ``` error[E0275]: overflow evaluating the requirement `<T as B>::Type == <T as B>::Type` --> $DIR/impl-wf-cycle-3.rs:7:1 | LL | / impl<T> B for T LL | | where LL | | T: A<Self::Type>, | |_____________________^ LL | { LL | type Type = bool; | --------- associated type `<T as B>::Type` is specified here | note: required for `T` to implement `B` --> $DIR/impl-wf-cycle-3.rs:7:9 | LL | impl<T> B for T | ^ ^ LL | where LL | T: A<Self::Type>, | ------------- unsatisfied trait bound introduced here help: replace the associated type with the type specified in this `impl` | LL | T: A<bool>, | ~~~~ ``` ``` error[E0275]: overflow evaluating the requirement `<T as Filter>::ToMatch == <T as Filter>::ToMatch` --> $DIR/impl-wf-cycle-4.rs:5:1 | LL | / impl<T> Filter for T LL | | where LL | | T: Fn(Self::ToMatch), | |_________________________^ | note: required for `T` to implement `Filter` --> $DIR/impl-wf-cycle-4.rs:5:9 | LL | impl<T> Filter for T | ^^^^^^ ^ LL | where LL | T: Fn(Self::ToMatch), | ----------------- unsatisfied trait bound introduced here note: associated types for the current `impl` cannot be restricted in `where` clauses --> $DIR/impl-wf-cycle-4.rs:7:11 | LL | T: Fn(Self::ToMatch), | ^^^^^^^^^^^^^ ``` Fix rust-lang#116925

Rollup of 8 pull requests Successful merges: - rust-lang#119305 (Add `AsyncFn` family of traits) - rust-lang#119389 (Provide more context on recursive `impl` evaluation overflow) - rust-lang#120062 (llvm: change data layout bug to an error and make it trigger more) - rust-lang#120099 (linker: Refactor library linking methods in `trait Linker`) - rust-lang#120201 (Bump some deps with syn 1.0 dependencies) - rust-lang#120230 (Assert that a single scope is passed to `for_scope`) - rust-lang#120278 (Remove --fatal-warnings on wasm targets) - rust-lang#120292 (coverage: Dismantle `Instrumentor` and flatten span refinement) r? `@ghost` `@rustbot` modify labels: rollup

…iaskrgr Rollup of 10 pull requests Successful merges: - rust-lang#119305 (Add `AsyncFn` family of traits) - rust-lang#119389 (Provide more context on recursive `impl` evaluation overflow) - rust-lang#119895 (Remove `track_errors` entirely) - rust-lang#120230 (Assert that a single scope is passed to `for_scope`) - rust-lang#120278 (Remove --fatal-warnings on wasm targets) - rust-lang#120292 (coverage: Dismantle `Instrumentor` and flatten span refinement) - rust-lang#120315 (On E0308 involving `dyn Trait`, mention trait objects) - rust-lang#120317 (pattern_analysis: Let `ctor_sub_tys` return any Iterator they want) - rust-lang#120318 (pattern_analysis: Reuse most of the `DeconstructedPat` `Debug` impl) - rust-lang#120325 (rustc_data_structures: use either instead of itertools) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#119389 - estebank:issue-116925, r=TaKO8Ki Provide more context on recursive `impl` evaluation overflow When an associated type `Self::Assoc` is part of a `where` clause, we end up unable to evaluate the requirement and emit a E0275. We now point at the associated type if specified in the `impl`. If so, we also suggest using that type instead of `Self::Assoc`. Otherwise, we explain that these are not allowed. ``` error[E0275]: overflow evaluating the requirement `<(T,) as Grault>::A == _` --> $DIR/impl-wf-cycle-1.rs:15:1 | LL | / impl<T: Grault> Grault for (T,) LL | | LL | | where LL | | Self::A: Baz, LL | | Self::B: Fiz, | |_________________^ LL | { LL | type A = (); | ------ associated type `<(T,) as Grault>::A` is specified here | note: required for `(T,)` to implement `Grault` --> $DIR/impl-wf-cycle-1.rs:15:17 | LL | impl<T: Grault> Grault for (T,) | ^^^^^^ ^^^^ ... LL | Self::A: Baz, | --- unsatisfied trait bound introduced here = note: 1 redundant requirement hidden = note: required for `(T,)` to implement `Grault` help: associated type for the current `impl` cannot be restricted in `where` clauses, remove this bound | LL - Self::A: Baz, | ``` ``` error[E0275]: overflow evaluating the requirement `<T as B>::Type == <T as B>::Type` --> $DIR/impl-wf-cycle-3.rs:7:1 | LL | / impl<T> B for T LL | | where LL | | T: A<Self::Type>, | |_____________________^ LL | { LL | type Type = bool; | --------- associated type `<T as B>::Type` is specified here | note: required for `T` to implement `B` --> $DIR/impl-wf-cycle-3.rs:7:9 | LL | impl<T> B for T | ^ ^ LL | where LL | T: A<Self::Type>, | ------------- unsatisfied trait bound introduced here help: replace the associated type with the type specified in this `impl` | LL | T: A<bool>, | ~~~~ ``` ``` error[E0275]: overflow evaluating the requirement `<T as Filter>::ToMatch == <T as Filter>::ToMatch` --> $DIR/impl-wf-cycle-4.rs:5:1 | LL | / impl<T> Filter for T LL | | where LL | | T: Fn(Self::ToMatch), | |_________________________^ | note: required for `T` to implement `Filter` --> $DIR/impl-wf-cycle-4.rs:5:9 | LL | impl<T> Filter for T | ^^^^^^ ^ LL | where LL | T: Fn(Self::ToMatch), | ----------------- unsatisfied trait bound introduced here note: associated types for the current `impl` cannot be restricted in `where` clauses --> $DIR/impl-wf-cycle-4.rs:7:11 | LL | T: Fn(Self::ToMatch), | ^^^^^^^^^^^^^ ``` Fix rust-lang#116925

rustbot assigned petrochenkov Dec 28, 2023

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Dec 28, 2023

estebank force-pushed the issue-116925 branch from bcc56ac to e1381ba Compare December 28, 2023 19:10

rustbot assigned TaKO8Ki and unassigned petrochenkov Dec 29, 2023

estebank force-pushed the issue-116925 branch from 1b953a7 to 48bcad6 Compare January 4, 2024 00:21

estebank force-pushed the issue-116925 branch from be7148f to 18caf3b Compare January 8, 2024 23:08

TaKO8Ki reviewed Jan 9, 2024

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 12, 2024

estebank added 3 commits January 19, 2024 23:55

Account for trailing comma in removal suggestion

c85bb27

Account for single where bound being removed

29bdf9e

estebank force-pushed the issue-116925 branch from 18caf3b to 29bdf9e Compare January 22, 2024 17:52

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 22, 2024

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 24, 2024

fmease mentioned this pull request Jan 24, 2024

Rollup of 8 pull requests #120304

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matthiaskrgr mentioned this pull request Jan 25, 2024

Rollup of 10 pull requests #120335

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bors merged commit fd92d88 into rust-lang:master Jan 25, 2024

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