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Merged
merged 3 commits into from
Dec 20, 2023
Merged

-Znext-solver: adapt overflow rules to avoid breakage #119071

merged 3 commits into from
Dec 20, 2023

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@lcnr lcnr commented Dec 18, 2023 •
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Do not erase overflow constraints if they are from equating the impl header when normalizing1.

This should be the minimal change to not break crates depending on the old project behavior of "apply impl constraints while only lazily evaluating any nested goals".

Fixes rust-lang/trait-system-refactor-initiative#70, see https://hackmd.io/ATf4hN0NRY-w2LIVgeFsVg for the reasoning behind this.

Only keeping constraints on overflow for normalize-to goals as that's the only thing needed for backcompat. It also allows us to not track the origin of root obligations. The issue with root goals would be something like the following:

trait Foo {}
trait Bar {}

trait FooBar {}
impl<T: Foo + Bar> FooBar for T {}

// These two should behave the same, rn we can drop constraints for both,
// but if we don't drop `Misc` goals we would only drop the constraints for
// `FooBar` unless we track origins of root obligations.
fn func1<T: Foo + Bar>() {}
fn func2<T: FooBaz>() {}

r? @compiler-errors

Footnotes

  1. mostly, the actual rules are slightly different ↩

@rustbot 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. WG-trait-system-refactor The Rustc Trait System Refactor Initiative (-Znext-solver) labels Dec 18, 2023
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rustbot commented Dec 18, 2023

Some changes occurred to the core trait solver

cc @rust-lang/initiative-trait-system-refactor

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lcnr
lcnr commented Dec 18, 2023
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r=me after adding that comment you said you would

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@rustbot 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 Dec 19, 2023
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lcnr commented Dec 19, 2023

@bors r=compiler-errors rollup

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bors commented Dec 19, 2023

📌 Commit 17705ea has been approved by compiler-errors

It is now in the queue for this repository.

@bors 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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Dec 19, 2023
compiler-errors added a commit to compiler-errors/rust that referenced this pull request Dec 19, 2023
@compiler-errors
Rollup merge of rust-lang#119071 - lcnr:overflowo, r=compiler-errors
49dc89d 
-Znext-solver: adapt overflow rules to avoid breakage

Do not erase overflow constraints if they are from equating the impl header when normalizing[^1].

This should be the minimal change to not break crates depending on the old project behavior of "apply impl constraints while only lazily evaluating any nested goals".

Fixes rust-lang/trait-system-refactor-initiative#70, see https://hackmd.io/ATf4hN0NRY-w2LIVgeFsVg for the reasoning behind this.

Only keeping constraints on overflow for `normalize-to` goals as that's the only thing needed for backcompat. It also allows us to not track the origin of root obligations. The issue with root goals would be something like the following:

```rust
trait Foo {}
trait Bar {}

trait FooBar {}
impl<T: Foo + Bar> FooBar for T {}

// These two should behave the same, rn we can drop constraints for both,
// but if we don't drop `Misc` goals we would only drop the constraints for
// `FooBar` unless we track origins of root obligations.
fn func1<T: Foo + Bar>() {}
fn func2<T: FooBaz>() {}
```

[^1]: mostly, the actual rules are slightly different

r? `@compiler-errors`
@compiler-errors compiler-errors mentioned this pull request Dec 19, 2023
Closed
bors added a commit to rust-lang-ci/rust that referenced this pull request Dec 19, 2023
@bors
Auto merge of rust-lang#119143 - compiler-errors:rollup-vps74yb, r=co…
29fdb02 
…mpiler-errors

Rollup of 7 pull requests

Successful merges:

 - rust-lang#118691 (Add check for possible CStr literals in pre-2021)
 - rust-lang#118973 (rustc_codegen_ssa: Don't drop `IncorrectCguReuseType` , make `rustc_expected_cgu_reuse` attr work)
 - rust-lang#119071 (-Znext-solver: adapt overflow rules to avoid breakage)
 - rust-lang#119089 (effects: fix a comment)
 - rust-lang#119096 (Yeet unnecessary param envs)
 - rust-lang#119118 (Fix arm64e-apple-ios target)
 - rust-lang#119134 (resolve: Feed visibilities for unresolved trait impl items)

r? `@ghost`
`@rustbot` modify labels: rollup
bors added a commit to rust-lang-ci/rust that referenced this pull request Dec 20, 2023
@bors
Auto merge of rust-lang#119143 - compiler-errors:rollup-vps74yb, r=co…
9d12984 
…mpiler-errors

Rollup of 7 pull requests

Successful merges:

 - rust-lang#118691 (Add check for possible CStr literals in pre-2021)
 - rust-lang#118973 (rustc_codegen_ssa: Don't drop `IncorrectCguReuseType` , make `rustc_expected_cgu_reuse` attr work)
 - rust-lang#119071 (-Znext-solver: adapt overflow rules to avoid breakage)
 - rust-lang#119089 (effects: fix a comment)
 - rust-lang#119096 (Yeet unnecessary param envs)
 - rust-lang#119118 (Fix arm64e-apple-ios target)
 - rust-lang#119134 (resolve: Feed visibilities for unresolved trait impl items)

r? `@ghost`
`@rustbot` modify labels: rollup
@matthiaskrgr matthiaskrgr mentioned this pull request Dec 20, 2023
Merged
bors added a commit to rust-lang-ci/rust that referenced this pull request Dec 20, 2023
@bors
Auto merge of rust-lang#119156 - matthiaskrgr:rollup-482ow65, r=matth…
3e4a15e 
…iaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#118691 (Add check for possible CStr literals in pre-2021)
 - rust-lang#118973 (rustc_codegen_ssa: Don't drop `IncorrectCguReuseType` , make `rustc_expected_cgu_reuse` attr work)
 - rust-lang#119071 (-Znext-solver: adapt overflow rules to avoid breakage)
 - rust-lang#119089 (effects: fix a comment)
 - rust-lang#119094 (Add function ABI and type layout to StableMIR)
 - rust-lang#119102 (Add arm-none-eabi and armv7r-none-eabi platform-support documentation.)
 - rust-lang#119107 (subtype_predicate: remove unnecessary probe)

Failed merges:

 - rust-lang#119135 (Fix crash due to `CrateItem::kind()` not handling constructors)
 - rust-lang#119141 (Add method to get instance instantiation arguments)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 16a231d into rust-lang:master Dec 20, 2023
@rustbot rustbot added this to the 1.76.0 milestone Dec 20, 2023
rust-timer added a commit to rust-lang-ci/rust that referenced this pull request Dec 20, 2023
@rust-timer
Unrolled build for rust-lang#119071
b3a9a2e 
Rollup merge of rust-lang#119071 - lcnr:overflowo, r=compiler-errors

-Znext-solver: adapt overflow rules to avoid breakage

Do not erase overflow constraints if they are from equating the impl header when normalizing[^1].

This should be the minimal change to not break crates depending on the old project behavior of "apply impl constraints while only lazily evaluating any nested goals".

Fixes rust-lang/trait-system-refactor-initiative#70, see https://hackmd.io/ATf4hN0NRY-w2LIVgeFsVg for the reasoning behind this.

Only keeping constraints on overflow for `normalize-to` goals as that's the only thing needed for backcompat. It also allows us to not track the origin of root obligations. The issue with root goals would be something like the following:

```rust
trait Foo {}
trait Bar {}

trait FooBar {}
impl<T: Foo + Bar> FooBar for T {}

// These two should behave the same, rn we can drop constraints for both,
// but if we don't drop `Misc` goals we would only drop the constraints for
// `FooBar` unless we track origins of root obligations.
fn func1<T: Foo + Bar>() {}
fn func2<T: FooBaz>() {}
```

[^1]: mostly, the actual rules are slightly different

r? ``@compiler-errors``
@lcnr lcnr deleted the overflowo branch December 20, 2023 14:06
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S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. WG-trait-system-refactor The Rustc Trait System Refactor Initiative (-Znext-solver)

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-Ztrait-solver=next-coherence: issue-90662-projection-caching.rs breaks

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