Projections, lifetimes, and WF tracking issue (RFC 1214) #27579

nikomatsakis · 2015-08-07T12:03:57Z

Tracking issue for rust-lang/rfcs#1214

After warning cycle is complete

Remove old WF check
Remove RFC1214 origins and warnings
Remove special treatment of ReEmpty in the outlives relation

Testing chart

Subject	Tests	Issues
OutlivesScalar	regions-outlives-scalar.rs
OutlivesNominalType	regions-outlives-nominal-type-struct.rs
	regions-outlives-nominal-type-enum.rs
OutlivesReference	all of the other tests
OutlivesObject	compile-fail/wf-in-obj-type-static.rs
OutlivesProjectionEnv	compile-fail/wf-in-obj-type-static.rs
WfObject, lifetime bounds	compile-fail/regions-wf-trait-object.rs
WfSlice	compile-file/wf-array-elem-sized.rs
const	wf-const-type.rs
struct, bound	wf-struct-bound.rs
struct, field	...many other tests...
enum, bound	wf-enum-bound.rs
enum, field	...many other tests...
trait, bound	wf-trait-bound.rs
trait, assoc type default	wf-trait-associated-type-trait.rs
	wf-trait-associated-type-region.rs
trait, assoc type bound	wf-trait-associated-type-bound.rs
trait, default fn, arg	wf-trait-default-fn-arg.rs
trait, default fn, return	wf-trait-default-fn-ret.rs
trait, default fn, where clause	wf-trait-default-fn-where-clause.rs
trait, fn, arg	wf-trait-fn-arg.rs
trait, fn, return	wf-trait-fn-ret.rs
trait, fn, where clause	wf-trait-fn-where-clause.rs
fn item, argument type	wf-in-fn-arg.rs
fn item, return type	wf-in-fn-ret.rs
fn item, where clause	wf-in-fn-where-clause.rs
inherent impl, where clause	wf-inherent-impl-where-clause.rs
inherent impl, fn, where clause	wf-inherent-impl-method-where-clause.rs
impl, assoc type default	wf-impl-associated-type-region.rs
	wf-impl-associated-type-trait.rs
fn type, argument type	wf-in-fn-type-arg.rs
fn type, return type	wf-in-fn-type-ret.rs
	wf-in-fn-type-static.rs
object type arg	compile-fail/wf-in-obj-type-static.rs
	compile-fail/wf-in-obj-type-region.rs
object safety	compile-fail/wf-object-safe.rs	#21953
`fn(T): 'a` affects `T`	compile-fail/wf-outlives-ty-in-fn-or-trait.rs
OutlivesProjection*	compile-fail/associated-types-outlives.rs	#24622
OutlivesProjection*	compile-fail/regions-assoc-type-outlives-container*.rs
OutlivesProjectionComponents	compile-fail/regions-close-associated-type-into-object.rs
implied bounds projection gap	compile-fail/regions-implied-bounds-projection-gap*rs

The text was updated successfully, but these errors were encountered:

jroesch · 2015-08-09T07:13:28Z

cc me

@nrc

This PR implements the majority of RFC 1214. In particular, it implements: - the new outlives relation - comprehensive WF checking For the most part, new code receives warnings, not errors, though 3 regressions were found via a crater run. There are some deviations from RFC 1214. Most notably: - we still consider implied bounds from fn ret; this intersects other soundness issues that I intend to address in detail in a follow-up RFC. Fixing this without breaking a lot of code probably requires rewriting compare-method somewhat (which is probably a good thing). - object types do not check trait bounds for fear of encountering `Self`; this was left as an unresolved question in RFC 1214, but ultimately feels inconsistent. Both of those two issues are highlighted in the tracking issue, #27579. #27579 also includes a testing matrix with new tests that I wrote -- these probably duplicate some existing tests, I tried to check but wasn't quite sure what to look for. I tried to be thorough in testing the WF relation, at least, but would welcome suggestions for missing tests. r? @nrc (or perhaps someone else?)

frewsxcv · 2015-09-05T18:30:28Z

#27592 and #27583 can be checked-off in the original description

also, is there a way to determine which crates are impacted by the changes proposed by RFC 1214?

mitchmindtree · 2015-09-10T14:34:06Z

Just wanted to mention that I'm really excited for these changes to land on stable 😸 I have a lot of where clauses that look something like this:

where
    P::HLI: 'a + 'b,
    P::PatternGenerator: 'a + 'b,
    P::PhraseGenerator: 'a + 'b,
    P::Instrument: 'a + 'b,
    <P::Instrument as Instrument>::Source: 'a + 'b,
    P::Effect: 'a + 'b,
    P::Sample: 'a + 'b,
    P::BusId: 'a + 'b,

If I understand these WF changes correctly, they will save me hundreds of lines being able to simply write

where P: 'a + 'b`

instead.

Stebalien · 2015-09-30T01:34:56Z

Also fixes #21837.

nikomatsakis · 2015-09-30T18:59:17Z

@Stebalien

Also fixes #21837.

Not quite, because the interaction of implied bounds with variance is still not being properly handled.

Stebalien · 2015-09-30T19:16:51Z

@nikomatsakis sorry, it fixes the current test case so I assumed it fixed the bug.

mitchmindtree · 2015-12-23T04:34:40Z

I'd love to know the status of this 😸

BTW, It looks like we may be able to check off some of the related issues in the original comment: #24622, #23442, #21748, #25692, #21953 and as @frewsxcv mentioned, #27592 and #27583.

brson · 2016-06-23T16:35:44Z

@nikomatsakis Is this still P-high? Can it be lowered or assigned?

pnkfelix · 2016-06-23T21:01:43Z

assigning to self to double-check what's done and what's not

pnkfelix · 2016-07-07T20:22:55Z

I don't know with tracking issues in terms of the P-markings. I treat tracking bugs like this like metabugs, so I'm going to remove the P-high since I don't think we should assign priorities to metabugs.

@nrc

This PR implements the majority of RFC 1214. In particular, it implements: - the new outlives relation - comprehensive WF checking For the most part, new code receives warnings, not errors, though 3 regressions were found via a crater run. There are some deviations from RFC 1214. Most notably: - we still consider implied bounds from fn ret; this intersects other soundness issues that I intend to address in detail in a follow-up RFC. Fixing this without breaking a lot of code probably requires rewriting compare-method somewhat (which is probably a good thing). - object types do not check trait bounds for fear of encountering `Self`; this was left as an unresolved question in RFC 1214, but ultimately feels inconsistent. Both of those two issues are highlighted in the tracking issue, rust-lang/rust#27579. #27579 also includes a testing matrix with new tests that I wrote -- these probably duplicate some existing tests, I tried to check but wasn't quite sure what to look for. I tried to be thorough in testing the WF relation, at least, but would welcome suggestions for missing tests. r? @nrc (or perhaps someone else?)

pnkfelix · 2019-02-21T10:41:20Z

unassigning self; i haven't done anything with this and I don't think I'm the right person to take charge here.

pnkfelix · 2022-03-04T15:31:05Z

Discussed at today's T-compiler backlog bonanza.

@rustbot label +T-lang +WG-traits +S-tracking-needs-summary

nikomatsakis · 2022-06-17T13:09:42Z

Discussed in @rust-lang/types triage today. Decided to close this issue -- RFC 1214 is long-since stabilized, and the work on a-mir-formality will help us deal with ensuring exhaustive testing.

@nrc

This PR implements the majority of RFC 1214. In particular, it implements: - the new outlives relation - comprehensive WF checking For the most part, new code receives warnings, not errors, though 3 regressions were found via a crater run. There are some deviations from RFC 1214. Most notably: - we still consider implied bounds from fn ret; this intersects other soundness issues that I intend to address in detail in a follow-up RFC. Fixing this without breaking a lot of code probably requires rewriting compare-method somewhat (which is probably a good thing). - object types do not check trait bounds for fear of encountering `Self`; this was left as an unresolved question in RFC 1214, but ultimately feels inconsistent. Both of those two issues are highlighted in the tracking issue, rust-lang/rust#27579. #27579 also includes a testing matrix with new tests that I wrote -- these probably duplicate some existing tests, I tried to check but wasn't quite sure what to look for. I tried to be thorough in testing the WF relation, at least, but would welcome suggestions for missing tests. r? @nrc (or perhaps someone else?)

nikomatsakis mentioned this issue Aug 7, 2015

[RFC] Clarify (and improve) rules for projections and well-formedness rust-lang/rfcs#1214

Merged

jroesch added the A-type-system label Aug 9, 2015

This was referenced Aug 10, 2015

format_args! returned from a closure causes corruption/crash #27592

Closed

Implement (most of) RFC 1214 #27641

Merged

mitaa mentioned this issue Aug 20, 2015

Encountered error Unimplemented selecting Binder(core::iter::IntoIterator) during trans #23281

Closed

Sean1708 mentioned this issue Sep 19, 2015

Fix compilation on the latest nightly. indigits/scirust#27

Merged

Boddlnagg mentioned this issue Oct 21, 2015

Investigate changes required by RFC 1214 Boddlnagg/midir#13

Closed

nikomatsakis added the P-high label Jan 18, 2016

brson added the I-nominated label Jun 23, 2016

pnkfelix added the T-compiler label Jun 23, 2016

pnkfelix self-assigned this Jun 23, 2016

pnkfelix removed P-high I-nominated labels Jul 7, 2016

Mark-Simulacrum added the C-tracking-issue label Jul 22, 2017

bstrie mentioned this issue Nov 17, 2017

Type alias fails to produce a type error for unsized type #46027

Closed

pnkfelix removed their assignment Feb 21, 2019

jonas-schievink added the B-RFC-approved label Aug 16, 2019

GuillaumeDIDIER mentioned this issue Feb 7, 2022

Implied bounds on nested references + variance = soundness hole #25860

Open

rustbot added S-tracking-needs-summary T-lang WG-traits labels Mar 4, 2022

nikomatsakis closed this as completed Jun 17, 2022

fmease added A-type-system and removed A-type-system labels Dec 21, 2024

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Projections, lifetimes, and WF tracking issue (RFC 1214) #27579

Projections, lifetimes, and WF tracking issue (RFC 1214) #27579

nikomatsakis commented Aug 7, 2015 •

edited by Mark-Simulacrum

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jroesch commented Aug 9, 2015

frewsxcv commented Sep 5, 2015

mitchmindtree commented Sep 10, 2015

Stebalien commented Sep 30, 2015

nikomatsakis commented Sep 30, 2015

Stebalien commented Sep 30, 2015

mitchmindtree commented Dec 23, 2015

brson commented Jun 23, 2016

pnkfelix commented Jun 23, 2016

pnkfelix commented Jul 7, 2016

pnkfelix commented Feb 21, 2019

pnkfelix commented Mar 4, 2022 •

edited

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nikomatsakis commented Jun 17, 2022

Projections, lifetimes, and WF tracking issue (RFC 1214) #27579

Projections, lifetimes, and WF tracking issue (RFC 1214) #27579

Comments

nikomatsakis commented Aug 7, 2015 • edited by Mark-Simulacrum Loading

Tracking issue for rust-lang/rfcs#1214

After warning cycle is complete

Testing chart

jroesch commented Aug 9, 2015

frewsxcv commented Sep 5, 2015

mitchmindtree commented Sep 10, 2015

Stebalien commented Sep 30, 2015

nikomatsakis commented Sep 30, 2015

Stebalien commented Sep 30, 2015

mitchmindtree commented Dec 23, 2015

brson commented Jun 23, 2016

pnkfelix commented Jun 23, 2016

pnkfelix commented Jul 7, 2016

pnkfelix commented Feb 21, 2019

pnkfelix commented Mar 4, 2022 • edited Loading

nikomatsakis commented Jun 17, 2022

nikomatsakis commented Aug 7, 2015 •

edited by Mark-Simulacrum

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pnkfelix commented Mar 4, 2022 •

edited

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