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Normalize all opaque types when converting ParamEnv to Reveal::All #65989

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merged 4 commits into from
Jul 31, 2020
Merged

Normalize all opaque types when converting ParamEnv to Reveal::All #65989

merged 4 commits into from
Jul 31, 2020

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Aaron1011
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When we normalize a type using a ParamEnv with a reveal mode of
RevealMode::All, we will normalize opaque types to their underlying
types (e.g. type MyOpaque = impl Foo -> StructThatImplsFoo).
However, the ParamEnv may still have predicates referring to the
un-normalized opaque type (e.g. <T as MyTrait<MyOpaque>>). This can
cause trait projection to fail, since a type containing normalized
opaque types will not match up with the un-normalized type in the
ParamEnv.

To fix this, we now explicitly normalize all opaque types in
caller_bounds of a ParamEnv when changing its mode to
RevealMode::All. This ensures that all predicatse will refer to the
underlying types of any opaque types involved, allowing them to be
matched up properly during projection. To reflect the fact that
normalization is occuring, ParamEnv::with_reveal_all is renamed to
ParamEnv::with_reveal_all_normalized

Fixes #65918

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r? @petrochenkov

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

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Oct 31, 2019
@Centril Centril added the F-type_alias_impl_trait `#[feature(type_alias_impl_trait)]` label Oct 31, 2019
Centril
Centril reviewed Oct 31, 2019
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Just some nits. :)
Nice PR!

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@Aaron1011
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@Centril I've addressed your comments.

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r? @eddyb for review or reassignment

@rust-highfive rust-highfive assigned eddyb and unassigned petrochenkov Nov 1, 2019
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eddyb commented Nov 2, 2019

This is @rust-lang/wg-traits territory.
r? @nikomatsakis

@rust-highfive rust-highfive assigned nikomatsakis and unassigned eddyb Nov 2, 2019
@JohnCSimon
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Ping from triage:
@nikomatsakis can you please review this?
cc: @petrochenkov @Aaron1011 @petrochenkov

Thanks!

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Pinging again from triage:
@nikomatsakis can you please review this?
cc: @petrochenkov @Aaron1011 @petrochenkov @rust-lang/wg-traits @nikomatsakis

Thanks!

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r? @petrochenkov

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I'm not qualified to review this.
r? @nikomatsakis

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bors commented Dec 1, 2019

☔ The latest upstream changes (presumably #66908) made this pull request unmergeable. Please resolve the merge conflicts.

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Will review -- sorry for radio silence

nikomatsakis
nikomatsakis reviewed Dec 7, 2019
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Yet another example of why it would be good to pursue an alternative normalization strategy, I suppose. I am curious though whether this has any performance impact. We may want to think about more aggressive caching.

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@bors try

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bors commented Dec 7, 2019

⌛ Trying commit 10a5c93 with merge ff0aa14...

bors added a commit that referenced this pull request Dec 7, 2019
@bors
Auto merge of #65989 - Aaron1011:fix/normalize-param-env, r=<try>
ff0aa14 
Normalize all opaque types when converting ParamEnv to Reveal::All

When we normalize a type using a ParamEnv with a reveal mode of
RevealMode::All, we will normalize opaque types to their underlying
types (e.g. `type MyOpaque = impl Foo` -> `StructThatImplsFoo`).
However, the ParamEnv may still have predicates referring to the
un-normalized opaque type (e.g. `<T as MyTrait<MyOpaque>>`). This can
cause trait projection to fail, since a type containing normalized
opaque types will not match up with the un-normalized type in the
`ParamEnv`.

To fix this, we now explicitly normalize all opaque types in
caller_bounds of a `ParamEnv` when changing its mode to
`RevealMode::All`. This ensures that all predicatse will refer to the
underlying types of any opaque types involved, allowing them to be
matched up properly during projection. To reflect the fact that
normalization is occuring, `ParamEnv::with_reveal_all` is renamed to
`ParamEnv::with_reveal_all_normalized`

Fixes #65918
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bors commented Dec 7, 2019

☀️ Try build successful - checks-azure
Build commit: ff0aa14 (ff0aa146df927e3857e94e7206d788076f3b500b)

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@nikomatsakis: Did you mean to do a perf run as well as a try build?

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@Aaron1011 dang it, yes I did

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Queued 95dcfa37cf97c1d630a7820e31d39a7a37ae2c1d with parent 4825e12, future comparison URL.

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Finished benchmarking try commit (95dcfa37cf97c1d630a7820e31d39a7a37ae2c1d): comparison url.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

@bors rollup=never

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Aaron1011 commented Jul 22, 2020 •
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@nikomatsakis: It looks like almost all of the perf impact is gone.

@Aaron1011 Aaron1011 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 Jul 23, 2020
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@bors r+

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bors commented Jul 27, 2020

📌 Commit 5e2e927 has been approved by nikomatsakis

@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-review Status: Awaiting review from the assignee but also interested parties. labels Jul 27, 2020
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bors commented Jul 27, 2020

⌛ Testing commit 5e2e927 with merge a7b1b8ea5d0b7b7e6d162fe0066eb0f1afc94778...

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bors commented Jul 27, 2020

💔 Test failed - checks-actions

@bors bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jul 27, 2020
@nikomatsakis nikomatsakis 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 Jul 28, 2020
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I think this was a spurious failure.

@bors r=nikomatsakis

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bors commented Jul 31, 2020

💡 This pull request was already approved, no need to approve it again.

  • This pull request previously failed. You should add more commits to fix the bug, or use retry to trigger a build again.
  • There's another pull request that is currently being tested, blocking this pull request: Enable the profiler on FreeBSD #74844

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bors commented Jul 31, 2020

📌 Commit 5e2e927 has been approved by nikomatsakis

@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 Jul 31, 2020
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bors commented Jul 31, 2020

⌛ Testing commit 5e2e927 with merge 6e87bac...

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bors commented Jul 31, 2020

☀️ Test successful - checks-actions, checks-azure
Approved by: nikomatsakis
Pushing 6e87bac to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Jul 31, 2020
@bors bors merged commit 6e87bac into rust-lang:master Jul 31, 2020
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@Mark-Simulacrum
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This was a slight performance regression, as expected.

ehuss added a commit to ehuss/rust that referenced this pull request Apr 15, 2023
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Unignore issue-65918
3a64565 
This test was fixed by rust-lang#65989
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F-type_alias_impl_trait `#[feature(type_alias_impl_trait)]` merged-by-bors This PR was explicitly merged by bors. S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion.
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ICE with impl Fn alias.