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Rollup merge of #106248 - dtolnay:revertupcastlint, r=jackh726

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Revert "Implement allow-by-default `multiple_supertrait_upcastable` lint"

This is a clean revert of #105484.

I confirmed that reverting that PR fixes the regression reported in #106247. ~~I can't say I understand what this code is doing, but maybe it can be re-landed with a different implementation.~~ **Edit:** https://github.com/rust-lang/rust/issues/106247#issuecomment-1367174384 has an explanation of why #105484 ends up surfacing spurious `where_clause_object_safety` errors. The implementation of `where_clause_object_safety` assumes we only check whether a trait is object safe when somebody actually uses that trait with `dyn`. However the implementation of `multiple_supertrait_upcastable` added in the problematic PR involves checking *every* trait for whether it is object-safe.

FYI `@nbdd0121` `@compiler-errors`
This commit is contained in:
Michael Goulet 2022-12-30 21:26:34 -08:00 • committed by GitHub
commit 5b74a33b8d
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12 changed files with 9 additions and 167 deletions
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12
src/test/ui/feature-gates/feature-gate-multiple_supertrait_upcastable.rs
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@ -1,12 +0,0 @@
// check-pass
#![deny(multiple_supertrait_upcastable)]
//~^ WARNING unknown lint: `multiple_supertrait_upcastable`
//~| WARNING unknown lint: `multiple_supertrait_upcastable`
//~| WARNING unknown lint: `multiple_supertrait_upcastable`
#![warn(multiple_supertrait_upcastable)]
//~^ WARNING unknown lint: `multiple_supertrait_upcastable`
//~| WARNING unknown lint: `multiple_supertrait_upcastable`
//~| WARNING unknown lint: `multiple_supertrait_upcastable`
fn main() {}

57
src/test/ui/feature-gates/feature-gate-multiple_supertrait_upcastable.stderr
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@ -1,57 +0,0 @@
warning: unknown lint: `multiple_supertrait_upcastable`
--> $DIR/feature-gate-multiple_supertrait_upcastable.rs:3:1
|
LL | #![deny(multiple_supertrait_upcastable)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: the `multiple_supertrait_upcastable` lint is unstable
= help: add `#![feature(multiple_supertrait_upcastable)]` to the crate attributes to enable
= note: `#[warn(unknown_lints)]` on by default
warning: unknown lint: `multiple_supertrait_upcastable`
--> $DIR/feature-gate-multiple_supertrait_upcastable.rs:7:1
|
LL | #![warn(multiple_supertrait_upcastable)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: the `multiple_supertrait_upcastable` lint is unstable
= help: add `#![feature(multiple_supertrait_upcastable)]` to the crate attributes to enable
warning: unknown lint: `multiple_supertrait_upcastable`
--> $DIR/feature-gate-multiple_supertrait_upcastable.rs:3:1
|
LL | #![deny(multiple_supertrait_upcastable)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: the `multiple_supertrait_upcastable` lint is unstable
= help: add `#![feature(multiple_supertrait_upcastable)]` to the crate attributes to enable
warning: unknown lint: `multiple_supertrait_upcastable`
--> $DIR/feature-gate-multiple_supertrait_upcastable.rs:7:1
|
LL | #![warn(multiple_supertrait_upcastable)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: the `multiple_supertrait_upcastable` lint is unstable
= help: add `#![feature(multiple_supertrait_upcastable)]` to the crate attributes to enable
warning: unknown lint: `multiple_supertrait_upcastable`
--> $DIR/feature-gate-multiple_supertrait_upcastable.rs:3:1
|
LL | #![deny(multiple_supertrait_upcastable)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: the `multiple_supertrait_upcastable` lint is unstable
= help: add `#![feature(multiple_supertrait_upcastable)]` to the crate attributes to enable
warning: unknown lint: `multiple_supertrait_upcastable`
--> $DIR/feature-gate-multiple_supertrait_upcastable.rs:7:1
|
LL | #![warn(multiple_supertrait_upcastable)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: the `multiple_supertrait_upcastable` lint is unstable
= help: add `#![feature(multiple_supertrait_upcastable)]` to the crate attributes to enable
warning: 6 warnings emitted

9
src/test/ui/object-safety/issue-106247.rs Normal file
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@ -0,0 +1,9 @@
// check-pass
#![deny(where_clauses_object_safety)]
pub trait Trait {
fn method(&self) where Self: Sync;
}
fn main() {}

10
src/test/ui/traits/trait-upcasting/multiple_supertrait_upcastable.rs
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@ -1,10 +0,0 @@
#![feature(multiple_supertrait_upcastable)]
#![deny(multiple_supertrait_upcastable)]
trait A {}
trait B {}
trait C: A + B {}
//~^ ERROR `C` is object-safe and has multiple supertraits
fn main() {}

14
src/test/ui/traits/trait-upcasting/multiple_supertrait_upcastable.stderr
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@ -1,14 +0,0 @@
error: `C` is object-safe and has multiple supertraits
--> $DIR/multiple_supertrait_upcastable.rs:7:1
|
LL | trait C: A + B {}
| ^^^^^^^^^^^^^^
|
note: the lint level is defined here
--> $DIR/multiple_supertrait_upcastable.rs:2:9
|
LL | #![deny(multiple_supertrait_upcastable)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to previous error