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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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1
library/core/src/error.rs
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@ -28,7 +28,6 @@ use crate::fmt::{Debug, Display};
#[stable(feature = "rust1", since = "1.0.0")]
#[cfg_attr(not(test), rustc_diagnostic_item = "Error")]
#[rustc_has_incoherent_inherent_impls]
#[cfg_attr(not(bootstrap), allow(multiple_supertrait_upcastable))]
pub trait Error: Debug + Display {
/// The lower-level source of this error, if any.
///

2
library/core/src/lib.rs
View file

@ -95,7 +95,6 @@
#![warn(missing_docs)]
#![allow(explicit_outlives_requirements)]
#![allow(incomplete_features)]
#![cfg_attr(not(bootstrap), warn(multiple_supertrait_upcastable))]
//
// Library features:
#![feature(const_align_offset)]
@ -232,7 +231,6 @@
#![feature(unsized_fn_params)]
#![feature(asm_const)]
#![feature(const_transmute_copy)]
#![cfg_attr(not(bootstrap), feature(multiple_supertrait_upcastable))]
//
// Target features:
#![feature(arm_target_feature)]