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experiment: remove value-based reasoning for interior mutability #122789

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experiment: remove value-based reasoning for interior mutability #122789

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experiment: remove value-based reasoning for interior mutability
RalfJung Mar 20, 2024
3660dd9
fix rustc build for new promotion rules
RalfJung Mar 20, 2024
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5 changes: 3 additions & 2 deletions compiler/rustc_pattern_analysis/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@

#![allow(rustc::untranslatable_diagnostic)]
#![allow(rustc::diagnostic_outside_of_impl)]
#![feature(freeze)]
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If this actually gets merged, please set this only when feature = "rustc". This crate needs to build on stable for rust-analyzer.

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is it needed just for this?

rust/compiler/rustc_pattern_analysis/src/pat.rs

Line 250 in 94b72d6

PatOrWild::Wild => &Wildcard,

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This is an experiment, it won't get merged. Also the crate can't build on stable any more with this rustc change.

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@RalfJung RalfJung Mar 20, 2024 •
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is it needed just for this?

Yes. That previously got promoted even though other enum variants have interior mutability, which is not entirely a sound thing to do (Cc rust-lang/unsafe-code-guidelines#493).


pub mod constructor;
#[cfg(feature = "rustc")]
Expand Down Expand Up @@ -90,9 +91,9 @@ pub trait PatCx: Sized + fmt::Debug {
/// Errors that can abort analysis.
type Error: fmt::Debug;
/// The index of an enum variant.
type VariantIdx: Clone + index::Idx + fmt::Debug;
type VariantIdx: Clone + index::Idx + fmt::Debug + std::marker::Freeze;
/// A string literal
type StrLit: Clone + PartialEq + fmt::Debug;
type StrLit: Clone + PartialEq + fmt::Debug + std::marker::Freeze;
/// Extra data to store in a match arm.
type ArmData: Copy + Clone + fmt::Debug;
/// Extra data to store in a pattern.
Expand Down