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Rollup merge of #121681 - jswrenn:nix-visibility-analysis, r=compiler-errors

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Safe Transmute: Revise safety analysis

This PR migrates `BikeshedIntrinsicFrom` to a simplified safety analysis (described [here](https://github.com/rust-lang/project-safe-transmute/issues/15)) that does not rely on analyzing the visibility of types and fields.

The revised analysis treats primitive types as safe, and user-defined types as potentially carrying safety invariants. If Rust gains explicit (un)safe fields, this PR is structured so that it will be fairly easy to thread support for those annotations into the analysis.

Notably, this PR removes the `Context` type parameter from `BikeshedIntrinsicFrom`. Most of the files changed by this PR are just UI tests tweaked to accommodate the removed parameter.

r? `@compiler-errors`
This commit is contained in:
Matthias Krüger 2024-02-29 20:50:03 +01:00 • committed by GitHub
commit 419f7aeed6
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127 changed files with 1387 additions and 1948 deletions
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7
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
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@ -310,8 +310,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
.collect(),
Condition::IfTransmutable { src, dst } => {
let trait_def_id = obligation.predicate.def_id();
let scope = predicate.trait_ref.args.type_at(2);
let assume_const = predicate.trait_ref.args.const_at(3);
let assume_const = predicate.trait_ref.args.const_at(2);
let make_obl = |from_ty, to_ty| {
let trait_ref1 = ty::TraitRef::new(
tcx,
@ -319,7 +318,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
[
ty::GenericArg::from(to_ty),
ty::GenericArg::from(from_ty),
ty::GenericArg::from(scope),
ty::GenericArg::from(assume_const),
],
);
@ -355,7 +353,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let Some(assume) = rustc_transmute::Assume::from_const(
self.infcx.tcx,
obligation.param_env,
predicate.trait_ref.args.const_at(3),
predicate.trait_ref.args.const_at(2),
) else {
return Err(Unimplemented);
};
@ -367,7 +365,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let maybe_transmutable = transmute_env.is_transmutable(
obligation.cause.clone(),
rustc_transmute::Types { dst, src },
predicate.trait_ref.args.type_at(2),
assume,
);