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Auto merge of #121491 - matthiaskrgr:rollup-wkzqawy, r=matthiaskrgr

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Rollup of 8 pull requests

Successful merges:

 - #121434 (Fix #121208 fallout)
 - #121471 (When encountering `<&T as Clone>::clone(x)` because `T: Clone`, suggest `#[derive(Clone)]`)
 - #121476 (remove `llvm.assertions=true` in compiler profile)
 - #121479 (fix generalizer unsoundness)
 - #121480 (Fix more #121208 fallout)
 - #121482 (Allow for a missing `adt_def` in `NamePrivacyVisitor`.)
 - #121484 (coverage: Use variable name `this` in `CoverageGraph::from_mir`)
 - #121487 (Explicitly call `emit_stashed_diagnostics`.)

r? `@ghost`
`@rustbot` modify labels: rollup
This commit is contained in:
bors 2024-02-23 12:12:49 +00:00
commit 52cea084bd
34 changed files with 377 additions and 133 deletions
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42
compiler/rustc_infer/src/infer/relate/generalize.rs
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@ -26,13 +26,13 @@ impl<'tcx> InferCtxt<'tcx> {
/// This is *not* expected to be used anywhere except for an implementation of
/// `TypeRelation`. Do not use this, and instead please use `At::eq`, for all
/// other usecases (i.e. setting the value of a type var).
#[instrument(level = "debug", skip(self, relation, target_is_expected))]
#[instrument(level = "debug", skip(self, relation))]
pub fn instantiate_ty_var<R: ObligationEmittingRelation<'tcx>>(
&self,
relation: &mut R,
target_is_expected: bool,
target_vid: ty::TyVid,
ambient_variance: ty::Variance,
instantiation_variance: ty::Variance,
source_ty: Ty<'tcx>,
) -> RelateResult<'tcx, ()> {
debug_assert!(self.inner.borrow_mut().type_variables().probe(target_vid).is_unknown());
@ -46,7 +46,7 @@ impl<'tcx> InferCtxt<'tcx> {
//
// We then relate `generalized_ty <: source_ty`,adding constraints like `'x: '?2` and `?1 <: ?3`.
let Generalization { value_may_be_infer: generalized_ty, has_unconstrained_ty_var } =
self.generalize(relation.span(), target_vid, ambient_variance, source_ty)?;
self.generalize(relation.span(), target_vid, instantiation_variance, source_ty)?;
// Constrain `b_vid` to the generalized type `generalized_ty`.
if let &ty::Infer(ty::TyVar(generalized_vid)) = generalized_ty.kind() {
@ -73,7 +73,7 @@ impl<'tcx> InferCtxt<'tcx> {
// the alias can be normalized to something which does not
// mention `?0`.
if self.next_trait_solver() {
let (lhs, rhs, direction) = match ambient_variance {
let (lhs, rhs, direction) = match instantiation_variance {
ty::Variance::Invariant => {
(generalized_ty.into(), source_ty.into(), AliasRelationDirection::Equate)
}
@ -106,22 +106,28 @@ impl<'tcx> InferCtxt<'tcx> {
}
}
} else {
// HACK: make sure that we `a_is_expected` continues to be
// correct when relating the generalized type with the source.
// NOTE: The `instantiation_variance` is not the same variance as
// used by the relation. When instantiating `b`, `target_is_expected`
// is flipped and the `instantion_variance` is also flipped. To
// constrain the `generalized_ty` while using the original relation,
// we therefore only have to flip the arguments.
//
// ```ignore (not code)
// ?a rel B
// instantiate_ty_var(?a, B) # expected and variance not flipped
// B' rel B
// ```
// or
// ```ignore (not code)
// A rel ?b
// instantiate_ty_var(?b, A) # expected and variance flipped
// A rel A'
// ```
if target_is_expected == relation.a_is_expected() {
relation.relate_with_variance(
ambient_variance,
ty::VarianceDiagInfo::default(),
generalized_ty,
source_ty,
)?;
relation.relate(generalized_ty, source_ty)?;
} else {
relation.relate_with_variance(
ambient_variance.xform(ty::Contravariant),
ty::VarianceDiagInfo::default(),
source_ty,
generalized_ty,
)?;
debug!("flip relation");
relation.relate(source_ty, generalized_ty)?;
}
}