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Auto merge of #120639 - fee1-dead-contrib:new-effects-desugaring, r=oli-obk

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Implement new effects desugaring

cc `@rust-lang/project-const-traits.` Will write down notes once I have finished.

* [x] See if we want `T: Tr` to desugar into `T: Tr, T::Effects: Compat<true>`
* [x] Fix ICEs on `type Assoc: ~const Tr` and `type Assoc<T: ~const Tr>`
* [ ] add types and traits to minicore test
* [ ] update rustc-dev-guide

Fixes #119717
Fixes #123664
Fixes #124857
Fixes #126148
This commit is contained in:
bors 2024-06-29 20:08:10 +00:00
commit ba1d7f4a08
175 changed files with 2234 additions and 1576 deletions
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49
compiler/rustc_hir_analysis/src/collect.rs
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@ -1638,44 +1638,19 @@ fn impl_trait_header(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<ty::ImplTrai
let icx = ItemCtxt::new(tcx, def_id);
let item = tcx.hir().expect_item(def_id);
let impl_ = item.expect_impl();
impl_
.of_trait
.as_ref()
.map(|hir_trait_ref| {
let self_ty = tcx.type_of(def_id).instantiate_identity();
impl_.of_trait.as_ref().map(|ast_trait_ref| {
let selfty = tcx.type_of(def_id).instantiate_identity();
let trait_ref = if let Some(ErrorGuaranteed { .. }) = check_impl_constness(
tcx,
tcx.is_const_trait_impl_raw(def_id.to_def_id()),
hir_trait_ref,
) {
// we have a const impl, but for a trait without `#[const_trait]`, so
// without the host param. If we continue with the HIR trait ref, we get
// ICEs for generic arg count mismatch. We do a little HIR editing to
// make HIR ty lowering happy.
let mut path_segments = hir_trait_ref.path.segments.to_vec();
let last_segment = path_segments.len() - 1;
let mut args = *path_segments[last_segment].args();
let last_arg = args.args.len() - 1;
assert!(matches!(args.args[last_arg], hir::GenericArg::Const(anon_const) if anon_const.is_desugared_from_effects));
args.args = &args.args[..args.args.len() - 1];
path_segments[last_segment].args = Some(tcx.hir_arena.alloc(args));
let path = hir::Path {
span: hir_trait_ref.path.span,
res: hir_trait_ref.path.res,
segments: tcx.hir_arena.alloc_slice(&path_segments),
};
let trait_ref = tcx.hir_arena.alloc(hir::TraitRef { path: tcx.hir_arena.alloc(path), hir_ref_id: hir_trait_ref.hir_ref_id });
icx.lowerer().lower_impl_trait_ref(trait_ref, self_ty)
} else {
icx.lowerer().lower_impl_trait_ref(hir_trait_ref, self_ty)
};
ty::ImplTraitHeader {
trait_ref: ty::EarlyBinder::bind(trait_ref),
safety: impl_.safety,
polarity: polarity_of_impl(tcx, def_id, impl_, item.span)
}
})
check_impl_constness(tcx, tcx.is_const_trait_impl_raw(def_id.to_def_id()), ast_trait_ref);
let trait_ref = icx.lowerer().lower_impl_trait_ref(ast_trait_ref, selfty);
ty::ImplTraitHeader {
trait_ref: ty::EarlyBinder::bind(trait_ref),
safety: impl_.safety,
polarity: polarity_of_impl(tcx, def_id, impl_, item.span),
}
})
}
fn check_impl_constness(