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Auto merge of rust-lang#122891 - compiler-errors:encode-implied-predi…
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…cates-always, r=oli-obk

Encode implied predicates for traits

In rust-lang#112629, we decided to make associated type bounds in the "supertrait" AST position *implied* even though they're not supertraits themselves.

This means that the `super_predicates` and `implied_predicates` queries now differ for regular traits. The assumption that they didn't differ was hard-coded in rust-lang#107614, so in cross-crate positions this means that we forget the implied predicates from associated type bounds.

This isn't unsound, just kind of annoying. This should be backported since associated type bounds are slated to stabilize for 1.78 -- either that, or associated type bounds can be reverted on beta and re-shipped in 1.79 with this patch.

Fixes rust-lang#122859
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bors authored and RenjiSann committed Mar 25, 2024
2 parents 8db63b3 + 3361488 commit 4871303
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Showing 4 changed files with 18 additions and 12 deletions.
13 changes: 1 addition & 12 deletions compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
Original file line number Diff line number Diff line change
Expand Up @@ -211,6 +211,7 @@ provide! { tcx, def_id, other, cdata,
generics_of => { table }
inferred_outlives_of => { table_defaulted_array }
super_predicates_of => { table }
implied_predicates_of => { table }
type_of => { table }
type_alias_is_lazy => { cdata.root.tables.type_alias_is_lazy.get(cdata, def_id.index) }
variances_of => { table }
Expand Down Expand Up @@ -276,18 +277,6 @@ provide! { tcx, def_id, other, cdata,
.map(|lazy| lazy.decode((cdata, tcx)))
.process_decoded(tcx, || panic!("{def_id:?} does not have trait_impl_trait_tys")))
}
implied_predicates_of => {
cdata
.root
.tables
.implied_predicates_of
.get(cdata, def_id.index)
.map(|lazy| lazy.decode((cdata, tcx)))
.unwrap_or_else(|| {
debug_assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
tcx.super_predicates_of(def_id)
})
}

associated_types_for_impl_traits_in_associated_fn => { table_defaulted_array }

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1 change: 1 addition & 0 deletions compiler/rustc_metadata/src/rmeta/encoder.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1435,6 +1435,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
if let DefKind::Trait = def_kind {
record!(self.tables.trait_def[def_id] <- self.tcx.trait_def(def_id));
record!(self.tables.super_predicates_of[def_id] <- self.tcx.super_predicates_of(def_id));
record!(self.tables.implied_predicates_of[def_id] <- self.tcx.implied_predicates_of(def_id));

let module_children = self.tcx.module_children_local(local_id);
record_array!(self.tables.module_children_non_reexports[def_id] <-
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Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
pub trait Bar: Super<SuperAssoc: Bound> {}

pub trait Super {
type SuperAssoc;
}

pub trait Bound {}
9 changes: 9 additions & 0 deletions tests/ui/associated-type-bounds/implied-predicates.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
//@ aux-build:implied-predicates.rs
//@ check-pass

extern crate implied_predicates;
use implied_predicates::Bar;

fn bar<B: Bar>() {}

fn main() {}

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