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Rollup merge of #125776 - compiler-errors:translate-args, r=lcnr 

Stop using `translate_args` in the new solver

It was unnecessary and also sketchy, since it was doing an out-of-search-graph fulfillment loop. Added a test for the only really minor subtlety of translating args, though not sure if it was being tested before, though I wouldn't be surprised if it wasn't.

r? lcnr
This commit is contained in:
Matthias Krüger 2024-05-31 17:05:25 +02:00 committed by GitHub
parent 7667a91778 20699fe6b2
commit 5109a7668a
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GPG Key ID: B5690EEEBB952194
7 changed files with 167 additions and 56 deletions
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11
compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
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@ -12,7 +12,6 @@ use rustc_middle::bug;
use rustc_middle::traits::solve::{
inspect, CanonicalInput, CanonicalResponse, Certainty, PredefinedOpaquesData, QueryResult,
};
use rustc_middle::traits::specialization_graph;
use rustc_middle::ty::AliasRelationDirection;
use rustc_middle::ty::TypeFolder;
use rustc_middle::ty::{
@ -900,16 +899,6 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
args
}
pub(super) fn translate_args(
&self,
param_env: ty::ParamEnv<'tcx>,
source_impl: DefId,
source_args: ty::GenericArgsRef<'tcx>,
target_node: specialization_graph::Node,
) -> ty::GenericArgsRef<'tcx> {
crate::traits::translate_args(self.infcx, param_env, source_impl, source_args, target_node)
}
pub(super) fn register_ty_outlives(&self, ty: Ty<'tcx>, lt: ty::Region<'tcx>) {
self.infcx.register_region_obligation_with_cause(ty, lt, &ObligationCause::dummy());
}

123
compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs
View File

@ -1,4 +1,4 @@
use crate::traits::specialization_graph;
use crate::traits::specialization_graph::{self, LeafDef, Node};
use super::assembly::structural_traits::AsyncCallableRelevantTypes;
use super::assembly::{self, structural_traits, Candidate};
@ -9,7 +9,6 @@ use rustc_infer::infer::InferCtxt;
use rustc_infer::traits::query::NoSolution;
use rustc_infer::traits::solve::inspect::ProbeKind;
use rustc_infer::traits::solve::MaybeCause;
use rustc_infer::traits::specialization_graph::LeafDef;
use rustc_infer::traits::Reveal;
use rustc_middle::traits::solve::{CandidateSource, Certainty, Goal, QueryResult};
use rustc_middle::traits::BuiltinImplSource;
@ -189,8 +188,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for NormalizesTo<'tcx> {
// In case the associated item is hidden due to specialization, we have to
// return ambiguity this would otherwise be incomplete, resulting in
// unsoundness during coherence (#105782).
let Some(assoc_def) = fetch_eligible_assoc_item_def(
ecx,
let Some(assoc_def) = ecx.fetch_eligible_assoc_item_def(
goal.param_env,
goal_trait_ref,
goal.predicate.def_id(),
@ -235,16 +233,10 @@ impl<'tcx> assembly::GoalKind<'tcx> for NormalizesTo<'tcx> {
//
// And then map these args to the args of the defining impl of `Assoc`, going
// from `[u32, u64]` to `[u32, i32, u64]`.
let impl_args_with_gat =
goal.predicate.alias.args.rebase_onto(tcx, goal_trait_ref.def_id, impl_args);
let args = ecx.translate_args(
goal.param_env,
impl_def_id,
impl_args_with_gat,
assoc_def.defining_node,
);
let associated_item_args =
ecx.translate_args(&assoc_def, goal, impl_def_id, impl_args, impl_trait_ref)?;
if !tcx.check_args_compatible(assoc_def.item.def_id, args) {
if !tcx.check_args_compatible(assoc_def.item.def_id, associated_item_args) {
return error_response(
ecx,
"associated item has mismatched generic item arguments",
@ -272,7 +264,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for NormalizesTo<'tcx> {
ty::AssocKind::Fn => unreachable!("we should never project to a fn"),
};
ecx.instantiate_normalizes_to_term(goal, term.instantiate(tcx, args));
ecx.instantiate_normalizes_to_term(goal, term.instantiate(tcx, associated_item_args));
ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
})
}
@ -889,38 +881,79 @@ impl<'tcx> assembly::GoalKind<'tcx> for NormalizesTo<'tcx> {
}
}
/// This behavior is also implemented in `rustc_ty_utils` and in the old `project` code.
///
/// FIXME: We should merge these 3 implementations as it's likely that they otherwise
/// diverge.
#[instrument(level = "trace", skip(ecx, param_env), ret)]
fn fetch_eligible_assoc_item_def<'tcx>(
ecx: &EvalCtxt<'_, InferCtxt<'tcx>>,
param_env: ty::ParamEnv<'tcx>,
goal_trait_ref: ty::TraitRef<'tcx>,
trait_assoc_def_id: DefId,
impl_def_id: DefId,
) -> Result<Option<LeafDef>, NoSolution> {
let node_item =
specialization_graph::assoc_def(ecx.interner(), impl_def_id, trait_assoc_def_id)
.map_err(|ErrorGuaranteed { .. }| NoSolution)?;
impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
fn translate_args(
&mut self,
assoc_def: &LeafDef,
goal: Goal<'tcx, ty::NormalizesTo<'tcx>>,
impl_def_id: DefId,
impl_args: ty::GenericArgsRef<'tcx>,
impl_trait_ref: rustc_type_ir::TraitRef<TyCtxt<'tcx>>,
) -> Result<ty::GenericArgsRef<'tcx>, NoSolution> {
let tcx = self.interner();
Ok(match assoc_def.defining_node {
Node::Trait(_) => goal.predicate.alias.args,
Node::Impl(target_impl_def_id) => {
if target_impl_def_id == impl_def_id {
// Same impl, no need to fully translate, just a rebase from
// the trait is sufficient.
goal.predicate.alias.args.rebase_onto(tcx, impl_trait_ref.def_id, impl_args)
} else {
let target_args = self.fresh_args_for_item(target_impl_def_id);
let target_trait_ref = tcx
.impl_trait_ref(target_impl_def_id)
.unwrap()
.instantiate(tcx, target_args);
// Relate source impl to target impl by equating trait refs.
self.eq(goal.param_env, impl_trait_ref, target_trait_ref)?;
// Also add predicates since they may be needed to constrain the
// target impl's params.
self.add_goals(
GoalSource::Misc,
tcx.predicates_of(target_impl_def_id)
.instantiate(tcx, target_args)
.into_iter()
.map(|(pred, _)| goal.with(tcx, pred)),
);
goal.predicate.alias.args.rebase_onto(tcx, impl_trait_ref.def_id, target_args)
}
}
})
}
let eligible = if node_item.is_final() {
// Non-specializable items are always projectable.
true
} else {
// Only reveal a specializable default if we're past type-checking
// and the obligation is monomorphic, otherwise passes such as
// transmute checking and polymorphic MIR optimizations could
// get a result which isn't correct for all monomorphizations.
if param_env.reveal() == Reveal::All {
let poly_trait_ref = ecx.resolve_vars_if_possible(goal_trait_ref);
!poly_trait_ref.still_further_specializable()
/// This behavior is also implemented in `rustc_ty_utils` and in the old `project` code.
///
/// FIXME: We should merge these 3 implementations as it's likely that they otherwise
/// diverge.
#[instrument(level = "trace", skip(self, param_env), ret)]
fn fetch_eligible_assoc_item_def(
&self,
param_env: ty::ParamEnv<'tcx>,
goal_trait_ref: ty::TraitRef<'tcx>,
trait_assoc_def_id: DefId,
impl_def_id: DefId,
) -> Result<Option<LeafDef>, NoSolution> {
let node_item =
specialization_graph::assoc_def(self.interner(), impl_def_id, trait_assoc_def_id)
.map_err(|ErrorGuaranteed { .. }| NoSolution)?;
let eligible = if node_item.is_final() {
// Non-specializable items are always projectable.
true
} else {
trace!(?node_item.item.def_id, "not eligible due to default");
false
}
};
// Only reveal a specializable default if we're past type-checking
// and the obligation is monomorphic, otherwise passes such as
// transmute checking and polymorphic MIR optimizations could
// get a result which isn't correct for all monomorphizations.
if param_env.reveal() == Reveal::All {
let poly_trait_ref = self.resolve_vars_if_possible(goal_trait_ref);
!poly_trait_ref.still_further_specializable()
} else {
trace!(?node_item.item.def_id, "not eligible due to default");
false
}
};
if eligible { Ok(Some(node_item)) } else { Ok(None) }
if eligible { Ok(Some(node_item)) } else { Ok(None) }
}
}

12
tests/ui/specialization/source-impl-requires-constraining-predicates-ambig.next.stderr Normal file
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@ -0,0 +1,12 @@
warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
--> $DIR/source-impl-requires-constraining-predicates-ambig.rs:14:12
|
LL | #![feature(specialization)]
| ^^^^^^^^^^^^^^
|
= note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
= help: consider using `min_specialization` instead, which is more stable and complete
= note: `#[warn(incomplete_features)]` on by default
warning: 1 warning emitted

29
tests/ui/specialization/source-impl-requires-constraining-predicates-ambig.rs Normal file
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@ -0,0 +1,29 @@
//@ revisions: current next
//@ ignore-compare-mode-next-solver (explicit revisions)
//@[next] compile-flags: -Znext-solver
//@[next] check-pass
//@[current] known-bug: unknown
//@[current] failure-status: 101
//@[current] dont-check-compiler-stderr
// Tests that rebasing from the concrete impl to the default impl also processes the
// `[u32; 0]: IntoIterator<Item = ?U>` predicate to constrain the `?U` impl arg.
// This test also makes sure that we don't do anything weird when rebasing the args
// is ambiguous.
#![feature(specialization)]
//[next]~^ WARN the feature `specialization` is incomplete
trait Spec {
type Assoc;
}
default impl<T, U> Spec for T where T: IntoIterator<Item = U> {
type Assoc = U;
}
impl<T> Spec for [T; 0] {}
fn main() {
let x: <[_; 0] as Spec>::Assoc = 1;
}

12
tests/ui/specialization/source-impl-requires-constraining-predicates.current.stderr Normal file
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@ -0,0 +1,12 @@
warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
--> $DIR/source-impl-requires-constraining-predicates.rs:9:12
|
LL | #![feature(specialization)]
| ^^^^^^^^^^^^^^
|
= note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
= help: consider using `min_specialization` instead, which is more stable and complete
= note: `#[warn(incomplete_features)]` on by default
warning: 1 warning emitted

12
tests/ui/specialization/source-impl-requires-constraining-predicates.next.stderr Normal file
View File

@ -0,0 +1,12 @@
warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
--> $DIR/source-impl-requires-constraining-predicates.rs:9:12
|
LL | #![feature(specialization)]
| ^^^^^^^^^^^^^^
|
= note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
= help: consider using `min_specialization` instead, which is more stable and complete
= note: `#[warn(incomplete_features)]` on by default
warning: 1 warning emitted

24
tests/ui/specialization/source-impl-requires-constraining-predicates.rs Normal file
View File

@ -0,0 +1,24 @@
//@ check-pass
//@ revisions: current next
//@ ignore-compare-mode-next-solver (explicit revisions)
//@[next] compile-flags: -Znext-solver
// Tests that rebasing from the concrete impl to the default impl also processes the
// `[u32; 0]: IntoIterator<Item = ?U>` predicate to constrain the `?U` impl arg.
#![feature(specialization)]
//~^ WARN the feature `specialization` is incomplete
trait Spec {
type Assoc;
}
default impl<T, U> Spec for T where T: IntoIterator<Item = U> {
type Assoc = U;
}
impl<T> Spec for [T; 0] {}
fn main() {
let x: <[u32; 0] as Spec>::Assoc = 1;
}