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Rollup merge of #118915 - compiler-errors:alias-nits, r=lcnr

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Add some comments, add `can_define_opaque_ty` check to `try_normalize_ty_recur`

Follow-up from #117278, since I was recently re-reviewing this code.
This commit is contained in:
Matthias Krüger 2024-01-11 03:02:39 +01:00 committed by GitHub
commit 859874f3eb
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8 changed files with 65 additions and 45 deletions
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4
compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
View File

@ -315,7 +315,7 @@ impl<'tcx> BorrowExplanation<'tcx> {
let mut failed = false;
let elaborated_args = std::iter::zip(*args, &generics.params).map(|(arg, param)| {
if let Some(ty::Dynamic(obj, _, ty::DynKind::Dyn)) = arg.as_type().map(Ty::kind) {
if let Some(ty::Dynamic(obj, _, ty::Dyn)) = arg.as_type().map(Ty::kind) {
let default = tcx.object_lifetime_default(param.def_id);
let re_static = tcx.lifetimes.re_static;
@ -339,7 +339,7 @@ impl<'tcx> BorrowExplanation<'tcx> {
has_dyn = true;
Ty::new_dynamic(tcx, obj, implied_region, ty::DynKind::Dyn).into()
Ty::new_dynamic(tcx, obj, implied_region, ty::Dyn).into()
} else {
arg
}

6
compiler/rustc_infer/src/infer/error_reporting/mod.rs
View File

@ -2348,11 +2348,11 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
GenericKind::Param(ref p) => format!("the parameter type `{p}`"),
GenericKind::Placeholder(ref p) => format!("the placeholder type `{p:?}`"),
GenericKind::Alias(ref p) => match p.kind(self.tcx) {
ty::AliasKind::Projection | ty::AliasKind::Inherent => {
ty::Projection | ty::Inherent => {
format!("the associated type `{p}`")
}
ty::AliasKind::Weak => format!("the type alias `{p}`"),
ty::AliasKind::Opaque => format!("the opaque type `{p}`"),
ty::Weak => format!("the type alias `{p}`"),
ty::Opaque => format!("the opaque type `{p}`"),
},
};

9
compiler/rustc_infer/src/infer/relate/combine.rs
View File

@ -510,7 +510,7 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
));
} else {
match a_ty.kind() {
&ty::Alias(ty::AliasKind::Projection, data) => {
&ty::Alias(ty::Projection, data) => {
// FIXME: This does not handle subtyping correctly, we could
// instead create a new inference variable for `a_ty`, emitting
// `Projection(a_ty, a_infer)` and `a_infer <: b_ty`.
@ -522,10 +522,9 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
))
}
// The old solver only accepts projection predicates for associated types.
ty::Alias(
ty::AliasKind::Inherent | ty::AliasKind::Weak | ty::AliasKind::Opaque,
_,
) => return Err(TypeError::CyclicTy(a_ty)),
ty::Alias(ty::Inherent | ty::Weak | ty::Opaque, _) => {
return Err(TypeError::CyclicTy(a_ty));
}
_ => bug!("generalizated `{a_ty:?} to infer, not an alias"),
}
}

3
compiler/rustc_lint/src/types.rs
View File

@ -29,7 +29,6 @@ use rustc_span::{Span, Symbol};
use rustc_target::abi::{Abi, Size, WrappingRange};
use rustc_target::abi::{Integer, TagEncoding, Variants};
use rustc_target::spec::abi::Abi as SpecAbi;
use rustc_type_ir::DynKind;
use std::iter;
use std::ops::ControlFlow;
@ -675,7 +674,7 @@ fn lint_wide_pointer<'tcx>(
}
match ty.kind() {
ty::RawPtr(TypeAndMut { mutbl: _, ty }) => (!ty.is_sized(cx.tcx, cx.param_env))
.then(|| (refs, matches!(ty.kind(), ty::Dynamic(_, _, DynKind::Dyn)))),
.then(|| (refs, matches!(ty.kind(), ty::Dynamic(_, _, ty::Dyn)))),
_ => None,
}
};

6
compiler/rustc_middle/src/ty/sty.rs
View File

@ -1225,7 +1225,7 @@ impl<'tcx> AliasTy<'tcx> {
/// Whether this alias type is an opaque.
pub fn is_opaque(self, tcx: TyCtxt<'tcx>) -> bool {
matches!(self.opt_kind(tcx), Some(ty::AliasKind::Opaque))
matches!(self.opt_kind(tcx), Some(ty::Opaque))
}
/// FIXME: rename `AliasTy` to `AliasTerm` and always handle
@ -2745,7 +2745,7 @@ impl<'tcx> Ty<'tcx> {
// Extern types have metadata = ().
| ty::Foreign(..)
// `dyn*` has no metadata
| ty::Dynamic(_, _, DynKind::DynStar)
| ty::Dynamic(_, _, ty::DynStar)
// If returned by `struct_tail_without_normalization` this is a unit struct
// without any fields, or not a struct, and therefore is Sized.
| ty::Adt(..)
@ -2754,7 +2754,7 @@ impl<'tcx> Ty<'tcx> {
| ty::Tuple(..) => (tcx.types.unit, false),
ty::Str | ty::Slice(_) => (tcx.types.usize, false),
ty::Dynamic(_, _, DynKind::Dyn) => {
ty::Dynamic(_, _, ty::Dyn) => {
let dyn_metadata = tcx.require_lang_item(LangItem::DynMetadata, None);
(tcx.type_of(dyn_metadata).instantiate(tcx, &[tail.into()]), false)
},

14
compiler/rustc_smir/src/rustc_smir/convert/ty.rs
View File

@ -12,12 +12,11 @@ use crate::rustc_smir::{alloc, Stable, Tables};
impl<'tcx> Stable<'tcx> for ty::AliasKind {
type T = stable_mir::ty::AliasKind;
fn stable(&self, _: &mut Tables<'tcx>) -> Self::T {
use rustc_middle::ty::AliasKind::*;
match self {
Projection => stable_mir::ty::AliasKind::Projection,
Inherent => stable_mir::ty::AliasKind::Inherent,
Opaque => stable_mir::ty::AliasKind::Opaque,
Weak => stable_mir::ty::AliasKind::Weak,
ty::Projection => stable_mir::ty::AliasKind::Projection,
ty::Inherent => stable_mir::ty::AliasKind::Inherent,
ty::Opaque => stable_mir::ty::AliasKind::Opaque,
ty::Weak => stable_mir::ty::AliasKind::Weak,
}
}
}
@ -34,10 +33,9 @@ impl<'tcx> Stable<'tcx> for ty::DynKind {
type T = stable_mir::ty::DynKind;
fn stable(&self, _: &mut Tables<'tcx>) -> Self::T {
use rustc_middle::ty::DynKind;
match self {
DynKind::Dyn => stable_mir::ty::DynKind::Dyn,
DynKind::DynStar => stable_mir::ty::DynKind::DynStar,
ty::Dyn => stable_mir::ty::DynKind::Dyn,
ty::DynStar => stable_mir::ty::DynKind::DynStar,
}
}
}

35
compiler/rustc_trait_selection/src/solve/alias_relate.rs
View File

@ -2,15 +2,29 @@
//! Doing this via a separate goal is called "deferred alias relation" and part
//! of our more general approach to "lazy normalization".
//!
//! This goal, e.g. `A alias-relate B`, may be satisfied by one of three branches:
//! * normalizes-to: If `A` is a projection, we can prove the equivalent
//! projection predicate with B as the right-hand side of the projection.
//! This goal is computed in both directions, if both are aliases.
//! * subst-relate: Equate `A` and `B` by their substs, if they're both
//! aliases with the same def-id.
//! * bidirectional-normalizes-to: If `A` and `B` are both projections, and both
//! may apply, then we can compute the "intersection" of both normalizes-to by
//! performing them together. This is used specifically to resolve ambiguities.
//! This is done by first normalizing both sides of the goal, ending up in
//! either a concrete type, rigid projection, opaque, or an infer variable.
//! These are related further according to the rules below:
//!
//! (1.) If we end up with a rigid projection and a rigid projection, then we
//! relate those projections structurally.
//!
//! (2.) If we end up with a rigid projection and an alias, then the opaque will
//! have its hidden type defined to be that rigid projection.
//!
//! (3.) If we end up with an opaque and an opaque, then we assemble two
//! candidates, one defining the LHS to be the hidden type of the RHS, and vice
//! versa.
//!
//! (4.) If we end up with an infer var and an opaque or rigid projection, then
//! we assign the alias to the infer var.
//!
//! (5.) If we end up with an opaque and a rigid (non-projection) type, then we
//! define the hidden type of the opaque to be the rigid type.
//!
//! (6.) Otherwise, if we end with two rigid (non-projection) or infer types,
//! relate them structurally.
use super::{EvalCtxt, GoalSource};
use rustc_infer::infer::DefineOpaqueTypes;
use rustc_infer::traits::query::NoSolution;
@ -50,6 +64,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
self.relate(param_env, lhs, variance, rhs)?;
self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
} else if alias.is_opaque(tcx) {
// FIXME: This doesn't account for variance.
self.define_opaque(param_env, alias, rhs)
} else {
Err(NoSolution)
@ -60,6 +75,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
self.relate(param_env, lhs, variance, rhs)?;
self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
} else if alias.is_opaque(tcx) {
// FIXME: This doesn't account for variance.
self.define_opaque(param_env, alias, lhs)
} else {
Err(NoSolution)
@ -72,6 +88,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
}
}
// FIXME: This needs a name that reflects that it's okay to bottom-out with an inference var.
/// Normalize the `term` to equate it later. This does not define opaque types.
#[instrument(level = "debug", skip(self, param_env), ret)]
fn try_normalize_term(

33
compiler/rustc_trait_selection/src/solve/mod.rs
View File

@ -22,6 +22,7 @@ use rustc_middle::traits::solve::{
CanonicalResponse, Certainty, ExternalConstraintsData, Goal, GoalSource, IsNormalizesToHack,
QueryResult, Response,
};
use rustc_middle::traits::Reveal;
use rustc_middle::ty::{self, OpaqueTypeKey, Ty, TyCtxt, UniverseIndex};
use rustc_middle::ty::{
CoercePredicate, RegionOutlivesPredicate, SubtypePredicate, TypeOutlivesPredicate,
@ -316,19 +317,25 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
return Some(ty);
};
// We do no always define opaque types eagerly to allow non-defining uses in the defining scope.
if let (DefineOpaqueTypes::No, ty::AliasKind::Opaque) = (define_opaque_types, kind) {
if let Some(def_id) = alias.def_id.as_local() {
if self
.unify_existing_opaque_tys(
param_env,
OpaqueTypeKey { def_id, args: alias.args },
self.next_ty_infer(),
)
.is_empty()
{
return Some(ty);
}
// We do no always define opaque types eagerly to allow non-defining uses
// in the defining scope. However, if we can unify this opaque to an existing
// opaque, then we should attempt to eagerly reveal the opaque, and we fall
// through.
if let DefineOpaqueTypes::No = define_opaque_types
&& let Reveal::UserFacing = param_env.reveal()
&& let ty::Opaque = kind
&& let Some(def_id) = alias.def_id.as_local()
&& self.can_define_opaque_ty(def_id)
{
if self
.unify_existing_opaque_tys(
param_env,
OpaqueTypeKey { def_id, args: alias.args },
self.next_ty_infer(),
)
.is_empty()
{
return Some(ty);
}
}