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Remove associated type based effects logic
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@compiler-errors
compiler-errors committed Oct 24, 2024
1 parent 8aca4ba commit a16d491
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Showing 73 changed files with 85 additions and 1,519 deletions.
205 changes: 19 additions & 186 deletions compiler/rustc_ast_lowering/src/item.rs
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20 changes: 3 additions & 17 deletions compiler/rustc_ast_lowering/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -154,17 +154,10 @@ struct LoweringContext<'a, 'hir> {
/// defined on the TAIT, so we have type Foo<'a1> = ... and we establish a mapping in this
/// field from the original parameter 'a to the new parameter 'a1.
generics_def_id_map: Vec<LocalDefIdMap<LocalDefId>>,

host_param_id: Option<LocalDefId>,
ast_index: &'a IndexSlice<LocalDefId, AstOwner<'a>>,
}

impl<'a, 'hir> LoweringContext<'a, 'hir> {
fn new(
tcx: TyCtxt<'hir>,
resolver: &'a mut ResolverAstLowering,
ast_index: &'a IndexSlice<LocalDefId, AstOwner<'a>>,
) -> Self {
fn new(tcx: TyCtxt<'hir>, resolver: &'a mut ResolverAstLowering) -> Self {
Self {
// Pseudo-globals.
tcx,
Expand Down Expand Up @@ -204,8 +197,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
// interact with `gen`/`async gen` blocks
allow_async_iterator: [sym::gen_future, sym::async_iterator].into(),
generics_def_id_map: Default::default(),
host_param_id: None,
ast_index,
}
}

Expand Down Expand Up @@ -2054,11 +2045,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
param: &GenericParam,
source: hir::GenericParamSource,
) -> hir::GenericParam<'hir> {
let (name, kind) = self.lower_generic_param_kind(
param,
source,
attr::contains_name(&param.attrs, sym::rustc_runtime),
);
let (name, kind) = self.lower_generic_param_kind(param, source);

let hir_id = self.lower_node_id(param.id);
self.lower_attrs(hir_id, &param.attrs);
Expand All @@ -2078,7 +2065,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
&mut self,
param: &GenericParam,
source: hir::GenericParamSource,
is_host_effect: bool,
) -> (hir::ParamName, hir::GenericParamKind<'hir>) {
match &param.kind {
GenericParamKind::Lifetime => {
Expand Down Expand Up @@ -2144,7 +2130,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {

(
hir::ParamName::Plain(self.lower_ident(param.ident)),
hir::GenericParamKind::Const { ty, default, is_host_effect, synthetic: false },
hir::GenericParamKind::Const { ty, default, synthetic: false },
)
}
}
Expand Down
4 changes: 0 additions & 4 deletions compiler/rustc_feature/src/builtin_attrs.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -838,10 +838,6 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
rustc_const_panic_str, Normal, template!(Word), WarnFollowing,
EncodeCrossCrate::Yes, INTERNAL_UNSTABLE
),
rustc_attr!(
rustc_runtime, Normal, template!(Word), WarnFollowing,
EncodeCrossCrate::No, INTERNAL_UNSTABLE
),

// ==========================================================================
// Internal attributes, Layout related:
Expand Down
1 change: 0 additions & 1 deletion compiler/rustc_hir/src/hir.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -580,7 +580,6 @@ pub enum GenericParamKind<'hir> {
ty: &'hir Ty<'hir>,
/// Optional default value for the const generic param
default: Option<&'hir ConstArg<'hir>>,
is_host_effect: bool,
synthetic: bool,
},
}
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_hir/src/intravisit.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -935,7 +935,7 @@ pub fn walk_generic_param<'v, V: Visitor<'v>>(
match param.kind {
GenericParamKind::Lifetime { .. } => {}
GenericParamKind::Type { ref default, .. } => visit_opt!(visitor, visit_ty, default),
GenericParamKind::Const { ref ty, ref default, is_host_effect: _, synthetic: _ } => {
GenericParamKind::Const { ref ty, ref default, synthetic: _ } => {
try_visit!(visitor.visit_ty(ty));
if let Some(ref default) = default {
try_visit!(visitor.visit_const_param_default(param.hir_id, default));
Expand Down
8 changes: 0 additions & 8 deletions compiler/rustc_hir/src/lang_items.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -415,14 +415,6 @@ language_item_table! {

String, sym::String, string, Target::Struct, GenericRequirement::None;
CStr, sym::CStr, c_str, Target::Struct, GenericRequirement::None;

EffectsRuntime, sym::EffectsRuntime, effects_runtime, Target::Struct, GenericRequirement::None;
EffectsNoRuntime, sym::EffectsNoRuntime, effects_no_runtime, Target::Struct, GenericRequirement::None;
EffectsMaybe, sym::EffectsMaybe, effects_maybe, Target::Struct, GenericRequirement::None;
EffectsIntersection, sym::EffectsIntersection, effects_intersection, Target::Trait, GenericRequirement::None;
EffectsIntersectionOutput, sym::EffectsIntersectionOutput, effects_intersection_output, Target::AssocTy, GenericRequirement::None;
EffectsCompat, sym::EffectsCompat, effects_compat, Target::Trait, GenericRequirement::Exact(1);
EffectsTyCompat, sym::EffectsTyCompat, effects_ty_compat, Target::Trait, GenericRequirement::Exact(1);
}

pub enum GenericRequirement {
Expand Down
139 changes: 0 additions & 139 deletions compiler/rustc_hir_analysis/src/bounds.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,13 +3,8 @@
use rustc_data_structures::fx::FxIndexMap;
use rustc_hir::LangItem;
use rustc_hir::def::DefKind;
use rustc_middle::ty::fold::FnMutDelegate;
use rustc_middle::ty::{self, Ty, TyCtxt, Upcast};
use rustc_span::Span;
use rustc_span::def_id::DefId;

use crate::hir_ty_lowering::PredicateFilter;

/// Collects together a list of type bounds. These lists of bounds occur in many places
/// in Rust's syntax:
Expand Down Expand Up @@ -47,12 +42,9 @@ impl<'tcx> Bounds<'tcx> {
pub(crate) fn push_trait_bound(
&mut self,
tcx: TyCtxt<'tcx>,
defining_def_id: DefId,
bound_trait_ref: ty::PolyTraitRef<'tcx>,
span: Span,
polarity: ty::PredicatePolarity,
constness: Option<ty::BoundConstness>,
predicate_filter: PredicateFilter,
) {
let clause = (
bound_trait_ref
Expand All @@ -68,137 +60,6 @@ impl<'tcx> Bounds<'tcx> {
} else {
self.clauses.push(clause);
}

// FIXME(effects): Lift this out of `push_trait_bound`, and move it somewhere else.
// Perhaps moving this into `lower_poly_trait_ref`, just like we lower associated
// type bounds.
if !tcx.features().effects() {
return;
}
match predicate_filter {
PredicateFilter::SelfOnly | PredicateFilter::SelfThatDefines(_) => {
return;
}
PredicateFilter::All | PredicateFilter::SelfAndAssociatedTypeBounds => {
// Ok.
}
}

// For `T: ~const Tr` or `T: const Tr`, we need to add an additional bound on the
// associated type of `<T as Tr>` and make sure that the effect is compatible.
let compat_val = match (tcx.def_kind(defining_def_id), constness) {
// FIXME(effects): revisit the correctness of this
(_, Some(ty::BoundConstness::Const)) => tcx.consts.false_,
// body owners that can have trait bounds
(
DefKind::Const | DefKind::Fn | DefKind::AssocFn,
Some(ty::BoundConstness::ConstIfConst),
) => tcx.expected_host_effect_param_for_body(defining_def_id),

(_, None) => {
if !tcx.is_const_trait(bound_trait_ref.def_id()) {
return;
}
tcx.consts.true_
}
(DefKind::Trait, Some(ty::BoundConstness::ConstIfConst)) => {
// we are in a trait, where `bound_trait_ref` could be:
// (1) a super trait `trait Foo: ~const Bar`.
// - This generates `<Self as Foo>::Effects: TyCompat<<Self as Bar>::Effects>`
//
// (2) a where clause `where for<..> Something: ~const Bar`.
// - This generates `for<..> <Self as Foo>::Effects: TyCompat<<Something as Bar>::Effects>`
let Some(own_fx) = tcx.associated_type_for_effects(defining_def_id) else {
tcx.dcx().span_delayed_bug(span, "should not have allowed `~const` on a trait that doesn't have `#[const_trait]`");
return;
};
let own_fx_ty = Ty::new_projection(
tcx,
own_fx,
ty::GenericArgs::identity_for_item(tcx, own_fx),
);
let Some(their_fx) = tcx.associated_type_for_effects(bound_trait_ref.def_id())
else {
tcx.dcx().span_delayed_bug(span, "`~const` on trait without Effects assoc");
return;
};
let their_fx_ty =
Ty::new_projection(tcx, their_fx, bound_trait_ref.skip_binder().args);
let compat = tcx.require_lang_item(LangItem::EffectsTyCompat, Some(span));
let clause = bound_trait_ref
.map_bound(|_| {
let trait_ref = ty::TraitRef::new(tcx, compat, [own_fx_ty, their_fx_ty]);
ty::ClauseKind::Trait(ty::TraitPredicate {
trait_ref,
polarity: ty::PredicatePolarity::Positive,
})
})
.upcast(tcx);

self.clauses.push((clause, span));
return;
}

(DefKind::Impl { of_trait: true }, Some(ty::BoundConstness::ConstIfConst)) => {
// this is a where clause on an impl header.
// push `<T as Tr>::Effects` into the set for the `Min` bound.
let Some(assoc) = tcx.associated_type_for_effects(bound_trait_ref.def_id()) else {
tcx.dcx().span_delayed_bug(span, "`~const` on trait without Effects assoc");
return;
};

let ty = bound_trait_ref
.map_bound(|trait_ref| Ty::new_projection(tcx, assoc, trait_ref.args));

// When the user has written `for<'a, T> X<'a, T>: ~const Foo`, replace the
// binders to dummy ones i.e. `X<'static, ()>` so they can be referenced in
// the `Min` associated type properly (which doesn't allow using `for<>`)
// This should work for any bound variables as long as they don't have any
// bounds e.g. `for<T: Trait>`.
// FIXME(effects) reconsider this approach to allow compatibility with `for<T: Tr>`
let ty = tcx.replace_bound_vars_uncached(ty, FnMutDelegate {
regions: &mut |_| tcx.lifetimes.re_static,
types: &mut |_| tcx.types.unit,
consts: &mut |_| unimplemented!("`~const` does not support const binders"),
});

self.effects_min_tys.insert(ty, span);
return;
}
// for
// ```
// trait Foo { type Bar: ~const Trait }
// ```
// ensure that `<Self::Bar as Trait>::Effects: TyCompat<Self::Effects>`.
//
// FIXME(effects) this is equality for now, which wouldn't be helpful for a non-const implementor
// that uses a `Bar` that implements `Trait` with `Maybe` effects.
(DefKind::AssocTy, Some(ty::BoundConstness::ConstIfConst)) => {
// FIXME(effects): implement this
return;
}
// probably illegal in this position.
(_, Some(ty::BoundConstness::ConstIfConst)) => {
tcx.dcx().span_delayed_bug(span, "invalid `~const` encountered");
return;
}
};
// create a new projection type `<T as Tr>::Effects`
let Some(assoc) = tcx.associated_type_for_effects(bound_trait_ref.def_id()) else {
tcx.dcx().span_delayed_bug(
span,
"`~const` trait bound has no effect assoc yet no errors encountered?",
);
return;
};
let self_ty = Ty::new_projection(tcx, assoc, bound_trait_ref.skip_binder().args);
// make `<T as Tr>::Effects: Compat<runtime>`
let new_trait_ref =
ty::TraitRef::new(tcx, tcx.require_lang_item(LangItem::EffectsCompat, Some(span)), [
ty::GenericArg::from(self_ty),
compat_val.into(),
]);
self.clauses.push((bound_trait_ref.rebind(new_trait_ref).upcast(tcx), span));
}

pub(crate) fn push_projection_bound(
Expand Down
8 changes: 1 addition & 7 deletions compiler/rustc_hir_analysis/src/check/intrinsic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -58,15 +58,9 @@ fn equate_intrinsic_type<'tcx>(

// the host effect param should be invisible as it shouldn't matter
// whether effects is enabled for the intrinsic provider crate.
let consts_count = if generics.host_effect_index.is_some() {
own_counts.consts - 1
} else {
own_counts.consts
};

if gen_count_ok(own_counts.lifetimes, n_lts, "lifetime")
&& gen_count_ok(own_counts.types, n_tps, "type")
&& gen_count_ok(consts_count, n_cts, "const")
&& gen_count_ok(own_counts.consts, n_cts, "const")
{
let _ = check_function_signature(
tcx,
Expand Down
7 changes: 1 addition & 6 deletions compiler/rustc_hir_analysis/src/check/wfcheck.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -913,12 +913,7 @@ fn check_param_wf(tcx: TyCtxt<'_>, param: &hir::GenericParam<'_>) -> Result<(),
hir::GenericParamKind::Lifetime { .. } | hir::GenericParamKind::Type { .. } => Ok(()),

// Const parameters are well formed if their type is structural match.
hir::GenericParamKind::Const {
ty: hir_ty,
default: _,
is_host_effect: _,
synthetic: _,
} => {
hir::GenericParamKind::Const { ty: hir_ty, default: _, synthetic: _ } => {
let ty = tcx.type_of(param.def_id).instantiate_identity();

if tcx.features().unsized_const_params() {
Expand Down
33 changes: 4 additions & 29 deletions compiler/rustc_hir_analysis/src/collect/generics_of.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,6 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
param_def_id_to_index,
has_self: opaque_ty_generics.has_self,
has_late_bound_regions: opaque_ty_generics.has_late_bound_regions,
host_effect_index: parent_generics.host_effect_index,
};
}

Expand Down Expand Up @@ -161,7 +160,6 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
param_def_id_to_index,
has_self: generics.has_self,
has_late_bound_regions: generics.has_late_bound_regions,
host_effect_index: None,
};
} else {
// HACK(eddyb) this provides the correct generics when
Expand Down Expand Up @@ -292,12 +290,10 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
let has_self = opt_self.is_some();
let mut parent_has_self = false;
let mut own_start = has_self as u32;
let mut host_effect_index = None;
let parent_count = parent_def_id.map_or(0, |def_id| {
let generics = tcx.generics_of(def_id);
assert!(!has_self);
parent_has_self = generics.has_self;
host_effect_index = generics.host_effect_index;
own_start = generics.count() as u32;
generics.parent_count + generics.own_params.len()
});
Expand Down Expand Up @@ -361,12 +357,8 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
kind,
})
}
GenericParamKind::Const { ty: _, default, is_host_effect, synthetic } => {
if !matches!(allow_defaults, Defaults::Allowed)
&& default.is_some()
// `host` effect params are allowed to have defaults.
&& !is_host_effect
{
GenericParamKind::Const { ty: _, default, synthetic } => {
if !matches!(allow_defaults, Defaults::Allowed) && default.is_some() {
tcx.dcx().span_err(
param.span,
"defaults for const parameters are only allowed in \
Expand All @@ -376,27 +368,12 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {

let index = next_index();

if is_host_effect {
if let Some(idx) = host_effect_index {
tcx.dcx().span_delayed_bug(
param.span,
format!("parent also has host effect param? index: {idx}, def: {def_id:?}"),
);
}

host_effect_index = Some(index as usize);
}

Some(ty::GenericParamDef {
index,
name: param.name.ident().name,
def_id: param.def_id.to_def_id(),
pure_wrt_drop: param.pure_wrt_drop,
kind: ty::GenericParamDefKind::Const {
has_default: default.is_some(),
is_host_effect,
synthetic,
},
kind: ty::GenericParamDefKind::Const { has_default: default.is_some(), synthetic },
})
}
}));
Expand Down Expand Up @@ -459,7 +436,6 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
param_def_id_to_index,
has_self: has_self || parent_has_self,
has_late_bound_regions: has_late_bound_regions(tcx, node),
host_effect_index,
}
}

Expand Down Expand Up @@ -540,8 +516,7 @@ impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
type Result = ControlFlow<()>;

fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) -> Self::Result {
if let GenericParamKind::Const { ty, default: _, is_host_effect: _, synthetic: _ } = p.kind
{
if let GenericParamKind::Const { ty, default: _, synthetic: _ } = p.kind {
let prev = self.in_param_ty;
self.in_param_ty = true;
let res = self.visit_ty(ty);
Expand Down
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