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lower impl const to bind to host effect param

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This commit is contained in:
Deadbeef 2023-07-25 05:58:53 +00:00
parent 4f7bb9890c
commit 92f4c59e48
24 changed files with 236 additions and 137 deletions
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10
compiler/rustc_ast/src/ast.rs
View File

@ -313,6 +313,16 @@ pub enum TraitBoundModifier {
MaybeConstMaybe,
}
impl TraitBoundModifier {
pub fn to_constness(self) -> Const {
match self {
// FIXME(effects) span
Self::MaybeConst => Const::Yes(DUMMY_SP),
_ => Const::No,
}
}
}
/// The AST represents all type param bounds as types.
/// `typeck::collect::compute_bounds` matches these against
/// the "special" built-in traits (see `middle::lang_items`) and

1
compiler/rustc_ast_lowering/src/asm.rs
View File

@ -207,6 +207,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
&sym.path,
ParamMode::Optional,
&ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
);
hir::InlineAsmOperand::SymStatic { path, def_id }
} else {

6
compiler/rustc_ast_lowering/src/expr.rs
View File

@ -100,6 +100,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
ParamMode::Optional,
ParenthesizedGenericArgs::Err,
&ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
));
let receiver = self.lower_expr(receiver);
let args =
@ -260,6 +261,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
path,
ParamMode::Optional,
&ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
);
hir::ExprKind::Path(qpath)
}
@ -307,6 +309,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
&se.path,
ParamMode::Optional,
&ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
)),
self.arena
.alloc_from_iter(se.fields.iter().map(|x| self.lower_expr_field(x))),
@ -1179,6 +1182,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
path,
ParamMode::Optional,
&ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
);
// Destructure like a tuple struct.
let tuple_struct_pat = hir::PatKind::TupleStruct(
@ -1198,6 +1202,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
path,
ParamMode::Optional,
&ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
);
// Destructure like a unit struct.
let unit_struct_pat = hir::PatKind::Path(qpath);
@ -1222,6 +1227,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
&se.path,
ParamMode::Optional,
&ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
);
let fields_omitted = match &se.rest {
StructRest::Base(e) => {

84
compiler/rustc_ast_lowering/src/item.rs
View File

@ -85,6 +85,7 @@ impl<'a, 'hir> ItemLowerer<'a, 'hir> {
allow_try_trait: Some([sym::try_trait_v2, sym::yeet_desugar_details][..].into()),
allow_gen_future: Some([sym::gen_future, sym::closure_track_caller][..].into()),
generics_def_id_map: Default::default(),
host_param_id: None,
};
lctx.with_hir_id_owner(owner, |lctx| f(lctx));
@ -139,8 +140,24 @@ impl<'a, 'hir> ItemLowerer<'a, 'hir> {
// This is used to track which lifetimes have already been defined,
// and which need to be replicated when lowering an async fn.
if let hir::ItemKind::Impl(impl_) = parent_hir.node().expect_item().kind {
lctx.is_in_trait_impl = impl_.of_trait.is_some();
match parent_hir.node().expect_item().kind {
hir::ItemKind::Impl(impl_) => {
lctx.is_in_trait_impl = impl_.of_trait.is_some();
}
hir::ItemKind::Trait(_, _, generics, _, _) if lctx.tcx.features().effects => {
lctx.host_param_id = generics
.params
.iter()
.find(|param| {
parent_hir
.attrs
.get(param.hir_id.local_id)
.iter()
.any(|attr| attr.has_name(sym::rustc_host))
})
.map(|param| param.def_id);
}
_ => {}
}
match ctxt {
@ -384,6 +401,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
self.lower_generics(ast_generics, *constness, id, &itctx, |this| {
let trait_ref = trait_ref.as_ref().map(|trait_ref| {
this.lower_trait_ref(
*constness,
trait_ref,
&ImplTraitContext::Disallowed(ImplTraitPosition::Trait),
)
@ -414,7 +432,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
polarity,
defaultness,
defaultness_span,
constness: self.lower_constness(*constness),
generics,
of_trait: trait_ref,
self_ty: lowered_ty,
@ -1358,6 +1375,29 @@ impl<'hir> LoweringContext<'_, 'hir> {
}
}
// Desugar `~const` bound in generics into an additional `const host: bool` param
// if the effects feature is enabled. This needs to be done before we lower where
// clauses since where clauses need to bind to the DefId of the host param
let host_param_parts = if let Const::Yes(span) = constness && self.tcx.features().effects {
if let Some(param) = generics.params.iter().find(|x| {
x.attrs.iter().any(|x| x.has_name(sym::rustc_host))
}) {
// user has manually specified a `rustc_host` param, in this case, we set
// the param id so that lowering logic can use that. But we don't create
// another host param, so this gives `None`.
self.host_param_id = Some(self.local_def_id(param.id));
None
} else {
let param_node_id = self.next_node_id();
let hir_id = self.next_id();
let def_id = self.create_def(self.local_def_id(parent_node_id), param_node_id, DefPathData::TypeNs(sym::host), span);
self.host_param_id = Some(def_id);
Some((span, hir_id, def_id))
}
} else {
None
};
let mut predicates: SmallVec<[hir::WherePredicate<'hir>; 4]> = SmallVec::new();
predicates.extend(generics.params.iter().filter_map(|param| {
self.lower_generic_bound_predicate(
@ -1405,22 +1445,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
let impl_trait_bounds = std::mem::take(&mut self.impl_trait_bounds);
predicates.extend(impl_trait_bounds.into_iter());
// Desugar `~const` bound in generics into an additional `const host: bool` param
// if the effects feature is enabled.
if let Const::Yes(span) = constness && self.tcx.features().effects
// Do not add host param if it already has it (manually specified)
&& !params.iter().any(|x| {
self.attrs.get(&x.hir_id.local_id).map_or(false, |attrs| {
attrs.iter().any(|x| x.has_name(sym::rustc_host))
})
})
{
let param_node_id = self.next_node_id();
if let Some((span, hir_id, def_id)) = host_param_parts {
let const_node_id = self.next_node_id();
let def_id = self.create_def(self.local_def_id(parent_node_id), param_node_id, DefPathData::TypeNs(sym::host), span);
let anon_const: LocalDefId = self.create_def(def_id, const_node_id, DefPathData::AnonConst, span);
let anon_const: LocalDefId =
self.create_def(def_id, const_node_id, DefPathData::AnonConst, span);
let hir_id = self.next_id();
let const_id = self.next_id();
let const_expr_id = self.next_id();
let bool_id = self.next_id();
@ -1430,14 +1459,15 @@ impl<'hir> LoweringContext<'_, 'hir> {
let attr_id = self.tcx.sess.parse_sess.attr_id_generator.mk_attr_id();
let attrs = self.arena.alloc_from_iter([
Attribute {
kind: AttrKind::Normal(P(NormalAttr::from_ident(Ident::new(sym::rustc_host, span)))),
let attrs = self.arena.alloc_from_iter([Attribute {
kind: AttrKind::Normal(P(NormalAttr::from_ident(Ident::new(
sym::rustc_host,
span,
id: attr_id,
style: AttrStyle::Outer,
},
]);
)))),
span,
id: attr_id,
style: AttrStyle::Outer,
}]);
self.attrs.insert(hir_id.local_id, attrs);
let const_body = self.lower_body(|this| {
@ -1476,7 +1506,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
}),
)),
)),
default: Some(hir::AnonConst { def_id: anon_const, hir_id: const_id, body: const_body }),
default: Some(hir::AnonConst {
def_id: anon_const,
hir_id: const_id,
body: const_body,
}),
},
colon_span: None,
pure_wrt_drop: false,

85
compiler/rustc_ast_lowering/src/lib.rs
View File

@ -142,6 +142,8 @@ 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<FxHashMap<LocalDefId, LocalDefId>>,
host_param_id: Option<LocalDefId>,
}
trait ResolverAstLoweringExt {
@ -1267,6 +1269,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
span: t.span
},
itctx,
ast::Const::No,
);
let bounds = this.arena.alloc_from_iter([bound]);
let lifetime_bound = this.elided_dyn_bound(t.span);
@ -1277,7 +1280,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
}
let id = self.lower_node_id(t.id);
let qpath = self.lower_qpath(t.id, qself, path, param_mode, itctx);
let qpath = self.lower_qpath(t.id, qself, path, param_mode, itctx, None);
self.ty_path(id, t.span, qpath)
}
@ -1361,10 +1364,12 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
this.arena.alloc_from_iter(bounds.iter().filter_map(|bound| match bound {
GenericBound::Trait(
ty,
TraitBoundModifier::None
modifier @ (TraitBoundModifier::None
| TraitBoundModifier::MaybeConst
| TraitBoundModifier::Negative,
) => Some(this.lower_poly_trait_ref(ty, itctx)),
| TraitBoundModifier::Negative),
) => {
Some(this.lower_poly_trait_ref(ty, itctx, modifier.to_constness()))
}
// `~const ?Bound` will cause an error during AST validation
// anyways, so treat it like `?Bound` as compilation proceeds.
GenericBound::Trait(
@ -2189,7 +2194,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
) -> hir::GenericBound<'hir> {
match tpb {
GenericBound::Trait(p, modifier) => hir::GenericBound::Trait(
self.lower_poly_trait_ref(p, itctx),
self.lower_poly_trait_ref(p, itctx, modifier.to_constness()),
self.lower_trait_bound_modifier(*modifier),
),
GenericBound::Outlives(lifetime) => {
@ -2332,8 +2337,20 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
}
}
fn lower_trait_ref(&mut self, p: &TraitRef, itctx: &ImplTraitContext) -> hir::TraitRef<'hir> {
let path = match self.lower_qpath(p.ref_id, &None, &p.path, ParamMode::Explicit, itctx) {
fn lower_trait_ref(
&mut self,
constness: ast::Const,
p: &TraitRef,
itctx: &ImplTraitContext,
) -> hir::TraitRef<'hir> {
let path = match self.lower_qpath(
p.ref_id,
&None,
&p.path,
ParamMode::Explicit,
itctx,
Some(constness),
) {
hir::QPath::Resolved(None, path) => path,
qpath => panic!("lower_trait_ref: unexpected QPath `{qpath:?}`"),
};
@ -2345,10 +2362,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
&mut self,
p: &PolyTraitRef,
itctx: &ImplTraitContext,
constness: ast::Const,
) -> hir::PolyTraitRef<'hir> {
let bound_generic_params =
self.lower_lifetime_binder(p.trait_ref.ref_id, &p.bound_generic_params);
let trait_ref = self.lower_trait_ref(&p.trait_ref, itctx);
let trait_ref = self.lower_trait_ref(constness, &p.trait_ref, itctx);
hir::PolyTraitRef { bound_generic_params, trait_ref, span: self.lower_span(p.span) }
}
@ -2702,6 +2720,57 @@ struct GenericArgsCtor<'hir> {
}
impl<'hir> GenericArgsCtor<'hir> {
fn push_constness(&mut self, lcx: &mut LoweringContext<'_, 'hir>, constness: ast::Const) {
if !lcx.tcx.features().effects {
return;
}
// if bound is non-const, don't add host effect param
let ast::Const::Yes(span) = constness else { return };
let span = lcx.lower_span(span);
let id = lcx.next_node_id();
let hir_id = lcx.next_id();
let body = lcx.lower_body(|lcx| {
(
&[],
match constness {
ast::Const::Yes(_) => {
let hir_id = lcx.next_id();
let res =
Res::Def(DefKind::ConstParam, lcx.host_param_id.unwrap().to_def_id());
let expr_kind = hir::ExprKind::Path(hir::QPath::Resolved(
None,
lcx.arena.alloc(hir::Path {
span,
res,
segments: arena_vec![lcx; hir::PathSegment::new(Ident {
name: sym::host,
span,
}, hir_id, res)],
}),
));
lcx.expr(span, expr_kind)
}
ast::Const::No => lcx.expr(
span,
hir::ExprKind::Lit(
lcx.arena.alloc(hir::Lit { span, node: ast::LitKind::Bool(true) }),
),
),
},
)
});
let def_id =
lcx.create_def(lcx.current_hir_id_owner.def_id, id, DefPathData::AnonConst, span);
lcx.children.push((def_id, hir::MaybeOwner::NonOwner(hir_id)));
self.args.push(hir::GenericArg::Const(hir::ConstArg {
value: hir::AnonConst { def_id, hir_id, body },
span,
}))
}
fn is_empty(&self) -> bool {
self.args.is_empty()
&& self.bindings.is_empty()

3
compiler/rustc_ast_lowering/src/pat.rs
View File

@ -38,6 +38,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
path,
ParamMode::Optional,
&ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
);
let (pats, ddpos) = self.lower_pat_tuple(pats, "tuple struct");
break hir::PatKind::TupleStruct(qpath, pats, ddpos);
@ -54,6 +55,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
path,
ParamMode::Optional,
&ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
);
break hir::PatKind::Path(qpath);
}
@ -64,6 +66,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
path,
ParamMode::Optional,
&ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
);
let fs = self.arena.alloc_from_iter(fields.iter().map(|f| {

13
compiler/rustc_ast_lowering/src/path.rs
View File

@ -23,6 +23,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
p: &Path,
param_mode: ParamMode,
itctx: &ImplTraitContext,
// constness of the impl/bound if this is a trait path
constness: Option<ast::Const>,
) -> hir::QPath<'hir> {
let qself_position = qself.as_ref().map(|q| q.position);
let qself = qself.as_ref().map(|q| self.lower_ty(&q.ty, itctx));
@ -73,6 +75,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
param_mode,
parenthesized_generic_args,
itctx,
// if this is the last segment, add constness to the trait path
if i == proj_start - 1 { constness } else { None },
)
},
)),
@ -119,6 +123,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
param_mode,
ParenthesizedGenericArgs::Err,
itctx,
None,
));
let qpath = hir::QPath::TypeRelative(ty, hir_segment);
@ -159,6 +164,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
param_mode,
ParenthesizedGenericArgs::Err,
&ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
)
})),
span: self.lower_span(p.span),
@ -172,8 +178,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
param_mode: ParamMode,
parenthesized_generic_args: ParenthesizedGenericArgs,
itctx: &ImplTraitContext,
constness: Option<ast::Const>,
) -> hir::PathSegment<'hir> {
debug!("path_span: {:?}, lower_path_segment(segment: {:?})", path_span, segment,);
debug!("path_span: {:?}, lower_path_segment(segment: {:?})", path_span, segment);
let (mut generic_args, infer_args) = if let Some(generic_args) = segment.args.as_deref() {
match generic_args {
GenericArgs::AngleBracketed(data) => {
@ -231,6 +238,10 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
)
};
if let Some(constness) = constness {
generic_args.push_constness(self, constness);
}
let has_lifetimes =
generic_args.args.iter().any(|arg| matches!(arg, GenericArg::Lifetime(_)));

2
compiler/rustc_const_eval/src/const_eval/fn_queries.rs
View File

@ -40,7 +40,7 @@ fn constness(tcx: TyCtxt<'_>, def_id: LocalDefId) -> hir::Constness {
| hir::Node::AnonConst(_)
| hir::Node::ConstBlock(_)
| hir::Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. }) => hir::Constness::Const,
hir::Node::Item(hir::Item { kind: hir::ItemKind::Impl(impl_), .. }) => impl_.constness,
hir::Node::Item(hir::Item { kind: hir::ItemKind::Impl(_), .. }) => tcx.generics_of(def_id).host_effect_index.map_or(hir::Constness::NotConst, |_| hir::Constness::Const),
hir::Node::ForeignItem(hir::ForeignItem { kind: hir::ForeignItemKind::Fn(..), .. }) => {
// Intrinsics use `rustc_const_{un,}stable` attributes to indicate constness. All other
// foreign items cannot be evaluated at compile-time.

9
compiler/rustc_const_eval/src/transform/check_consts/mod.rs
View File

@ -127,15 +127,8 @@ fn is_parent_const_stable_trait(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
let hir_id = tcx.local_def_id_to_hir_id(local_def_id);
let Some(parent) = tcx.hir().opt_parent_id(hir_id) else { return false };
let parent_def = tcx.hir().get(parent);
if !matches!(
parent_def,
hir::Node::Item(hir::Item {
kind: hir::ItemKind::Impl(hir::Impl { constness: hir::Constness::Const, .. }),
..
})
) {
if !tcx.is_const_trait_impl_raw(parent.owner.def_id.to_def_id()) {
return false;
}

7
compiler/rustc_const_eval/src/transform/check_consts/ops.rs
View File

@ -145,8 +145,11 @@ impl<'tcx> NonConstOp<'tcx> for FnCallNonConst<'tcx> {
let implsrc = selcx.select(&obligation);
if let Ok(Some(ImplSource::UserDefined(data))) = implsrc {
let span = tcx.def_span(data.impl_def_id);
err.subdiagnostic(errors::NonConstImplNote { span });
// FIXME(effects) revisit this
if !tcx.is_const_trait_impl_raw(data.impl_def_id) {
let span = tcx.def_span(data.impl_def_id);
err.subdiagnostic(errors::NonConstImplNote { span });
}
}
}
_ => {}

1
compiler/rustc_hir/src/hir.rs
View File

@ -3357,7 +3357,6 @@ pub struct Impl<'hir> {
// We do not put a `Span` in `Defaultness` because it breaks foreign crate metadata
// decoding as `Span`s cannot be decoded when a `Session` is not available.
pub defaultness_span: Option<Span>,
pub constness: Constness,
pub generics: &'hir Generics<'hir>,
/// The trait being implemented, if any.

1
compiler/rustc_hir/src/intravisit.rs
View File

@ -522,7 +522,6 @@ pub fn walk_item<'v, V: Visitor<'v>>(visitor: &mut V, item: &'v Item<'v>) {
unsafety: _,
defaultness: _,
polarity: _,
constness: _,
defaultness_span: _,
ref generics,
ref of_trait,

12
compiler/rustc_hir_analysis/src/astconv/mod.rs
View File

@ -532,6 +532,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
if let Err(guar) = ty.error_reported() {
return ty::Const::new_error(tcx, guar, ty).into();
}
// FIXME(effects) see if we should special case effect params here
if !infer_args && has_default {
tcx.const_param_default(param.def_id)
.instantiate(tcx, args.unwrap())
@ -659,7 +660,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
&self,
trait_ref: &hir::TraitRef<'_>,
self_ty: Ty<'tcx>,
constness: ty::BoundConstness,
) -> ty::TraitRef<'tcx> {
self.prohibit_generics(trait_ref.path.segments.split_last().unwrap().1.iter(), |_| {});
@ -669,7 +669,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
self_ty,
trait_ref.path.segments.last().unwrap(),
true,
constness,
ty::BoundConstness::NotConst,
)
}
@ -849,6 +849,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
self_ty: Ty<'tcx>,
trait_segment: &hir::PathSegment<'_>,
is_impl: bool,
// FIXME(effects) move all host param things in astconv to hir lowering
constness: ty::BoundConstness,
) -> ty::TraitRef<'tcx> {
let (generic_args, _) = self.create_args_for_ast_trait_ref(
@ -2712,11 +2713,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
};
let i = hir.get_parent(fn_hir_id).expect_item().expect_impl();
let trait_ref = self.instantiate_mono_trait_ref(
i.of_trait.as_ref()?,
self.ast_ty_to_ty(i.self_ty),
ty::BoundConstness::NotConst,
);
let trait_ref =
self.instantiate_mono_trait_ref(i.of_trait.as_ref()?, self.ast_ty_to_ty(i.self_ty));
let assoc = tcx.associated_items(trait_ref.def_id).find_by_name_and_kind(
tcx,

45
compiler/rustc_hir_analysis/src/collect.rs
View File

@ -1358,38 +1358,29 @@ fn impl_trait_ref(
.of_trait
.as_ref()
.map(|ast_trait_ref| {
let selfty = tcx.type_of(def_id).instantiate_identity();
icx.astconv().instantiate_mono_trait_ref(
check_impl_constness(
tcx,
tcx.is_const_trait_impl_raw(def_id.to_def_id()),
ast_trait_ref,
selfty,
check_impl_constness(tcx, impl_.constness, ast_trait_ref),
)
);
let selfty = tcx.type_of(def_id).instantiate_identity();
icx.astconv().instantiate_mono_trait_ref(ast_trait_ref, selfty)
})
.map(ty::EarlyBinder::bind)
}
fn check_impl_constness(
tcx: TyCtxt<'_>,
constness: hir::Constness,
ast_trait_ref: &hir::TraitRef<'_>,
) -> ty::BoundConstness {
match constness {
hir::Constness::Const => {
if let Some(trait_def_id) = ast_trait_ref.trait_def_id() && !tcx.has_attr(trait_def_id, sym::const_trait) {
let trait_name = tcx.item_name(trait_def_id).to_string();
tcx.sess.emit_err(errors::ConstImplForNonConstTrait {
trait_ref_span: ast_trait_ref.path.span,
trait_name,
local_trait_span: trait_def_id.as_local().map(|_| tcx.def_span(trait_def_id).shrink_to_lo()),
marking: (),
adding: (),
});
ty::BoundConstness::NotConst
} else {
ty::BoundConstness::ConstIfConst
}
},
hir::Constness::NotConst => ty::BoundConstness::NotConst,
fn check_impl_constness(tcx: TyCtxt<'_>, is_const: bool, ast_trait_ref: &hir::TraitRef<'_>) {
if is_const {
if let Some(trait_def_id) = ast_trait_ref.trait_def_id() && !tcx.has_attr(trait_def_id, sym::const_trait) {
let trait_name = tcx.item_name(trait_def_id).to_string();
tcx.sess.emit_err(errors::ConstImplForNonConstTrait {
trait_ref_span: ast_trait_ref.path.span,
trait_name,
local_trait_span: trait_def_id.as_local().map(|_| tcx.def_span(trait_def_id).shrink_to_lo()),
marking: (),
adding: (),
});
}
}
}

2
compiler/rustc_hir_analysis/src/collect/generics_of.rs
View File

@ -320,7 +320,7 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
bug!("parent also has host effect param? index: {idx}, def: {def_id:?}");
}
host_effect_index = Some(parent_count + index as usize);
host_effect_index = Some(index as usize);
}
Some(ty::GenericParamDef {

3
compiler/rustc_hir_analysis/src/structured_errors/wrong_number_of_generic_args.rs
View File

@ -578,6 +578,9 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
MissingTypesOrConsts { .. } => {
self.suggest_adding_type_and_const_args(err);
}
ExcessTypesOrConsts { .. } => {
// this can happen with `~const T` where T isn't a const_trait.
}
_ => unreachable!(),
}
}

5
compiler/rustc_hir_pretty/src/lib.rs
View File

@ -626,7 +626,6 @@ impl<'a> State<'a> {
unsafety,
polarity,
defaultness,
constness,
defaultness_span: _,
generics,
ref of_trait,
@ -643,10 +642,6 @@ impl<'a> State<'a> {
self.space();
}
if constness == hir::Constness::Const {
self.word_nbsp("const");
}
if let hir::ImplPolarity::Negative(_) = polarity {
self.word("!");
}

37
compiler/rustc_hir_typeck/src/callee.rs
View File

@ -767,9 +767,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
) {
let tcx = self.tcx;
if !tcx.features().effects || tcx.sess.opts.unstable_opts.unleash_the_miri_inside_of_you {
return;
}
// fast-reject if callee doesn't have the host effect param (non-const)
let generics = tcx.generics_of(callee_did);
let Some(host_effect_index) = generics.host_effect_index else { return };
// if the callee does have the param, we need to equate the param to some const
// value no matter whether the effects feature is enabled in the local crate,
// because inference will fail if we don't.
let mut host_always_on =
!tcx.features().effects || tcx.sess.opts.unstable_opts.unleash_the_miri_inside_of_you;
// Compute the constness required by the context.
let context = tcx.hir().enclosing_body_owner(call_expr_hir);
@ -780,10 +786,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
if tcx.has_attr(context.to_def_id(), sym::rustc_do_not_const_check) {
trace!("do not const check this context");
return;
host_always_on = true;
}
let effect = match const_context {
_ if host_always_on => tcx.consts.true_,
Some(hir::ConstContext::Static(_) | hir::ConstContext::Const) => tcx.consts.false_,
Some(hir::ConstContext::ConstFn) => {
let args = ty::GenericArgs::identity_for_item(tcx, context);
@ -792,21 +799,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
None => tcx.consts.true_,
};
let generics = tcx.generics_of(callee_did);
trace!(?effect, ?generics, ?callee_args);
if let Some(idx) = generics.host_effect_index {
let param = callee_args.const_at(idx);
let cause = self.misc(span);
match self.at(&cause, self.param_env).eq(infer::DefineOpaqueTypes::No, effect, param) {
Ok(infer::InferOk { obligations, value: () }) => {
self.register_predicates(obligations);
}
Err(e) => {
// FIXME(effects): better diagnostic
self.err_ctxt().report_mismatched_consts(&cause, effect, param, e).emit();
}
let param = callee_args.const_at(host_effect_index);
let cause = self.misc(span);
match self.at(&cause, self.param_env).eq(infer::DefineOpaqueTypes::No, effect, param) {
Ok(infer::InferOk { obligations, value: () }) => {
self.register_predicates(obligations);
}
Err(e) => {
// FIXME(effects): better diagnostic
self.err_ctxt().report_mismatched_consts(&cause, effect, param, e).emit();
}
}
}

5
compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
View File

@ -1349,7 +1349,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
}
GenericParamDefKind::Const { has_default } => {
if !infer_args && has_default {
if !infer_args
&& has_default
&& !tcx.has_attr(param.def_id, sym::rustc_host)
{
tcx.const_param_default(param.def_id)
.instantiate(tcx, args.unwrap())
.into()

4
compiler/rustc_middle/src/ty/context.rs
View File

@ -1963,9 +1963,9 @@ impl<'tcx> TyCtxt<'tcx> {
matches!(
node,
hir::Node::Item(hir::Item {
kind: hir::ItemKind::Impl(hir::Impl { constness: hir::Constness::Const, .. }),
kind: hir::ItemKind::Impl(hir::Impl { generics, .. }),
..
})
}) if generics.params.iter().any(|p| self.has_attr(p.def_id, sym::rustc_host))
)
}

5
compiler/rustc_middle/src/ty/print/pretty.rs
View File

@ -2841,6 +2841,11 @@ define_print_and_forward_display! {
ty::TraitPredicate<'tcx> {
p!(print(self.trait_ref.self_ty()), ": ");
if let Some(idx) = cx.tcx().generics_of(self.trait_ref.def_id).host_effect_index {
if self.trait_ref.args.const_at(idx) != cx.tcx().consts.true_ {
p!("~const ");
}
}
// FIXME(effects) print `~const` here
if let ty::ImplPolarity::Negative = self.polarity {
p!("!");

10
compiler/rustc_passes/src/stability.rs
View File

@ -732,13 +732,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'tcx> {
// For implementations of traits, check the stability of each item
// individually as it's possible to have a stable trait with unstable
// items.
hir::ItemKind::Impl(hir::Impl {
of_trait: Some(ref t),
self_ty,
items,
constness,
..
}) => {
hir::ItemKind::Impl(hir::Impl { of_trait: Some(ref t), self_ty, items, .. }) => {
let features = self.tcx.features();
if features.staged_api {
let attrs = self.tcx.hir().attrs(item.hir_id());
@ -769,7 +763,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'tcx> {
// `#![feature(const_trait_impl)]` is unstable, so any impl declared stable
// needs to have an error emitted.
if features.const_trait_impl
&& *constness == hir::Constness::Const
&& self.tcx.is_const_trait_impl_raw(item.owner_id.to_def_id())
&& const_stab.is_some_and(|(stab, _)| stab.is_const_stable())
{
self.tcx.sess.emit_err(errors::TraitImplConstStable { span: item.span });

21
compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
View File

@ -3102,27 +3102,6 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
) -> UnsatisfiedConst {
let unsatisfied_const = UnsatisfiedConst(false);
// FIXME(effects)
/* if trait_predicate.is_const_if_const() {
let non_const_predicate = trait_ref.without_const();
let non_const_obligation = Obligation {
cause: obligation.cause.clone(),
param_env: obligation.param_env,
predicate: non_const_predicate.to_predicate(self.tcx),
recursion_depth: obligation.recursion_depth,
};
if self.predicate_may_hold(&non_const_obligation) {
unsatisfied_const = UnsatisfiedConst(true);
err.span_note(
span,
format!(
"the trait `{}` is implemented for `{}`, \
but that implementation is not `const`",
non_const_predicate.print_modifiers_and_trait_path(),
trait_ref.skip_binder().self_ty(),
),
);
}
} */
unsatisfied_const
}

2
tests/ui/rfcs/rfc-2632-const-trait-impl/const-drop-fail-2.rs
View File

@ -1,5 +1,5 @@
// known-bug: #110395
#![feature(const_trait_impl)]
#![feature(const_trait_impl, effects)]
#![feature(const_mut_refs)]
#![cfg_attr(precise, feature(const_precise_live_drops))]