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Add effects during lowering for ~const bounds
1 parent 2d5d56b commit 1c837cb

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3 files changed

+121
-17
lines changed

3 files changed

+121
-17
lines changed

‎compiler/rustc_ast/src/ast.rs‎

Lines changed: 9 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2652,6 +2652,15 @@ pub struct NormalAttr {
26522652
pub tokens: Option<LazyAttrTokenStream>,
26532653
}
26542654

2655+
impl NormalAttr {
2656+
pub fn from_ident(ident: Ident) -> Self {
2657+
Self {
2658+
item: AttrItem { path: Path::from_ident(ident), args: AttrArgs::Empty, tokens: None },
2659+
tokens: None,
2660+
}
2661+
}
2662+
}
2663+
26552664
#[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
26562665
pub struct AttrItem {
26572666
pub path: Path,

‎compiler/rustc_ast_lowering/src/expr.rs‎

Lines changed: 1 addition & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -673,14 +673,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
673673
self.lower_attrs(
674674
inner_hir_id,
675675
&[Attribute {
676-
kind: AttrKind::Normal(ptr::P(NormalAttr {
677-
item: AttrItem {
678-
path: Path::from_ident(Ident::new(sym::track_caller, span)),
679-
args: AttrArgs::Empty,
680-
tokens: None,
681-
},
682-
tokens: None,
683-
})),
676+
kind: AttrKind::Normal(ptr::P(NormalAttr::from_ident(Ident::new(sym::track_caller, span)))),
684677
id: self.tcx.sess.parse_sess.attr_id_generator.mk_attr_id(),
685678
style: AttrStyle::Outer,
686679
span: unstable_span,

‎compiler/rustc_ast_lowering/src/item.rs‎

Lines changed: 111 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -3,6 +3,7 @@ use super::ResolverAstLoweringExt;
33
use super::{AstOwner, ImplTraitContext, ImplTraitPosition};
44
use super::{FnDeclKind, LoweringContext, ParamMode};
55

6+
use hir::definitions::DefPathData;
67
use rustc_ast::ptr::P;
78
use rustc_ast::visit::AssocCtxt;
89
use rustc_ast::*;
@@ -257,10 +258,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
257258
);
258259

259260
let itctx = ImplTraitContext::Universal;
260-
let (generics, decl) = this.lower_generics(generics, id, &itctx, |this| {
261-
let ret_id = asyncness.opt_return_id();
262-
this.lower_fn_decl(&decl, id, *fn_sig_span, FnDeclKind::Fn, ret_id)
263-
});
261+
let (generics, decl) =
262+
this.lower_generics(generics, header.constness, id, &itctx, |this| {
263+
let ret_id = asyncness.opt_return_id();
264+
this.lower_fn_decl(&decl, id, *fn_sig_span, FnDeclKind::Fn, ret_id)
265+
});
264266
let sig = hir::FnSig {
265267
decl,
266268
header: this.lower_fn_header(*header),
@@ -295,6 +297,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
295297
add_ty_alias_where_clause(&mut generics, *where_clauses, true);
296298
let (generics, ty) = self.lower_generics(
297299
&generics,
300+
Const::No,
298301
id,
299302
&ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
300303
|this| match ty {
@@ -316,6 +319,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
316319
ItemKind::Enum(enum_definition, generics) => {
317320
let (generics, variants) = self.lower_generics(
318321
generics,
322+
Const::No,
319323
id,
320324
&ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
321325
|this| {
@@ -329,6 +333,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
329333
ItemKind::Struct(struct_def, generics) => {
330334
let (generics, struct_def) = self.lower_generics(
331335
generics,
336+
Const::No,
332337
id,
333338
&ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
334339
|this| this.lower_variant_data(hir_id, struct_def),
@@ -338,6 +343,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
338343
ItemKind::Union(vdata, generics) => {
339344
let (generics, vdata) = self.lower_generics(
340345
generics,
346+
Const::No,
341347
id,
342348
&ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
343349
|this| this.lower_variant_data(hir_id, vdata),
@@ -369,7 +375,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
369375
// parent lifetime.
370376
let itctx = ImplTraitContext::Universal;
371377
let (generics, (trait_ref, lowered_ty)) =
372-
self.lower_generics(ast_generics, id, &itctx, |this| {
378+
self.lower_generics(ast_generics, *constness, id, &itctx, |this| {
373379
let trait_ref = trait_ref.as_ref().map(|trait_ref| {
374380
this.lower_trait_ref(
375381
trait_ref,
@@ -410,8 +416,18 @@ impl<'hir> LoweringContext<'_, 'hir> {
410416
}))
411417
}
412418
ItemKind::Trait(box Trait { is_auto, unsafety, generics, bounds, items }) => {
419+
// FIXME(const_trait_impl, effects, fee1-dead) this should be simplified if possible
420+
let constness = if let Some(attrs) = attrs {
421+
attrs
422+
.iter()
423+
.find(|x| x.has_name(sym::const_trait))
424+
.map_or(Const::No, |x| Const::Yes(x.span))
425+
} else {
426+
Const::No
427+
};
413428
let (generics, (unsafety, items, bounds)) = self.lower_generics(
414429
generics,
430+
constness,
415431
id,
416432
&ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
417433
|this| {
@@ -431,6 +447,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
431447
ItemKind::TraitAlias(generics, bounds) => {
432448
let (generics, bounds) = self.lower_generics(
433449
generics,
450+
Const::No,
434451
id,
435452
&ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
436453
|this| {
@@ -593,7 +610,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
593610
let fdec = &sig.decl;
594611
let itctx = ImplTraitContext::Universal;
595612
let (generics, (fn_dec, fn_args)) =
596-
self.lower_generics(generics, i.id, &itctx, |this| {
613+
self.lower_generics(generics, Const::No, i.id, &itctx, |this| {
597614
(
598615
// Disallow `impl Trait` in foreign items.
599616
this.lower_fn_decl(
@@ -745,6 +762,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
745762
add_ty_alias_where_clause(&mut generics, *where_clauses, false);
746763
let (generics, kind) = self.lower_generics(
747764
&generics,
765+
Const::No,
748766
i.id,
749767
&ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
750768
|this| {
@@ -843,6 +861,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
843861
add_ty_alias_where_clause(&mut generics, *where_clauses, false);
844862
self.lower_generics(
845863
&generics,
864+
Const::No,
846865
i.id,
847866
&ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
848867
|this| match ty {
@@ -1201,9 +1220,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
12011220
) -> (&'hir hir::Generics<'hir>, hir::FnSig<'hir>) {
12021221
let header = self.lower_fn_header(sig.header);
12031222
let itctx = ImplTraitContext::Universal;
1204-
let (generics, decl) = self.lower_generics(generics, id, &itctx, |this| {
1205-
this.lower_fn_decl(&sig.decl, id, sig.span, kind, is_async)
1206-
});
1223+
let (generics, decl) =
1224+
self.lower_generics(generics, sig.header.constness, id, &itctx, |this| {
1225+
this.lower_fn_decl(&sig.decl, id, sig.span, kind, is_async)
1226+
});
12071227
(generics, hir::FnSig { header, decl, span: self.lower_span(sig.span) })
12081228
}
12091229

@@ -1275,6 +1295,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
12751295
fn lower_generics<T>(
12761296
&mut self,
12771297
generics: &Generics,
1298+
constness: Const,
12781299
parent_node_id: NodeId,
12791300
itctx: &ImplTraitContext,
12801301
f: impl FnOnce(&mut Self) -> T,
@@ -1372,6 +1393,87 @@ impl<'hir> LoweringContext<'_, 'hir> {
13721393
let impl_trait_bounds = std::mem::take(&mut self.impl_trait_bounds);
13731394
predicates.extend(impl_trait_bounds.into_iter());
13741395

1396+
// Desugar `~const` bound in generics into an additional `const host: bool` param
1397+
// if the effects feature is enabled.
1398+
if let Const::Yes(span) = constness && self.tcx.features().effects
1399+
// Do not add host param if it already has it (manually specified)
1400+
&& !params.iter().any(|x| {
1401+
self.attrs.get(&x.hir_id.local_id).map_or(false, |attrs| {
1402+
attrs.iter().any(|x| x.has_name(sym::rustc_host))
1403+
})
1404+
})
1405+
{
1406+
let param_node_id = self.next_node_id();
1407+
let const_node_id = self.next_node_id();
1408+
let def_id = self.create_def(self.local_def_id(parent_node_id), param_node_id, DefPathData::TypeNs(sym::host), span);
1409+
let anon_const: LocalDefId = self.create_def(def_id, const_node_id, DefPathData::AnonConst, span);
1410+
1411+
let hir_id = self.next_id();
1412+
let const_id = self.next_id();
1413+
let const_expr_id = self.next_id();
1414+
let bool_id = self.next_id();
1415+
1416+
self.children.push((def_id, hir::MaybeOwner::NonOwner(hir_id)));
1417+
self.children.push((anon_const, hir::MaybeOwner::NonOwner(const_id)));
1418+
1419+
let attr_id = self.tcx.sess.parse_sess.attr_id_generator.mk_attr_id();
1420+
1421+
let attrs = self.arena.alloc_from_iter([
1422+
Attribute {
1423+
kind: AttrKind::Normal(P(NormalAttr::from_ident(Ident::new(sym::rustc_host, span)))),
1424+
span,
1425+
id: attr_id,
1426+
style: AttrStyle::Outer,
1427+
},
1428+
]);
1429+
self.attrs.insert(hir_id.local_id, attrs);
1430+
1431+
let const_body = self.lower_body(|this| {
1432+
(
1433+
&[],
1434+
hir::Expr {
1435+
hir_id: const_expr_id,
1436+
kind: hir::ExprKind::Lit(
1437+
this.arena.alloc(hir::Lit { node: LitKind::Bool(true), span }),
1438+
),
1439+
span,
1440+
},
1441+
)
1442+
});
1443+
1444+
let param = hir::GenericParam {
1445+
def_id,
1446+
hir_id,
1447+
name: hir::ParamName::Plain(Ident { name: sym::host, span }),
1448+
span,
1449+
kind: hir::GenericParamKind::Const {
1450+
ty: self.arena.alloc(self.ty(
1451+
span,
1452+
hir::TyKind::Path(hir::QPath::Resolved(
1453+
None,
1454+
self.arena.alloc(hir::Path {
1455+
res: Res::PrimTy(hir::PrimTy::Bool),
1456+
span,
1457+
segments: self.arena.alloc_from_iter([hir::PathSegment {
1458+
ident: Ident { name: sym::bool, span },
1459+
hir_id: bool_id,
1460+
res: Res::PrimTy(hir::PrimTy::Bool),
1461+
args: None,
1462+
infer_args: false,
1463+
}]),
1464+
}),
1465+
)),
1466+
)),
1467+
default: Some(hir::AnonConst { def_id: anon_const, hir_id: const_id, body: const_body }),
1468+
},
1469+
colon_span: None,
1470+
pure_wrt_drop: false,
1471+
source: hir::GenericParamSource::Generics,
1472+
};
1473+
1474+
params.push(param);
1475+
}
1476+
13751477
let lowered_generics = self.arena.alloc(hir::Generics {
13761478
params: self.arena.alloc_from_iter(params),
13771479
predicates: self.arena.alloc_from_iter(predicates),

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