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Implment #[cfg] and #[cfg_attr] in where clauses
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38 files changed

+3296
-88
lines changed

38 files changed

+3296
-88
lines changed

Diff for: ‎compiler/rustc_ast/src/ast.rs

+2
Original file line numberDiff line numberDiff line change
@@ -417,9 +417,11 @@ impl WhereClause {
417417
/// A single predicate in a where-clause.
418418
#[derive(Clone, Encodable, Decodable, Debug)]
419419
pub struct WherePredicate {
420+
pub attrs: AttrVec,
420421
pub kind: WherePredicateKind,
421422
pub id: NodeId,
422423
pub span: Span,
424+
pub is_placeholder: bool,
423425
}
424426

425427
/// Predicate kind in where-clause.

Diff for: ‎compiler/rustc_ast/src/ast_traits.rs

+13-2
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@ use crate::tokenstream::LazyAttrTokenStream;
1111
use crate::{
1212
Arm, AssocItem, AttrItem, AttrKind, AttrVec, Attribute, Block, Crate, Expr, ExprField,
1313
FieldDef, ForeignItem, GenericParam, Item, NodeId, Param, Pat, PatField, Path, Stmt, StmtKind,
14-
Ty, Variant, Visibility,
14+
Ty, Variant, Visibility, WherePredicate,
1515
};
1616

1717
/// A utility trait to reduce boilerplate.
@@ -79,6 +79,7 @@ impl_has_node_id!(
7979
Stmt,
8080
Ty,
8181
Variant,
82+
WherePredicate,
8283
);
8384

8485
impl<T: AstDeref<Target: HasNodeId>> HasNodeId for T {
@@ -127,7 +128,16 @@ macro_rules! impl_has_tokens_none {
127128
}
128129

129130
impl_has_tokens!(AssocItem, AttrItem, Block, Expr, ForeignItem, Item, Pat, Path, Ty, Visibility);
130-
impl_has_tokens_none!(Arm, ExprField, FieldDef, GenericParam, Param, PatField, Variant);
131+
impl_has_tokens_none!(
132+
Arm,
133+
ExprField,
134+
FieldDef,
135+
GenericParam,
136+
Param,
137+
PatField,
138+
Variant,
139+
WherePredicate
140+
);
131141

132142
impl<T: AstDeref<Target: HasTokens>> HasTokens for T {
133143
fn tokens(&self) -> Option<&LazyAttrTokenStream> {
@@ -279,6 +289,7 @@ impl_has_attrs!(
279289
Param,
280290
PatField,
281291
Variant,
292+
WherePredicate,
282293
);
283294
impl_has_attrs_none!(Attribute, AttrItem, Block, Pat, Path, Ty, Visibility);
284295

Diff for: ‎compiler/rustc_ast/src/mut_visit.rs

+13-5
Original file line numberDiff line numberDiff line change
@@ -338,8 +338,11 @@ pub trait MutVisitor: Sized {
338338
walk_where_clause(self, where_clause);
339339
}
340340

341-
fn visit_where_predicate(&mut self, where_predicate: &mut WherePredicate) {
342-
walk_where_predicate(self, where_predicate)
341+
fn flat_map_where_predicate(
342+
&mut self,
343+
where_predicate: WherePredicate,
344+
) -> SmallVec<[WherePredicate; 1]> {
345+
walk_flat_map_where_predicate(self, where_predicate)
343346
}
344347

345348
fn visit_where_predicate_kind(&mut self, kind: &mut WherePredicateKind) {
@@ -1097,15 +1100,20 @@ fn walk_ty_alias_where_clauses<T: MutVisitor>(vis: &mut T, tawcs: &mut TyAliasWh
10971100

10981101
fn walk_where_clause<T: MutVisitor>(vis: &mut T, wc: &mut WhereClause) {
10991102
let WhereClause { has_where_token: _, predicates, span } = wc;
1100-
visit_thin_vec(predicates, |predicate| vis.visit_where_predicate(predicate));
1103+
predicates.flat_map_in_place(|predicate| vis.flat_map_where_predicate(predicate));
11011104
vis.visit_span(span);
11021105
}
11031106

1104-
pub fn walk_where_predicate<T: MutVisitor>(vis: &mut T, pred: &mut WherePredicate) {
1105-
let WherePredicate { kind, id, span } = pred;
1107+
pub fn walk_flat_map_where_predicate<T: MutVisitor>(
1108+
vis: &mut T,
1109+
mut pred: WherePredicate,
1110+
) -> SmallVec<[WherePredicate; 1]> {
1111+
let WherePredicate { attrs, kind, id, span, is_placeholder: _ } = &mut pred;
11061112
vis.visit_id(id);
1113+
visit_attrs(vis, attrs);
11071114
vis.visit_where_predicate_kind(kind);
11081115
vis.visit_span(span);
1116+
smallvec![pred]
11091117
}
11101118

11111119
pub fn walk_where_predicate_kind<T: MutVisitor>(vis: &mut T, kind: &mut WherePredicateKind) {

Diff for: ‎compiler/rustc_ast/src/visit.rs

+2-1
Original file line numberDiff line numberDiff line change
@@ -833,7 +833,8 @@ pub fn walk_where_predicate<'a, V: Visitor<'a>>(
833833
visitor: &mut V,
834834
predicate: &'a WherePredicate,
835835
) -> V::Result {
836-
let WherePredicate { kind, id: _, span: _ } = predicate;
836+
let WherePredicate { attrs, kind, id: _, span: _, is_placeholder: _ } = predicate;
837+
walk_list!(visitor, visit_attribute, attrs);
837838
visitor.visit_where_predicate_kind(kind)
838839
}
839840

Diff for: ‎compiler/rustc_ast_lowering/src/item.rs

+1
Original file line numberDiff line numberDiff line change
@@ -1728,6 +1728,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
17281728
fn lower_where_predicate(&mut self, pred: &WherePredicate) -> hir::WherePredicate<'hir> {
17291729
let hir_id = self.lower_node_id(pred.id);
17301730
let span = self.lower_span(pred.span);
1731+
self.lower_attrs(hir_id, &pred.attrs, span);
17311732
let kind = self.arena.alloc(match &pred.kind {
17321733
WherePredicateKind::BoundPredicate(WhereBoundPredicate {
17331734
bound_generic_params,

Diff for: ‎compiler/rustc_ast_passes/src/feature_gate.rs

+1
Original file line numberDiff line numberDiff line change
@@ -503,6 +503,7 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) {
503503
gate_all!(unsafe_binders, "unsafe binder types are experimental");
504504
gate_all!(contracts, "contracts are incomplete");
505505
gate_all!(contracts_internals, "contract internal machinery is for internal use only");
506+
gate_all!(where_clause_attrs, "attributes in `where` clause are unstable");
506507

507508
if !visitor.features.never_patterns() {
508509
if let Some(spans) = spans.get(&sym::never_patterns) {

Diff for: ‎compiler/rustc_ast_pretty/src/pprust/state/item.rs

+2-1
Original file line numberDiff line numberDiff line change
@@ -735,7 +735,8 @@ impl<'a> State<'a> {
735735
}
736736

737737
pub fn print_where_predicate(&mut self, predicate: &ast::WherePredicate) {
738-
let ast::WherePredicate { kind, id: _, span: _ } = predicate;
738+
let ast::WherePredicate { attrs, kind, id: _, span: _, is_placeholder: _ } = predicate;
739+
self.print_outer_attributes(attrs);
739740
match kind {
740741
ast::WherePredicateKind::BoundPredicate(where_bound_predicate) => {
741742
self.print_where_bound_predicate(where_bound_predicate);

Diff for: ‎compiler/rustc_builtin_macros/src/deriving/coerce_pointee.rs

+11-8
Original file line numberDiff line numberDiff line change
@@ -300,13 +300,16 @@ pub(crate) fn expand_deriving_coerce_pointee(
300300
to_ty: &s_ty,
301301
rewritten: false,
302302
};
303-
let mut predicate = ast::WherePredicate {
304-
kind: ast::WherePredicateKind::BoundPredicate(bound.clone()),
305-
span: predicate.span,
306-
id: ast::DUMMY_NODE_ID,
307-
};
308-
substitution.visit_where_predicate(&mut predicate);
303+
let mut kind = ast::WherePredicateKind::BoundPredicate(bound.clone());
304+
substitution.visit_where_predicate_kind(&mut kind);
309305
if substitution.rewritten {
306+
let predicate = ast::WherePredicate {
307+
attrs: predicate.attrs.clone(),
308+
kind,
309+
span: predicate.span,
310+
id: ast::DUMMY_NODE_ID,
311+
is_placeholder: false,
312+
};
310313
impl_generics.where_clause.predicates.push(predicate);
311314
}
312315
}
@@ -388,8 +391,8 @@ impl<'a> ast::mut_visit::MutVisitor for TypeSubstitution<'a> {
388391
}
389392
}
390393

391-
fn visit_where_predicate(&mut self, where_predicate: &mut ast::WherePredicate) {
392-
match &mut where_predicate.kind {
394+
fn visit_where_predicate_kind(&mut self, kind: &mut ast::WherePredicateKind) {
395+
match kind {
393396
rustc_ast::WherePredicateKind::BoundPredicate(bound) => {
394397
bound
395398
.bound_generic_params

Diff for: ‎compiler/rustc_builtin_macros/src/deriving/generic/mod.rs

+9-2
Original file line numberDiff line numberDiff line change
@@ -687,9 +687,11 @@ impl<'a> TraitDef<'a> {
687687
// and similarly for where clauses
688688
where_clause.predicates.extend(generics.where_clause.predicates.iter().map(|clause| {
689689
ast::WherePredicate {
690+
attrs: clause.attrs.clone(),
690691
kind: clause.kind.clone(),
691692
id: ast::DUMMY_NODE_ID,
692693
span: clause.span.with_ctxt(ctxt),
694+
is_placeholder: false,
693695
}
694696
}));
695697

@@ -744,8 +746,13 @@ impl<'a> TraitDef<'a> {
744746
};
745747

746748
let kind = ast::WherePredicateKind::BoundPredicate(predicate);
747-
let predicate =
748-
ast::WherePredicate { kind, id: ast::DUMMY_NODE_ID, span: self.span };
749+
let predicate = ast::WherePredicate {
750+
attrs: ThinVec::new(),
751+
kind,
752+
id: ast::DUMMY_NODE_ID,
753+
span: self.span,
754+
is_placeholder: false,
755+
};
749756
where_clause.predicates.push(predicate);
750757
}
751758
}

Diff for: ‎compiler/rustc_expand/src/base.rs

+16
Original file line numberDiff line numberDiff line change
@@ -53,6 +53,7 @@ pub enum Annotatable {
5353
Param(ast::Param),
5454
FieldDef(ast::FieldDef),
5555
Variant(ast::Variant),
56+
WherePredicate(ast::WherePredicate),
5657
Crate(ast::Crate),
5758
}
5859

@@ -71,6 +72,7 @@ impl Annotatable {
7172
Annotatable::Param(p) => p.span,
7273
Annotatable::FieldDef(sf) => sf.span,
7374
Annotatable::Variant(v) => v.span,
75+
Annotatable::WherePredicate(wp) => wp.span,
7476
Annotatable::Crate(c) => c.spans.inner_span,
7577
}
7678
}
@@ -89,6 +91,7 @@ impl Annotatable {
8991
Annotatable::Param(p) => p.visit_attrs(f),
9092
Annotatable::FieldDef(sf) => sf.visit_attrs(f),
9193
Annotatable::Variant(v) => v.visit_attrs(f),
94+
Annotatable::WherePredicate(wp) => wp.visit_attrs(f),
9295
Annotatable::Crate(c) => c.visit_attrs(f),
9396
}
9497
}
@@ -107,6 +110,7 @@ impl Annotatable {
107110
Annotatable::Param(p) => visitor.visit_param(p),
108111
Annotatable::FieldDef(sf) => visitor.visit_field_def(sf),
109112
Annotatable::Variant(v) => visitor.visit_variant(v),
113+
Annotatable::WherePredicate(wp) => visitor.visit_where_predicate(wp),
110114
Annotatable::Crate(c) => visitor.visit_crate(c),
111115
}
112116
}
@@ -128,6 +132,7 @@ impl Annotatable {
128132
| Annotatable::Param(..)
129133
| Annotatable::FieldDef(..)
130134
| Annotatable::Variant(..)
135+
| Annotatable::WherePredicate(..)
131136
| Annotatable::Crate(..) => panic!("unexpected annotatable"),
132137
}
133138
}
@@ -223,6 +228,13 @@ impl Annotatable {
223228
}
224229
}
225230

231+
pub fn expect_where_predicate(self) -> ast::WherePredicate {
232+
match self {
233+
Annotatable::WherePredicate(wp) => wp,
234+
_ => panic!("expected where predicate"),
235+
}
236+
}
237+
226238
pub fn expect_crate(self) -> ast::Crate {
227239
match self {
228240
Annotatable::Crate(krate) => krate,
@@ -446,6 +458,10 @@ pub trait MacResult {
446458
None
447459
}
448460

461+
fn make_where_predicates(self: Box<Self>) -> Option<SmallVec<[ast::WherePredicate; 1]>> {
462+
None
463+
}
464+
449465
fn make_crate(self: Box<Self>) -> Option<ast::Crate> {
450466
// Fn-like macros cannot produce a crate.
451467
unreachable!()

Diff for: ‎compiler/rustc_expand/src/expand.rs

+35-3
Original file line numberDiff line numberDiff line change
@@ -227,6 +227,12 @@ ast_fragments! {
227227
Variants(SmallVec<[ast::Variant; 1]>) {
228228
"variant"; many fn flat_map_variant; fn visit_variant(); fn make_variants;
229229
}
230+
WherePredicates(SmallVec<[ast::WherePredicate; 1]>) {
231+
"where predicate";
232+
many fn flat_map_where_predicate;
233+
fn visit_where_predicate();
234+
fn make_where_predicates;
235+
}
230236
Crate(ast::Crate) { "crate"; one fn visit_crate; fn visit_crate; fn make_crate; }
231237
}
232238

@@ -259,7 +265,8 @@ impl AstFragmentKind {
259265
| AstFragmentKind::GenericParams
260266
| AstFragmentKind::Params
261267
| AstFragmentKind::FieldDefs
262-
| AstFragmentKind::Variants => SupportsMacroExpansion::No,
268+
| AstFragmentKind::Variants
269+
| AstFragmentKind::WherePredicates => SupportsMacroExpansion::No,
263270
}
264271
}
265272

@@ -290,6 +297,9 @@ impl AstFragmentKind {
290297
AstFragmentKind::Variants => {
291298
AstFragment::Variants(items.map(Annotatable::expect_variant).collect())
292299
}
300+
AstFragmentKind::WherePredicates => AstFragment::WherePredicates(
301+
items.map(Annotatable::expect_where_predicate).collect(),
302+
),
293303
AstFragmentKind::Items => {
294304
AstFragment::Items(items.map(Annotatable::expect_item).collect())
295305
}
@@ -865,7 +875,8 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
865875
| Annotatable::GenericParam(..)
866876
| Annotatable::Param(..)
867877
| Annotatable::FieldDef(..)
868-
| Annotatable::Variant(..) => panic!("unexpected annotatable"),
878+
| Annotatable::Variant(..)
879+
| Annotatable::WherePredicate(..) => panic!("unexpected annotatable"),
869880
};
870881
if self.cx.ecfg.features.proc_macro_hygiene() {
871882
return;
@@ -1002,7 +1013,8 @@ pub fn parse_ast_fragment<'a>(
10021013
| AstFragmentKind::GenericParams
10031014
| AstFragmentKind::Params
10041015
| AstFragmentKind::FieldDefs
1005-
| AstFragmentKind::Variants => panic!("unexpected AST fragment kind"),
1016+
| AstFragmentKind::Variants
1017+
| AstFragmentKind::WherePredicates => panic!("unexpected AST fragment kind"),
10061018
})
10071019
}
10081020

@@ -1414,6 +1426,19 @@ impl InvocationCollectorNode for ast::Variant {
14141426
}
14151427
}
14161428

1429+
impl InvocationCollectorNode for ast::WherePredicate {
1430+
const KIND: AstFragmentKind = AstFragmentKind::WherePredicates;
1431+
fn to_annotatable(self) -> Annotatable {
1432+
Annotatable::WherePredicate(self)
1433+
}
1434+
fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1435+
fragment.make_where_predicates()
1436+
}
1437+
fn walk_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
1438+
walk_flat_map_where_predicate(visitor, self)
1439+
}
1440+
}
1441+
14171442
impl InvocationCollectorNode for ast::FieldDef {
14181443
const KIND: AstFragmentKind = AstFragmentKind::FieldDefs;
14191444
fn to_annotatable(self) -> Annotatable {
@@ -2116,6 +2141,13 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
21162141
self.flat_map_node(node)
21172142
}
21182143

2144+
fn flat_map_where_predicate(
2145+
&mut self,
2146+
node: ast::WherePredicate,
2147+
) -> SmallVec<[ast::WherePredicate; 1]> {
2148+
self.flat_map_node(node)
2149+
}
2150+
21192151
fn flat_map_field_def(&mut self, node: ast::FieldDef) -> SmallVec<[ast::FieldDef; 1]> {
21202152
self.flat_map_node(node)
21212153
}

Diff for: ‎compiler/rustc_expand/src/placeholders.rs

+24
Original file line numberDiff line numberDiff line change
@@ -188,6 +188,19 @@ pub(crate) fn placeholder(
188188
vis,
189189
is_placeholder: true,
190190
}]),
191+
AstFragmentKind::WherePredicates => {
192+
AstFragment::WherePredicates(smallvec![ast::WherePredicate {
193+
attrs: Default::default(),
194+
id,
195+
span,
196+
kind: ast::WherePredicateKind::BoundPredicate(ast::WhereBoundPredicate {
197+
bound_generic_params: Default::default(),
198+
bounded_ty: ty(),
199+
bounds: Default::default(),
200+
}),
201+
is_placeholder: true,
202+
}])
203+
}
191204
}
192205
}
193206

@@ -267,6 +280,17 @@ impl MutVisitor for PlaceholderExpander {
267280
}
268281
}
269282

283+
fn flat_map_where_predicate(
284+
&mut self,
285+
predicate: ast::WherePredicate,
286+
) -> SmallVec<[ast::WherePredicate; 1]> {
287+
if predicate.is_placeholder {
288+
self.remove(predicate.id).make_where_predicates()
289+
} else {
290+
walk_flat_map_where_predicate(self, predicate)
291+
}
292+
}
293+
270294
fn flat_map_item(&mut self, item: P<ast::Item>) -> SmallVec<[P<ast::Item>; 1]> {
271295
match item.kind {
272296
ast::ItemKind::MacCall(_) => self.remove(item.id).make_items(),

Diff for: ‎compiler/rustc_feature/src/unstable.rs

+2
Original file line numberDiff line numberDiff line change
@@ -659,6 +659,8 @@ declare_features! (
659659
(unstable, unsized_tuple_coercion, "1.20.0", Some(42877)),
660660
/// Allows using the `#[used(linker)]` (or `#[used(compiler)]`) attribute.
661661
(unstable, used_with_arg, "1.60.0", Some(93798)),
662+
/// Allows use of attributes in `where` clauses.
663+
(unstable, where_clause_attrs, "CURRENT_RUSTC_VERSION", Some(115590)),
662664
/// Allows use of x86 `AMX` target-feature attributes and intrinsics
663665
(unstable, x86_amx_intrinsics, "1.81.0", Some(126622)),
664666
/// Allows use of the `xop` target-feature

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