1 //! "Collection" is the process of determining the type and other external
2 //! details of each item in Rust. Collection is specifically concerned
3 //! with *inter-procedural* things -- for example, for a function
4 //! definition, collection will figure out the type and signature of the
5 //! function, but it will not visit the *body* of the function in any way,
6 //! nor examine type annotations on local variables (that's the job of
7 //! type *checking*).
8 //!
9 //! Collecting is ultimately defined by a bundle of queries that
10 //! inquire after various facts about the items in the crate (e.g.,
11 //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
12 //! for the full set.
13 //!
14 //! At present, however, we do run collection across all items in the
15 //! crate as a kind of pass. This should eventually be factored away.
16
17 use crate::astconv::AstConv;
18 use crate::bounds::Bounds;
19 use crate::check::intrinsic::intrinsic_operation_unsafety;
20 use crate::constrained_generic_params as cgp;
21 use crate::errors;
22 use crate::middle::resolve_lifetime as rl;
23 use rustc_ast as ast;
24 use rustc_ast::Attribute;
25 use rustc_ast::{MetaItemKind, NestedMetaItem};
26 use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
27 use rustc_data_structures::captures::Captures;
28 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
29 use rustc_errors::{struct_span_err, Applicability};
30 use rustc_hir as hir;
31 use rustc_hir::def::{CtorKind, DefKind};
32 use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
33 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
34 use rustc_hir::weak_lang_items;
35 use rustc_hir::{GenericParamKind, HirId, Node};
36 use rustc_middle::hir::map::Map;
37 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
38 use rustc_middle::mir::mono::Linkage;
39 use rustc_middle::ty::query::Providers;
40 use rustc_middle::ty::subst::InternalSubsts;
41 use rustc_middle::ty::util::Discr;
42 use rustc_middle::ty::util::IntTypeExt;
43 use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, Ty, TyCtxt};
44 use rustc_middle::ty::{ReprOptions, ToPredicate, WithConstness};
45 use rustc_session::lint;
46 use rustc_session::parse::feature_err;
47 use rustc_span::symbol::{kw, sym, Ident, Symbol};
48 use rustc_span::{Span, DUMMY_SP};
49 use rustc_target::spec::{abi, PanicStrategy, SanitizerSet};
50 use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
51 use std::iter;
52
53 mod item_bounds;
54 mod type_of;
55
56 struct OnlySelfBounds(bool);
57
58 ///////////////////////////////////////////////////////////////////////////
59 // Main entry point
60
collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId)61 fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
62 tcx.hir().visit_item_likes_in_module(
63 module_def_id,
64 &mut CollectItemTypesVisitor { tcx }.as_deep_visitor(),
65 );
66 }
67
provide(providers: &mut Providers)68 pub fn provide(providers: &mut Providers) {
69 *providers = Providers {
70 opt_const_param_of: type_of::opt_const_param_of,
71 default_anon_const_substs: type_of::default_anon_const_substs,
72 type_of: type_of::type_of,
73 item_bounds: item_bounds::item_bounds,
74 explicit_item_bounds: item_bounds::explicit_item_bounds,
75 generics_of,
76 predicates_of,
77 predicates_defined_on,
78 explicit_predicates_of,
79 super_predicates_of,
80 super_predicates_that_define_assoc_type,
81 trait_explicit_predicates_and_bounds,
82 type_param_predicates,
83 trait_def,
84 adt_def,
85 fn_sig,
86 impl_trait_ref,
87 impl_polarity,
88 is_foreign_item,
89 static_mutability,
90 generator_kind,
91 codegen_fn_attrs,
92 collect_mod_item_types,
93 should_inherit_track_caller,
94 ..*providers
95 };
96 }
97
98 ///////////////////////////////////////////////////////////////////////////
99
100 /// Context specific to some particular item. This is what implements
101 /// `AstConv`. It has information about the predicates that are defined
102 /// on the trait. Unfortunately, this predicate information is
103 /// available in various different forms at various points in the
104 /// process. So we can't just store a pointer to e.g., the AST or the
105 /// parsed ty form, we have to be more flexible. To this end, the
106 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
107 /// `get_type_parameter_bounds` requests, drawing the information from
108 /// the AST (`hir::Generics`), recursively.
109 pub struct ItemCtxt<'tcx> {
110 tcx: TyCtxt<'tcx>,
111 item_def_id: DefId,
112 }
113
114 ///////////////////////////////////////////////////////////////////////////
115
116 #[derive(Default)]
117 crate struct PlaceholderHirTyCollector(crate Vec<Span>);
118
119 impl<'v> Visitor<'v> for PlaceholderHirTyCollector {
120 type Map = intravisit::ErasedMap<'v>;
121
nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map>122 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
123 NestedVisitorMap::None
124 }
visit_ty(&mut self, t: &'v hir::Ty<'v>)125 fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
126 if let hir::TyKind::Infer = t.kind {
127 self.0.push(t.span);
128 }
129 intravisit::walk_ty(self, t)
130 }
visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>)131 fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
132 match generic_arg {
133 hir::GenericArg::Infer(inf) => {
134 self.0.push(inf.span);
135 intravisit::walk_inf(self, inf);
136 }
137 hir::GenericArg::Type(t) => self.visit_ty(t),
138 _ => {}
139 }
140 }
141 }
142
143 struct CollectItemTypesVisitor<'tcx> {
144 tcx: TyCtxt<'tcx>,
145 }
146
147 /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
148 /// and suggest adding type parameters in the appropriate place, taking into consideration any and
149 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
placeholder_type_error( tcx: TyCtxt<'tcx>, span: Option<Span>, generics: &[hir::GenericParam<'_>], placeholder_types: Vec<Span>, suggest: bool, hir_ty: Option<&hir::Ty<'_>>, kind: &'static str, )150 crate fn placeholder_type_error(
151 tcx: TyCtxt<'tcx>,
152 span: Option<Span>,
153 generics: &[hir::GenericParam<'_>],
154 placeholder_types: Vec<Span>,
155 suggest: bool,
156 hir_ty: Option<&hir::Ty<'_>>,
157 kind: &'static str,
158 ) {
159 if placeholder_types.is_empty() {
160 return;
161 }
162
163 let type_name = generics.next_type_param_name(None);
164 let mut sugg: Vec<_> =
165 placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
166
167 if generics.is_empty() {
168 if let Some(span) = span {
169 sugg.push((span, format!("<{}>", type_name)));
170 }
171 } else if let Some(arg) = generics
172 .iter()
173 .find(|arg| matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. })))
174 {
175 // Account for `_` already present in cases like `struct S<_>(_);` and suggest
176 // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
177 sugg.push((arg.span, (*type_name).to_string()));
178 } else {
179 let last = generics.iter().last().unwrap();
180 sugg.push((
181 // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
182 last.bounds_span().unwrap_or(last.span).shrink_to_hi(),
183 format!(", {}", type_name),
184 ));
185 }
186
187 let mut err = bad_placeholder_type(tcx, placeholder_types, kind);
188
189 // Suggest, but only if it is not a function in const or static
190 if suggest {
191 let mut is_fn = false;
192 let mut is_const_or_static = false;
193
194 if let Some(hir_ty) = hir_ty {
195 if let hir::TyKind::BareFn(_) = hir_ty.kind {
196 is_fn = true;
197
198 // Check if parent is const or static
199 let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id);
200 let parent_node = tcx.hir().get(parent_id);
201
202 is_const_or_static = matches!(
203 parent_node,
204 Node::Item(&hir::Item {
205 kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..),
206 ..
207 }) | Node::TraitItem(&hir::TraitItem {
208 kind: hir::TraitItemKind::Const(..),
209 ..
210 }) | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
211 );
212 }
213 }
214
215 // if function is wrapped around a const or static,
216 // then don't show the suggestion
217 if !(is_fn && is_const_or_static) {
218 err.multipart_suggestion(
219 "use type parameters instead",
220 sugg,
221 Applicability::HasPlaceholders,
222 );
223 }
224 }
225 err.emit();
226 }
227
reject_placeholder_type_signatures_in_item(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>)228 fn reject_placeholder_type_signatures_in_item(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) {
229 let (generics, suggest) = match &item.kind {
230 hir::ItemKind::Union(_, generics)
231 | hir::ItemKind::Enum(_, generics)
232 | hir::ItemKind::TraitAlias(generics, _)
233 | hir::ItemKind::Trait(_, _, generics, ..)
234 | hir::ItemKind::Impl(hir::Impl { generics, .. })
235 | hir::ItemKind::Struct(_, generics) => (generics, true),
236 hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
237 | hir::ItemKind::TyAlias(_, generics) => (generics, false),
238 // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
239 _ => return,
240 };
241
242 let mut visitor = PlaceholderHirTyCollector::default();
243 visitor.visit_item(item);
244
245 placeholder_type_error(
246 tcx,
247 Some(generics.span),
248 generics.params,
249 visitor.0,
250 suggest,
251 None,
252 item.kind.descr(),
253 );
254 }
255
256 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
257 type Map = Map<'tcx>;
258
nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map>259 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
260 NestedVisitorMap::OnlyBodies(self.tcx.hir())
261 }
262
visit_item(&mut self, item: &'tcx hir::Item<'tcx>)263 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
264 convert_item(self.tcx, item.item_id());
265 reject_placeholder_type_signatures_in_item(self.tcx, item);
266 intravisit::walk_item(self, item);
267 }
268
visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>)269 fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
270 for param in generics.params {
271 match param.kind {
272 hir::GenericParamKind::Lifetime { .. } => {}
273 hir::GenericParamKind::Type { default: Some(_), .. } => {
274 let def_id = self.tcx.hir().local_def_id(param.hir_id);
275 self.tcx.ensure().type_of(def_id);
276 }
277 hir::GenericParamKind::Type { .. } => {}
278 hir::GenericParamKind::Const { default, .. } => {
279 let def_id = self.tcx.hir().local_def_id(param.hir_id);
280 self.tcx.ensure().type_of(def_id);
281 if let Some(default) = default {
282 let default_def_id = self.tcx.hir().local_def_id(default.hir_id);
283 // need to store default and type of default
284 self.tcx.ensure().type_of(default_def_id);
285 self.tcx.ensure().const_param_default(def_id);
286 }
287 }
288 }
289 }
290 intravisit::walk_generics(self, generics);
291 }
292
visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>)293 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
294 if let hir::ExprKind::Closure(..) = expr.kind {
295 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
296 self.tcx.ensure().generics_of(def_id);
297 self.tcx.ensure().type_of(def_id);
298 }
299 intravisit::walk_expr(self, expr);
300 }
301
visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>)302 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
303 convert_trait_item(self.tcx, trait_item.trait_item_id());
304 intravisit::walk_trait_item(self, trait_item);
305 }
306
visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>)307 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
308 convert_impl_item(self.tcx, impl_item.impl_item_id());
309 intravisit::walk_impl_item(self, impl_item);
310 }
311 }
312
313 ///////////////////////////////////////////////////////////////////////////
314 // Utility types and common code for the above passes.
315
bad_placeholder_type( tcx: TyCtxt<'tcx>, mut spans: Vec<Span>, kind: &'static str, ) -> rustc_errors::DiagnosticBuilder<'tcx>316 fn bad_placeholder_type(
317 tcx: TyCtxt<'tcx>,
318 mut spans: Vec<Span>,
319 kind: &'static str,
320 ) -> rustc_errors::DiagnosticBuilder<'tcx> {
321 let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
322
323 spans.sort();
324 let mut err = struct_span_err!(
325 tcx.sess,
326 spans.clone(),
327 E0121,
328 "the type placeholder `_` is not allowed within types on item signatures for {}",
329 kind
330 );
331 for span in spans {
332 err.span_label(span, "not allowed in type signatures");
333 }
334 err
335 }
336
337 impl ItemCtxt<'tcx> {
new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx>338 pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
339 ItemCtxt { tcx, item_def_id }
340 }
341
to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx>342 pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
343 <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
344 }
345
hir_id(&self) -> hir::HirId346 pub fn hir_id(&self) -> hir::HirId {
347 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
348 }
349
node(&self) -> hir::Node<'tcx>350 pub fn node(&self) -> hir::Node<'tcx> {
351 self.tcx.hir().get(self.hir_id())
352 }
353 }
354
355 impl AstConv<'tcx> for ItemCtxt<'tcx> {
tcx(&self) -> TyCtxt<'tcx>356 fn tcx(&self) -> TyCtxt<'tcx> {
357 self.tcx
358 }
359
item_def_id(&self) -> Option<DefId>360 fn item_def_id(&self) -> Option<DefId> {
361 Some(self.item_def_id)
362 }
363
get_type_parameter_bounds( &self, span: Span, def_id: DefId, assoc_name: Ident, ) -> ty::GenericPredicates<'tcx>364 fn get_type_parameter_bounds(
365 &self,
366 span: Span,
367 def_id: DefId,
368 assoc_name: Ident,
369 ) -> ty::GenericPredicates<'tcx> {
370 self.tcx.at(span).type_param_predicates((
371 self.item_def_id,
372 def_id.expect_local(),
373 assoc_name,
374 ))
375 }
376
re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>>377 fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
378 None
379 }
380
allow_ty_infer(&self) -> bool381 fn allow_ty_infer(&self) -> bool {
382 false
383 }
384
ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx>385 fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
386 self.tcx().ty_error_with_message(span, "bad_placeholder_type")
387 }
388
ct_infer( &self, ty: Ty<'tcx>, _: Option<&ty::GenericParamDef>, span: Span, ) -> &'tcx Const<'tcx>389 fn ct_infer(
390 &self,
391 ty: Ty<'tcx>,
392 _: Option<&ty::GenericParamDef>,
393 span: Span,
394 ) -> &'tcx Const<'tcx> {
395 bad_placeholder_type(self.tcx(), vec![span], "generic").emit();
396 // Typeck doesn't expect erased regions to be returned from `type_of`.
397 let ty = self.tcx.fold_regions(ty, &mut false, |r, _| match r {
398 ty::ReErased => self.tcx.lifetimes.re_static,
399 _ => r,
400 });
401 self.tcx().const_error(ty)
402 }
403
projected_ty_from_poly_trait_ref( &self, span: Span, item_def_id: DefId, item_segment: &hir::PathSegment<'_>, poly_trait_ref: ty::PolyTraitRef<'tcx>, ) -> Ty<'tcx>404 fn projected_ty_from_poly_trait_ref(
405 &self,
406 span: Span,
407 item_def_id: DefId,
408 item_segment: &hir::PathSegment<'_>,
409 poly_trait_ref: ty::PolyTraitRef<'tcx>,
410 ) -> Ty<'tcx> {
411 if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
412 let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
413 self,
414 self.tcx,
415 span,
416 item_def_id,
417 item_segment,
418 trait_ref.substs,
419 );
420 self.tcx().mk_projection(item_def_id, item_substs)
421 } else {
422 // There are no late-bound regions; we can just ignore the binder.
423 let mut err = struct_span_err!(
424 self.tcx().sess,
425 span,
426 E0212,
427 "cannot use the associated type of a trait \
428 with uninferred generic parameters"
429 );
430
431 match self.node() {
432 hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
433 let item =
434 self.tcx.hir().expect_item(self.tcx.hir().get_parent_item(self.hir_id()));
435 match &item.kind {
436 hir::ItemKind::Enum(_, generics)
437 | hir::ItemKind::Struct(_, generics)
438 | hir::ItemKind::Union(_, generics) => {
439 let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
440 let (lt_sp, sugg) = match generics.params {
441 [] => (generics.span, format!("<{}>", lt_name)),
442 [bound, ..] => {
443 (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
444 }
445 };
446 let suggestions = vec![
447 (lt_sp, sugg),
448 (
449 span.with_hi(item_segment.ident.span.lo()),
450 format!(
451 "{}::",
452 // Replace the existing lifetimes with a new named lifetime.
453 self.tcx
454 .replace_late_bound_regions(poly_trait_ref, |_| {
455 self.tcx.mk_region(ty::ReEarlyBound(
456 ty::EarlyBoundRegion {
457 def_id: item_def_id,
458 index: 0,
459 name: Symbol::intern(<_name),
460 },
461 ))
462 })
463 .0,
464 ),
465 ),
466 ];
467 err.multipart_suggestion(
468 "use a fully qualified path with explicit lifetimes",
469 suggestions,
470 Applicability::MaybeIncorrect,
471 );
472 }
473 _ => {}
474 }
475 }
476 hir::Node::Item(hir::Item {
477 kind:
478 hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
479 ..
480 }) => {}
481 hir::Node::Item(_)
482 | hir::Node::ForeignItem(_)
483 | hir::Node::TraitItem(_)
484 | hir::Node::ImplItem(_) => {
485 err.span_suggestion_verbose(
486 span.with_hi(item_segment.ident.span.lo()),
487 "use a fully qualified path with inferred lifetimes",
488 format!(
489 "{}::",
490 // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
491 self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
492 ),
493 Applicability::MaybeIncorrect,
494 );
495 }
496 _ => {}
497 }
498 err.emit();
499 self.tcx().ty_error()
500 }
501 }
502
normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx>503 fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
504 // Types in item signatures are not normalized to avoid undue dependencies.
505 ty
506 }
507
set_tainted_by_errors(&self)508 fn set_tainted_by_errors(&self) {
509 // There's no obvious place to track this, so just let it go.
510 }
511
record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span)512 fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
513 // There's no place to record types from signatures?
514 }
515 }
516
517 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
get_new_lifetime_name<'tcx>( tcx: TyCtxt<'tcx>, poly_trait_ref: ty::PolyTraitRef<'tcx>, generics: &hir::Generics<'tcx>, ) -> String518 fn get_new_lifetime_name<'tcx>(
519 tcx: TyCtxt<'tcx>,
520 poly_trait_ref: ty::PolyTraitRef<'tcx>,
521 generics: &hir::Generics<'tcx>,
522 ) -> String {
523 let existing_lifetimes = tcx
524 .collect_referenced_late_bound_regions(&poly_trait_ref)
525 .into_iter()
526 .filter_map(|lt| {
527 if let ty::BoundRegionKind::BrNamed(_, name) = lt {
528 Some(name.as_str().to_string())
529 } else {
530 None
531 }
532 })
533 .chain(generics.params.iter().filter_map(|param| {
534 if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind {
535 Some(param.name.ident().as_str().to_string())
536 } else {
537 None
538 }
539 }))
540 .collect::<FxHashSet<String>>();
541
542 let a_to_z_repeat_n = |n| {
543 (b'a'..=b'z').map(move |c| {
544 let mut s = '\''.to_string();
545 s.extend(std::iter::repeat(char::from(c)).take(n));
546 s
547 })
548 };
549
550 // If all single char lifetime names are present, we wrap around and double the chars.
551 (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
552 }
553
554 /// Returns the predicates defined on `item_def_id` of the form
555 /// `X: Foo` where `X` is the type parameter `def_id`.
type_param_predicates( tcx: TyCtxt<'_>, (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident), ) -> ty::GenericPredicates<'_>556 fn type_param_predicates(
557 tcx: TyCtxt<'_>,
558 (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
559 ) -> ty::GenericPredicates<'_> {
560 use rustc_hir::*;
561
562 // In the AST, bounds can derive from two places. Either
563 // written inline like `<T: Foo>` or in a where-clause like
564 // `where T: Foo`.
565
566 let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
567 let param_owner = tcx.hir().ty_param_owner(param_id);
568 let param_owner_def_id = tcx.hir().local_def_id(param_owner);
569 let generics = tcx.generics_of(param_owner_def_id);
570 let index = generics.param_def_id_to_index[&def_id.to_def_id()];
571 let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
572
573 // Don't look for bounds where the type parameter isn't in scope.
574 let parent = if item_def_id == param_owner_def_id.to_def_id() {
575 None
576 } else {
577 tcx.generics_of(item_def_id).parent
578 };
579
580 let mut result = parent
581 .map(|parent| {
582 let icx = ItemCtxt::new(tcx, parent);
583 icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
584 })
585 .unwrap_or_default();
586 let mut extend = None;
587
588 let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
589 let ast_generics = match tcx.hir().get(item_hir_id) {
590 Node::TraitItem(item) => &item.generics,
591
592 Node::ImplItem(item) => &item.generics,
593
594 Node::Item(item) => {
595 match item.kind {
596 ItemKind::Fn(.., ref generics, _)
597 | ItemKind::Impl(hir::Impl { ref generics, .. })
598 | ItemKind::TyAlias(_, ref generics)
599 | ItemKind::OpaqueTy(OpaqueTy { ref generics, impl_trait_fn: None, .. })
600 | ItemKind::Enum(_, ref generics)
601 | ItemKind::Struct(_, ref generics)
602 | ItemKind::Union(_, ref generics) => generics,
603 ItemKind::Trait(_, _, ref generics, ..) => {
604 // Implied `Self: Trait` and supertrait bounds.
605 if param_id == item_hir_id {
606 let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
607 extend =
608 Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
609 }
610 generics
611 }
612 _ => return result,
613 }
614 }
615
616 Node::ForeignItem(item) => match item.kind {
617 ForeignItemKind::Fn(_, _, ref generics) => generics,
618 _ => return result,
619 },
620
621 _ => return result,
622 };
623
624 let icx = ItemCtxt::new(tcx, item_def_id);
625 let extra_predicates = extend.into_iter().chain(
626 icx.type_parameter_bounds_in_generics(
627 ast_generics,
628 param_id,
629 ty,
630 OnlySelfBounds(true),
631 Some(assoc_name),
632 )
633 .into_iter()
634 .filter(|(predicate, _)| match predicate.kind().skip_binder() {
635 ty::PredicateKind::Trait(data) => data.self_ty().is_param(index),
636 _ => false,
637 }),
638 );
639 result.predicates =
640 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
641 result
642 }
643
644 impl ItemCtxt<'tcx> {
645 /// Finds bounds from `hir::Generics`. This requires scanning through the
646 /// AST. We do this to avoid having to convert *all* the bounds, which
647 /// would create artificial cycles. Instead, we can only convert the
648 /// bounds for a type parameter `X` if `X::Foo` is used.
type_parameter_bounds_in_generics( &self, ast_generics: &'tcx hir::Generics<'tcx>, param_id: hir::HirId, ty: Ty<'tcx>, only_self_bounds: OnlySelfBounds, assoc_name: Option<Ident>, ) -> Vec<(ty::Predicate<'tcx>, Span)>649 fn type_parameter_bounds_in_generics(
650 &self,
651 ast_generics: &'tcx hir::Generics<'tcx>,
652 param_id: hir::HirId,
653 ty: Ty<'tcx>,
654 only_self_bounds: OnlySelfBounds,
655 assoc_name: Option<Ident>,
656 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
657 let from_ty_params = ast_generics
658 .params
659 .iter()
660 .filter_map(|param| match param.kind {
661 GenericParamKind::Type { .. } if param.hir_id == param_id => Some(¶m.bounds),
662 _ => None,
663 })
664 .flat_map(|bounds| bounds.iter())
665 .filter(|b| match assoc_name {
666 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
667 None => true,
668 })
669 .flat_map(|b| predicates_from_bound(self, ty, b));
670
671 let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id();
672 let from_where_clauses = ast_generics
673 .where_clause
674 .predicates
675 .iter()
676 .filter_map(|wp| match *wp {
677 hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
678 _ => None,
679 })
680 .flat_map(|bp| {
681 let bt = if bp.is_param_bound(param_def_id) {
682 Some(ty)
683 } else if !only_self_bounds.0 {
684 Some(self.to_ty(bp.bounded_ty))
685 } else {
686 None
687 };
688 bp.bounds
689 .iter()
690 .filter(|b| match assoc_name {
691 Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
692 None => true,
693 })
694 .filter_map(move |b| bt.map(|bt| (bt, b)))
695 })
696 .flat_map(|(bt, b)| predicates_from_bound(self, bt, b));
697
698 from_ty_params.chain(from_where_clauses).collect()
699 }
700
bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool701 fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
702 debug!("bound_defines_assoc_item(b={:?}, assoc_name={:?})", b, assoc_name);
703
704 match b {
705 hir::GenericBound::Trait(poly_trait_ref, _) => {
706 let trait_ref = &poly_trait_ref.trait_ref;
707 if let Some(trait_did) = trait_ref.trait_def_id() {
708 self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
709 } else {
710 false
711 }
712 }
713 _ => false,
714 }
715 }
716 }
717
convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId)718 fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
719 let it = tcx.hir().item(item_id);
720 debug!("convert: item {} with id {}", it.ident, it.hir_id());
721 let def_id = item_id.def_id;
722
723 match it.kind {
724 // These don't define types.
725 hir::ItemKind::ExternCrate(_)
726 | hir::ItemKind::Use(..)
727 | hir::ItemKind::Macro(_)
728 | hir::ItemKind::Mod(_)
729 | hir::ItemKind::GlobalAsm(_) => {}
730 hir::ItemKind::ForeignMod { items, .. } => {
731 for item in items {
732 let item = tcx.hir().foreign_item(item.id);
733 tcx.ensure().generics_of(item.def_id);
734 tcx.ensure().type_of(item.def_id);
735 tcx.ensure().predicates_of(item.def_id);
736 match item.kind {
737 hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id),
738 hir::ForeignItemKind::Static(..) => {
739 let mut visitor = PlaceholderHirTyCollector::default();
740 visitor.visit_foreign_item(item);
741 placeholder_type_error(
742 tcx,
743 None,
744 &[],
745 visitor.0,
746 false,
747 None,
748 "static variable",
749 );
750 }
751 _ => (),
752 }
753 }
754 }
755 hir::ItemKind::Enum(ref enum_definition, _) => {
756 tcx.ensure().generics_of(def_id);
757 tcx.ensure().type_of(def_id);
758 tcx.ensure().predicates_of(def_id);
759 convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants);
760 }
761 hir::ItemKind::Impl { .. } => {
762 tcx.ensure().generics_of(def_id);
763 tcx.ensure().type_of(def_id);
764 tcx.ensure().impl_trait_ref(def_id);
765 tcx.ensure().predicates_of(def_id);
766 }
767 hir::ItemKind::Trait(..) => {
768 tcx.ensure().generics_of(def_id);
769 tcx.ensure().trait_def(def_id);
770 tcx.at(it.span).super_predicates_of(def_id);
771 tcx.ensure().predicates_of(def_id);
772 }
773 hir::ItemKind::TraitAlias(..) => {
774 tcx.ensure().generics_of(def_id);
775 tcx.at(it.span).super_predicates_of(def_id);
776 tcx.ensure().predicates_of(def_id);
777 }
778 hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
779 tcx.ensure().generics_of(def_id);
780 tcx.ensure().type_of(def_id);
781 tcx.ensure().predicates_of(def_id);
782
783 for f in struct_def.fields() {
784 let def_id = tcx.hir().local_def_id(f.hir_id);
785 tcx.ensure().generics_of(def_id);
786 tcx.ensure().type_of(def_id);
787 tcx.ensure().predicates_of(def_id);
788 }
789
790 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
791 convert_variant_ctor(tcx, ctor_hir_id);
792 }
793 }
794
795 // Desugared from `impl Trait`, so visited by the function's return type.
796 hir::ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn: Some(_), .. }) => {}
797
798 // Don't call `type_of` on opaque types, since that depends on type
799 // checking function bodies. `check_item_type` ensures that it's called
800 // instead.
801 hir::ItemKind::OpaqueTy(..) => {
802 tcx.ensure().generics_of(def_id);
803 tcx.ensure().predicates_of(def_id);
804 tcx.ensure().explicit_item_bounds(def_id);
805 }
806 hir::ItemKind::TyAlias(..)
807 | hir::ItemKind::Static(..)
808 | hir::ItemKind::Const(..)
809 | hir::ItemKind::Fn(..) => {
810 tcx.ensure().generics_of(def_id);
811 tcx.ensure().type_of(def_id);
812 tcx.ensure().predicates_of(def_id);
813 match it.kind {
814 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
815 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
816 hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
817 // (#75889): Account for `const C: dyn Fn() -> _ = "";`
818 if let hir::TyKind::TraitObject(..) = ty.kind {
819 let mut visitor = PlaceholderHirTyCollector::default();
820 visitor.visit_item(it);
821 placeholder_type_error(
822 tcx,
823 None,
824 &[],
825 visitor.0,
826 false,
827 None,
828 it.kind.descr(),
829 );
830 }
831 }
832 _ => (),
833 }
834 }
835 }
836 }
837
convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId)838 fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
839 let trait_item = tcx.hir().trait_item(trait_item_id);
840 tcx.ensure().generics_of(trait_item_id.def_id);
841
842 match trait_item.kind {
843 hir::TraitItemKind::Fn(..) => {
844 tcx.ensure().type_of(trait_item_id.def_id);
845 tcx.ensure().fn_sig(trait_item_id.def_id);
846 }
847
848 hir::TraitItemKind::Const(.., Some(_)) => {
849 tcx.ensure().type_of(trait_item_id.def_id);
850 }
851
852 hir::TraitItemKind::Const(..) => {
853 tcx.ensure().type_of(trait_item_id.def_id);
854 // Account for `const C: _;`.
855 let mut visitor = PlaceholderHirTyCollector::default();
856 visitor.visit_trait_item(trait_item);
857 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "constant");
858 }
859
860 hir::TraitItemKind::Type(_, Some(_)) => {
861 tcx.ensure().item_bounds(trait_item_id.def_id);
862 tcx.ensure().type_of(trait_item_id.def_id);
863 // Account for `type T = _;`.
864 let mut visitor = PlaceholderHirTyCollector::default();
865 visitor.visit_trait_item(trait_item);
866 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
867 }
868
869 hir::TraitItemKind::Type(_, None) => {
870 tcx.ensure().item_bounds(trait_item_id.def_id);
871 // #74612: Visit and try to find bad placeholders
872 // even if there is no concrete type.
873 let mut visitor = PlaceholderHirTyCollector::default();
874 visitor.visit_trait_item(trait_item);
875
876 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
877 }
878 };
879
880 tcx.ensure().predicates_of(trait_item_id.def_id);
881 }
882
convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId)883 fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
884 let def_id = impl_item_id.def_id;
885 tcx.ensure().generics_of(def_id);
886 tcx.ensure().type_of(def_id);
887 tcx.ensure().predicates_of(def_id);
888 let impl_item = tcx.hir().impl_item(impl_item_id);
889 match impl_item.kind {
890 hir::ImplItemKind::Fn(..) => {
891 tcx.ensure().fn_sig(def_id);
892 }
893 hir::ImplItemKind::TyAlias(_) => {
894 // Account for `type T = _;`
895 let mut visitor = PlaceholderHirTyCollector::default();
896 visitor.visit_impl_item(impl_item);
897
898 placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
899 }
900 hir::ImplItemKind::Const(..) => {}
901 }
902 }
903
convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId)904 fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
905 let def_id = tcx.hir().local_def_id(ctor_id);
906 tcx.ensure().generics_of(def_id);
907 tcx.ensure().type_of(def_id);
908 tcx.ensure().predicates_of(def_id);
909 }
910
convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>])911 fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
912 let def = tcx.adt_def(def_id);
913 let repr_type = def.repr.discr_type();
914 let initial = repr_type.initial_discriminant(tcx);
915 let mut prev_discr = None::<Discr<'_>>;
916
917 // fill the discriminant values and field types
918 for variant in variants {
919 let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
920 prev_discr = Some(
921 if let Some(ref e) = variant.disr_expr {
922 let expr_did = tcx.hir().local_def_id(e.hir_id);
923 def.eval_explicit_discr(tcx, expr_did.to_def_id())
924 } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
925 Some(discr)
926 } else {
927 struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
928 .span_label(
929 variant.span,
930 format!("overflowed on value after {}", prev_discr.unwrap()),
931 )
932 .note(&format!(
933 "explicitly set `{} = {}` if that is desired outcome",
934 variant.ident, wrapped_discr
935 ))
936 .emit();
937 None
938 }
939 .unwrap_or(wrapped_discr),
940 );
941
942 for f in variant.data.fields() {
943 let def_id = tcx.hir().local_def_id(f.hir_id);
944 tcx.ensure().generics_of(def_id);
945 tcx.ensure().type_of(def_id);
946 tcx.ensure().predicates_of(def_id);
947 }
948
949 // Convert the ctor, if any. This also registers the variant as
950 // an item.
951 if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
952 convert_variant_ctor(tcx, ctor_hir_id);
953 }
954 }
955 }
956
convert_variant( tcx: TyCtxt<'_>, variant_did: Option<LocalDefId>, ctor_did: Option<LocalDefId>, ident: Ident, discr: ty::VariantDiscr, def: &hir::VariantData<'_>, adt_kind: ty::AdtKind, parent_did: LocalDefId, ) -> ty::VariantDef957 fn convert_variant(
958 tcx: TyCtxt<'_>,
959 variant_did: Option<LocalDefId>,
960 ctor_did: Option<LocalDefId>,
961 ident: Ident,
962 discr: ty::VariantDiscr,
963 def: &hir::VariantData<'_>,
964 adt_kind: ty::AdtKind,
965 parent_did: LocalDefId,
966 ) -> ty::VariantDef {
967 let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
968 let fields = def
969 .fields()
970 .iter()
971 .map(|f| {
972 let fid = tcx.hir().local_def_id(f.hir_id);
973 let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
974 if let Some(prev_span) = dup_span {
975 tcx.sess.emit_err(errors::FieldAlreadyDeclared {
976 field_name: f.ident,
977 span: f.span,
978 prev_span,
979 });
980 } else {
981 seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
982 }
983
984 ty::FieldDef { did: fid.to_def_id(), ident: f.ident, vis: tcx.visibility(fid) }
985 })
986 .collect();
987 let recovered = match def {
988 hir::VariantData::Struct(_, r) => *r,
989 _ => false,
990 };
991 ty::VariantDef::new(
992 ident,
993 variant_did.map(LocalDefId::to_def_id),
994 ctor_did.map(LocalDefId::to_def_id),
995 discr,
996 fields,
997 CtorKind::from_hir(def),
998 adt_kind,
999 parent_did.to_def_id(),
1000 recovered,
1001 adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
1002 || variant_did.map_or(false, |variant_did| {
1003 tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
1004 }),
1005 )
1006 }
1007
adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef1008 fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
1009 use rustc_hir::*;
1010
1011 let def_id = def_id.expect_local();
1012 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1013 let item = match tcx.hir().get(hir_id) {
1014 Node::Item(item) => item,
1015 _ => bug!(),
1016 };
1017
1018 let repr = ReprOptions::new(tcx, def_id.to_def_id());
1019 let (kind, variants) = match item.kind {
1020 ItemKind::Enum(ref def, _) => {
1021 let mut distance_from_explicit = 0;
1022 let variants = def
1023 .variants
1024 .iter()
1025 .map(|v| {
1026 let variant_did = Some(tcx.hir().local_def_id(v.id));
1027 let ctor_did =
1028 v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1029
1030 let discr = if let Some(ref e) = v.disr_expr {
1031 distance_from_explicit = 0;
1032 ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
1033 } else {
1034 ty::VariantDiscr::Relative(distance_from_explicit)
1035 };
1036 distance_from_explicit += 1;
1037
1038 convert_variant(
1039 tcx,
1040 variant_did,
1041 ctor_did,
1042 v.ident,
1043 discr,
1044 &v.data,
1045 AdtKind::Enum,
1046 def_id,
1047 )
1048 })
1049 .collect();
1050
1051 (AdtKind::Enum, variants)
1052 }
1053 ItemKind::Struct(ref def, _) => {
1054 let variant_did = None::<LocalDefId>;
1055 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1056
1057 let variants = std::iter::once(convert_variant(
1058 tcx,
1059 variant_did,
1060 ctor_did,
1061 item.ident,
1062 ty::VariantDiscr::Relative(0),
1063 def,
1064 AdtKind::Struct,
1065 def_id,
1066 ))
1067 .collect();
1068
1069 (AdtKind::Struct, variants)
1070 }
1071 ItemKind::Union(ref def, _) => {
1072 let variant_did = None;
1073 let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
1074
1075 let variants = std::iter::once(convert_variant(
1076 tcx,
1077 variant_did,
1078 ctor_did,
1079 item.ident,
1080 ty::VariantDiscr::Relative(0),
1081 def,
1082 AdtKind::Union,
1083 def_id,
1084 ))
1085 .collect();
1086
1087 (AdtKind::Union, variants)
1088 }
1089 _ => bug!(),
1090 };
1091 tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
1092 }
1093
1094 /// Ensures that the super-predicates of the trait with a `DefId`
1095 /// of `trait_def_id` are converted and stored. This also ensures that
1096 /// the transitive super-predicates are converted.
super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_>1097 fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
1098 debug!("super_predicates(trait_def_id={:?})", trait_def_id);
1099 tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
1100 }
1101
1102 /// Ensures that the super-predicates of the trait with a `DefId`
1103 /// of `trait_def_id` are converted and stored. This also ensures that
1104 /// the transitive super-predicates are converted.
super_predicates_that_define_assoc_type( tcx: TyCtxt<'_>, (trait_def_id, assoc_name): (DefId, Option<Ident>), ) -> ty::GenericPredicates<'_>1105 fn super_predicates_that_define_assoc_type(
1106 tcx: TyCtxt<'_>,
1107 (trait_def_id, assoc_name): (DefId, Option<Ident>),
1108 ) -> ty::GenericPredicates<'_> {
1109 debug!(
1110 "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
1111 trait_def_id, assoc_name
1112 );
1113 if trait_def_id.is_local() {
1114 debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
1115 let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
1116
1117 let item = match tcx.hir().get(trait_hir_id) {
1118 Node::Item(item) => item,
1119 _ => bug!("trait_node_id {} is not an item", trait_hir_id),
1120 };
1121
1122 let (generics, bounds) = match item.kind {
1123 hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
1124 hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
1125 _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
1126 };
1127
1128 let icx = ItemCtxt::new(tcx, trait_def_id);
1129
1130 // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
1131 let self_param_ty = tcx.types.self_param;
1132 let superbounds1 = if let Some(assoc_name) = assoc_name {
1133 <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
1134 &icx,
1135 self_param_ty,
1136 bounds,
1137 assoc_name,
1138 )
1139 } else {
1140 <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
1141 };
1142
1143 let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1144
1145 // Convert any explicit superbounds in the where-clause,
1146 // e.g., `trait Foo where Self: Bar`.
1147 // In the case of trait aliases, however, we include all bounds in the where-clause,
1148 // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
1149 // as one of its "superpredicates".
1150 let is_trait_alias = tcx.is_trait_alias(trait_def_id);
1151 let superbounds2 = icx.type_parameter_bounds_in_generics(
1152 generics,
1153 item.hir_id(),
1154 self_param_ty,
1155 OnlySelfBounds(!is_trait_alias),
1156 assoc_name,
1157 );
1158
1159 // Combine the two lists to form the complete set of superbounds:
1160 let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
1161
1162 // Now require that immediate supertraits are converted,
1163 // which will, in turn, reach indirect supertraits.
1164 if assoc_name.is_none() {
1165 // Now require that immediate supertraits are converted,
1166 // which will, in turn, reach indirect supertraits.
1167 for &(pred, span) in superbounds {
1168 debug!("superbound: {:?}", pred);
1169 if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
1170 tcx.at(span).super_predicates_of(bound.def_id());
1171 }
1172 }
1173 }
1174
1175 ty::GenericPredicates { parent: None, predicates: superbounds }
1176 } else {
1177 // if `assoc_name` is None, then the query should've been redirected to an
1178 // external provider
1179 assert!(assoc_name.is_some());
1180 tcx.super_predicates_of(trait_def_id)
1181 }
1182 }
1183
trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef1184 fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
1185 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1186 let item = tcx.hir().expect_item(hir_id);
1187
1188 let (is_auto, unsafety) = match item.kind {
1189 hir::ItemKind::Trait(is_auto, unsafety, ..) => (is_auto == hir::IsAuto::Yes, unsafety),
1190 hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal),
1191 _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
1192 };
1193
1194 let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
1195 if paren_sugar && !tcx.features().unboxed_closures {
1196 tcx.sess
1197 .struct_span_err(
1198 item.span,
1199 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1200 which traits can use parenthetical notation",
1201 )
1202 .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
1203 .emit();
1204 }
1205
1206 let is_marker = tcx.has_attr(def_id, sym::marker);
1207 let skip_array_during_method_dispatch =
1208 tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch);
1209 let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
1210 ty::trait_def::TraitSpecializationKind::Marker
1211 } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
1212 ty::trait_def::TraitSpecializationKind::AlwaysApplicable
1213 } else {
1214 ty::trait_def::TraitSpecializationKind::None
1215 };
1216 let def_path_hash = tcx.def_path_hash(def_id);
1217 ty::TraitDef::new(
1218 def_id,
1219 unsafety,
1220 paren_sugar,
1221 is_auto,
1222 is_marker,
1223 skip_array_during_method_dispatch,
1224 spec_kind,
1225 def_path_hash,
1226 )
1227 }
1228
has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span>1229 fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
1230 struct LateBoundRegionsDetector<'tcx> {
1231 tcx: TyCtxt<'tcx>,
1232 outer_index: ty::DebruijnIndex,
1233 has_late_bound_regions: Option<Span>,
1234 }
1235
1236 impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
1237 type Map = intravisit::ErasedMap<'tcx>;
1238
1239 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1240 NestedVisitorMap::None
1241 }
1242
1243 fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
1244 if self.has_late_bound_regions.is_some() {
1245 return;
1246 }
1247 match ty.kind {
1248 hir::TyKind::BareFn(..) => {
1249 self.outer_index.shift_in(1);
1250 intravisit::walk_ty(self, ty);
1251 self.outer_index.shift_out(1);
1252 }
1253 _ => intravisit::walk_ty(self, ty),
1254 }
1255 }
1256
1257 fn visit_poly_trait_ref(
1258 &mut self,
1259 tr: &'tcx hir::PolyTraitRef<'tcx>,
1260 m: hir::TraitBoundModifier,
1261 ) {
1262 if self.has_late_bound_regions.is_some() {
1263 return;
1264 }
1265 self.outer_index.shift_in(1);
1266 intravisit::walk_poly_trait_ref(self, tr, m);
1267 self.outer_index.shift_out(1);
1268 }
1269
1270 fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
1271 if self.has_late_bound_regions.is_some() {
1272 return;
1273 }
1274
1275 match self.tcx.named_region(lt.hir_id) {
1276 Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
1277 Some(
1278 rl::Region::LateBound(debruijn, _, _, _)
1279 | rl::Region::LateBoundAnon(debruijn, _, _),
1280 ) if debruijn < self.outer_index => {}
1281 Some(
1282 rl::Region::LateBound(..)
1283 | rl::Region::LateBoundAnon(..)
1284 | rl::Region::Free(..),
1285 )
1286 | None => {
1287 self.has_late_bound_regions = Some(lt.span);
1288 }
1289 }
1290 }
1291 }
1292
1293 fn has_late_bound_regions<'tcx>(
1294 tcx: TyCtxt<'tcx>,
1295 generics: &'tcx hir::Generics<'tcx>,
1296 decl: &'tcx hir::FnDecl<'tcx>,
1297 ) -> Option<Span> {
1298 let mut visitor = LateBoundRegionsDetector {
1299 tcx,
1300 outer_index: ty::INNERMOST,
1301 has_late_bound_regions: None,
1302 };
1303 for param in generics.params {
1304 if let GenericParamKind::Lifetime { .. } = param.kind {
1305 if tcx.is_late_bound(param.hir_id) {
1306 return Some(param.span);
1307 }
1308 }
1309 }
1310 visitor.visit_fn_decl(decl);
1311 visitor.has_late_bound_regions
1312 }
1313
1314 match node {
1315 Node::TraitItem(item) => match item.kind {
1316 hir::TraitItemKind::Fn(ref sig, _) => {
1317 has_late_bound_regions(tcx, &item.generics, sig.decl)
1318 }
1319 _ => None,
1320 },
1321 Node::ImplItem(item) => match item.kind {
1322 hir::ImplItemKind::Fn(ref sig, _) => {
1323 has_late_bound_regions(tcx, &item.generics, sig.decl)
1324 }
1325 _ => None,
1326 },
1327 Node::ForeignItem(item) => match item.kind {
1328 hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => {
1329 has_late_bound_regions(tcx, generics, fn_decl)
1330 }
1331 _ => None,
1332 },
1333 Node::Item(item) => match item.kind {
1334 hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
1335 has_late_bound_regions(tcx, generics, sig.decl)
1336 }
1337 _ => None,
1338 },
1339 _ => None,
1340 }
1341 }
1342
1343 struct AnonConstInParamTyDetector {
1344 in_param_ty: bool,
1345 found_anon_const_in_param_ty: bool,
1346 ct: HirId,
1347 }
1348
1349 impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
1350 type Map = intravisit::ErasedMap<'v>;
1351
nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map>1352 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
1353 NestedVisitorMap::None
1354 }
1355
visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>)1356 fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
1357 if let GenericParamKind::Const { ty, default: _ } = p.kind {
1358 let prev = self.in_param_ty;
1359 self.in_param_ty = true;
1360 self.visit_ty(ty);
1361 self.in_param_ty = prev;
1362 }
1363 }
1364
visit_anon_const(&mut self, c: &'v hir::AnonConst)1365 fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
1366 if self.in_param_ty && self.ct == c.hir_id {
1367 self.found_anon_const_in_param_ty = true;
1368 } else {
1369 intravisit::walk_anon_const(self, c)
1370 }
1371 }
1372 }
1373
generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics1374 fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
1375 use rustc_hir::*;
1376
1377 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1378
1379 let node = tcx.hir().get(hir_id);
1380 let parent_def_id = match node {
1381 Node::ImplItem(_)
1382 | Node::TraitItem(_)
1383 | Node::Variant(_)
1384 | Node::Ctor(..)
1385 | Node::Field(_) => {
1386 let parent_id = tcx.hir().get_parent_item(hir_id);
1387 Some(tcx.hir().local_def_id(parent_id).to_def_id())
1388 }
1389 // FIXME(#43408) always enable this once `lazy_normalization` is
1390 // stable enough and does not need a feature gate anymore.
1391 Node::AnonConst(_) => {
1392 let parent_id = tcx.hir().get_parent_item(hir_id);
1393 let parent_def_id = tcx.hir().local_def_id(parent_id);
1394
1395 let mut in_param_ty = false;
1396 for (_parent, node) in tcx.hir().parent_iter(hir_id) {
1397 if let Some(generics) = node.generics() {
1398 let mut visitor = AnonConstInParamTyDetector {
1399 in_param_ty: false,
1400 found_anon_const_in_param_ty: false,
1401 ct: hir_id,
1402 };
1403
1404 visitor.visit_generics(generics);
1405 in_param_ty = visitor.found_anon_const_in_param_ty;
1406 break;
1407 }
1408 }
1409
1410 if in_param_ty {
1411 // We do not allow generic parameters in anon consts if we are inside
1412 // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
1413 None
1414 } else if tcx.lazy_normalization() {
1415 if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
1416 // If the def_id we are calling generics_of on is an anon ct default i.e:
1417 //
1418 // struct Foo<const N: usize = { .. }>;
1419 // ^^^ ^ ^^^^^^ def id of this anon const
1420 // ^ ^ param_id
1421 // ^ parent_def_id
1422 //
1423 // then we only want to return generics for params to the left of `N`. If we don't do that we
1424 // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
1425 //
1426 // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
1427 // we substitute the defaults with the partially built substs when we build the substs. Subst'ing
1428 // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
1429 //
1430 // We fix this by having this function return the parent's generics ourselves and truncating the
1431 // generics to only include non-forward declared params (with the exception of the `Self` ty)
1432 //
1433 // For the above code example that means we want `substs: []`
1434 // For the following struct def we want `substs: [N#0]` when generics_of is called on
1435 // the def id of the `{ N + 1 }` anon const
1436 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
1437 //
1438 // This has some implications for how we get the predicates available to the anon const
1439 // see `explicit_predicates_of` for more information on this
1440 let generics = tcx.generics_of(parent_def_id.to_def_id());
1441 let param_def = tcx.hir().local_def_id(param_id).to_def_id();
1442 let param_def_idx = generics.param_def_id_to_index[¶m_def];
1443 // In the above example this would be .params[..N#0]
1444 let params = generics.params[..param_def_idx as usize].to_owned();
1445 let param_def_id_to_index =
1446 params.iter().map(|param| (param.def_id, param.index)).collect();
1447
1448 return ty::Generics {
1449 // we set the parent of these generics to be our parent's parent so that we
1450 // dont end up with substs: [N, M, N] for the const default on a struct like this:
1451 // struct Foo<const N: usize, const M: usize = { ... }>;
1452 parent: generics.parent,
1453 parent_count: generics.parent_count,
1454 params,
1455 param_def_id_to_index,
1456 has_self: generics.has_self,
1457 has_late_bound_regions: generics.has_late_bound_regions,
1458 };
1459 }
1460
1461 // HACK(eddyb) this provides the correct generics when
1462 // `feature(generic_const_expressions)` is enabled, so that const expressions
1463 // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
1464 //
1465 // Note that we do not supply the parent generics when using
1466 // `min_const_generics`.
1467 Some(parent_def_id.to_def_id())
1468 } else {
1469 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1470 match parent_node {
1471 // HACK(eddyb) this provides the correct generics for repeat
1472 // expressions' count (i.e. `N` in `[x; N]`), and explicit
1473 // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
1474 // as they shouldn't be able to cause query cycle errors.
1475 Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
1476 | Node::Variant(Variant { disr_expr: Some(ref constant), .. })
1477 if constant.hir_id == hir_id =>
1478 {
1479 Some(parent_def_id.to_def_id())
1480 }
1481 Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
1482 Some(tcx.typeck_root_def_id(def_id))
1483 }
1484 _ => None,
1485 }
1486 }
1487 }
1488 Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1489 Some(tcx.typeck_root_def_id(def_id))
1490 }
1491 Node::Item(item) => match item.kind {
1492 ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => {
1493 impl_trait_fn.or_else(|| {
1494 let parent_id = tcx.hir().get_parent_item(hir_id);
1495 assert!(parent_id != hir_id && parent_id != CRATE_HIR_ID);
1496 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
1497 // Opaque types are always nested within another item, and
1498 // inherit the generics of the item.
1499 Some(tcx.hir().local_def_id(parent_id).to_def_id())
1500 })
1501 }
1502 _ => None,
1503 },
1504 _ => None,
1505 };
1506
1507 let mut opt_self = None;
1508 let mut allow_defaults = false;
1509
1510 let no_generics = hir::Generics::empty();
1511 let ast_generics = match node {
1512 Node::TraitItem(item) => &item.generics,
1513
1514 Node::ImplItem(item) => &item.generics,
1515
1516 Node::Item(item) => {
1517 match item.kind {
1518 ItemKind::Fn(.., ref generics, _)
1519 | ItemKind::Impl(hir::Impl { ref generics, .. }) => generics,
1520
1521 ItemKind::TyAlias(_, ref generics)
1522 | ItemKind::Enum(_, ref generics)
1523 | ItemKind::Struct(_, ref generics)
1524 | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
1525 | ItemKind::Union(_, ref generics) => {
1526 allow_defaults = true;
1527 generics
1528 }
1529
1530 ItemKind::Trait(_, _, ref generics, ..)
1531 | ItemKind::TraitAlias(ref generics, ..) => {
1532 // Add in the self type parameter.
1533 //
1534 // Something of a hack: use the node id for the trait, also as
1535 // the node id for the Self type parameter.
1536 let param_id = item.def_id;
1537
1538 opt_self = Some(ty::GenericParamDef {
1539 index: 0,
1540 name: kw::SelfUpper,
1541 def_id: param_id.to_def_id(),
1542 pure_wrt_drop: false,
1543 kind: ty::GenericParamDefKind::Type {
1544 has_default: false,
1545 object_lifetime_default: rl::Set1::Empty,
1546 synthetic: false,
1547 },
1548 });
1549
1550 allow_defaults = true;
1551 generics
1552 }
1553
1554 _ => &no_generics,
1555 }
1556 }
1557
1558 Node::ForeignItem(item) => match item.kind {
1559 ForeignItemKind::Static(..) => &no_generics,
1560 ForeignItemKind::Fn(_, _, ref generics) => generics,
1561 ForeignItemKind::Type => &no_generics,
1562 },
1563
1564 _ => &no_generics,
1565 };
1566
1567 let has_self = opt_self.is_some();
1568 let mut parent_has_self = false;
1569 let mut own_start = has_self as u32;
1570 let parent_count = parent_def_id.map_or(0, |def_id| {
1571 let generics = tcx.generics_of(def_id);
1572 assert!(!has_self);
1573 parent_has_self = generics.has_self;
1574 own_start = generics.count() as u32;
1575 generics.parent_count + generics.params.len()
1576 });
1577
1578 let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
1579
1580 if let Some(opt_self) = opt_self {
1581 params.push(opt_self);
1582 }
1583
1584 let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics);
1585 params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
1586 name: param.name.ident().name,
1587 index: own_start + i as u32,
1588 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1589 pure_wrt_drop: param.pure_wrt_drop,
1590 kind: ty::GenericParamDefKind::Lifetime,
1591 }));
1592
1593 let object_lifetime_defaults = tcx.object_lifetime_defaults(hir_id);
1594
1595 // Now create the real type and const parameters.
1596 let type_start = own_start - has_self as u32 + params.len() as u32;
1597 let mut i = 0;
1598
1599 params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
1600 GenericParamKind::Lifetime { .. } => None,
1601 GenericParamKind::Type { ref default, synthetic, .. } => {
1602 if !allow_defaults && default.is_some() {
1603 if !tcx.features().default_type_parameter_fallback {
1604 tcx.struct_span_lint_hir(
1605 lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1606 param.hir_id,
1607 param.span,
1608 |lint| {
1609 lint.build(
1610 "defaults for type parameters are only allowed in \
1611 `struct`, `enum`, `type`, or `trait` definitions",
1612 )
1613 .emit();
1614 },
1615 );
1616 }
1617 }
1618
1619 let kind = ty::GenericParamDefKind::Type {
1620 has_default: default.is_some(),
1621 object_lifetime_default: object_lifetime_defaults
1622 .as_ref()
1623 .map_or(rl::Set1::Empty, |o| o[i]),
1624 synthetic,
1625 };
1626
1627 let param_def = ty::GenericParamDef {
1628 index: type_start + i as u32,
1629 name: param.name.ident().name,
1630 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1631 pure_wrt_drop: param.pure_wrt_drop,
1632 kind,
1633 };
1634 i += 1;
1635 Some(param_def)
1636 }
1637 GenericParamKind::Const { default, .. } => {
1638 if !allow_defaults && default.is_some() {
1639 tcx.sess.span_err(
1640 param.span,
1641 "defaults for const parameters are only allowed in \
1642 `struct`, `enum`, `type`, or `trait` definitions",
1643 );
1644 }
1645
1646 let param_def = ty::GenericParamDef {
1647 index: type_start + i as u32,
1648 name: param.name.ident().name,
1649 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
1650 pure_wrt_drop: param.pure_wrt_drop,
1651 kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
1652 };
1653 i += 1;
1654 Some(param_def)
1655 }
1656 }));
1657
1658 // provide junk type parameter defs - the only place that
1659 // cares about anything but the length is instantiation,
1660 // and we don't do that for closures.
1661 if let Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure(.., gen), .. }) = node {
1662 let dummy_args = if gen.is_some() {
1663 &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
1664 } else {
1665 &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
1666 };
1667
1668 params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef {
1669 index: type_start + i as u32,
1670 name: Symbol::intern(arg),
1671 def_id,
1672 pure_wrt_drop: false,
1673 kind: ty::GenericParamDefKind::Type {
1674 has_default: false,
1675 object_lifetime_default: rl::Set1::Empty,
1676 synthetic: false,
1677 },
1678 }));
1679 }
1680
1681 // provide junk type parameter defs for const blocks.
1682 if let Node::AnonConst(_) = node {
1683 let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
1684 if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
1685 params.push(ty::GenericParamDef {
1686 index: type_start,
1687 name: Symbol::intern("<const_ty>"),
1688 def_id,
1689 pure_wrt_drop: false,
1690 kind: ty::GenericParamDefKind::Type {
1691 has_default: false,
1692 object_lifetime_default: rl::Set1::Empty,
1693 synthetic: false,
1694 },
1695 });
1696 }
1697 }
1698
1699 let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
1700
1701 ty::Generics {
1702 parent: parent_def_id,
1703 parent_count,
1704 params,
1705 param_def_id_to_index,
1706 has_self: has_self || parent_has_self,
1707 has_late_bound_regions: has_late_bound_regions(tcx, node),
1708 }
1709 }
1710
are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool1711 fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
1712 generic_args.iter().any(|arg| match arg {
1713 hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty),
1714 hir::GenericArg::Infer(_) => true,
1715 _ => false,
1716 })
1717 }
1718
1719 /// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
1720 /// use inference to provide suggestions for the appropriate type if possible.
is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool1721 fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
1722 use hir::TyKind::*;
1723 match &ty.kind {
1724 Infer => true,
1725 Slice(ty) | Array(ty, _) => is_suggestable_infer_ty(ty),
1726 Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
1727 Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
1728 OpaqueDef(_, generic_args) => are_suggestable_generic_args(generic_args),
1729 Path(hir::QPath::TypeRelative(ty, segment)) => {
1730 is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
1731 }
1732 Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
1733 ty_opt.map_or(false, is_suggestable_infer_ty)
1734 || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
1735 }
1736 _ => false,
1737 }
1738 }
1739
get_infer_ret_ty(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>>1740 pub fn get_infer_ret_ty(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
1741 if let hir::FnRetTy::Return(ty) = output {
1742 if is_suggestable_infer_ty(ty) {
1743 return Some(&*ty);
1744 }
1745 }
1746 None
1747 }
1748
fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_>1749 fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
1750 use rustc_hir::Node::*;
1751 use rustc_hir::*;
1752
1753 let def_id = def_id.expect_local();
1754 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
1755
1756 let icx = ItemCtxt::new(tcx, def_id.to_def_id());
1757
1758 match tcx.hir().get(hir_id) {
1759 TraitItem(hir::TraitItem {
1760 kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
1761 ident,
1762 generics,
1763 ..
1764 })
1765 | ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), ident, generics, .. })
1766 | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), ident, .. }) => {
1767 match get_infer_ret_ty(&sig.decl.output) {
1768 Some(ty) => {
1769 let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
1770 // Typeck doesn't expect erased regions to be returned from `type_of`.
1771 let fn_sig = tcx.fold_regions(fn_sig, &mut false, |r, _| match r {
1772 ty::ReErased => tcx.lifetimes.re_static,
1773 _ => r,
1774 });
1775 let fn_sig = ty::Binder::dummy(fn_sig);
1776
1777 let mut visitor = PlaceholderHirTyCollector::default();
1778 visitor.visit_ty(ty);
1779 let mut diag = bad_placeholder_type(tcx, visitor.0, "return type");
1780 let ret_ty = fn_sig.skip_binder().output();
1781 if ret_ty != tcx.ty_error() {
1782 if !ret_ty.is_closure() {
1783 let ret_ty_str = match ret_ty.kind() {
1784 // Suggest a function pointer return type instead of a unique function definition
1785 // (e.g. `fn() -> i32` instead of `fn() -> i32 { f }`, the latter of which is invalid
1786 // syntax)
1787 ty::FnDef(..) => ret_ty.fn_sig(tcx).to_string(),
1788 _ => ret_ty.to_string(),
1789 };
1790 diag.span_suggestion(
1791 ty.span,
1792 "replace with the correct return type",
1793 ret_ty_str,
1794 Applicability::MaybeIncorrect,
1795 );
1796 } else {
1797 // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
1798 // to prevent the user from getting a papercut while trying to use the unique closure
1799 // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
1800 diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
1801 diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
1802 }
1803 }
1804 diag.emit();
1805
1806 fn_sig
1807 }
1808 None => <dyn AstConv<'_>>::ty_of_fn(
1809 &icx,
1810 hir_id,
1811 sig.header.unsafety,
1812 sig.header.abi,
1813 sig.decl,
1814 generics,
1815 Some(ident.span),
1816 None,
1817 ),
1818 }
1819 }
1820
1821 TraitItem(hir::TraitItem {
1822 kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
1823 ident,
1824 generics,
1825 ..
1826 }) => <dyn AstConv<'_>>::ty_of_fn(
1827 &icx,
1828 hir_id,
1829 header.unsafety,
1830 header.abi,
1831 decl,
1832 generics,
1833 Some(ident.span),
1834 None,
1835 ),
1836
1837 ForeignItem(&hir::ForeignItem {
1838 kind: ForeignItemKind::Fn(fn_decl, _, _), ident, ..
1839 }) => {
1840 let abi = tcx.hir().get_foreign_abi(hir_id);
1841 compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi, ident)
1842 }
1843
1844 Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
1845 let ty = tcx.type_of(tcx.hir().get_parent_did(hir_id).to_def_id());
1846 let inputs =
1847 data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
1848 ty::Binder::dummy(tcx.mk_fn_sig(
1849 inputs,
1850 ty,
1851 false,
1852 hir::Unsafety::Normal,
1853 abi::Abi::Rust,
1854 ))
1855 }
1856
1857 Expr(&hir::Expr { kind: hir::ExprKind::Closure(..), .. }) => {
1858 // Closure signatures are not like other function
1859 // signatures and cannot be accessed through `fn_sig`. For
1860 // example, a closure signature excludes the `self`
1861 // argument. In any case they are embedded within the
1862 // closure type as part of the `ClosureSubsts`.
1863 //
1864 // To get the signature of a closure, you should use the
1865 // `sig` method on the `ClosureSubsts`:
1866 //
1867 // substs.as_closure().sig(def_id, tcx)
1868 bug!(
1869 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1870 );
1871 }
1872
1873 x => {
1874 bug!("unexpected sort of node in fn_sig(): {:?}", x);
1875 }
1876 }
1877 }
1878
impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>>1879 fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
1880 let icx = ItemCtxt::new(tcx, def_id);
1881
1882 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1883 match tcx.hir().expect_item(hir_id).kind {
1884 hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
1885 let selfty = tcx.type_of(def_id);
1886 <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
1887 }),
1888 _ => bug!(),
1889 }
1890 }
1891
impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity1892 fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
1893 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
1894 let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
1895 let item = tcx.hir().expect_item(hir_id);
1896 match &item.kind {
1897 hir::ItemKind::Impl(hir::Impl {
1898 polarity: hir::ImplPolarity::Negative(span),
1899 of_trait,
1900 ..
1901 }) => {
1902 if is_rustc_reservation {
1903 let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
1904 tcx.sess.span_err(span, "reservation impls can't be negative");
1905 }
1906 ty::ImplPolarity::Negative
1907 }
1908 hir::ItemKind::Impl(hir::Impl {
1909 polarity: hir::ImplPolarity::Positive,
1910 of_trait: None,
1911 ..
1912 }) => {
1913 if is_rustc_reservation {
1914 tcx.sess.span_err(item.span, "reservation impls can't be inherent");
1915 }
1916 ty::ImplPolarity::Positive
1917 }
1918 hir::ItemKind::Impl(hir::Impl {
1919 polarity: hir::ImplPolarity::Positive,
1920 of_trait: Some(_),
1921 ..
1922 }) => {
1923 if is_rustc_reservation {
1924 ty::ImplPolarity::Reservation
1925 } else {
1926 ty::ImplPolarity::Positive
1927 }
1928 }
1929 item => bug!("impl_polarity: {:?} not an impl", item),
1930 }
1931 }
1932
1933 /// Returns the early-bound lifetimes declared in this generics
1934 /// listing. For anything other than fns/methods, this is just all
1935 /// the lifetimes that are declared. For fns or methods, we have to
1936 /// screen out those that do not appear in any where-clauses etc using
1937 /// `resolve_lifetime::early_bound_lifetimes`.
early_bound_lifetimes_from_generics<'a, 'tcx: 'a>( tcx: TyCtxt<'tcx>, generics: &'a hir::Generics<'a>, ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx>1938 fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
1939 tcx: TyCtxt<'tcx>,
1940 generics: &'a hir::Generics<'a>,
1941 ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
1942 generics.params.iter().filter(move |param| match param.kind {
1943 GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
1944 _ => false,
1945 })
1946 }
1947
1948 /// Returns a list of type predicates for the definition with ID `def_id`, including inferred
1949 /// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
1950 /// inferred constraints concerning which regions outlive other regions.
predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_>1951 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1952 debug!("predicates_defined_on({:?})", def_id);
1953 let mut result = tcx.explicit_predicates_of(def_id);
1954 debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
1955 let inferred_outlives = tcx.inferred_outlives_of(def_id);
1956 if !inferred_outlives.is_empty() {
1957 debug!(
1958 "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
1959 def_id, inferred_outlives,
1960 );
1961 if result.predicates.is_empty() {
1962 result.predicates = inferred_outlives;
1963 } else {
1964 result.predicates = tcx
1965 .arena
1966 .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
1967 }
1968 }
1969
1970 debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
1971 result
1972 }
1973
1974 /// Returns a list of all type predicates (explicit and implicit) for the definition with
1975 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
1976 /// `Self: Trait` predicates for traits.
predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_>1977 fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
1978 let mut result = tcx.predicates_defined_on(def_id);
1979
1980 if tcx.is_trait(def_id) {
1981 // For traits, add `Self: Trait` predicate. This is
1982 // not part of the predicates that a user writes, but it
1983 // is something that one must prove in order to invoke a
1984 // method or project an associated type.
1985 //
1986 // In the chalk setup, this predicate is not part of the
1987 // "predicates" for a trait item. But it is useful in
1988 // rustc because if you directly (e.g.) invoke a trait
1989 // method like `Trait::method(...)`, you must naturally
1990 // prove that the trait applies to the types that were
1991 // used, and adding the predicate into this list ensures
1992 // that this is done.
1993 //
1994 // We use a DUMMY_SP here as a way to signal trait bounds that come
1995 // from the trait itself that *shouldn't* be shown as the source of
1996 // an obligation and instead be skipped. Otherwise we'd use
1997 // `tcx.def_span(def_id);`
1998 let span = rustc_span::DUMMY_SP;
1999 result.predicates =
2000 tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
2001 ty::TraitRef::identity(tcx, def_id).without_const().to_predicate(tcx),
2002 span,
2003 ))));
2004 }
2005 debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
2006 result
2007 }
2008
2009 /// Returns a list of user-specified type predicates for the definition with ID `def_id`.
2010 /// N.B., this does not include any implied/inferred constraints.
gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_>2011 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2012 use rustc_hir::*;
2013
2014 debug!("explicit_predicates_of(def_id={:?})", def_id);
2015
2016 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2017 let node = tcx.hir().get(hir_id);
2018
2019 let mut is_trait = None;
2020 let mut is_default_impl_trait = None;
2021
2022 let icx = ItemCtxt::new(tcx, def_id);
2023
2024 const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
2025
2026 // We use an `IndexSet` to preserves order of insertion.
2027 // Preserving the order of insertion is important here so as not to break UI tests.
2028 let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
2029
2030 let ast_generics = match node {
2031 Node::TraitItem(item) => &item.generics,
2032
2033 Node::ImplItem(item) => &item.generics,
2034
2035 Node::Item(item) => {
2036 match item.kind {
2037 ItemKind::Impl(ref impl_) => {
2038 if impl_.defaultness.is_default() {
2039 is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
2040 }
2041 &impl_.generics
2042 }
2043 ItemKind::Fn(.., ref generics, _)
2044 | ItemKind::TyAlias(_, ref generics)
2045 | ItemKind::Enum(_, ref generics)
2046 | ItemKind::Struct(_, ref generics)
2047 | ItemKind::Union(_, ref generics) => generics,
2048
2049 ItemKind::Trait(_, _, ref generics, ..) => {
2050 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2051 generics
2052 }
2053 ItemKind::TraitAlias(ref generics, _) => {
2054 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
2055 generics
2056 }
2057 ItemKind::OpaqueTy(OpaqueTy {
2058 bounds: _,
2059 impl_trait_fn,
2060 ref generics,
2061 origin: _,
2062 }) => {
2063 if impl_trait_fn.is_some() {
2064 // return-position impl trait
2065 //
2066 // We don't inherit predicates from the parent here:
2067 // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
2068 // then the return type is `f::<'static, T>::{{opaque}}`.
2069 //
2070 // If we inherited the predicates of `f` then we would
2071 // require that `T: 'static` to show that the return
2072 // type is well-formed.
2073 //
2074 // The only way to have something with this opaque type
2075 // is from the return type of the containing function,
2076 // which will ensure that the function's predicates
2077 // hold.
2078 return ty::GenericPredicates { parent: None, predicates: &[] };
2079 } else {
2080 // type-alias impl trait
2081 generics
2082 }
2083 }
2084
2085 _ => NO_GENERICS,
2086 }
2087 }
2088
2089 Node::ForeignItem(item) => match item.kind {
2090 ForeignItemKind::Static(..) => NO_GENERICS,
2091 ForeignItemKind::Fn(_, _, ref generics) => generics,
2092 ForeignItemKind::Type => NO_GENERICS,
2093 },
2094
2095 _ => NO_GENERICS,
2096 };
2097
2098 let generics = tcx.generics_of(def_id);
2099 let parent_count = generics.parent_count as u32;
2100 let has_own_self = generics.has_self && parent_count == 0;
2101
2102 // Below we'll consider the bounds on the type parameters (including `Self`)
2103 // and the explicit where-clauses, but to get the full set of predicates
2104 // on a trait we need to add in the supertrait bounds and bounds found on
2105 // associated types.
2106 if let Some(_trait_ref) = is_trait {
2107 predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
2108 }
2109
2110 // In default impls, we can assume that the self type implements
2111 // the trait. So in:
2112 //
2113 // default impl Foo for Bar { .. }
2114 //
2115 // we add a default where clause `Foo: Bar`. We do a similar thing for traits
2116 // (see below). Recall that a default impl is not itself an impl, but rather a
2117 // set of defaults that can be incorporated into another impl.
2118 if let Some(trait_ref) = is_default_impl_trait {
2119 predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
2120 }
2121
2122 // Collect the region predicates that were declared inline as
2123 // well. In the case of parameters declared on a fn or method, we
2124 // have to be careful to only iterate over early-bound regions.
2125 let mut index = parent_count + has_own_self as u32;
2126 for param in early_bound_lifetimes_from_generics(tcx, ast_generics) {
2127 let region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
2128 def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
2129 index,
2130 name: param.name.ident().name,
2131 }));
2132 index += 1;
2133
2134 match param.kind {
2135 GenericParamKind::Lifetime { .. } => {
2136 param.bounds.iter().for_each(|bound| match bound {
2137 hir::GenericBound::Outlives(lt) => {
2138 let bound = <dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None);
2139 let outlives = ty::Binder::dummy(ty::OutlivesPredicate(region, bound));
2140 predicates.insert((outlives.to_predicate(tcx), lt.span));
2141 }
2142 _ => bug!(),
2143 });
2144 }
2145 _ => bug!(),
2146 }
2147 }
2148
2149 // Collect the predicates that were written inline by the user on each
2150 // type parameter (e.g., `<T: Foo>`).
2151 for param in ast_generics.params {
2152 match param.kind {
2153 // We already dealt with early bound lifetimes above.
2154 GenericParamKind::Lifetime { .. } => (),
2155 GenericParamKind::Type { .. } => {
2156 let name = param.name.ident().name;
2157 let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
2158 index += 1;
2159
2160 let mut bounds = <dyn AstConv<'_>>::compute_bounds(&icx, param_ty, param.bounds);
2161 // Params are implicitly sized unless a `?Sized` bound is found
2162 <dyn AstConv<'_>>::add_implicitly_sized(
2163 &icx,
2164 &mut bounds,
2165 param.bounds,
2166 Some((param.hir_id, ast_generics.where_clause.predicates)),
2167 param.span,
2168 );
2169 predicates.extend(bounds.predicates(tcx, param_ty));
2170 }
2171 GenericParamKind::Const { .. } => {
2172 // Bounds on const parameters are currently not possible.
2173 debug_assert!(param.bounds.is_empty());
2174 index += 1;
2175 }
2176 }
2177 }
2178
2179 // Add in the bounds that appear in the where-clause.
2180 let where_clause = &ast_generics.where_clause;
2181 for predicate in where_clause.predicates {
2182 match predicate {
2183 hir::WherePredicate::BoundPredicate(bound_pred) => {
2184 let ty = icx.to_ty(bound_pred.bounded_ty);
2185 let bound_vars = icx.tcx.late_bound_vars(bound_pred.bounded_ty.hir_id);
2186
2187 // Keep the type around in a dummy predicate, in case of no bounds.
2188 // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
2189 // is still checked for WF.
2190 if bound_pred.bounds.is_empty() {
2191 if let ty::Param(_) = ty.kind() {
2192 // This is a `where T:`, which can be in the HIR from the
2193 // transformation that moves `?Sized` to `T`'s declaration.
2194 // We can skip the predicate because type parameters are
2195 // trivially WF, but also we *should*, to avoid exposing
2196 // users who never wrote `where Type:,` themselves, to
2197 // compiler/tooling bugs from not handling WF predicates.
2198 } else {
2199 let span = bound_pred.bounded_ty.span;
2200 let re_root_empty = tcx.lifetimes.re_root_empty;
2201 let predicate = ty::Binder::bind_with_vars(
2202 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
2203 ty,
2204 re_root_empty,
2205 )),
2206 bound_vars,
2207 );
2208 predicates.insert((predicate.to_predicate(tcx), span));
2209 }
2210 }
2211
2212 let mut bounds = Bounds::default();
2213 <dyn AstConv<'_>>::add_bounds(
2214 &icx,
2215 ty,
2216 bound_pred.bounds.iter(),
2217 &mut bounds,
2218 bound_vars,
2219 );
2220 predicates.extend(bounds.predicates(tcx, ty));
2221 }
2222
2223 hir::WherePredicate::RegionPredicate(region_pred) => {
2224 let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None);
2225 predicates.extend(region_pred.bounds.iter().map(|bound| {
2226 let (r2, span) = match bound {
2227 hir::GenericBound::Outlives(lt) => {
2228 (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
2229 }
2230 _ => bug!(),
2231 };
2232 let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
2233 ty::OutlivesPredicate(r1, r2),
2234 ))
2235 .to_predicate(icx.tcx);
2236
2237 (pred, span)
2238 }))
2239 }
2240
2241 hir::WherePredicate::EqPredicate(..) => {
2242 // FIXME(#20041)
2243 }
2244 }
2245 }
2246
2247 if tcx.features().generic_const_exprs {
2248 predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
2249 }
2250
2251 let mut predicates: Vec<_> = predicates.into_iter().collect();
2252
2253 // Subtle: before we store the predicates into the tcx, we
2254 // sort them so that predicates like `T: Foo<Item=U>` come
2255 // before uses of `U`. This avoids false ambiguity errors
2256 // in trait checking. See `setup_constraining_predicates`
2257 // for details.
2258 if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
2259 let self_ty = tcx.type_of(def_id);
2260 let trait_ref = tcx.impl_trait_ref(def_id);
2261 cgp::setup_constraining_predicates(
2262 tcx,
2263 &mut predicates,
2264 trait_ref,
2265 &mut cgp::parameters_for_impl(tcx, self_ty, trait_ref),
2266 );
2267 }
2268
2269 let result = ty::GenericPredicates {
2270 parent: generics.parent,
2271 predicates: tcx.arena.alloc_from_iter(predicates),
2272 };
2273 debug!("explicit_predicates_of(def_id={:?}) = {:?}", def_id, result);
2274 result
2275 }
2276
const_evaluatable_predicates_of<'tcx>( tcx: TyCtxt<'tcx>, def_id: LocalDefId, ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)>2277 fn const_evaluatable_predicates_of<'tcx>(
2278 tcx: TyCtxt<'tcx>,
2279 def_id: LocalDefId,
2280 ) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
2281 struct ConstCollector<'tcx> {
2282 tcx: TyCtxt<'tcx>,
2283 preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
2284 }
2285
2286 impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
2287 type Map = Map<'tcx>;
2288
2289 fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
2290 intravisit::NestedVisitorMap::None
2291 }
2292
2293 fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
2294 let def_id = self.tcx.hir().local_def_id(c.hir_id);
2295 let ct = ty::Const::from_anon_const(self.tcx, def_id);
2296 if let ty::ConstKind::Unevaluated(uv) = ct.val {
2297 assert_eq!(uv.promoted, None);
2298 let span = self.tcx.hir().span(c.hir_id);
2299 self.preds.insert((
2300 ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv.shrink()))
2301 .to_predicate(self.tcx),
2302 span,
2303 ));
2304 }
2305 }
2306
2307 fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
2308 // Do not look into const param defaults,
2309 // these get checked when they are actually instantiated.
2310 //
2311 // We do not want the following to error:
2312 //
2313 // struct Foo<const N: usize, const M: usize = { N + 1 }>;
2314 // struct Bar<const N: usize>(Foo<N, 3>);
2315 }
2316 }
2317
2318 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2319 let node = tcx.hir().get(hir_id);
2320
2321 let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
2322 if let hir::Node::Item(item) = node {
2323 if let hir::ItemKind::Impl(ref impl_) = item.kind {
2324 if let Some(of_trait) = &impl_.of_trait {
2325 debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
2326 collector.visit_trait_ref(of_trait);
2327 }
2328
2329 debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
2330 collector.visit_ty(impl_.self_ty);
2331 }
2332 }
2333
2334 if let Some(generics) = node.generics() {
2335 debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
2336 collector.visit_generics(generics);
2337 }
2338
2339 if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
2340 debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
2341 collector.visit_fn_decl(fn_sig.decl);
2342 }
2343 debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
2344
2345 collector.preds
2346 }
2347
trait_explicit_predicates_and_bounds( tcx: TyCtxt<'_>, def_id: LocalDefId, ) -> ty::GenericPredicates<'_>2348 fn trait_explicit_predicates_and_bounds(
2349 tcx: TyCtxt<'_>,
2350 def_id: LocalDefId,
2351 ) -> ty::GenericPredicates<'_> {
2352 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
2353 gather_explicit_predicates_of(tcx, def_id.to_def_id())
2354 }
2355
explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_>2356 fn explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
2357 let def_kind = tcx.def_kind(def_id);
2358 if let DefKind::Trait = def_kind {
2359 // Remove bounds on associated types from the predicates, they will be
2360 // returned by `explicit_item_bounds`.
2361 let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
2362 let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
2363
2364 let is_assoc_item_ty = |ty: Ty<'_>| {
2365 // For a predicate from a where clause to become a bound on an
2366 // associated type:
2367 // * It must use the identity substs of the item.
2368 // * Since any generic parameters on the item are not in scope,
2369 // this means that the item is not a GAT, and its identity
2370 // substs are the same as the trait's.
2371 // * It must be an associated type for this trait (*not* a
2372 // supertrait).
2373 if let ty::Projection(projection) = ty.kind() {
2374 projection.substs == trait_identity_substs
2375 && tcx.associated_item(projection.item_def_id).container.id() == def_id
2376 } else {
2377 false
2378 }
2379 };
2380
2381 let predicates: Vec<_> = predicates_and_bounds
2382 .predicates
2383 .iter()
2384 .copied()
2385 .filter(|(pred, _)| match pred.kind().skip_binder() {
2386 ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()),
2387 ty::PredicateKind::Projection(proj) => {
2388 !is_assoc_item_ty(proj.projection_ty.self_ty())
2389 }
2390 ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
2391 _ => true,
2392 })
2393 .collect();
2394 if predicates.len() == predicates_and_bounds.predicates.len() {
2395 predicates_and_bounds
2396 } else {
2397 ty::GenericPredicates {
2398 parent: predicates_and_bounds.parent,
2399 predicates: tcx.arena.alloc_slice(&predicates),
2400 }
2401 }
2402 } else {
2403 if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
2404 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2405 if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() {
2406 // In `generics_of` we set the generics' parent to be our parent's parent which means that
2407 // we lose out on the predicates of our actual parent if we dont return those predicates here.
2408 // (See comment in `generics_of` for more information on why the parent shenanigans is necessary)
2409 //
2410 // struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait;
2411 // ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling
2412 // ^^^ explicit_predicates_of on
2413 // parent item we dont have set as the
2414 // parent of generics returned by `generics_of`
2415 //
2416 // In the above code we want the anon const to have predicates in its param env for `T: Trait`
2417 let item_id = tcx.hir().get_parent_item(hir_id);
2418 let item_def_id = tcx.hir().local_def_id(item_id).to_def_id();
2419 // In the above code example we would be calling `explicit_predicates_of(Foo)` here
2420 return tcx.explicit_predicates_of(item_def_id);
2421 }
2422 }
2423 gather_explicit_predicates_of(tcx, def_id)
2424 }
2425 }
2426
2427 /// Converts a specific `GenericBound` from the AST into a set of
2428 /// predicates that apply to the self type. A vector is returned
2429 /// because this can be anywhere from zero predicates (`T: ?Sized` adds no
2430 /// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
2431 /// and `<T as Bar>::X == i32`).
predicates_from_bound<'tcx>( astconv: &dyn AstConv<'tcx>, param_ty: Ty<'tcx>, bound: &'tcx hir::GenericBound<'tcx>, ) -> Vec<(ty::Predicate<'tcx>, Span)>2432 fn predicates_from_bound<'tcx>(
2433 astconv: &dyn AstConv<'tcx>,
2434 param_ty: Ty<'tcx>,
2435 bound: &'tcx hir::GenericBound<'tcx>,
2436 ) -> Vec<(ty::Predicate<'tcx>, Span)> {
2437 let mut bounds = Bounds::default();
2438 astconv.add_bounds(
2439 param_ty,
2440 std::array::IntoIter::new([bound]),
2441 &mut bounds,
2442 ty::List::empty(),
2443 );
2444 bounds.predicates(astconv.tcx(), param_ty)
2445 }
2446
compute_sig_of_foreign_fn_decl<'tcx>( tcx: TyCtxt<'tcx>, def_id: DefId, decl: &'tcx hir::FnDecl<'tcx>, abi: abi::Abi, ident: Ident, ) -> ty::PolyFnSig<'tcx>2447 fn compute_sig_of_foreign_fn_decl<'tcx>(
2448 tcx: TyCtxt<'tcx>,
2449 def_id: DefId,
2450 decl: &'tcx hir::FnDecl<'tcx>,
2451 abi: abi::Abi,
2452 ident: Ident,
2453 ) -> ty::PolyFnSig<'tcx> {
2454 let unsafety = if abi == abi::Abi::RustIntrinsic {
2455 intrinsic_operation_unsafety(tcx.item_name(def_id))
2456 } else {
2457 hir::Unsafety::Unsafe
2458 };
2459 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
2460 let fty = <dyn AstConv<'_>>::ty_of_fn(
2461 &ItemCtxt::new(tcx, def_id),
2462 hir_id,
2463 unsafety,
2464 abi,
2465 decl,
2466 &hir::Generics::empty(),
2467 Some(ident.span),
2468 None,
2469 );
2470
2471 // Feature gate SIMD types in FFI, since I am not sure that the
2472 // ABIs are handled at all correctly. -huonw
2473 if abi != abi::Abi::RustIntrinsic
2474 && abi != abi::Abi::PlatformIntrinsic
2475 && !tcx.features().simd_ffi
2476 {
2477 let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
2478 if ty.is_simd() {
2479 let snip = tcx
2480 .sess
2481 .source_map()
2482 .span_to_snippet(ast_ty.span)
2483 .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
2484 tcx.sess
2485 .struct_span_err(
2486 ast_ty.span,
2487 &format!(
2488 "use of SIMD type{} in FFI is highly experimental and \
2489 may result in invalid code",
2490 snip
2491 ),
2492 )
2493 .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
2494 .emit();
2495 }
2496 };
2497 for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) {
2498 check(input, ty)
2499 }
2500 if let hir::FnRetTy::Return(ref ty) = decl.output {
2501 check(ty, fty.output().skip_binder())
2502 }
2503 }
2504
2505 fty
2506 }
2507
is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool2508 fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
2509 match tcx.hir().get_if_local(def_id) {
2510 Some(Node::ForeignItem(..)) => true,
2511 Some(_) => false,
2512 _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
2513 }
2514 }
2515
static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability>2516 fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability> {
2517 match tcx.hir().get_if_local(def_id) {
2518 Some(
2519 Node::Item(&hir::Item { kind: hir::ItemKind::Static(_, mutbl, _), .. })
2520 | Node::ForeignItem(&hir::ForeignItem {
2521 kind: hir::ForeignItemKind::Static(_, mutbl),
2522 ..
2523 }),
2524 ) => Some(mutbl),
2525 Some(_) => None,
2526 _ => bug!("static_mutability applied to non-local def-id {:?}", def_id),
2527 }
2528 }
2529
generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind>2530 fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
2531 match tcx.hir().get_if_local(def_id) {
2532 Some(Node::Expr(&rustc_hir::Expr {
2533 kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
2534 ..
2535 })) => tcx.hir().body(body_id).generator_kind(),
2536 Some(_) => None,
2537 _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
2538 }
2539 }
2540
from_target_feature( tcx: TyCtxt<'_>, id: DefId, attr: &ast::Attribute, supported_target_features: &FxHashMap<String, Option<Symbol>>, target_features: &mut Vec<Symbol>, )2541 fn from_target_feature(
2542 tcx: TyCtxt<'_>,
2543 id: DefId,
2544 attr: &ast::Attribute,
2545 supported_target_features: &FxHashMap<String, Option<Symbol>>,
2546 target_features: &mut Vec<Symbol>,
2547 ) {
2548 let list = match attr.meta_item_list() {
2549 Some(list) => list,
2550 None => return,
2551 };
2552 let bad_item = |span| {
2553 let msg = "malformed `target_feature` attribute input";
2554 let code = "enable = \"..\"".to_owned();
2555 tcx.sess
2556 .struct_span_err(span, msg)
2557 .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
2558 .emit();
2559 };
2560 let rust_features = tcx.features();
2561 for item in list {
2562 // Only `enable = ...` is accepted in the meta-item list.
2563 if !item.has_name(sym::enable) {
2564 bad_item(item.span());
2565 continue;
2566 }
2567
2568 // Must be of the form `enable = "..."` (a string).
2569 let value = match item.value_str() {
2570 Some(value) => value,
2571 None => {
2572 bad_item(item.span());
2573 continue;
2574 }
2575 };
2576
2577 // We allow comma separation to enable multiple features.
2578 target_features.extend(value.as_str().split(',').filter_map(|feature| {
2579 let feature_gate = match supported_target_features.get(feature) {
2580 Some(g) => g,
2581 None => {
2582 let msg =
2583 format!("the feature named `{}` is not valid for this target", feature);
2584 let mut err = tcx.sess.struct_span_err(item.span(), &msg);
2585 err.span_label(
2586 item.span(),
2587 format!("`{}` is not valid for this target", feature),
2588 );
2589 if let Some(stripped) = feature.strip_prefix('+') {
2590 let valid = supported_target_features.contains_key(stripped);
2591 if valid {
2592 err.help("consider removing the leading `+` in the feature name");
2593 }
2594 }
2595 err.emit();
2596 return None;
2597 }
2598 };
2599
2600 // Only allow features whose feature gates have been enabled.
2601 let allowed = match feature_gate.as_ref().copied() {
2602 Some(sym::arm_target_feature) => rust_features.arm_target_feature,
2603 Some(sym::aarch64_target_feature) => rust_features.aarch64_target_feature,
2604 Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
2605 Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
2606 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
2607 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
2608 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
2609 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
2610 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
2611 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
2612 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
2613 Some(sym::adx_target_feature) => rust_features.adx_target_feature,
2614 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
2615 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
2616 Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
2617 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
2618 Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
2619 Some(name) => bug!("unknown target feature gate {}", name),
2620 None => true,
2621 };
2622 if !allowed && id.is_local() {
2623 feature_err(
2624 &tcx.sess.parse_sess,
2625 feature_gate.unwrap(),
2626 item.span(),
2627 &format!("the target feature `{}` is currently unstable", feature),
2628 )
2629 .emit();
2630 }
2631 Some(Symbol::intern(feature))
2632 }));
2633 }
2634 }
2635
linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage2636 fn linkage_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Linkage {
2637 use rustc_middle::mir::mono::Linkage::*;
2638
2639 // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
2640 // applicable to variable declarations and may not really make sense for
2641 // Rust code in the first place but allow them anyway and trust that the
2642 // user knows what s/he's doing. Who knows, unanticipated use cases may pop
2643 // up in the future.
2644 //
2645 // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
2646 // and don't have to be, LLVM treats them as no-ops.
2647 match name {
2648 "appending" => Appending,
2649 "available_externally" => AvailableExternally,
2650 "common" => Common,
2651 "extern_weak" => ExternalWeak,
2652 "external" => External,
2653 "internal" => Internal,
2654 "linkonce" => LinkOnceAny,
2655 "linkonce_odr" => LinkOnceODR,
2656 "private" => Private,
2657 "weak" => WeakAny,
2658 "weak_odr" => WeakODR,
2659 _ => {
2660 let span = tcx.hir().span_if_local(def_id);
2661 if let Some(span) = span {
2662 tcx.sess.span_fatal(span, "invalid linkage specified")
2663 } else {
2664 tcx.sess.fatal(&format!("invalid linkage specified: {}", name))
2665 }
2666 }
2667 }
2668 }
2669
codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs2670 fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
2671 let attrs = tcx.get_attrs(id);
2672
2673 let mut codegen_fn_attrs = CodegenFnAttrs::new();
2674 if tcx.should_inherit_track_caller(id) {
2675 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2676 }
2677
2678 // With -Z panic-in-drop=abort, drop_in_place never unwinds.
2679 if tcx.sess.opts.debugging_opts.panic_in_drop == PanicStrategy::Abort {
2680 if Some(id) == tcx.lang_items().drop_in_place_fn() {
2681 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2682 }
2683 }
2684
2685 let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
2686
2687 let mut inline_span = None;
2688 let mut link_ordinal_span = None;
2689 let mut no_sanitize_span = None;
2690 for attr in attrs.iter() {
2691 if attr.has_name(sym::cold) {
2692 codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
2693 } else if attr.has_name(sym::rustc_allocator) {
2694 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
2695 } else if attr.has_name(sym::ffi_returns_twice) {
2696 if tcx.is_foreign_item(id) {
2697 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
2698 } else {
2699 // `#[ffi_returns_twice]` is only allowed `extern fn`s.
2700 struct_span_err!(
2701 tcx.sess,
2702 attr.span,
2703 E0724,
2704 "`#[ffi_returns_twice]` may only be used on foreign functions"
2705 )
2706 .emit();
2707 }
2708 } else if attr.has_name(sym::ffi_pure) {
2709 if tcx.is_foreign_item(id) {
2710 if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
2711 // `#[ffi_const]` functions cannot be `#[ffi_pure]`
2712 struct_span_err!(
2713 tcx.sess,
2714 attr.span,
2715 E0757,
2716 "`#[ffi_const]` function cannot be `#[ffi_pure]`"
2717 )
2718 .emit();
2719 } else {
2720 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
2721 }
2722 } else {
2723 // `#[ffi_pure]` is only allowed on foreign functions
2724 struct_span_err!(
2725 tcx.sess,
2726 attr.span,
2727 E0755,
2728 "`#[ffi_pure]` may only be used on foreign functions"
2729 )
2730 .emit();
2731 }
2732 } else if attr.has_name(sym::ffi_const) {
2733 if tcx.is_foreign_item(id) {
2734 codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
2735 } else {
2736 // `#[ffi_const]` is only allowed on foreign functions
2737 struct_span_err!(
2738 tcx.sess,
2739 attr.span,
2740 E0756,
2741 "`#[ffi_const]` may only be used on foreign functions"
2742 )
2743 .emit();
2744 }
2745 } else if attr.has_name(sym::rustc_allocator_nounwind) {
2746 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
2747 } else if attr.has_name(sym::naked) {
2748 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
2749 } else if attr.has_name(sym::no_mangle) {
2750 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
2751 } else if attr.has_name(sym::no_coverage) {
2752 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
2753 } else if attr.has_name(sym::rustc_std_internal_symbol) {
2754 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
2755 } else if attr.has_name(sym::used) {
2756 codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
2757 } else if attr.has_name(sym::cmse_nonsecure_entry) {
2758 if !matches!(tcx.fn_sig(id).abi(), abi::Abi::C { .. }) {
2759 struct_span_err!(
2760 tcx.sess,
2761 attr.span,
2762 E0776,
2763 "`#[cmse_nonsecure_entry]` requires C ABI"
2764 )
2765 .emit();
2766 }
2767 if !tcx.sess.target.llvm_target.contains("thumbv8m") {
2768 struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
2769 .emit();
2770 }
2771 codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
2772 } else if attr.has_name(sym::thread_local) {
2773 codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
2774 } else if attr.has_name(sym::track_caller) {
2775 if !tcx.is_closure(id) && tcx.fn_sig(id).abi() != abi::Abi::Rust {
2776 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
2777 .emit();
2778 }
2779 if tcx.is_closure(id) && !tcx.features().closure_track_caller {
2780 feature_err(
2781 &tcx.sess.parse_sess,
2782 sym::closure_track_caller,
2783 attr.span,
2784 "`#[track_caller]` on closures is currently unstable",
2785 )
2786 .emit();
2787 }
2788 codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
2789 } else if attr.has_name(sym::export_name) {
2790 if let Some(s) = attr.value_str() {
2791 if s.as_str().contains('\0') {
2792 // `#[export_name = ...]` will be converted to a null-terminated string,
2793 // so it may not contain any null characters.
2794 struct_span_err!(
2795 tcx.sess,
2796 attr.span,
2797 E0648,
2798 "`export_name` may not contain null characters"
2799 )
2800 .emit();
2801 }
2802 codegen_fn_attrs.export_name = Some(s);
2803 }
2804 } else if attr.has_name(sym::target_feature) {
2805 if !tcx.is_closure(id) && tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
2806 if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
2807 // The `#[target_feature]` attribute is allowed on
2808 // WebAssembly targets on all functions, including safe
2809 // ones. Other targets require that `#[target_feature]` is
2810 // only applied to unsafe funtions (pending the
2811 // `target_feature_11` feature) because on most targets
2812 // execution of instructions that are not supported is
2813 // considered undefined behavior. For WebAssembly which is a
2814 // 100% safe target at execution time it's not possible to
2815 // execute undefined instructions, and even if a future
2816 // feature was added in some form for this it would be a
2817 // deterministic trap. There is no undefined behavior when
2818 // executing WebAssembly so `#[target_feature]` is allowed
2819 // on safe functions (but again, only for WebAssembly)
2820 //
2821 // Note that this is also allowed if `actually_rustdoc` so
2822 // if a target is documenting some wasm-specific code then
2823 // it's not spuriously denied.
2824 } else if !tcx.features().target_feature_11 {
2825 let mut err = feature_err(
2826 &tcx.sess.parse_sess,
2827 sym::target_feature_11,
2828 attr.span,
2829 "`#[target_feature(..)]` can only be applied to `unsafe` functions",
2830 );
2831 err.span_label(tcx.def_span(id), "not an `unsafe` function");
2832 err.emit();
2833 } else if let Some(local_id) = id.as_local() {
2834 check_target_feature_trait_unsafe(tcx, local_id, attr.span);
2835 }
2836 }
2837 from_target_feature(
2838 tcx,
2839 id,
2840 attr,
2841 supported_target_features,
2842 &mut codegen_fn_attrs.target_features,
2843 );
2844 } else if attr.has_name(sym::linkage) {
2845 if let Some(val) = attr.value_str() {
2846 codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, id, &val.as_str()));
2847 }
2848 } else if attr.has_name(sym::link_section) {
2849 if let Some(val) = attr.value_str() {
2850 if val.as_str().bytes().any(|b| b == 0) {
2851 let msg = format!(
2852 "illegal null byte in link_section \
2853 value: `{}`",
2854 &val
2855 );
2856 tcx.sess.span_err(attr.span, &msg);
2857 } else {
2858 codegen_fn_attrs.link_section = Some(val);
2859 }
2860 }
2861 } else if attr.has_name(sym::link_name) {
2862 codegen_fn_attrs.link_name = attr.value_str();
2863 } else if attr.has_name(sym::link_ordinal) {
2864 link_ordinal_span = Some(attr.span);
2865 if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
2866 codegen_fn_attrs.link_ordinal = ordinal;
2867 }
2868 } else if attr.has_name(sym::no_sanitize) {
2869 no_sanitize_span = Some(attr.span);
2870 if let Some(list) = attr.meta_item_list() {
2871 for item in list.iter() {
2872 if item.has_name(sym::address) {
2873 codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
2874 } else if item.has_name(sym::cfi) {
2875 codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
2876 } else if item.has_name(sym::memory) {
2877 codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
2878 } else if item.has_name(sym::thread) {
2879 codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
2880 } else if item.has_name(sym::hwaddress) {
2881 codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
2882 } else {
2883 tcx.sess
2884 .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
2885 .note("expected one of: `address`, `hwaddress`, `memory` or `thread`")
2886 .emit();
2887 }
2888 }
2889 }
2890 } else if attr.has_name(sym::instruction_set) {
2891 codegen_fn_attrs.instruction_set = match attr.meta().map(|i| i.kind) {
2892 Some(MetaItemKind::List(ref items)) => match items.as_slice() {
2893 [NestedMetaItem::MetaItem(set)] => {
2894 let segments =
2895 set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
2896 match segments.as_slice() {
2897 [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
2898 if !tcx.sess.target.has_thumb_interworking {
2899 struct_span_err!(
2900 tcx.sess.diagnostic(),
2901 attr.span,
2902 E0779,
2903 "target does not support `#[instruction_set]`"
2904 )
2905 .emit();
2906 None
2907 } else if segments[1] == sym::a32 {
2908 Some(InstructionSetAttr::ArmA32)
2909 } else if segments[1] == sym::t32 {
2910 Some(InstructionSetAttr::ArmT32)
2911 } else {
2912 unreachable!()
2913 }
2914 }
2915 _ => {
2916 struct_span_err!(
2917 tcx.sess.diagnostic(),
2918 attr.span,
2919 E0779,
2920 "invalid instruction set specified",
2921 )
2922 .emit();
2923 None
2924 }
2925 }
2926 }
2927 [] => {
2928 struct_span_err!(
2929 tcx.sess.diagnostic(),
2930 attr.span,
2931 E0778,
2932 "`#[instruction_set]` requires an argument"
2933 )
2934 .emit();
2935 None
2936 }
2937 _ => {
2938 struct_span_err!(
2939 tcx.sess.diagnostic(),
2940 attr.span,
2941 E0779,
2942 "cannot specify more than one instruction set"
2943 )
2944 .emit();
2945 None
2946 }
2947 },
2948 _ => {
2949 struct_span_err!(
2950 tcx.sess.diagnostic(),
2951 attr.span,
2952 E0778,
2953 "must specify an instruction set"
2954 )
2955 .emit();
2956 None
2957 }
2958 };
2959 } else if attr.has_name(sym::repr) {
2960 codegen_fn_attrs.alignment = match attr.meta_item_list() {
2961 Some(items) => match items.as_slice() {
2962 [item] => match item.name_value_literal() {
2963 Some((sym::align, literal)) => {
2964 let alignment = rustc_attr::parse_alignment(&literal.kind);
2965
2966 match alignment {
2967 Ok(align) => Some(align),
2968 Err(msg) => {
2969 struct_span_err!(
2970 tcx.sess.diagnostic(),
2971 attr.span,
2972 E0589,
2973 "invalid `repr(align)` attribute: {}",
2974 msg
2975 )
2976 .emit();
2977
2978 None
2979 }
2980 }
2981 }
2982 _ => None,
2983 },
2984 [] => None,
2985 _ => None,
2986 },
2987 None => None,
2988 };
2989 }
2990 }
2991
2992 codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
2993 if !attr.has_name(sym::inline) {
2994 return ia;
2995 }
2996 match attr.meta().map(|i| i.kind) {
2997 Some(MetaItemKind::Word) => InlineAttr::Hint,
2998 Some(MetaItemKind::List(ref items)) => {
2999 inline_span = Some(attr.span);
3000 if items.len() != 1 {
3001 struct_span_err!(
3002 tcx.sess.diagnostic(),
3003 attr.span,
3004 E0534,
3005 "expected one argument"
3006 )
3007 .emit();
3008 InlineAttr::None
3009 } else if list_contains_name(&items[..], sym::always) {
3010 InlineAttr::Always
3011 } else if list_contains_name(&items[..], sym::never) {
3012 InlineAttr::Never
3013 } else {
3014 struct_span_err!(
3015 tcx.sess.diagnostic(),
3016 items[0].span(),
3017 E0535,
3018 "invalid argument"
3019 )
3020 .emit();
3021
3022 InlineAttr::None
3023 }
3024 }
3025 Some(MetaItemKind::NameValue(_)) => ia,
3026 None => ia,
3027 }
3028 });
3029
3030 codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
3031 if !attr.has_name(sym::optimize) {
3032 return ia;
3033 }
3034 let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
3035 match attr.meta().map(|i| i.kind) {
3036 Some(MetaItemKind::Word) => {
3037 err(attr.span, "expected one argument");
3038 ia
3039 }
3040 Some(MetaItemKind::List(ref items)) => {
3041 inline_span = Some(attr.span);
3042 if items.len() != 1 {
3043 err(attr.span, "expected one argument");
3044 OptimizeAttr::None
3045 } else if list_contains_name(&items[..], sym::size) {
3046 OptimizeAttr::Size
3047 } else if list_contains_name(&items[..], sym::speed) {
3048 OptimizeAttr::Speed
3049 } else {
3050 err(items[0].span(), "invalid argument");
3051 OptimizeAttr::None
3052 }
3053 }
3054 Some(MetaItemKind::NameValue(_)) => ia,
3055 None => ia,
3056 }
3057 });
3058
3059 // #73631: closures inherit `#[target_feature]` annotations
3060 if tcx.features().target_feature_11 && tcx.is_closure(id) {
3061 let owner_id = tcx.parent(id).expect("closure should have a parent");
3062 codegen_fn_attrs
3063 .target_features
3064 .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied())
3065 }
3066
3067 // If a function uses #[target_feature] it can't be inlined into general
3068 // purpose functions as they wouldn't have the right target features
3069 // enabled. For that reason we also forbid #[inline(always)] as it can't be
3070 // respected.
3071 if !codegen_fn_attrs.target_features.is_empty() {
3072 if codegen_fn_attrs.inline == InlineAttr::Always {
3073 if let Some(span) = inline_span {
3074 tcx.sess.span_err(
3075 span,
3076 "cannot use `#[inline(always)]` with \
3077 `#[target_feature]`",
3078 );
3079 }
3080 }
3081 }
3082
3083 if !codegen_fn_attrs.no_sanitize.is_empty() {
3084 if codegen_fn_attrs.inline == InlineAttr::Always {
3085 if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
3086 let hir_id = tcx.hir().local_def_id_to_hir_id(id.expect_local());
3087 tcx.struct_span_lint_hir(
3088 lint::builtin::INLINE_NO_SANITIZE,
3089 hir_id,
3090 no_sanitize_span,
3091 |lint| {
3092 lint.build("`no_sanitize` will have no effect after inlining")
3093 .span_note(inline_span, "inlining requested here")
3094 .emit();
3095 },
3096 )
3097 }
3098 }
3099 }
3100
3101 // Weak lang items have the same semantics as "std internal" symbols in the
3102 // sense that they're preserved through all our LTO passes and only
3103 // strippable by the linker.
3104 //
3105 // Additionally weak lang items have predetermined symbol names.
3106 if tcx.is_weak_lang_item(id) {
3107 codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
3108 }
3109 let check_name = |attr: &Attribute, sym| attr.has_name(sym);
3110 if let Some(name) = weak_lang_items::link_name(check_name, attrs) {
3111 codegen_fn_attrs.export_name = Some(name);
3112 codegen_fn_attrs.link_name = Some(name);
3113 }
3114 check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
3115
3116 // Internal symbols to the standard library all have no_mangle semantics in
3117 // that they have defined symbol names present in the function name. This
3118 // also applies to weak symbols where they all have known symbol names.
3119 if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
3120 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
3121 }
3122
3123 // Any linkage to LLVM intrinsics for now forcibly marks them all as never
3124 // unwinds since LLVM sometimes can't handle codegen which `invoke`s
3125 // intrinsic functions.
3126 if let Some(name) = &codegen_fn_attrs.link_name {
3127 if name.as_str().starts_with("llvm.") {
3128 codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
3129 }
3130 }
3131
3132 codegen_fn_attrs
3133 }
3134
3135 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
3136 /// applied to the method prototype.
should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool3137 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
3138 if let Some(impl_item) = tcx.opt_associated_item(def_id) {
3139 if let ty::AssocItemContainer::ImplContainer(impl_def_id) = impl_item.container {
3140 if let Some(trait_def_id) = tcx.trait_id_of_impl(impl_def_id) {
3141 if let Some(trait_item) = tcx
3142 .associated_items(trait_def_id)
3143 .filter_by_name_unhygienic(impl_item.ident.name)
3144 .find(move |trait_item| {
3145 trait_item.kind == ty::AssocKind::Fn
3146 && tcx.hygienic_eq(impl_item.ident, trait_item.ident, trait_def_id)
3147 })
3148 {
3149 return tcx
3150 .codegen_fn_attrs(trait_item.def_id)
3151 .flags
3152 .intersects(CodegenFnAttrFlags::TRACK_CALLER);
3153 }
3154 }
3155 }
3156 }
3157
3158 false
3159 }
3160
check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16>3161 fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
3162 use rustc_ast::{Lit, LitIntType, LitKind};
3163 let meta_item_list = attr.meta_item_list();
3164 let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
3165 let sole_meta_list = match meta_item_list {
3166 Some([item]) => item.literal(),
3167 Some(_) => {
3168 tcx.sess
3169 .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
3170 .note("the attribute requires exactly one argument")
3171 .emit();
3172 return None;
3173 }
3174 _ => None,
3175 };
3176 if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
3177 // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
3178 // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
3179 // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
3180 // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
3181 //
3182 // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
3183 // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
3184 // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
3185 // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
3186 // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
3187 // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
3188 // about LINK.EXE failing.)
3189 if *ordinal <= u16::MAX as u128 {
3190 Some(*ordinal as u16)
3191 } else {
3192 let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
3193 tcx.sess
3194 .struct_span_err(attr.span, &msg)
3195 .note("the value may not exceed `u16::MAX`")
3196 .emit();
3197 None
3198 }
3199 } else {
3200 tcx.sess
3201 .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
3202 .note("an unsuffixed integer value, e.g., `1`, is expected")
3203 .emit();
3204 None
3205 }
3206 }
3207
check_link_name_xor_ordinal( tcx: TyCtxt<'_>, codegen_fn_attrs: &CodegenFnAttrs, inline_span: Option<Span>, )3208 fn check_link_name_xor_ordinal(
3209 tcx: TyCtxt<'_>,
3210 codegen_fn_attrs: &CodegenFnAttrs,
3211 inline_span: Option<Span>,
3212 ) {
3213 if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
3214 return;
3215 }
3216 let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
3217 if let Some(span) = inline_span {
3218 tcx.sess.span_err(span, msg);
3219 } else {
3220 tcx.sess.err(msg);
3221 }
3222 }
3223
3224 /// Checks the function annotated with `#[target_feature]` is not a safe
3225 /// trait method implementation, reporting an error if it is.
check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span)3226 fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
3227 let hir_id = tcx.hir().local_def_id_to_hir_id(id);
3228 let node = tcx.hir().get(hir_id);
3229 if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
3230 let parent_id = tcx.hir().get_parent_item(hir_id);
3231 let parent_item = tcx.hir().expect_item(parent_id);
3232 if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
3233 tcx.sess
3234 .struct_span_err(
3235 attr_span,
3236 "`#[target_feature(..)]` cannot be applied to safe trait method",
3237 )
3238 .span_label(attr_span, "cannot be applied to safe trait method")
3239 .span_label(tcx.def_span(id), "not an `unsafe` function")
3240 .emit();
3241 }
3242 }
3243 }
3244