1 //! Util methods for [`rustc_middle::ty`]
3 #![allow(clippy::module_name_repetitions)]
5 use core::ops::ControlFlow;
6 use rustc_ast::ast::Mutability;
7 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
9 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
10 use rustc_hir::def_id::DefId;
11 use rustc_hir::{Expr, FnDecl, LangItem, TyKind, Unsafety};
12 use rustc_infer::infer::TyCtxtInferExt;
13 use rustc_lint::LateContext;
14 use rustc_middle::mir::interpret::{ConstValue, Scalar};
15 use rustc_middle::ty::{
16 self, AdtDef, Binder, BoundRegion, DefIdTree, FnSig, IntTy, ParamEnv, Predicate, PredicateKind, ProjectionTy,
17 Region, RegionKind, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor, UintTy, VariantDef, VariantDiscr,
19 use rustc_middle::ty::{GenericArg, GenericArgKind};
20 use rustc_span::symbol::Ident;
21 use rustc_span::{sym, Span, Symbol};
22 use rustc_target::abi::{Size, VariantIdx};
23 use rustc_trait_selection::infer::InferCtxtExt;
24 use rustc_trait_selection::traits::query::normalize::AtExt;
27 use crate::{match_def_path, path_res, paths};
29 // Checks if the given type implements copy.
30 pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
31 ty.is_copy_modulo_regions(cx.tcx, cx.param_env)
34 /// This checks whether a given type is known to implement Debug.
35 pub fn has_debug_impl<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
37 .get_diagnostic_item(sym::Debug)
38 .map_or(false, |debug| implements_trait(cx, ty, debug, &[]))
41 /// Checks whether a type can be partially moved.
42 pub fn can_partially_move_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
43 if has_drop(cx, ty) || is_copy(cx, ty) {
47 ty::Param(_) => false,
48 ty::Adt(def, subs) => def.all_fields().any(|f| !is_copy(cx, f.ty(cx.tcx, subs))),
53 /// Walks into `ty` and returns `true` if any inner type is an instance of the given adt
55 pub fn contains_adt_constructor<'tcx>(ty: Ty<'tcx>, adt: AdtDef<'tcx>) -> bool {
56 ty.walk().any(|inner| match inner.unpack() {
57 GenericArgKind::Type(inner_ty) => inner_ty.ty_adt_def() == Some(adt),
58 GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => false,
62 /// Resolves `<T as Iterator>::Item` for `T`
63 /// Do not invoke without first verifying that the type implements `Iterator`
64 pub fn get_iterator_item_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'tcx>> {
66 .get_diagnostic_item(sym::Iterator)
67 .and_then(|iter_did| get_associated_type(cx, ty, iter_did, "Item"))
70 /// Returns the associated type `name` for `ty` as an implementation of `trait_id`.
71 /// Do not invoke without first verifying that the type implements the trait.
72 pub fn get_associated_type<'tcx>(
73 cx: &LateContext<'tcx>,
77 ) -> Option<Ty<'tcx>> {
79 .associated_items(trait_id)
80 .find_by_name_and_kind(cx.tcx, Ident::from_str(name), ty::AssocKind::Type, trait_id)
82 let proj = cx.tcx.mk_projection(assoc.def_id, cx.tcx.mk_substs_trait(ty, &[]));
83 cx.tcx.try_normalize_erasing_regions(cx.param_env, proj).ok()
87 /// Get the diagnostic name of a type, e.g. `sym::HashMap`. To check if a type
88 /// implements a trait marked with a diagnostic item use [`implements_trait`].
90 /// For a further exploitation what diagnostic items are see [diagnostic items] in
93 /// [Diagnostic Items]: https://rustc-dev-guide.rust-lang.org/diagnostics/diagnostic-items.html
94 pub fn get_type_diagnostic_name(cx: &LateContext<'_>, ty: Ty<'_>) -> Option<Symbol> {
96 ty::Adt(adt, _) => cx.tcx.get_diagnostic_name(adt.did()),
101 /// Returns true if ty has `iter` or `iter_mut` methods
102 pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<Symbol> {
103 // FIXME: instead of this hard-coded list, we should check if `<adt>::iter`
104 // exists and has the desired signature. Unfortunately FnCtxt is not exported
105 // so we can't use its `lookup_method` method.
106 let into_iter_collections: &[Symbol] = &[
122 let ty_to_check = match probably_ref_ty.kind() {
123 ty::Ref(_, ty_to_check, _) => *ty_to_check,
124 _ => probably_ref_ty,
127 let def_id = match ty_to_check.kind() {
128 ty::Array(..) => return Some(sym::array),
129 ty::Slice(..) => return Some(sym::slice),
130 ty::Adt(adt, _) => adt.did(),
134 for &name in into_iter_collections {
135 if cx.tcx.is_diagnostic_item(name, def_id) {
136 return Some(cx.tcx.item_name(def_id));
142 /// Checks whether a type implements a trait.
143 /// The function returns false in case the type contains an inference variable.
146 /// * [`get_trait_def_id`](super::get_trait_def_id) to get a trait [`DefId`].
147 /// * [Common tools for writing lints] for an example how to use this function and other options.
149 /// [Common tools for writing lints]: https://github.com/rust-lang/rust-clippy/blob/master/book/src/development/common_tools_writing_lints.md#checking-if-a-type-implements-a-specific-trait
150 pub fn implements_trait<'tcx>(
151 cx: &LateContext<'tcx>,
154 ty_params: &[GenericArg<'tcx>],
156 implements_trait_with_env(cx.tcx, cx.param_env, ty, trait_id, ty_params)
159 /// Same as `implements_trait` but allows using a `ParamEnv` different from the lint context.
160 pub fn implements_trait_with_env<'tcx>(
162 param_env: ParamEnv<'tcx>,
165 ty_params: &[GenericArg<'tcx>],
167 // Clippy shouldn't have infer types
168 assert!(!ty.needs_infer());
170 let ty = tcx.erase_regions(ty);
171 if ty.has_escaping_bound_vars() {
174 let ty_params = tcx.mk_substs(ty_params.iter());
175 let infcx = tcx.infer_ctxt().build();
177 .type_implements_trait(trait_id, ty, ty_params, param_env)
178 .must_apply_modulo_regions()
181 /// Checks whether this type implements `Drop`.
182 pub fn has_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
183 match ty.ty_adt_def() {
184 Some(def) => def.has_dtor(cx.tcx),
189 // Returns whether the type has #[must_use] attribute
190 pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
192 ty::Adt(adt, _) => cx.tcx.has_attr(adt.did(), sym::must_use),
193 ty::Foreign(did) => cx.tcx.has_attr(*did, sym::must_use),
194 ty::Slice(ty) | ty::Array(ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) => {
195 // for the Array case we don't need to care for the len == 0 case
196 // because we don't want to lint functions returning empty arrays
197 is_must_use_ty(cx, *ty)
199 ty::Tuple(substs) => substs.iter().any(|ty| is_must_use_ty(cx, ty)),
200 ty::Opaque(def_id, _) => {
201 for (predicate, _) in cx.tcx.explicit_item_bounds(*def_id) {
202 if let ty::PredicateKind::Trait(trait_predicate) = predicate.kind().skip_binder() {
203 if cx.tcx.has_attr(trait_predicate.trait_ref.def_id, sym::must_use) {
210 ty::Dynamic(binder, _, _) => {
211 for predicate in binder.iter() {
212 if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
213 if cx.tcx.has_attr(trait_ref.def_id, sym::must_use) {
224 // FIXME: Per https://doc.rust-lang.org/nightly/nightly-rustc/rustc_trait_selection/infer/at/struct.At.html#method.normalize
225 // this function can be removed once the `normalize` method does not panic when normalization does
227 /// Checks if `Ty` is normalizable. This function is useful
228 /// to avoid crashes on `layout_of`.
229 pub fn is_normalizable<'tcx>(cx: &LateContext<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
230 is_normalizable_helper(cx, param_env, ty, &mut FxHashMap::default())
233 fn is_normalizable_helper<'tcx>(
234 cx: &LateContext<'tcx>,
235 param_env: ty::ParamEnv<'tcx>,
237 cache: &mut FxHashMap<Ty<'tcx>, bool>,
239 if let Some(&cached_result) = cache.get(&ty) {
240 return cached_result;
242 // prevent recursive loops, false-negative is better than endless loop leading to stack overflow
243 cache.insert(ty, false);
244 let infcx = cx.tcx.infer_ctxt().build();
245 let cause = rustc_middle::traits::ObligationCause::dummy();
246 let result = if infcx.at(&cause, param_env).normalize(ty).is_ok() {
248 ty::Adt(def, substs) => def.variants().iter().all(|variant| {
252 .all(|field| is_normalizable_helper(cx, param_env, field.ty(cx.tcx, substs), cache))
254 _ => ty.walk().all(|generic_arg| match generic_arg.unpack() {
255 GenericArgKind::Type(inner_ty) if inner_ty != ty => {
256 is_normalizable_helper(cx, param_env, inner_ty, cache)
258 _ => true, // if inner_ty == ty, we've already checked it
264 cache.insert(ty, result);
268 /// Returns `true` if the given type is a non aggregate primitive (a `bool` or `char`, any
269 /// integer or floating-point number type). For checking aggregation of primitive types (e.g.
270 /// tuples and slices of primitive type) see `is_recursively_primitive_type`
271 pub fn is_non_aggregate_primitive_type(ty: Ty<'_>) -> bool {
272 matches!(ty.kind(), ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_))
275 /// Returns `true` if the given type is a primitive (a `bool` or `char`, any integer or
276 /// floating-point number type, a `str`, or an array, slice, or tuple of those types).
277 pub fn is_recursively_primitive_type(ty: Ty<'_>) -> bool {
279 ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str => true,
280 ty::Ref(_, inner, _) if *inner.kind() == ty::Str => true,
281 ty::Array(inner_type, _) | ty::Slice(inner_type) => is_recursively_primitive_type(inner_type),
282 ty::Tuple(inner_types) => inner_types.iter().all(is_recursively_primitive_type),
287 /// Checks if the type is a reference equals to a diagnostic item
288 pub fn is_type_ref_to_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
290 ty::Ref(_, ref_ty, _) => match ref_ty.kind() {
291 ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did()),
298 /// Checks if the type is equal to a diagnostic item. To check if a type implements a
299 /// trait marked with a diagnostic item use [`implements_trait`].
301 /// For a further exploitation what diagnostic items are see [diagnostic items] in
306 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
308 /// [Diagnostic Items]: https://rustc-dev-guide.rust-lang.org/diagnostics/diagnostic-items.html
309 pub fn is_type_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
311 ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did()),
316 /// Checks if the type is equal to a lang item.
318 /// Returns `false` if the `LangItem` is not defined.
319 pub fn is_type_lang_item(cx: &LateContext<'_>, ty: Ty<'_>, lang_item: hir::LangItem) -> bool {
321 ty::Adt(adt, _) => cx.tcx.lang_items().get(lang_item) == Some(adt.did()),
326 /// Return `true` if the passed `typ` is `isize` or `usize`.
327 pub fn is_isize_or_usize(typ: Ty<'_>) -> bool {
328 matches!(typ.kind(), ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize))
331 /// Checks if type is struct, enum or union type with the given def path.
333 /// If the type is a diagnostic item, use `is_type_diagnostic_item` instead.
334 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
335 pub fn match_type(cx: &LateContext<'_>, ty: Ty<'_>, path: &[&str]) -> bool {
337 ty::Adt(adt, _) => match_def_path(cx, adt.did(), path),
342 /// Checks if the drop order for a type matters. Some std types implement drop solely to
343 /// deallocate memory. For these types, and composites containing them, changing the drop order
344 /// won't result in any observable side effects.
345 pub fn needs_ordered_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
346 fn needs_ordered_drop_inner<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, seen: &mut FxHashSet<Ty<'tcx>>) -> bool {
347 if !seen.insert(ty) {
350 if !ty.has_significant_drop(cx.tcx, cx.param_env) {
353 // Check for std types which implement drop, but only for memory allocation.
354 else if is_type_lang_item(cx, ty, LangItem::OwnedBox)
356 get_type_diagnostic_name(cx, ty),
357 Some(sym::HashSet | sym::Rc | sym::Arc | sym::cstring_type)
359 || match_type(cx, ty, &paths::WEAK_RC)
360 || match_type(cx, ty, &paths::WEAK_ARC)
362 // Check all of the generic arguments.
363 if let ty::Adt(_, subs) = ty.kind() {
364 subs.types().any(|ty| needs_ordered_drop_inner(cx, ty, seen))
372 .map_or(false, |id| implements_trait(cx, ty, id, &[]))
374 // This type doesn't implement drop, so no side effects here.
375 // Check if any component type has any.
377 ty::Tuple(fields) => fields.iter().any(|ty| needs_ordered_drop_inner(cx, ty, seen)),
378 ty::Array(ty, _) => needs_ordered_drop_inner(cx, *ty, seen),
379 ty::Adt(adt, subs) => adt
381 .map(|f| f.ty(cx.tcx, subs))
382 .any(|ty| needs_ordered_drop_inner(cx, ty, seen)),
390 needs_ordered_drop_inner(cx, ty, &mut FxHashSet::default())
393 /// Peels off all references on the type. Returns the underlying type and the number of references
395 pub fn peel_mid_ty_refs(ty: Ty<'_>) -> (Ty<'_>, usize) {
396 fn peel(ty: Ty<'_>, count: usize) -> (Ty<'_>, usize) {
397 if let ty::Ref(_, ty, _) = ty.kind() {
406 /// Peels off all references on the type. Returns the underlying type, the number of references
407 /// removed, and whether the pointer is ultimately mutable or not.
408 pub fn peel_mid_ty_refs_is_mutable(ty: Ty<'_>) -> (Ty<'_>, usize, Mutability) {
409 fn f(ty: Ty<'_>, count: usize, mutability: Mutability) -> (Ty<'_>, usize, Mutability) {
411 ty::Ref(_, ty, Mutability::Mut) => f(*ty, count + 1, mutability),
412 ty::Ref(_, ty, Mutability::Not) => f(*ty, count + 1, Mutability::Not),
413 _ => (ty, count, mutability),
416 f(ty, 0, Mutability::Mut)
419 /// Returns `true` if the given type is an `unsafe` function.
420 pub fn type_is_unsafe_function<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
422 ty::FnDef(..) | ty::FnPtr(_) => ty.fn_sig(cx.tcx).unsafety() == Unsafety::Unsafe,
427 /// Returns the base type for HIR references and pointers.
428 pub fn walk_ptrs_hir_ty<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
430 TyKind::Ptr(ref mut_ty) | TyKind::Rptr(_, ref mut_ty) => walk_ptrs_hir_ty(mut_ty.ty),
435 /// Returns the base type for references and raw pointers, and count reference
437 pub fn walk_ptrs_ty_depth(ty: Ty<'_>) -> (Ty<'_>, usize) {
438 fn inner(ty: Ty<'_>, depth: usize) -> (Ty<'_>, usize) {
440 ty::Ref(_, ty, _) => inner(*ty, depth + 1),
447 /// Returns `true` if types `a` and `b` are same types having same `Const` generic args,
448 /// otherwise returns `false`
449 pub fn same_type_and_consts<'tcx>(a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
450 match (&a.kind(), &b.kind()) {
451 (&ty::Adt(did_a, substs_a), &ty::Adt(did_b, substs_b)) => {
458 .zip(substs_b.iter())
459 .all(|(arg_a, arg_b)| match (arg_a.unpack(), arg_b.unpack()) {
460 (GenericArgKind::Const(inner_a), GenericArgKind::Const(inner_b)) => inner_a == inner_b,
461 (GenericArgKind::Type(type_a), GenericArgKind::Type(type_b)) => {
462 same_type_and_consts(type_a, type_b)
471 /// Checks if a given type looks safe to be uninitialized.
472 pub fn is_uninit_value_valid_for_ty(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
474 ty::Array(component, _) => is_uninit_value_valid_for_ty(cx, component),
475 ty::Tuple(types) => types.iter().all(|ty| is_uninit_value_valid_for_ty(cx, ty)),
476 ty::Adt(adt, _) => cx.tcx.lang_items().maybe_uninit() == Some(adt.did()),
481 /// Gets an iterator over all predicates which apply to the given item.
482 pub fn all_predicates_of(tcx: TyCtxt<'_>, id: DefId) -> impl Iterator<Item = &(Predicate<'_>, Span)> {
483 let mut next_id = Some(id);
484 iter::from_fn(move || {
485 next_id.take().map(|id| {
486 let preds = tcx.predicates_of(id);
487 next_id = preds.parent;
488 preds.predicates.iter()
494 /// A signature for a function like type.
495 #[derive(Clone, Copy)]
496 pub enum ExprFnSig<'tcx> {
497 Sig(Binder<'tcx, FnSig<'tcx>>, Option<DefId>),
498 Closure(Option<&'tcx FnDecl<'tcx>>, Binder<'tcx, FnSig<'tcx>>),
499 Trait(Binder<'tcx, Ty<'tcx>>, Option<Binder<'tcx, Ty<'tcx>>>, Option<DefId>),
501 impl<'tcx> ExprFnSig<'tcx> {
502 /// Gets the argument type at the given offset. This will return `None` when the index is out of
503 /// bounds only for variadic functions, otherwise this will panic.
504 pub fn input(self, i: usize) -> Option<Binder<'tcx, Ty<'tcx>>> {
506 Self::Sig(sig, _) => {
507 if sig.c_variadic() {
508 sig.inputs().map_bound(|inputs| inputs.get(i).copied()).transpose()
513 Self::Closure(_, sig) => Some(sig.input(0).map_bound(|ty| ty.tuple_fields()[i])),
514 Self::Trait(inputs, _, _) => Some(inputs.map_bound(|ty| ty.tuple_fields()[i])),
518 /// Gets the argument type at the given offset. For closures this will also get the type as
519 /// written. This will return `None` when the index is out of bounds only for variadic
520 /// functions, otherwise this will panic.
521 pub fn input_with_hir(self, i: usize) -> Option<(Option<&'tcx hir::Ty<'tcx>>, Binder<'tcx, Ty<'tcx>>)> {
523 Self::Sig(sig, _) => {
524 if sig.c_variadic() {
526 .map_bound(|inputs| inputs.get(i).copied())
528 .map(|arg| (None, arg))
530 Some((None, sig.input(i)))
533 Self::Closure(decl, sig) => Some((
534 decl.and_then(|decl| decl.inputs.get(i)),
535 sig.input(0).map_bound(|ty| ty.tuple_fields()[i]),
537 Self::Trait(inputs, _, _) => Some((None, inputs.map_bound(|ty| ty.tuple_fields()[i]))),
541 /// Gets the result type, if one could be found. Note that the result type of a trait may not be
543 pub fn output(self) -> Option<Binder<'tcx, Ty<'tcx>>> {
545 Self::Sig(sig, _) | Self::Closure(_, sig) => Some(sig.output()),
546 Self::Trait(_, output, _) => output,
550 pub fn predicates_id(&self) -> Option<DefId> {
551 if let ExprFnSig::Sig(_, id) | ExprFnSig::Trait(_, _, id) = *self {
559 /// If the expression is function like, get the signature for it.
560 pub fn expr_sig<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) -> Option<ExprFnSig<'tcx>> {
561 if let Res::Def(DefKind::Fn | DefKind::Ctor(_, CtorKind::Fn) | DefKind::AssocFn, id) = path_res(cx, expr) {
562 Some(ExprFnSig::Sig(cx.tcx.fn_sig(id), Some(id)))
564 ty_sig(cx, cx.typeck_results().expr_ty_adjusted(expr).peel_refs())
568 /// If the type is function like, get the signature for it.
569 pub fn ty_sig<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<ExprFnSig<'tcx>> {
571 return ty_sig(cx, ty.boxed_ty());
574 ty::Closure(id, subs) => {
577 .and_then(|id| cx.tcx.hir().fn_decl_by_hir_id(cx.tcx.hir().local_def_id_to_hir_id(id)));
578 Some(ExprFnSig::Closure(decl, subs.as_closure().sig()))
580 ty::FnDef(id, subs) => Some(ExprFnSig::Sig(cx.tcx.bound_fn_sig(id).subst(cx.tcx, subs), Some(id))),
581 ty::Opaque(id, _) => sig_from_bounds(cx, ty, cx.tcx.item_bounds(id), cx.tcx.opt_parent(id)),
582 ty::FnPtr(sig) => Some(ExprFnSig::Sig(sig, None)),
583 ty::Dynamic(bounds, _, _) => {
584 let lang_items = cx.tcx.lang_items();
585 match bounds.principal() {
587 if Some(bound.def_id()) == lang_items.fn_trait()
588 || Some(bound.def_id()) == lang_items.fn_once_trait()
589 || Some(bound.def_id()) == lang_items.fn_mut_trait() =>
593 .find(|p| lang_items.fn_once_output().map_or(false, |id| id == p.item_def_id()))
594 .map(|p| p.map_bound(|p| p.term.ty().unwrap()));
595 Some(ExprFnSig::Trait(bound.map_bound(|b| b.substs.type_at(0)), output, None))
600 ty::Projection(proj) => match cx.tcx.try_normalize_erasing_regions(cx.param_env, ty) {
601 Ok(normalized_ty) if normalized_ty != ty => ty_sig(cx, normalized_ty),
602 _ => sig_for_projection(cx, proj).or_else(|| sig_from_bounds(cx, ty, cx.param_env.caller_bounds(), None)),
604 ty::Param(_) => sig_from_bounds(cx, ty, cx.param_env.caller_bounds(), None),
609 fn sig_from_bounds<'tcx>(
610 cx: &LateContext<'tcx>,
612 predicates: &'tcx [Predicate<'tcx>],
613 predicates_id: Option<DefId>,
614 ) -> Option<ExprFnSig<'tcx>> {
615 let mut inputs = None;
616 let mut output = None;
617 let lang_items = cx.tcx.lang_items();
619 for pred in predicates {
620 match pred.kind().skip_binder() {
621 PredicateKind::Trait(p)
622 if (lang_items.fn_trait() == Some(p.def_id())
623 || lang_items.fn_mut_trait() == Some(p.def_id())
624 || lang_items.fn_once_trait() == Some(p.def_id()))
625 && p.self_ty() == ty =>
627 let i = pred.kind().rebind(p.trait_ref.substs.type_at(1));
628 if inputs.map_or(false, |inputs| i != inputs) {
629 // Multiple different fn trait impls. Is this even allowed?
634 PredicateKind::Projection(p)
635 if Some(p.projection_ty.item_def_id) == lang_items.fn_once_output()
636 && p.projection_ty.self_ty() == ty =>
638 if output.is_some() {
639 // Multiple different fn trait impls. Is this even allowed?
642 output = Some(pred.kind().rebind(p.term.ty().unwrap()));
648 inputs.map(|ty| ExprFnSig::Trait(ty, output, predicates_id))
651 fn sig_for_projection<'tcx>(cx: &LateContext<'tcx>, ty: ProjectionTy<'tcx>) -> Option<ExprFnSig<'tcx>> {
652 let mut inputs = None;
653 let mut output = None;
654 let lang_items = cx.tcx.lang_items();
658 .bound_explicit_item_bounds(ty.item_def_id)
659 .subst_iter_copied(cx.tcx, ty.substs)
661 match pred.kind().skip_binder() {
662 PredicateKind::Trait(p)
663 if (lang_items.fn_trait() == Some(p.def_id())
664 || lang_items.fn_mut_trait() == Some(p.def_id())
665 || lang_items.fn_once_trait() == Some(p.def_id())) =>
667 let i = pred.kind().rebind(p.trait_ref.substs.type_at(1));
669 if inputs.map_or(false, |inputs| inputs != i) {
670 // Multiple different fn trait impls. Is this even allowed?
675 PredicateKind::Projection(p) if Some(p.projection_ty.item_def_id) == lang_items.fn_once_output() => {
676 if output.is_some() {
677 // Multiple different fn trait impls. Is this even allowed?
680 output = pred.kind().rebind(p.term.ty()).transpose();
686 inputs.map(|ty| ExprFnSig::Trait(ty, output, None))
689 #[derive(Clone, Copy)]
694 impl core::ops::Add<u32> for EnumValue {
696 fn add(self, n: u32) -> Self::Output {
698 Self::Unsigned(x) => Self::Unsigned(x + u128::from(n)),
699 Self::Signed(x) => Self::Signed(x + i128::from(n)),
704 /// Attempts to read the given constant as though it were an an enum value.
705 #[expect(clippy::cast_possible_truncation, clippy::cast_possible_wrap)]
706 pub fn read_explicit_enum_value(tcx: TyCtxt<'_>, id: DefId) -> Option<EnumValue> {
707 if let Ok(ConstValue::Scalar(Scalar::Int(value))) = tcx.const_eval_poly(id) {
708 match tcx.type_of(id).kind() {
709 ty::Int(_) => Some(EnumValue::Signed(match value.size().bytes() {
710 1 => i128::from(value.assert_bits(Size::from_bytes(1)) as u8 as i8),
711 2 => i128::from(value.assert_bits(Size::from_bytes(2)) as u16 as i16),
712 4 => i128::from(value.assert_bits(Size::from_bytes(4)) as u32 as i32),
713 8 => i128::from(value.assert_bits(Size::from_bytes(8)) as u64 as i64),
714 16 => value.assert_bits(Size::from_bytes(16)) as i128,
717 ty::Uint(_) => Some(EnumValue::Unsigned(match value.size().bytes() {
718 1 => value.assert_bits(Size::from_bytes(1)),
719 2 => value.assert_bits(Size::from_bytes(2)),
720 4 => value.assert_bits(Size::from_bytes(4)),
721 8 => value.assert_bits(Size::from_bytes(8)),
722 16 => value.assert_bits(Size::from_bytes(16)),
732 /// Gets the value of the given variant.
733 pub fn get_discriminant_value(tcx: TyCtxt<'_>, adt: AdtDef<'_>, i: VariantIdx) -> EnumValue {
734 let variant = &adt.variant(i);
735 match variant.discr {
736 VariantDiscr::Explicit(id) => read_explicit_enum_value(tcx, id).unwrap(),
737 VariantDiscr::Relative(x) => match adt.variant((i.as_usize() - x as usize).into()).discr {
738 VariantDiscr::Explicit(id) => read_explicit_enum_value(tcx, id).unwrap() + x,
739 VariantDiscr::Relative(_) => EnumValue::Unsigned(x.into()),
744 /// Check if the given type is either `core::ffi::c_void`, `std::os::raw::c_void`, or one of the
745 /// platform specific `libc::<platform>::c_void` types in libc.
746 pub fn is_c_void(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
747 if let ty::Adt(adt, _) = ty.kind()
748 && let &[krate, .., name] = &*cx.get_def_path(adt.did())
749 && let sym::libc | sym::core | sym::std = krate
750 && name.as_str() == "c_void"
758 pub fn for_each_top_level_late_bound_region<B>(
760 f: impl FnMut(BoundRegion) -> ControlFlow<B>,
761 ) -> ControlFlow<B> {
766 impl<'tcx, B, F: FnMut(BoundRegion) -> ControlFlow<B>> TypeVisitor<'tcx> for V<F> {
768 fn visit_region(&mut self, r: Region<'tcx>) -> ControlFlow<Self::BreakTy> {
769 if let RegionKind::ReLateBound(idx, bound) = r.kind() && idx.as_u32() == self.index {
772 ControlFlow::Continue(())
775 fn visit_binder<T: TypeVisitable<'tcx>>(&mut self, t: &Binder<'tcx, T>) -> ControlFlow<Self::BreakTy> {
777 let res = t.super_visit_with(self);
782 ty.visit_with(&mut V { index: 0, f })
785 /// Gets the struct or enum variant from the given `Res`
786 pub fn variant_of_res<'tcx>(cx: &LateContext<'tcx>, res: Res) -> Option<&'tcx VariantDef> {
788 Res::Def(DefKind::Struct, id) => Some(cx.tcx.adt_def(id).non_enum_variant()),
789 Res::Def(DefKind::Variant, id) => Some(cx.tcx.adt_def(cx.tcx.parent(id)).variant_with_id(id)),
790 Res::Def(DefKind::Ctor(CtorOf::Struct, _), id) => Some(cx.tcx.adt_def(cx.tcx.parent(id)).non_enum_variant()),
791 Res::Def(DefKind::Ctor(CtorOf::Variant, _), id) => {
792 let var_id = cx.tcx.parent(id);
793 Some(cx.tcx.adt_def(cx.tcx.parent(var_id)).variant_with_id(var_id))
795 Res::SelfCtor(id) => Some(cx.tcx.type_of(id).ty_adt_def().unwrap().non_enum_variant()),
800 /// Checks if the type is a type parameter implementing `FnOnce`, but not `FnMut`.
801 pub fn ty_is_fn_once_param<'tcx>(tcx: TyCtxt<'_>, ty: Ty<'tcx>, predicates: &'tcx [Predicate<'_>]) -> bool {
802 let ty::Param(ty) = *ty.kind() else {
805 let lang = tcx.lang_items();
806 let (Some(fn_once_id), Some(fn_mut_id), Some(fn_id))
807 = (lang.fn_once_trait(), lang.fn_mut_trait(), lang.fn_trait())
813 .try_fold(false, |found, p| {
814 if let PredicateKind::Trait(p) = p.kind().skip_binder()
815 && let ty::Param(self_ty) = p.trait_ref.self_ty().kind()
816 && ty.index == self_ty.index
818 // This should use `super_traits_of`, but that's a private function.
819 if p.trait_ref.def_id == fn_once_id {
821 } else if p.trait_ref.def_id == fn_mut_id || p.trait_ref.def_id == fn_id {
830 /// Comes up with an "at least" guesstimate for the type's size, not taking into
831 /// account the layout of type parameters.
832 pub fn approx_ty_size<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> u64 {
833 use rustc_middle::ty::layout::LayoutOf;
834 if !is_normalizable(cx, cx.param_env, ty) {
837 match (cx.layout_of(ty).map(|layout| layout.size.bytes()), ty.kind()) {
838 (Ok(size), _) => size,
839 (Err(_), ty::Tuple(list)) => list.as_substs().types().map(|t| approx_ty_size(cx, t)).sum(),
840 (Err(_), ty::Array(t, n)) => {
841 n.try_eval_usize(cx.tcx, cx.param_env).unwrap_or_default() * approx_ty_size(cx, *t)
843 (Err(_), ty::Adt(def, subst)) if def.is_struct() => def
849 .map(|field| approx_ty_size(cx, field.ty(cx.tcx, subst)))
853 (Err(_), ty::Adt(def, subst)) if def.is_enum() => def
859 .map(|field| approx_ty_size(cx, field.ty(cx.tcx, subst)))
863 .unwrap_or_default(),
864 (Err(_), ty::Adt(def, subst)) if def.is_union() => def
870 .map(|field| approx_ty_size(cx, field.ty(cx.tcx, subst)))
875 .unwrap_or_default(),