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, DUMMY_SP};
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.at(DUMMY_SP), 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
325 .map_or(false, |li| li == adt.did()),
330 /// Return `true` if the passed `typ` is `isize` or `usize`.
331 pub fn is_isize_or_usize(typ: Ty<'_>) -> bool {
332 matches!(typ.kind(), ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize))
335 /// Checks if type is struct, enum or union type with the given def path.
337 /// If the type is a diagnostic item, use `is_type_diagnostic_item` instead.
338 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
339 pub fn match_type(cx: &LateContext<'_>, ty: Ty<'_>, path: &[&str]) -> bool {
341 ty::Adt(adt, _) => match_def_path(cx, adt.did(), path),
346 /// Checks if the drop order for a type matters. Some std types implement drop solely to
347 /// deallocate memory. For these types, and composites containing them, changing the drop order
348 /// won't result in any observable side effects.
349 pub fn needs_ordered_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
350 fn needs_ordered_drop_inner<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, seen: &mut FxHashSet<Ty<'tcx>>) -> bool {
351 if !seen.insert(ty) {
354 if !ty.has_significant_drop(cx.tcx, cx.param_env) {
357 // Check for std types which implement drop, but only for memory allocation.
358 else if is_type_lang_item(cx, ty, LangItem::OwnedBox)
360 get_type_diagnostic_name(cx, ty),
361 Some(sym::HashSet | sym::Rc | sym::Arc | sym::cstring_type)
363 || match_type(cx, ty, &paths::WEAK_RC)
364 || match_type(cx, ty, &paths::WEAK_ARC)
366 // Check all of the generic arguments.
367 if let ty::Adt(_, subs) = ty.kind() {
368 subs.types().any(|ty| needs_ordered_drop_inner(cx, ty, seen))
376 .map_or(false, |id| implements_trait(cx, ty, id, &[]))
378 // This type doesn't implement drop, so no side effects here.
379 // Check if any component type has any.
381 ty::Tuple(fields) => fields.iter().any(|ty| needs_ordered_drop_inner(cx, ty, seen)),
382 ty::Array(ty, _) => needs_ordered_drop_inner(cx, *ty, seen),
383 ty::Adt(adt, subs) => adt
385 .map(|f| f.ty(cx.tcx, subs))
386 .any(|ty| needs_ordered_drop_inner(cx, ty, seen)),
394 needs_ordered_drop_inner(cx, ty, &mut FxHashSet::default())
397 /// Peels off all references on the type. Returns the underlying type and the number of references
399 pub fn peel_mid_ty_refs(ty: Ty<'_>) -> (Ty<'_>, usize) {
400 fn peel(ty: Ty<'_>, count: usize) -> (Ty<'_>, usize) {
401 if let ty::Ref(_, ty, _) = ty.kind() {
410 /// Peels off all references on the type. Returns the underlying type, the number of references
411 /// removed, and whether the pointer is ultimately mutable or not.
412 pub fn peel_mid_ty_refs_is_mutable(ty: Ty<'_>) -> (Ty<'_>, usize, Mutability) {
413 fn f(ty: Ty<'_>, count: usize, mutability: Mutability) -> (Ty<'_>, usize, Mutability) {
415 ty::Ref(_, ty, Mutability::Mut) => f(*ty, count + 1, mutability),
416 ty::Ref(_, ty, Mutability::Not) => f(*ty, count + 1, Mutability::Not),
417 _ => (ty, count, mutability),
420 f(ty, 0, Mutability::Mut)
423 /// Returns `true` if the given type is an `unsafe` function.
424 pub fn type_is_unsafe_function<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
426 ty::FnDef(..) | ty::FnPtr(_) => ty.fn_sig(cx.tcx).unsafety() == Unsafety::Unsafe,
431 /// Returns the base type for HIR references and pointers.
432 pub fn walk_ptrs_hir_ty<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
434 TyKind::Ptr(ref mut_ty) | TyKind::Rptr(_, ref mut_ty) => walk_ptrs_hir_ty(mut_ty.ty),
439 /// Returns the base type for references and raw pointers, and count reference
441 pub fn walk_ptrs_ty_depth(ty: Ty<'_>) -> (Ty<'_>, usize) {
442 fn inner(ty: Ty<'_>, depth: usize) -> (Ty<'_>, usize) {
444 ty::Ref(_, ty, _) => inner(*ty, depth + 1),
451 /// Returns `true` if types `a` and `b` are same types having same `Const` generic args,
452 /// otherwise returns `false`
453 pub fn same_type_and_consts<'tcx>(a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
454 match (&a.kind(), &b.kind()) {
455 (&ty::Adt(did_a, substs_a), &ty::Adt(did_b, substs_b)) => {
462 .zip(substs_b.iter())
463 .all(|(arg_a, arg_b)| match (arg_a.unpack(), arg_b.unpack()) {
464 (GenericArgKind::Const(inner_a), GenericArgKind::Const(inner_b)) => inner_a == inner_b,
465 (GenericArgKind::Type(type_a), GenericArgKind::Type(type_b)) => {
466 same_type_and_consts(type_a, type_b)
475 /// Checks if a given type looks safe to be uninitialized.
476 pub fn is_uninit_value_valid_for_ty(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
478 ty::Array(component, _) => is_uninit_value_valid_for_ty(cx, component),
479 ty::Tuple(types) => types.iter().all(|ty| is_uninit_value_valid_for_ty(cx, ty)),
480 ty::Adt(adt, _) => cx.tcx.lang_items().maybe_uninit() == Some(adt.did()),
485 /// Gets an iterator over all predicates which apply to the given item.
486 pub fn all_predicates_of(tcx: TyCtxt<'_>, id: DefId) -> impl Iterator<Item = &(Predicate<'_>, Span)> {
487 let mut next_id = Some(id);
488 iter::from_fn(move || {
489 next_id.take().map(|id| {
490 let preds = tcx.predicates_of(id);
491 next_id = preds.parent;
492 preds.predicates.iter()
498 /// A signature for a function like type.
499 #[derive(Clone, Copy)]
500 pub enum ExprFnSig<'tcx> {
501 Sig(Binder<'tcx, FnSig<'tcx>>, Option<DefId>),
502 Closure(Option<&'tcx FnDecl<'tcx>>, Binder<'tcx, FnSig<'tcx>>),
503 Trait(Binder<'tcx, Ty<'tcx>>, Option<Binder<'tcx, Ty<'tcx>>>, Option<DefId>),
505 impl<'tcx> ExprFnSig<'tcx> {
506 /// Gets the argument type at the given offset. This will return `None` when the index is out of
507 /// bounds only for variadic functions, otherwise this will panic.
508 pub fn input(self, i: usize) -> Option<Binder<'tcx, Ty<'tcx>>> {
510 Self::Sig(sig, _) => {
511 if sig.c_variadic() {
512 sig.inputs().map_bound(|inputs| inputs.get(i).copied()).transpose()
517 Self::Closure(_, sig) => Some(sig.input(0).map_bound(|ty| ty.tuple_fields()[i])),
518 Self::Trait(inputs, _, _) => Some(inputs.map_bound(|ty| ty.tuple_fields()[i])),
522 /// Gets the argument type at the given offset. For closures this will also get the type as
523 /// written. This will return `None` when the index is out of bounds only for variadic
524 /// functions, otherwise this will panic.
525 pub fn input_with_hir(self, i: usize) -> Option<(Option<&'tcx hir::Ty<'tcx>>, Binder<'tcx, Ty<'tcx>>)> {
527 Self::Sig(sig, _) => {
528 if sig.c_variadic() {
530 .map_bound(|inputs| inputs.get(i).copied())
532 .map(|arg| (None, arg))
534 Some((None, sig.input(i)))
537 Self::Closure(decl, sig) => Some((
538 decl.and_then(|decl| decl.inputs.get(i)),
539 sig.input(0).map_bound(|ty| ty.tuple_fields()[i]),
541 Self::Trait(inputs, _, _) => Some((None, inputs.map_bound(|ty| ty.tuple_fields()[i]))),
545 /// Gets the result type, if one could be found. Note that the result type of a trait may not be
547 pub fn output(self) -> Option<Binder<'tcx, Ty<'tcx>>> {
549 Self::Sig(sig, _) | Self::Closure(_, sig) => Some(sig.output()),
550 Self::Trait(_, output, _) => output,
554 pub fn predicates_id(&self) -> Option<DefId> {
555 if let ExprFnSig::Sig(_, id) | ExprFnSig::Trait(_, _, id) = *self {
563 /// If the expression is function like, get the signature for it.
564 pub fn expr_sig<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) -> Option<ExprFnSig<'tcx>> {
565 if let Res::Def(DefKind::Fn | DefKind::Ctor(_, CtorKind::Fn) | DefKind::AssocFn, id) = path_res(cx, expr) {
566 Some(ExprFnSig::Sig(cx.tcx.fn_sig(id), Some(id)))
568 ty_sig(cx, cx.typeck_results().expr_ty_adjusted(expr).peel_refs())
572 /// If the type is function like, get the signature for it.
573 pub fn ty_sig<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<ExprFnSig<'tcx>> {
575 return ty_sig(cx, ty.boxed_ty());
578 ty::Closure(id, subs) => {
581 .and_then(|id| cx.tcx.hir().fn_decl_by_hir_id(cx.tcx.hir().local_def_id_to_hir_id(id)));
582 Some(ExprFnSig::Closure(decl, subs.as_closure().sig()))
584 ty::FnDef(id, subs) => Some(ExprFnSig::Sig(cx.tcx.bound_fn_sig(id).subst(cx.tcx, subs), Some(id))),
585 ty::Opaque(id, _) => sig_from_bounds(cx, ty, cx.tcx.item_bounds(id), cx.tcx.opt_parent(id)),
586 ty::FnPtr(sig) => Some(ExprFnSig::Sig(sig, None)),
587 ty::Dynamic(bounds, _, _) => {
588 let lang_items = cx.tcx.lang_items();
589 match bounds.principal() {
591 if Some(bound.def_id()) == lang_items.fn_trait()
592 || Some(bound.def_id()) == lang_items.fn_once_trait()
593 || Some(bound.def_id()) == lang_items.fn_mut_trait() =>
597 .find(|p| lang_items.fn_once_output().map_or(false, |id| id == p.item_def_id()))
598 .map(|p| p.map_bound(|p| p.term.ty().unwrap()));
599 Some(ExprFnSig::Trait(bound.map_bound(|b| b.substs.type_at(0)), output, None))
604 ty::Projection(proj) => match cx.tcx.try_normalize_erasing_regions(cx.param_env, ty) {
605 Ok(normalized_ty) if normalized_ty != ty => ty_sig(cx, normalized_ty),
606 _ => sig_for_projection(cx, proj).or_else(|| sig_from_bounds(cx, ty, cx.param_env.caller_bounds(), None)),
608 ty::Param(_) => sig_from_bounds(cx, ty, cx.param_env.caller_bounds(), None),
613 fn sig_from_bounds<'tcx>(
614 cx: &LateContext<'tcx>,
616 predicates: &'tcx [Predicate<'tcx>],
617 predicates_id: Option<DefId>,
618 ) -> Option<ExprFnSig<'tcx>> {
619 let mut inputs = None;
620 let mut output = None;
621 let lang_items = cx.tcx.lang_items();
623 for pred in predicates {
624 match pred.kind().skip_binder() {
625 PredicateKind::Trait(p)
626 if (lang_items.fn_trait() == Some(p.def_id())
627 || lang_items.fn_mut_trait() == Some(p.def_id())
628 || lang_items.fn_once_trait() == Some(p.def_id()))
629 && p.self_ty() == ty =>
631 let i = pred.kind().rebind(p.trait_ref.substs.type_at(1));
632 if inputs.map_or(false, |inputs| i != inputs) {
633 // Multiple different fn trait impls. Is this even allowed?
638 PredicateKind::Projection(p)
639 if Some(p.projection_ty.item_def_id) == lang_items.fn_once_output()
640 && p.projection_ty.self_ty() == ty =>
642 if output.is_some() {
643 // Multiple different fn trait impls. Is this even allowed?
646 output = Some(pred.kind().rebind(p.term.ty().unwrap()));
652 inputs.map(|ty| ExprFnSig::Trait(ty, output, predicates_id))
655 fn sig_for_projection<'tcx>(cx: &LateContext<'tcx>, ty: ProjectionTy<'tcx>) -> Option<ExprFnSig<'tcx>> {
656 let mut inputs = None;
657 let mut output = None;
658 let lang_items = cx.tcx.lang_items();
662 .bound_explicit_item_bounds(ty.item_def_id)
664 .map(|x| x.map_bound(|(p, _)| p))
666 match pred.0.kind().skip_binder() {
667 PredicateKind::Trait(p)
668 if (lang_items.fn_trait() == Some(p.def_id())
669 || lang_items.fn_mut_trait() == Some(p.def_id())
670 || lang_items.fn_once_trait() == Some(p.def_id())) =>
673 .map_bound(|pred| pred.kind().rebind(p.trait_ref.substs.type_at(1)))
674 .subst(cx.tcx, ty.substs);
676 if inputs.map_or(false, |inputs| inputs != i) {
677 // Multiple different fn trait impls. Is this even allowed?
682 PredicateKind::Projection(p) if Some(p.projection_ty.item_def_id) == lang_items.fn_once_output() => {
683 if output.is_some() {
684 // Multiple different fn trait impls. Is this even allowed?
688 pred.map_bound(|pred| pred.kind().rebind(p.term.ty().unwrap()))
689 .subst(cx.tcx, ty.substs),
696 inputs.map(|ty| ExprFnSig::Trait(ty, output, None))
699 #[derive(Clone, Copy)]
704 impl core::ops::Add<u32> for EnumValue {
706 fn add(self, n: u32) -> Self::Output {
708 Self::Unsigned(x) => Self::Unsigned(x + u128::from(n)),
709 Self::Signed(x) => Self::Signed(x + i128::from(n)),
714 /// Attempts to read the given constant as though it were an an enum value.
715 #[expect(clippy::cast_possible_truncation, clippy::cast_possible_wrap)]
716 pub fn read_explicit_enum_value(tcx: TyCtxt<'_>, id: DefId) -> Option<EnumValue> {
717 if let Ok(ConstValue::Scalar(Scalar::Int(value))) = tcx.const_eval_poly(id) {
718 match tcx.type_of(id).kind() {
719 ty::Int(_) => Some(EnumValue::Signed(match value.size().bytes() {
720 1 => i128::from(value.assert_bits(Size::from_bytes(1)) as u8 as i8),
721 2 => i128::from(value.assert_bits(Size::from_bytes(2)) as u16 as i16),
722 4 => i128::from(value.assert_bits(Size::from_bytes(4)) as u32 as i32),
723 8 => i128::from(value.assert_bits(Size::from_bytes(8)) as u64 as i64),
724 16 => value.assert_bits(Size::from_bytes(16)) as i128,
727 ty::Uint(_) => Some(EnumValue::Unsigned(match value.size().bytes() {
728 1 => value.assert_bits(Size::from_bytes(1)),
729 2 => value.assert_bits(Size::from_bytes(2)),
730 4 => value.assert_bits(Size::from_bytes(4)),
731 8 => value.assert_bits(Size::from_bytes(8)),
732 16 => value.assert_bits(Size::from_bytes(16)),
742 /// Gets the value of the given variant.
743 pub fn get_discriminant_value(tcx: TyCtxt<'_>, adt: AdtDef<'_>, i: VariantIdx) -> EnumValue {
744 let variant = &adt.variant(i);
745 match variant.discr {
746 VariantDiscr::Explicit(id) => read_explicit_enum_value(tcx, id).unwrap(),
747 VariantDiscr::Relative(x) => match adt.variant((i.as_usize() - x as usize).into()).discr {
748 VariantDiscr::Explicit(id) => read_explicit_enum_value(tcx, id).unwrap() + x,
749 VariantDiscr::Relative(_) => EnumValue::Unsigned(x.into()),
754 /// Check if the given type is either `core::ffi::c_void`, `std::os::raw::c_void`, or one of the
755 /// platform specific `libc::<platform>::c_void` types in libc.
756 pub fn is_c_void(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
757 if let ty::Adt(adt, _) = ty.kind()
758 && let &[krate, .., name] = &*cx.get_def_path(adt.did())
759 && let sym::libc | sym::core | sym::std = krate
760 && name.as_str() == "c_void"
768 pub fn for_each_top_level_late_bound_region<B>(
770 f: impl FnMut(BoundRegion) -> ControlFlow<B>,
771 ) -> ControlFlow<B> {
776 impl<'tcx, B, F: FnMut(BoundRegion) -> ControlFlow<B>> TypeVisitor<'tcx> for V<F> {
778 fn visit_region(&mut self, r: Region<'tcx>) -> ControlFlow<Self::BreakTy> {
779 if let RegionKind::ReLateBound(idx, bound) = r.kind() && idx.as_u32() == self.index {
782 ControlFlow::Continue(())
785 fn visit_binder<T: TypeVisitable<'tcx>>(&mut self, t: &Binder<'tcx, T>) -> ControlFlow<Self::BreakTy> {
787 let res = t.super_visit_with(self);
792 ty.visit_with(&mut V { index: 0, f })
795 /// Gets the struct or enum variant from the given `Res`
796 pub fn variant_of_res<'tcx>(cx: &LateContext<'tcx>, res: Res) -> Option<&'tcx VariantDef> {
798 Res::Def(DefKind::Struct, id) => Some(cx.tcx.adt_def(id).non_enum_variant()),
799 Res::Def(DefKind::Variant, id) => Some(cx.tcx.adt_def(cx.tcx.parent(id)).variant_with_id(id)),
800 Res::Def(DefKind::Ctor(CtorOf::Struct, _), id) => Some(cx.tcx.adt_def(cx.tcx.parent(id)).non_enum_variant()),
801 Res::Def(DefKind::Ctor(CtorOf::Variant, _), id) => {
802 let var_id = cx.tcx.parent(id);
803 Some(cx.tcx.adt_def(cx.tcx.parent(var_id)).variant_with_id(var_id))
805 Res::SelfCtor(id) => Some(cx.tcx.type_of(id).ty_adt_def().unwrap().non_enum_variant()),
810 /// Checks if the type is a type parameter implementing `FnOnce`, but not `FnMut`.
811 pub fn ty_is_fn_once_param<'tcx>(tcx: TyCtxt<'_>, ty: Ty<'tcx>, predicates: &'tcx [Predicate<'_>]) -> bool {
812 let ty::Param(ty) = *ty.kind() else {
815 let lang = tcx.lang_items();
816 let (Some(fn_once_id), Some(fn_mut_id), Some(fn_id))
817 = (lang.fn_once_trait(), lang.fn_mut_trait(), lang.fn_trait())
823 .try_fold(false, |found, p| {
824 if let PredicateKind::Trait(p) = p.kind().skip_binder()
825 && let ty::Param(self_ty) = p.trait_ref.self_ty().kind()
826 && ty.index == self_ty.index
828 // This should use `super_traits_of`, but that's a private function.
829 if p.trait_ref.def_id == fn_once_id {
831 } else if p.trait_ref.def_id == fn_mut_id || p.trait_ref.def_id == fn_id {
840 /// Comes up with an "at least" guesstimate for the type's size, not taking into
841 /// account the layout of type parameters.
842 pub fn approx_ty_size<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> u64 {
843 use rustc_middle::ty::layout::LayoutOf;
844 if !is_normalizable(cx, cx.param_env, ty) {
847 match (cx.layout_of(ty).map(|layout| layout.size.bytes()), ty.kind()) {
848 (Ok(size), _) => size,
849 (Err(_), ty::Tuple(list)) => list.as_substs().types().map(|t| approx_ty_size(cx, t)).sum(),
850 (Err(_), ty::Array(t, n)) => {
851 n.try_eval_usize(cx.tcx, cx.param_env).unwrap_or_default() * approx_ty_size(cx, *t)
853 (Err(_), ty::Adt(def, subst)) if def.is_struct() => def
859 .map(|field| approx_ty_size(cx, field.ty(cx.tcx, subst)))
863 (Err(_), ty::Adt(def, subst)) if def.is_enum() => def
869 .map(|field| approx_ty_size(cx, field.ty(cx.tcx, subst)))
873 .unwrap_or_default(),
874 (Err(_), ty::Adt(def, subst)) if def.is_union() => def
880 .map(|field| approx_ty_size(cx, field.ty(cx.tcx, subst)))
885 .unwrap_or_default(),