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::subst::{GenericArg, GenericArgKind, Subst};
16 use rustc_middle::ty::{
17 self, AdtDef, Binder, BoundRegion, DefIdTree, FnSig, IntTy, ParamEnv, Predicate, PredicateKind, ProjectionTy,
18 Region, RegionKind, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor, UintTy, VariantDef, VariantDiscr,
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 /// Checks whether a type can be partially moved.
35 pub fn can_partially_move_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
36 if has_drop(cx, ty) || is_copy(cx, ty) {
40 ty::Param(_) => false,
41 ty::Adt(def, subs) => def.all_fields().any(|f| !is_copy(cx, f.ty(cx.tcx, subs))),
46 /// Walks into `ty` and returns `true` if any inner type is an instance of the given adt
48 pub fn contains_adt_constructor<'tcx>(ty: Ty<'tcx>, adt: AdtDef<'tcx>) -> bool {
49 ty.walk().any(|inner| match inner.unpack() {
50 GenericArgKind::Type(inner_ty) => inner_ty.ty_adt_def() == Some(adt),
51 GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => false,
55 /// Resolves `<T as Iterator>::Item` for `T`
56 /// Do not invoke without first verifying that the type implements `Iterator`
57 pub fn get_iterator_item_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'tcx>> {
59 .get_diagnostic_item(sym::Iterator)
60 .and_then(|iter_did| get_associated_type(cx, ty, iter_did, "Item"))
63 /// Returns the associated type `name` for `ty` as an implementation of `trait_id`.
64 /// Do not invoke without first verifying that the type implements the trait.
65 pub fn get_associated_type<'tcx>(
66 cx: &LateContext<'tcx>,
70 ) -> Option<Ty<'tcx>> {
72 .associated_items(trait_id)
73 .find_by_name_and_kind(cx.tcx, Ident::from_str(name), ty::AssocKind::Type, trait_id)
75 let proj = cx.tcx.mk_projection(assoc.def_id, cx.tcx.mk_substs_trait(ty, &[]));
76 cx.tcx.try_normalize_erasing_regions(cx.param_env, proj).ok()
80 /// Get the diagnostic name of a type, e.g. `sym::HashMap`. To check if a type
81 /// implements a trait marked with a diagnostic item use [`implements_trait`].
83 /// For a further exploitation what diagnostic items are see [diagnostic items] in
86 /// [Diagnostic Items]: https://rustc-dev-guide.rust-lang.org/diagnostics/diagnostic-items.html
87 pub fn get_type_diagnostic_name(cx: &LateContext<'_>, ty: Ty<'_>) -> Option<Symbol> {
89 ty::Adt(adt, _) => cx.tcx.get_diagnostic_name(adt.did()),
94 /// Returns true if ty has `iter` or `iter_mut` methods
95 pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<Symbol> {
96 // FIXME: instead of this hard-coded list, we should check if `<adt>::iter`
97 // exists and has the desired signature. Unfortunately FnCtxt is not exported
98 // so we can't use its `lookup_method` method.
99 let into_iter_collections: &[Symbol] = &[
115 let ty_to_check = match probably_ref_ty.kind() {
116 ty::Ref(_, ty_to_check, _) => *ty_to_check,
117 _ => probably_ref_ty,
120 let def_id = match ty_to_check.kind() {
121 ty::Array(..) => return Some(sym::array),
122 ty::Slice(..) => return Some(sym::slice),
123 ty::Adt(adt, _) => adt.did(),
127 for &name in into_iter_collections {
128 if cx.tcx.is_diagnostic_item(name, def_id) {
129 return Some(cx.tcx.item_name(def_id));
135 /// Checks whether a type implements a trait.
136 /// The function returns false in case the type contains an inference variable.
139 /// * [`get_trait_def_id`](super::get_trait_def_id) to get a trait [`DefId`].
140 /// * [Common tools for writing lints] for an example how to use this function and other options.
142 /// [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
143 pub fn implements_trait<'tcx>(
144 cx: &LateContext<'tcx>,
147 ty_params: &[GenericArg<'tcx>],
149 implements_trait_with_env(cx.tcx, cx.param_env, ty, trait_id, ty_params)
152 /// Same as `implements_trait` but allows using a `ParamEnv` different from the lint context.
153 pub fn implements_trait_with_env<'tcx>(
155 param_env: ParamEnv<'tcx>,
158 ty_params: &[GenericArg<'tcx>],
160 // Clippy shouldn't have infer types
161 assert!(!ty.needs_infer());
163 let ty = tcx.erase_regions(ty);
164 if ty.has_escaping_bound_vars() {
167 let ty_params = tcx.mk_substs(ty_params.iter());
168 tcx.infer_ctxt().enter(|infcx| {
170 .type_implements_trait(trait_id, ty, ty_params, param_env)
171 .must_apply_modulo_regions()
175 /// Checks whether this type implements `Drop`.
176 pub fn has_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
177 match ty.ty_adt_def() {
178 Some(def) => def.has_dtor(cx.tcx),
183 // Returns whether the type has #[must_use] attribute
184 pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
186 ty::Adt(adt, _) => cx.tcx.has_attr(adt.did(), sym::must_use),
187 ty::Foreign(did) => cx.tcx.has_attr(*did, sym::must_use),
188 ty::Slice(ty) | ty::Array(ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) => {
189 // for the Array case we don't need to care for the len == 0 case
190 // because we don't want to lint functions returning empty arrays
191 is_must_use_ty(cx, *ty)
193 ty::Tuple(substs) => substs.iter().any(|ty| is_must_use_ty(cx, ty)),
194 ty::Opaque(def_id, _) => {
195 for (predicate, _) in cx.tcx.explicit_item_bounds(*def_id) {
196 if let ty::PredicateKind::Trait(trait_predicate) = predicate.kind().skip_binder() {
197 if cx.tcx.has_attr(trait_predicate.trait_ref.def_id, sym::must_use) {
204 ty::Dynamic(binder, _) => {
205 for predicate in binder.iter() {
206 if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
207 if cx.tcx.has_attr(trait_ref.def_id, sym::must_use) {
218 // FIXME: Per https://doc.rust-lang.org/nightly/nightly-rustc/rustc_trait_selection/infer/at/struct.At.html#method.normalize
219 // this function can be removed once the `normalize` method does not panic when normalization does
221 /// Checks if `Ty` is normalizable. This function is useful
222 /// to avoid crashes on `layout_of`.
223 pub fn is_normalizable<'tcx>(cx: &LateContext<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
224 is_normalizable_helper(cx, param_env, ty, &mut FxHashMap::default())
227 fn is_normalizable_helper<'tcx>(
228 cx: &LateContext<'tcx>,
229 param_env: ty::ParamEnv<'tcx>,
231 cache: &mut FxHashMap<Ty<'tcx>, bool>,
233 if let Some(&cached_result) = cache.get(&ty) {
234 return cached_result;
236 // prevent recursive loops, false-negative is better than endless loop leading to stack overflow
237 cache.insert(ty, false);
238 let result = cx.tcx.infer_ctxt().enter(|infcx| {
239 let cause = rustc_middle::traits::ObligationCause::dummy();
240 if infcx.at(&cause, param_env).normalize(ty).is_ok() {
242 ty::Adt(def, substs) => def.variants().iter().all(|variant| {
246 .all(|field| is_normalizable_helper(cx, param_env, field.ty(cx.tcx, substs), cache))
248 _ => ty.walk().all(|generic_arg| match generic_arg.unpack() {
249 GenericArgKind::Type(inner_ty) if inner_ty != ty => {
250 is_normalizable_helper(cx, param_env, inner_ty, cache)
252 _ => true, // if inner_ty == ty, we've already checked it
259 cache.insert(ty, result);
263 /// Returns `true` if the given type is a non aggregate primitive (a `bool` or `char`, any
264 /// integer or floating-point number type). For checking aggregation of primitive types (e.g.
265 /// tuples and slices of primitive type) see `is_recursively_primitive_type`
266 pub fn is_non_aggregate_primitive_type(ty: Ty<'_>) -> bool {
267 matches!(ty.kind(), ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_))
270 /// Returns `true` if the given type is a primitive (a `bool` or `char`, any integer or
271 /// floating-point number type, a `str`, or an array, slice, or tuple of those types).
272 pub fn is_recursively_primitive_type(ty: Ty<'_>) -> bool {
274 ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str => true,
275 ty::Ref(_, inner, _) if *inner.kind() == ty::Str => true,
276 ty::Array(inner_type, _) | ty::Slice(inner_type) => is_recursively_primitive_type(inner_type),
277 ty::Tuple(inner_types) => inner_types.iter().all(is_recursively_primitive_type),
282 /// Checks if the type is a reference equals to a diagnostic item
283 pub fn is_type_ref_to_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
285 ty::Ref(_, ref_ty, _) => match ref_ty.kind() {
286 ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did()),
293 /// Checks if the type is equal to a diagnostic item. To check if a type implements a
294 /// trait marked with a diagnostic item use [`implements_trait`].
296 /// For a further exploitation what diagnostic items are see [diagnostic items] in
301 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
303 /// [Diagnostic Items]: https://rustc-dev-guide.rust-lang.org/diagnostics/diagnostic-items.html
304 pub fn is_type_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
306 ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did()),
311 /// Checks if the type is equal to a lang item.
313 /// Returns `false` if the `LangItem` is not defined.
314 pub fn is_type_lang_item(cx: &LateContext<'_>, ty: Ty<'_>, lang_item: hir::LangItem) -> bool {
316 ty::Adt(adt, _) => cx
320 .map_or(false, |li| li == adt.did()),
325 /// Return `true` if the passed `typ` is `isize` or `usize`.
326 pub fn is_isize_or_usize(typ: Ty<'_>) -> bool {
327 matches!(typ.kind(), ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize))
330 /// Checks if type is struct, enum or union type with the given def path.
332 /// If the type is a diagnostic item, use `is_type_diagnostic_item` instead.
333 /// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
334 pub fn match_type(cx: &LateContext<'_>, ty: Ty<'_>, path: &[&str]) -> bool {
336 ty::Adt(adt, _) => match_def_path(cx, adt.did(), path),
341 /// Checks if the drop order for a type matters. Some std types implement drop solely to
342 /// deallocate memory. For these types, and composites containing them, changing the drop order
343 /// won't result in any observable side effects.
344 pub fn needs_ordered_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
345 fn needs_ordered_drop_inner<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, seen: &mut FxHashSet<Ty<'tcx>>) -> bool {
346 if !seen.insert(ty) {
349 if !ty.has_significant_drop(cx.tcx, cx.param_env) {
352 // Check for std types which implement drop, but only for memory allocation.
353 else if is_type_lang_item(cx, ty, LangItem::OwnedBox)
355 get_type_diagnostic_name(cx, ty),
356 Some(sym::HashSet | sym::Rc | sym::Arc | sym::cstring_type)
358 || match_type(cx, ty, &paths::WEAK_RC)
359 || match_type(cx, ty, &paths::WEAK_ARC)
361 // Check all of the generic arguments.
362 if let ty::Adt(_, subs) = ty.kind() {
363 subs.types().any(|ty| needs_ordered_drop_inner(cx, ty, seen))
371 .map_or(false, |id| implements_trait(cx, ty, id, &[]))
373 // This type doesn't implement drop, so no side effects here.
374 // Check if any component type has any.
376 ty::Tuple(fields) => fields.iter().any(|ty| needs_ordered_drop_inner(cx, ty, seen)),
377 ty::Array(ty, _) => needs_ordered_drop_inner(cx, *ty, seen),
378 ty::Adt(adt, subs) => adt
380 .map(|f| f.ty(cx.tcx, subs))
381 .any(|ty| needs_ordered_drop_inner(cx, ty, seen)),
389 needs_ordered_drop_inner(cx, ty, &mut FxHashSet::default())
392 /// Peels off all references on the type. Returns the underlying type and the number of references
394 pub fn peel_mid_ty_refs(ty: Ty<'_>) -> (Ty<'_>, usize) {
395 fn peel(ty: Ty<'_>, count: usize) -> (Ty<'_>, usize) {
396 if let ty::Ref(_, ty, _) = ty.kind() {
405 /// Peels off all references on the type. Returns the underlying type, the number of references
406 /// removed, and whether the pointer is ultimately mutable or not.
407 pub fn peel_mid_ty_refs_is_mutable(ty: Ty<'_>) -> (Ty<'_>, usize, Mutability) {
408 fn f(ty: Ty<'_>, count: usize, mutability: Mutability) -> (Ty<'_>, usize, Mutability) {
410 ty::Ref(_, ty, Mutability::Mut) => f(*ty, count + 1, mutability),
411 ty::Ref(_, ty, Mutability::Not) => f(*ty, count + 1, Mutability::Not),
412 _ => (ty, count, mutability),
415 f(ty, 0, Mutability::Mut)
418 /// Returns `true` if the given type is an `unsafe` function.
419 pub fn type_is_unsafe_function<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
421 ty::FnDef(..) | ty::FnPtr(_) => ty.fn_sig(cx.tcx).unsafety() == Unsafety::Unsafe,
426 /// Returns the base type for HIR references and pointers.
427 pub fn walk_ptrs_hir_ty<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
429 TyKind::Ptr(ref mut_ty) | TyKind::Rptr(_, ref mut_ty) => walk_ptrs_hir_ty(mut_ty.ty),
434 /// Returns the base type for references and raw pointers, and count reference
436 pub fn walk_ptrs_ty_depth(ty: Ty<'_>) -> (Ty<'_>, usize) {
437 fn inner(ty: Ty<'_>, depth: usize) -> (Ty<'_>, usize) {
439 ty::Ref(_, ty, _) => inner(*ty, depth + 1),
446 /// Returns `true` if types `a` and `b` are same types having same `Const` generic args,
447 /// otherwise returns `false`
448 pub fn same_type_and_consts<'tcx>(a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
449 match (&a.kind(), &b.kind()) {
450 (&ty::Adt(did_a, substs_a), &ty::Adt(did_b, substs_b)) => {
457 .zip(substs_b.iter())
458 .all(|(arg_a, arg_b)| match (arg_a.unpack(), arg_b.unpack()) {
459 (GenericArgKind::Const(inner_a), GenericArgKind::Const(inner_b)) => inner_a == inner_b,
460 (GenericArgKind::Type(type_a), GenericArgKind::Type(type_b)) => {
461 same_type_and_consts(type_a, type_b)
470 /// Checks if a given type looks safe to be uninitialized.
471 pub fn is_uninit_value_valid_for_ty(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
473 ty::Array(component, _) => is_uninit_value_valid_for_ty(cx, component),
474 ty::Tuple(types) => types.iter().all(|ty| is_uninit_value_valid_for_ty(cx, ty)),
475 ty::Adt(adt, _) => cx.tcx.lang_items().maybe_uninit() == Some(adt.did()),
480 /// Gets an iterator over all predicates which apply to the given item.
481 pub fn all_predicates_of(tcx: TyCtxt<'_>, id: DefId) -> impl Iterator<Item = &(Predicate<'_>, Span)> {
482 let mut next_id = Some(id);
483 iter::from_fn(move || {
484 next_id.take().map(|id| {
485 let preds = tcx.predicates_of(id);
486 next_id = preds.parent;
487 preds.predicates.iter()
493 /// A signature for a function like type.
494 #[derive(Clone, Copy)]
495 pub enum ExprFnSig<'tcx> {
496 Sig(Binder<'tcx, FnSig<'tcx>>, Option<DefId>),
497 Closure(Option<&'tcx FnDecl<'tcx>>, Binder<'tcx, FnSig<'tcx>>),
498 Trait(Binder<'tcx, Ty<'tcx>>, Option<Binder<'tcx, Ty<'tcx>>>, Option<DefId>),
500 impl<'tcx> ExprFnSig<'tcx> {
501 /// Gets the argument type at the given offset. This will return `None` when the index is out of
502 /// bounds only for variadic functions, otherwise this will panic.
503 pub fn input(self, i: usize) -> Option<Binder<'tcx, Ty<'tcx>>> {
505 Self::Sig(sig, _) => {
506 if sig.c_variadic() {
507 sig.inputs().map_bound(|inputs| inputs.get(i).copied()).transpose()
512 Self::Closure(_, sig) => Some(sig.input(0).map_bound(|ty| ty.tuple_fields()[i])),
513 Self::Trait(inputs, _, _) => Some(inputs.map_bound(|ty| ty.tuple_fields()[i])),
517 /// Gets the argument type at the given offset. For closures this will also get the type as
518 /// written. This will return `None` when the index is out of bounds only for variadic
519 /// functions, otherwise this will panic.
520 pub fn input_with_hir(self, i: usize) -> Option<(Option<&'tcx hir::Ty<'tcx>>, Binder<'tcx, Ty<'tcx>>)> {
522 Self::Sig(sig, _) => {
523 if sig.c_variadic() {
525 .map_bound(|inputs| inputs.get(i).copied())
527 .map(|arg| (None, arg))
529 Some((None, sig.input(i)))
532 Self::Closure(decl, sig) => Some((
533 decl.and_then(|decl| decl.inputs.get(i)),
534 sig.input(0).map_bound(|ty| ty.tuple_fields()[i]),
536 Self::Trait(inputs, _, _) => Some((None, inputs.map_bound(|ty| ty.tuple_fields()[i]))),
540 /// Gets the result type, if one could be found. Note that the result type of a trait may not be
542 pub fn output(self) -> Option<Binder<'tcx, Ty<'tcx>>> {
544 Self::Sig(sig, _) | Self::Closure(_, sig) => Some(sig.output()),
545 Self::Trait(_, output, _) => output,
549 pub fn predicates_id(&self) -> Option<DefId> {
550 if let ExprFnSig::Sig(_, id) | ExprFnSig::Trait(_, _, id) = *self {
558 /// If the expression is function like, get the signature for it.
559 pub fn expr_sig<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) -> Option<ExprFnSig<'tcx>> {
560 if let Res::Def(DefKind::Fn | DefKind::Ctor(_, CtorKind::Fn) | DefKind::AssocFn, id) = path_res(cx, expr) {
561 Some(ExprFnSig::Sig(cx.tcx.fn_sig(id), Some(id)))
563 ty_sig(cx, cx.typeck_results().expr_ty_adjusted(expr).peel_refs())
567 /// If the type is function like, get the signature for it.
568 pub fn ty_sig<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<ExprFnSig<'tcx>> {
570 return ty_sig(cx, ty.boxed_ty());
573 ty::Closure(id, subs) => {
576 .and_then(|id| cx.tcx.hir().fn_decl_by_hir_id(cx.tcx.hir().local_def_id_to_hir_id(id)));
577 Some(ExprFnSig::Closure(decl, subs.as_closure().sig()))
579 ty::FnDef(id, subs) => Some(ExprFnSig::Sig(cx.tcx.bound_fn_sig(id).subst(cx.tcx, subs), Some(id))),
580 ty::Opaque(id, _) => sig_from_bounds(cx, ty, cx.tcx.item_bounds(id), cx.tcx.opt_parent(id)),
581 ty::FnPtr(sig) => Some(ExprFnSig::Sig(sig, None)),
582 ty::Dynamic(bounds, _) => {
583 let lang_items = cx.tcx.lang_items();
584 match bounds.principal() {
586 if Some(bound.def_id()) == lang_items.fn_trait()
587 || Some(bound.def_id()) == lang_items.fn_once_trait()
588 || Some(bound.def_id()) == lang_items.fn_mut_trait() =>
592 .find(|p| lang_items.fn_once_output().map_or(false, |id| id == p.item_def_id()))
593 .map(|p| p.map_bound(|p| p.term.ty().unwrap()));
594 Some(ExprFnSig::Trait(bound.map_bound(|b| b.substs.type_at(0)), output, None))
599 ty::Projection(proj) => match cx.tcx.try_normalize_erasing_regions(cx.param_env, ty) {
600 Ok(normalized_ty) if normalized_ty != ty => ty_sig(cx, normalized_ty),
601 _ => sig_for_projection(cx, proj).or_else(|| sig_from_bounds(cx, ty, cx.param_env.caller_bounds(), None)),
603 ty::Param(_) => sig_from_bounds(cx, ty, cx.param_env.caller_bounds(), None),
608 fn sig_from_bounds<'tcx>(
609 cx: &LateContext<'tcx>,
611 predicates: &'tcx [Predicate<'tcx>],
612 predicates_id: Option<DefId>,
613 ) -> Option<ExprFnSig<'tcx>> {
614 let mut inputs = None;
615 let mut output = None;
616 let lang_items = cx.tcx.lang_items();
618 for pred in predicates {
619 match pred.kind().skip_binder() {
620 PredicateKind::Trait(p)
621 if (lang_items.fn_trait() == Some(p.def_id())
622 || lang_items.fn_mut_trait() == Some(p.def_id())
623 || lang_items.fn_once_trait() == Some(p.def_id()))
624 && p.self_ty() == ty =>
626 let i = pred.kind().rebind(p.trait_ref.substs.type_at(1));
627 if inputs.map_or(false, |inputs| i != inputs) {
628 // Multiple different fn trait impls. Is this even allowed?
633 PredicateKind::Projection(p)
634 if Some(p.projection_ty.item_def_id) == lang_items.fn_once_output()
635 && p.projection_ty.self_ty() == ty =>
637 if output.is_some() {
638 // Multiple different fn trait impls. Is this even allowed?
641 output = Some(pred.kind().rebind(p.term.ty().unwrap()));
647 inputs.map(|ty| ExprFnSig::Trait(ty, output, predicates_id))
650 fn sig_for_projection<'tcx>(cx: &LateContext<'tcx>, ty: ProjectionTy<'tcx>) -> Option<ExprFnSig<'tcx>> {
651 let mut inputs = None;
652 let mut output = None;
653 let lang_items = cx.tcx.lang_items();
657 .bound_explicit_item_bounds(ty.item_def_id)
659 .map(|x| x.map_bound(|(p, _)| p))
661 match pred.0.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())) =>
668 .map_bound(|pred| pred.kind().rebind(p.trait_ref.substs.type_at(1)))
669 .subst(cx.tcx, ty.substs);
671 if inputs.map_or(false, |inputs| inputs != i) {
672 // Multiple different fn trait impls. Is this even allowed?
677 PredicateKind::Projection(p) if Some(p.projection_ty.item_def_id) == lang_items.fn_once_output() => {
678 if output.is_some() {
679 // Multiple different fn trait impls. Is this even allowed?
683 pred.map_bound(|pred| pred.kind().rebind(p.term.ty().unwrap()))
684 .subst(cx.tcx, ty.substs),
691 inputs.map(|ty| ExprFnSig::Trait(ty, output, None))
694 #[derive(Clone, Copy)]
699 impl core::ops::Add<u32> for EnumValue {
701 fn add(self, n: u32) -> Self::Output {
703 Self::Unsigned(x) => Self::Unsigned(x + u128::from(n)),
704 Self::Signed(x) => Self::Signed(x + i128::from(n)),
709 /// Attempts to read the given constant as though it were an an enum value.
710 #[expect(clippy::cast_possible_truncation, clippy::cast_possible_wrap)]
711 pub fn read_explicit_enum_value(tcx: TyCtxt<'_>, id: DefId) -> Option<EnumValue> {
712 if let Ok(ConstValue::Scalar(Scalar::Int(value))) = tcx.const_eval_poly(id) {
713 match tcx.type_of(id).kind() {
714 ty::Int(_) => Some(EnumValue::Signed(match value.size().bytes() {
715 1 => i128::from(value.assert_bits(Size::from_bytes(1)) as u8 as i8),
716 2 => i128::from(value.assert_bits(Size::from_bytes(2)) as u16 as i16),
717 4 => i128::from(value.assert_bits(Size::from_bytes(4)) as u32 as i32),
718 8 => i128::from(value.assert_bits(Size::from_bytes(8)) as u64 as i64),
719 16 => value.assert_bits(Size::from_bytes(16)) as i128,
722 ty::Uint(_) => Some(EnumValue::Unsigned(match value.size().bytes() {
723 1 => value.assert_bits(Size::from_bytes(1)),
724 2 => value.assert_bits(Size::from_bytes(2)),
725 4 => value.assert_bits(Size::from_bytes(4)),
726 8 => value.assert_bits(Size::from_bytes(8)),
727 16 => value.assert_bits(Size::from_bytes(16)),
737 /// Gets the value of the given variant.
738 pub fn get_discriminant_value(tcx: TyCtxt<'_>, adt: AdtDef<'_>, i: VariantIdx) -> EnumValue {
739 let variant = &adt.variant(i);
740 match variant.discr {
741 VariantDiscr::Explicit(id) => read_explicit_enum_value(tcx, id).unwrap(),
742 VariantDiscr::Relative(x) => match adt.variant((i.as_usize() - x as usize).into()).discr {
743 VariantDiscr::Explicit(id) => read_explicit_enum_value(tcx, id).unwrap() + x,
744 VariantDiscr::Relative(_) => EnumValue::Unsigned(x.into()),
749 /// Check if the given type is either `core::ffi::c_void`, `std::os::raw::c_void`, or one of the
750 /// platform specific `libc::<platform>::c_void` types in libc.
751 pub fn is_c_void(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
752 if let ty::Adt(adt, _) = ty.kind()
753 && let &[krate, .., name] = &*cx.get_def_path(adt.did())
754 && let sym::libc | sym::core | sym::std = krate
755 && name.as_str() == "c_void"
763 pub fn for_each_top_level_late_bound_region<B>(
765 f: impl FnMut(BoundRegion) -> ControlFlow<B>,
766 ) -> ControlFlow<B> {
771 impl<'tcx, B, F: FnMut(BoundRegion) -> ControlFlow<B>> TypeVisitor<'tcx> for V<F> {
773 fn visit_region(&mut self, r: Region<'tcx>) -> ControlFlow<Self::BreakTy> {
774 if let RegionKind::ReLateBound(idx, bound) = r.kind() && idx.as_u32() == self.index {
777 ControlFlow::Continue(())
780 fn visit_binder<T: TypeVisitable<'tcx>>(&mut self, t: &Binder<'tcx, T>) -> ControlFlow<Self::BreakTy> {
782 let res = t.super_visit_with(self);
787 ty.visit_with(&mut V { index: 0, f })
790 /// Gets the struct or enum variant from the given `Res`
791 pub fn variant_of_res<'tcx>(cx: &LateContext<'tcx>, res: Res) -> Option<&'tcx VariantDef> {
793 Res::Def(DefKind::Struct, id) => Some(cx.tcx.adt_def(id).non_enum_variant()),
794 Res::Def(DefKind::Variant, id) => Some(cx.tcx.adt_def(cx.tcx.parent(id)).variant_with_id(id)),
795 Res::Def(DefKind::Ctor(CtorOf::Struct, _), id) => Some(cx.tcx.adt_def(cx.tcx.parent(id)).non_enum_variant()),
796 Res::Def(DefKind::Ctor(CtorOf::Variant, _), id) => {
797 let var_id = cx.tcx.parent(id);
798 Some(cx.tcx.adt_def(cx.tcx.parent(var_id)).variant_with_id(var_id))
800 Res::SelfCtor(id) => Some(cx.tcx.type_of(id).ty_adt_def().unwrap().non_enum_variant()),
805 /// Checks if the type is a type parameter implementing `FnOnce`, but not `FnMut`.
806 pub fn ty_is_fn_once_param<'tcx>(tcx: TyCtxt<'_>, ty: Ty<'tcx>, predicates: &'tcx [Predicate<'_>]) -> bool {
807 let ty::Param(ty) = *ty.kind() else {
810 let lang = tcx.lang_items();
811 let (Some(fn_once_id), Some(fn_mut_id), Some(fn_id))
812 = (lang.fn_once_trait(), lang.fn_mut_trait(), lang.fn_trait())
818 .try_fold(false, |found, p| {
819 if let PredicateKind::Trait(p) = p.kind().skip_binder()
820 && let ty::Param(self_ty) = p.trait_ref.self_ty().kind()
821 && ty.index == self_ty.index
823 // This should use `super_traits_of`, but that's a private function.
824 if p.trait_ref.def_id == fn_once_id {
826 } else if p.trait_ref.def_id == fn_mut_id || p.trait_ref.def_id == fn_id {
835 /// Comes up with an "at least" guesstimate for the type's size, not taking into
836 /// account the layout of type parameters.
837 pub fn approx_ty_size<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> u64 {
838 use rustc_middle::ty::layout::LayoutOf;
839 if !is_normalizable(cx, cx.param_env, ty) {
842 match (cx.layout_of(ty).map(|layout| layout.size.bytes()), ty.kind()) {
843 (Ok(size), _) => size,
844 (Err(_), ty::Tuple(list)) => list.as_substs().types().map(|t| approx_ty_size(cx, t)).sum(),
845 (Err(_), ty::Array(t, n)) => {
846 n.try_eval_usize(cx.tcx, cx.param_env).unwrap_or_default() * approx_ty_size(cx, *t)
848 (Err(_), ty::Adt(def, subst)) if def.is_struct() => def
854 .map(|field| approx_ty_size(cx, field.ty(cx.tcx, subst)))
858 (Err(_), ty::Adt(def, subst)) if def.is_enum() => def
864 .map(|field| approx_ty_size(cx, field.ty(cx.tcx, subst)))
868 .unwrap_or_default(),
869 (Err(_), ty::Adt(def, subst)) if def.is_union() => def
875 .map(|field| approx_ty_size(cx, field.ty(cx.tcx, subst)))
880 .unwrap_or_default(),