575 lines
22 KiB
Rust
575 lines
22 KiB
Rust
//! Util methods for [`rustc_middle::ty`]
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#![allow(clippy::module_name_repetitions)]
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use rustc_ast::ast::Mutability;
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use rustc_data_structures::fx::FxHashMap;
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use rustc_hir as hir;
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use rustc_hir::def::{CtorKind, DefKind, Res};
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use rustc_hir::def_id::DefId;
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use rustc_hir::{Expr, TyKind, Unsafety};
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use rustc_infer::infer::TyCtxtInferExt;
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use rustc_lint::LateContext;
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use rustc_middle::mir::interpret::{ConstValue, Scalar};
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use rustc_middle::ty::subst::{GenericArg, GenericArgKind, Subst};
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use rustc_middle::ty::{
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self, AdtDef, Binder, FnSig, IntTy, Predicate, PredicateKind, Ty, TyCtxt, TypeFoldable, UintTy, VariantDiscr,
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};
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use rustc_span::symbol::Ident;
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use rustc_span::{sym, Span, Symbol, DUMMY_SP};
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use rustc_target::abi::{Size, VariantIdx};
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use rustc_trait_selection::infer::InferCtxtExt;
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use rustc_trait_selection::traits::query::normalize::AtExt;
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use std::iter;
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use crate::{match_def_path, must_use_attr, path_res};
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// Checks if the given type implements copy.
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pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
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ty.is_copy_modulo_regions(cx.tcx.at(DUMMY_SP), cx.param_env)
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}
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/// Checks whether a type can be partially moved.
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pub fn can_partially_move_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
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if has_drop(cx, ty) || is_copy(cx, ty) {
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return false;
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}
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match ty.kind() {
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ty::Param(_) => false,
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ty::Adt(def, subs) => def.all_fields().any(|f| !is_copy(cx, f.ty(cx.tcx, subs))),
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_ => true,
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}
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}
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/// Walks into `ty` and returns `true` if any inner type is the same as `other_ty`
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pub fn contains_ty(ty: Ty<'_>, other_ty: Ty<'_>) -> bool {
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ty.walk().any(|inner| match inner.unpack() {
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GenericArgKind::Type(inner_ty) => other_ty == inner_ty,
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GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => false,
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})
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}
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/// Walks into `ty` and returns `true` if any inner type is an instance of the given adt
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/// constructor.
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pub fn contains_adt_constructor(ty: Ty<'_>, adt: &AdtDef) -> bool {
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ty.walk().any(|inner| match inner.unpack() {
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GenericArgKind::Type(inner_ty) => inner_ty.ty_adt_def() == Some(adt),
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GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => false,
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})
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}
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/// Resolves `<T as Iterator>::Item` for `T`
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/// Do not invoke without first verifying that the type implements `Iterator`
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pub fn get_iterator_item_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'tcx>> {
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cx.tcx
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.get_diagnostic_item(sym::Iterator)
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.and_then(|iter_did| get_associated_type(cx, ty, iter_did, "Item"))
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}
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/// Returns the associated type `name` for `ty` as an implementation of `trait_id`.
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/// Do not invoke without first verifying that the type implements the trait.
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pub fn get_associated_type<'tcx>(
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cx: &LateContext<'tcx>,
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ty: Ty<'tcx>,
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trait_id: DefId,
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name: &str,
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) -> Option<Ty<'tcx>> {
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cx.tcx
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.associated_items(trait_id)
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.find_by_name_and_kind(cx.tcx, Ident::from_str(name), ty::AssocKind::Type, trait_id)
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.map(|assoc| {
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let proj = cx.tcx.mk_projection(assoc.def_id, cx.tcx.mk_substs_trait(ty, &[]));
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cx.tcx.normalize_erasing_regions(cx.param_env, proj)
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})
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}
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/// Returns true if ty has `iter` or `iter_mut` methods
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pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<Symbol> {
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// FIXME: instead of this hard-coded list, we should check if `<adt>::iter`
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// exists and has the desired signature. Unfortunately FnCtxt is not exported
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// so we can't use its `lookup_method` method.
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let into_iter_collections: &[Symbol] = &[
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sym::Vec,
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sym::Option,
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sym::Result,
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sym::BTreeMap,
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sym::BTreeSet,
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sym::VecDeque,
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sym::LinkedList,
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sym::BinaryHeap,
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sym::HashSet,
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sym::HashMap,
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sym::PathBuf,
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sym::Path,
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sym::Receiver,
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];
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let ty_to_check = match probably_ref_ty.kind() {
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ty::Ref(_, ty_to_check, _) => ty_to_check,
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_ => probably_ref_ty,
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};
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let def_id = match ty_to_check.kind() {
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ty::Array(..) => return Some(sym::array),
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ty::Slice(..) => return Some(sym::slice),
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ty::Adt(adt, _) => adt.did,
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_ => return None,
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};
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for &name in into_iter_collections {
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if cx.tcx.is_diagnostic_item(name, def_id) {
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return Some(cx.tcx.item_name(def_id));
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}
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}
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None
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}
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/// Checks whether a type implements a trait.
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/// The function returns false in case the type contains an inference variable.
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///
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/// See:
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/// * [`get_trait_def_id`](super::get_trait_def_id) to get a trait [`DefId`].
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/// * [Common tools for writing lints] for an example how to use this function and other options.
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///
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/// [Common tools for writing lints]: https://github.com/rust-lang/rust-clippy/blob/master/doc/common_tools_writing_lints.md#checking-if-a-type-implements-a-specific-trait
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pub fn implements_trait<'tcx>(
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cx: &LateContext<'tcx>,
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ty: Ty<'tcx>,
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trait_id: DefId,
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ty_params: &[GenericArg<'tcx>],
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) -> bool {
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// Clippy shouldn't have infer types
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assert!(!ty.needs_infer());
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let ty = cx.tcx.erase_regions(ty);
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if ty.has_escaping_bound_vars() {
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return false;
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}
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let ty_params = cx.tcx.mk_substs(ty_params.iter());
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cx.tcx.infer_ctxt().enter(|infcx| {
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infcx
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.type_implements_trait(trait_id, ty, ty_params, cx.param_env)
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.must_apply_modulo_regions()
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})
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}
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/// Checks whether this type implements `Drop`.
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pub fn has_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
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match ty.ty_adt_def() {
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Some(def) => def.has_dtor(cx.tcx),
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None => false,
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}
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}
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// Returns whether the type has #[must_use] attribute
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pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
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match ty.kind() {
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ty::Adt(adt, _) => must_use_attr(cx.tcx.get_attrs(adt.did)).is_some(),
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ty::Foreign(ref did) => must_use_attr(cx.tcx.get_attrs(*did)).is_some(),
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ty::Slice(ty) | ty::Array(ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) => {
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// for the Array case we don't need to care for the len == 0 case
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// because we don't want to lint functions returning empty arrays
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is_must_use_ty(cx, *ty)
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},
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ty::Tuple(substs) => substs.types().any(|ty| is_must_use_ty(cx, ty)),
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ty::Opaque(ref def_id, _) => {
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for (predicate, _) in cx.tcx.explicit_item_bounds(*def_id) {
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if let ty::PredicateKind::Trait(trait_predicate) = predicate.kind().skip_binder() {
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if must_use_attr(cx.tcx.get_attrs(trait_predicate.trait_ref.def_id)).is_some() {
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return true;
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}
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}
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}
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false
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},
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ty::Dynamic(binder, _) => {
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for predicate in binder.iter() {
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if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
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if must_use_attr(cx.tcx.get_attrs(trait_ref.def_id)).is_some() {
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return true;
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}
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}
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}
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false
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},
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_ => false,
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}
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}
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// FIXME: Per https://doc.rust-lang.org/nightly/nightly-rustc/rustc_trait_selection/infer/at/struct.At.html#method.normalize
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// this function can be removed once the `normalize` method does not panic when normalization does
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// not succeed
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/// Checks if `Ty` is normalizable. This function is useful
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/// to avoid crashes on `layout_of`.
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pub fn is_normalizable<'tcx>(cx: &LateContext<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
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is_normalizable_helper(cx, param_env, ty, &mut FxHashMap::default())
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}
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fn is_normalizable_helper<'tcx>(
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cx: &LateContext<'tcx>,
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param_env: ty::ParamEnv<'tcx>,
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ty: Ty<'tcx>,
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cache: &mut FxHashMap<Ty<'tcx>, bool>,
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) -> bool {
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if let Some(&cached_result) = cache.get(ty) {
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return cached_result;
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}
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// prevent recursive loops, false-negative is better than endless loop leading to stack overflow
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cache.insert(ty, false);
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let result = cx.tcx.infer_ctxt().enter(|infcx| {
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let cause = rustc_middle::traits::ObligationCause::dummy();
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if infcx.at(&cause, param_env).normalize(ty).is_ok() {
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match ty.kind() {
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ty::Adt(def, substs) => def.variants.iter().all(|variant| {
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variant
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.fields
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.iter()
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.all(|field| is_normalizable_helper(cx, param_env, field.ty(cx.tcx, substs), cache))
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}),
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_ => ty.walk().all(|generic_arg| match generic_arg.unpack() {
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GenericArgKind::Type(inner_ty) if inner_ty != ty => {
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is_normalizable_helper(cx, param_env, inner_ty, cache)
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},
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_ => true, // if inner_ty == ty, we've already checked it
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}),
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}
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} else {
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false
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}
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});
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cache.insert(ty, result);
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result
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}
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/// Returns `true` if the given type is a non aggregate primitive (a `bool` or `char`, any
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/// integer or floating-point number type). For checking aggregation of primitive types (e.g.
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/// tuples and slices of primitive type) see `is_recursively_primitive_type`
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pub fn is_non_aggregate_primitive_type(ty: Ty<'_>) -> bool {
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matches!(ty.kind(), ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_))
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}
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/// Returns `true` if the given type is a primitive (a `bool` or `char`, any integer or
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/// floating-point number type, a `str`, or an array, slice, or tuple of those types).
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pub fn is_recursively_primitive_type(ty: Ty<'_>) -> bool {
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match ty.kind() {
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ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str => true,
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ty::Ref(_, inner, _) if *inner.kind() == ty::Str => true,
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ty::Array(inner_type, _) | ty::Slice(inner_type) => is_recursively_primitive_type(inner_type),
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ty::Tuple(inner_types) => inner_types.types().all(is_recursively_primitive_type),
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_ => false,
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}
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}
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/// Checks if the type is a reference equals to a diagnostic item
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pub fn is_type_ref_to_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
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match ty.kind() {
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ty::Ref(_, ref_ty, _) => match ref_ty.kind() {
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ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did),
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_ => false,
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},
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_ => false,
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}
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}
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/// Checks if the type is equal to a diagnostic item. To check if a type implements a
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/// trait marked with a diagnostic item use [`implements_trait`].
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///
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/// For a further exploitation what diagnostic items are see [diagnostic items] in
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/// rustc-dev-guide.
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///
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/// ---
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///
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/// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
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///
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/// [Diagnostic Items]: https://rustc-dev-guide.rust-lang.org/diagnostics/diagnostic-items.html
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pub fn is_type_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symbol) -> bool {
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match ty.kind() {
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ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(diag_item, adt.did),
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_ => false,
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}
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}
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/// Checks if the type is equal to a lang item.
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///
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/// Returns `false` if the `LangItem` is not defined.
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pub fn is_type_lang_item(cx: &LateContext<'_>, ty: Ty<'_>, lang_item: hir::LangItem) -> bool {
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match ty.kind() {
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ty::Adt(adt, _) => cx.tcx.lang_items().require(lang_item).map_or(false, |li| li == adt.did),
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_ => false,
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}
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}
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/// Return `true` if the passed `typ` is `isize` or `usize`.
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pub fn is_isize_or_usize(typ: Ty<'_>) -> bool {
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matches!(typ.kind(), ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize))
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}
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/// Checks if type is struct, enum or union type with the given def path.
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///
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/// If the type is a diagnostic item, use `is_type_diagnostic_item` instead.
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/// If you change the signature, remember to update the internal lint `MatchTypeOnDiagItem`
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pub fn match_type(cx: &LateContext<'_>, ty: Ty<'_>, path: &[&str]) -> bool {
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match ty.kind() {
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ty::Adt(adt, _) => match_def_path(cx, adt.did, path),
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_ => false,
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}
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}
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/// Peels off all references on the type. Returns the underlying type and the number of references
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/// removed.
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pub fn peel_mid_ty_refs(ty: Ty<'_>) -> (Ty<'_>, usize) {
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fn peel(ty: Ty<'_>, count: usize) -> (Ty<'_>, usize) {
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if let ty::Ref(_, ty, _) = ty.kind() {
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peel(ty, count + 1)
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} else {
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(ty, count)
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}
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}
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peel(ty, 0)
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}
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/// Peels off all references on the type.Returns the underlying type, the number of references
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/// removed, and whether the pointer is ultimately mutable or not.
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pub fn peel_mid_ty_refs_is_mutable(ty: Ty<'_>) -> (Ty<'_>, usize, Mutability) {
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fn f(ty: Ty<'_>, count: usize, mutability: Mutability) -> (Ty<'_>, usize, Mutability) {
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match ty.kind() {
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ty::Ref(_, ty, Mutability::Mut) => f(ty, count + 1, mutability),
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ty::Ref(_, ty, Mutability::Not) => f(ty, count + 1, Mutability::Not),
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_ => (ty, count, mutability),
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}
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}
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f(ty, 0, Mutability::Mut)
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}
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/// Returns `true` if the given type is an `unsafe` function.
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pub fn type_is_unsafe_function<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
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match ty.kind() {
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ty::FnDef(..) | ty::FnPtr(_) => ty.fn_sig(cx.tcx).unsafety() == Unsafety::Unsafe,
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_ => false,
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}
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}
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/// Returns the base type for HIR references and pointers.
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pub fn walk_ptrs_hir_ty<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
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match ty.kind {
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TyKind::Ptr(ref mut_ty) | TyKind::Rptr(_, ref mut_ty) => walk_ptrs_hir_ty(mut_ty.ty),
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_ => ty,
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}
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}
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/// Returns the base type for references and raw pointers, and count reference
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/// depth.
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pub fn walk_ptrs_ty_depth(ty: Ty<'_>) -> (Ty<'_>, usize) {
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fn inner(ty: Ty<'_>, depth: usize) -> (Ty<'_>, usize) {
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match ty.kind() {
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ty::Ref(_, ty, _) => inner(ty, depth + 1),
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_ => (ty, depth),
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}
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}
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inner(ty, 0)
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}
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/// Returns `true` if types `a` and `b` are same types having same `Const` generic args,
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/// otherwise returns `false`
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pub fn same_type_and_consts<'tcx>(a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
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match (&a.kind(), &b.kind()) {
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(&ty::Adt(did_a, substs_a), &ty::Adt(did_b, substs_b)) => {
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if did_a != did_b {
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return false;
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}
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substs_a
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.iter()
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.zip(substs_b.iter())
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.all(|(arg_a, arg_b)| match (arg_a.unpack(), arg_b.unpack()) {
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(GenericArgKind::Const(inner_a), GenericArgKind::Const(inner_b)) => inner_a == inner_b,
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(GenericArgKind::Type(type_a), GenericArgKind::Type(type_b)) => {
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same_type_and_consts(type_a, type_b)
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},
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_ => true,
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})
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},
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_ => a == b,
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}
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}
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/// Checks if a given type looks safe to be uninitialized.
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pub fn is_uninit_value_valid_for_ty(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
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match ty.kind() {
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ty::Array(component, _) => is_uninit_value_valid_for_ty(cx, component),
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ty::Tuple(types) => types.types().all(|ty| is_uninit_value_valid_for_ty(cx, ty)),
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ty::Adt(adt, _) => cx.tcx.lang_items().maybe_uninit() == Some(adt.did),
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_ => false,
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}
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}
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/// Gets an iterator over all predicates which apply to the given item.
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pub fn all_predicates_of(tcx: TyCtxt<'_>, id: DefId) -> impl Iterator<Item = &(Predicate<'_>, Span)> {
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let mut next_id = Some(id);
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iter::from_fn(move || {
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next_id.take().map(|id| {
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let preds = tcx.predicates_of(id);
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next_id = preds.parent;
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preds.predicates.iter()
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})
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})
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.flatten()
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}
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/// A signature for a function like type.
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#[derive(Clone, Copy)]
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pub enum ExprFnSig<'tcx> {
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Sig(Binder<'tcx, FnSig<'tcx>>),
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Closure(Binder<'tcx, FnSig<'tcx>>),
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Trait(Binder<'tcx, Ty<'tcx>>, Option<Binder<'tcx, Ty<'tcx>>>),
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}
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impl<'tcx> ExprFnSig<'tcx> {
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/// Gets the argument type at the given offset.
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pub fn input(self, i: usize) -> Binder<'tcx, Ty<'tcx>> {
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match self {
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Self::Sig(sig) => sig.input(i),
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Self::Closure(sig) => sig.input(0).map_bound(|ty| ty.tuple_element_ty(i).unwrap()),
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Self::Trait(inputs, _) => inputs.map_bound(|ty| ty.tuple_element_ty(i).unwrap()),
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}
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}
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/// Gets the result type, if one could be found. Note that the result type of a trait may not be
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/// specified.
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pub fn output(self) -> Option<Binder<'tcx, Ty<'tcx>>> {
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match self {
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Self::Sig(sig) | Self::Closure(sig) => Some(sig.output()),
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Self::Trait(_, output) => output,
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}
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}
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}
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/// If the expression is function like, get the signature for it.
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pub fn expr_sig<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) -> Option<ExprFnSig<'tcx>> {
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if let Res::Def(DefKind::Fn | DefKind::Ctor(_, CtorKind::Fn) | DefKind::AssocFn, id) = path_res(cx, expr) {
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Some(ExprFnSig::Sig(cx.tcx.fn_sig(id)))
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} else {
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let ty = cx.typeck_results().expr_ty_adjusted(expr).peel_refs();
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match *ty.kind() {
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ty::Closure(_, subs) => Some(ExprFnSig::Closure(subs.as_closure().sig())),
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ty::FnDef(id, subs) => Some(ExprFnSig::Sig(cx.tcx.fn_sig(id).subst(cx.tcx, subs))),
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ty::FnPtr(sig) => Some(ExprFnSig::Sig(sig)),
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ty::Dynamic(bounds, _) => {
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let lang_items = cx.tcx.lang_items();
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match bounds.principal() {
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Some(bound)
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if Some(bound.def_id()) == lang_items.fn_trait()
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|| Some(bound.def_id()) == lang_items.fn_once_trait()
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|| Some(bound.def_id()) == lang_items.fn_mut_trait() =>
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{
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let output = bounds
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.projection_bounds()
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.find(|p| lang_items.fn_once_output().map_or(false, |id| id == p.item_def_id()))
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.map(|p| p.map_bound(|p| p.term.ty().expect("return type was a const")));
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Some(ExprFnSig::Trait(bound.map_bound(|b| b.substs.type_at(0)), output))
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},
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_ => None,
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}
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},
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ty::Param(_) | ty::Projection(..) => {
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let mut inputs = None;
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let mut output = None;
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let lang_items = cx.tcx.lang_items();
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for (pred, _) in all_predicates_of(cx.tcx, cx.typeck_results().hir_owner.to_def_id()) {
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let mut is_input = false;
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if let Some(ty) = pred
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.kind()
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.map_bound(|pred| match pred {
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PredicateKind::Trait(p)
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if (lang_items.fn_trait() == Some(p.def_id())
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|| lang_items.fn_mut_trait() == Some(p.def_id())
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|| lang_items.fn_once_trait() == Some(p.def_id()))
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&& p.self_ty() == ty =>
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{
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is_input = true;
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Some(p.trait_ref.substs.type_at(1))
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},
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PredicateKind::Projection(p)
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if Some(p.projection_ty.item_def_id) == lang_items.fn_once_output()
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&& p.projection_ty.self_ty() == ty =>
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{
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is_input = false;
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p.term.ty()
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},
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_ => None,
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})
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.transpose()
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{
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if is_input && inputs.is_none() {
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inputs = Some(ty);
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} else if !is_input && output.is_none() {
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output = Some(ty);
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} else {
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// Multiple different fn trait impls. Is this even allowed?
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return None;
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}
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}
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}
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inputs.map(|ty| ExprFnSig::Trait(ty, output))
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},
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_ => None,
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}
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}
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}
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#[derive(Clone, Copy)]
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pub enum EnumValue {
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Unsigned(u128),
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Signed(i128),
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}
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impl core::ops::Add<u32> for EnumValue {
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type Output = Self;
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fn add(self, n: u32) -> Self::Output {
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match self {
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Self::Unsigned(x) => Self::Unsigned(x + u128::from(n)),
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Self::Signed(x) => Self::Signed(x + i128::from(n)),
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}
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}
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}
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/// Attempts to read the given constant as though it were an an enum value.
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#[allow(clippy::cast_possible_truncation, clippy::cast_possible_wrap)]
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pub fn read_explicit_enum_value(tcx: TyCtxt<'_>, id: DefId) -> Option<EnumValue> {
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if let Ok(ConstValue::Scalar(Scalar::Int(value))) = tcx.const_eval_poly(id) {
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match tcx.type_of(id).kind() {
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ty::Int(_) => Some(EnumValue::Signed(match value.size().bytes() {
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1 => i128::from(value.assert_bits(Size::from_bytes(1)) as u8 as i8),
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2 => i128::from(value.assert_bits(Size::from_bytes(2)) as u16 as i16),
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4 => i128::from(value.assert_bits(Size::from_bytes(4)) as u32 as i32),
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8 => i128::from(value.assert_bits(Size::from_bytes(8)) as u64 as i64),
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16 => value.assert_bits(Size::from_bytes(16)) as i128,
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_ => return None,
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})),
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ty::Uint(_) => Some(EnumValue::Unsigned(match value.size().bytes() {
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1 => value.assert_bits(Size::from_bytes(1)),
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2 => value.assert_bits(Size::from_bytes(2)),
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4 => value.assert_bits(Size::from_bytes(4)),
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8 => value.assert_bits(Size::from_bytes(8)),
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16 => value.assert_bits(Size::from_bytes(16)),
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_ => return None,
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})),
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_ => None,
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}
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} else {
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None
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}
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}
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/// Gets the value of the given variant.
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pub fn get_discriminant_value(tcx: TyCtxt<'_>, adt: &'_ AdtDef, i: VariantIdx) -> EnumValue {
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let variant = &adt.variants[i];
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match variant.discr {
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VariantDiscr::Explicit(id) => read_explicit_enum_value(tcx, id).unwrap(),
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VariantDiscr::Relative(x) => match adt.variants[(i.as_usize() - x as usize).into()].discr {
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VariantDiscr::Explicit(id) => read_explicit_enum_value(tcx, id).unwrap() + x,
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VariantDiscr::Relative(_) => EnumValue::Unsigned(x.into()),
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},
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}
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}
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