1 //! Common logic for borrowck use-after-move errors when moved into a `fn(self)`,
2 //! as well as errors when attempting to call a non-const function in a const
5 use rustc_hir::def_id::DefId;
6 use rustc_hir::{lang_items, LangItem};
7 use rustc_middle::ty::subst::SubstsRef;
8 use rustc_middle::ty::{AssocItemContainer, Instance, ParamEnv, Ty, TyCtxt};
9 use rustc_span::symbol::Ident;
10 use rustc_span::{sym, DesugaringKind, Span};
12 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
13 pub enum CallDesugaringKind {
14 /// for _ in x {} calls x.into_iter()
16 /// x? calls x.branch()
18 /// x? calls type_of(x)::from_residual()
20 /// try { ..; x } calls type_of(x)::from_output(x)
24 impl CallDesugaringKind {
25 pub fn trait_def_id(self, tcx: TyCtxt<'_>) -> DefId {
27 Self::ForLoopIntoIter => tcx.get_diagnostic_item(sym::IntoIterator).unwrap(),
28 Self::QuestionBranch | Self::TryBlockFromOutput => {
29 tcx.require_lang_item(LangItem::Try, None)
31 Self::QuestionFromResidual => tcx.get_diagnostic_item(sym::FromResidual).unwrap(),
36 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
37 pub enum CallKind<'tcx> {
38 /// A normal method call of the form `receiver.foo(a, b, c)`
40 self_arg: Option<Ident>,
41 desugaring: Option<(CallDesugaringKind, Ty<'tcx>)>,
43 method_substs: SubstsRef<'tcx>,
45 /// A call to `Fn(..)::call(..)`, desugared from `my_closure(a, b, c)`
46 FnCall { fn_trait_id: DefId, self_ty: Ty<'tcx> },
47 /// A call to an operator trait, desugared from operator syntax (e.g. `a << b`)
48 Operator { self_arg: Option<Ident>, trait_id: DefId, self_ty: Ty<'tcx> },
50 /// The `Span` of the `Target` associated type
51 /// in the `Deref` impl we are using.
53 /// The type `T::Deref` we are dereferencing to
54 deref_target_ty: Ty<'tcx>,
59 pub fn call_kind<'tcx>(
61 param_env: ParamEnv<'tcx>,
63 method_substs: SubstsRef<'tcx>,
66 self_arg: Option<Ident>,
68 let parent = tcx.opt_associated_item(method_did).and_then(|assoc| {
69 let container_id = assoc.container_id(tcx);
70 match assoc.container {
71 AssocItemContainer::ImplContainer => tcx.trait_id_of_impl(container_id),
72 AssocItemContainer::TraitContainer => Some(container_id),
76 let fn_call = parent.and_then(|p| {
77 lang_items::FN_TRAITS.iter().filter_map(|&l| tcx.lang_items().get(l)).find(|&id| id == p)
80 let operator = if !from_hir_call && let Some(p) = parent {
81 lang_items::OPERATORS.iter().filter_map(|&l| tcx.lang_items().get(l)).find(|&id| id == p)
86 let is_deref = !from_hir_call && tcx.is_diagnostic_item(sym::deref_method, method_did);
88 // Check for a 'special' use of 'self' -
89 // an FnOnce call, an operator (e.g. `<<`), or a
91 let kind = if let Some(trait_id) = fn_call {
92 Some(CallKind::FnCall { fn_trait_id: trait_id, self_ty: method_substs.type_at(0) })
93 } else if let Some(trait_id) = operator {
94 Some(CallKind::Operator { self_arg, trait_id, self_ty: method_substs.type_at(0) })
96 let deref_target = tcx.get_diagnostic_item(sym::deref_target).and_then(|deref_target| {
97 Instance::resolve(tcx, param_env, deref_target, method_substs).transpose()
99 if let Some(Ok(instance)) = deref_target {
100 let deref_target_ty = instance.ty(tcx, param_env);
101 Some(CallKind::DerefCoercion {
102 deref_target: tcx.def_span(instance.def_id()),
104 self_ty: method_substs.type_at(0),
113 kind.unwrap_or_else(|| {
114 // This isn't a 'special' use of `self`
115 debug!(?method_did, ?fn_call_span);
116 let desugaring = if Some(method_did) == tcx.lang_items().into_iter_fn()
117 && fn_call_span.desugaring_kind() == Some(DesugaringKind::ForLoop)
119 Some((CallDesugaringKind::ForLoopIntoIter, method_substs.type_at(0)))
120 } else if fn_call_span.desugaring_kind() == Some(DesugaringKind::QuestionMark) {
121 if Some(method_did) == tcx.lang_items().branch_fn() {
122 Some((CallDesugaringKind::QuestionBranch, method_substs.type_at(0)))
123 } else if Some(method_did) == tcx.lang_items().from_residual_fn() {
124 Some((CallDesugaringKind::QuestionFromResidual, method_substs.type_at(0)))
128 } else if Some(method_did) == tcx.lang_items().from_output_fn()
129 && fn_call_span.desugaring_kind() == Some(DesugaringKind::TryBlock)
131 Some((CallDesugaringKind::TryBlockFromOutput, method_substs.type_at(0)))
135 CallKind::Normal { self_arg, desugaring, method_did, method_substs }