compiler/rustc_trait_selection/src/solve/trait_goals/structural_traits.rs

   1 use rustc_hir::{Movability, Mutability};
   2 use rustc_infer::{infer::InferCtxt, traits::query::NoSolution};
   3 use rustc_middle::ty::{self, Ty, TyCtxt};
   4
   5 // Calculates the constituent types of a type for `auto trait` purposes.
   6 //
   7 // For types with an "existential" binder, i.e. generator witnesses, we also
   8 // instantiate the binder with placeholders eagerly.
   9 pub(super) fn instantiate_constituent_tys_for_auto_trait<'tcx>(
  10     infcx: &InferCtxt<'tcx>,
  11     ty: Ty<'tcx>,
  12 ) -> Result<Vec<Ty<'tcx>>, NoSolution> {
  13     let tcx = infcx.tcx;
  14     match *ty.kind() {
  15         ty::Uint(_)
  16         | ty::Int(_)
  17         | ty::Bool
  18         | ty::Float(_)
  19         | ty::FnDef(..)
  20         | ty::FnPtr(_)
  21         | ty::Str
  22         | ty::Error(_)
  23         | ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
  24         | ty::Never
  25         | ty::Char => Ok(vec![]),
  26
  27         ty::Placeholder(..)
  28         | ty::Dynamic(..)
  29         | ty::Param(..)
  30         | ty::Foreign(..)
  31         | ty::Alias(ty::Projection, ..)
  32         | ty::Bound(..)
  33         | ty::Infer(ty::TyVar(_)) => Err(NoSolution),
  34
  35         ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => bug!(),
  36
  37         ty::RawPtr(ty::TypeAndMut { ty: element_ty, .. }) | ty::Ref(_, element_ty, _) => {
  38             Ok(vec![element_ty])
  39         }
  40
  41         ty::Array(element_ty, _) | ty::Slice(element_ty) => Ok(vec![element_ty]),
  42
  43         ty::Tuple(ref tys) => {
  44             // (T1, ..., Tn) -- meets any bound that all of T1...Tn meet
  45             Ok(tys.iter().collect())
  46         }
  47
  48         ty::Closure(_, ref substs) => Ok(vec![substs.as_closure().tupled_upvars_ty()]),
  49
  50         ty::Generator(_, ref substs, _) => {
  51             let generator_substs = substs.as_generator();
  52             Ok(vec![generator_substs.tupled_upvars_ty(), generator_substs.witness()])
  53         }
  54
  55         ty::GeneratorWitness(types) => {
  56             Ok(infcx.replace_bound_vars_with_placeholders(types).to_vec())
  57         }
  58
  59         // For `PhantomData<T>`, we pass `T`.
  60         ty::Adt(def, substs) if def.is_phantom_data() => Ok(vec![substs.type_at(0)]),
  61
  62         ty::Adt(def, substs) => Ok(def.all_fields().map(|f| f.ty(tcx, substs)).collect()),
  63
  64         ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs, .. }) => {
  65             // We can resolve the `impl Trait` to its concrete type,
  66             // which enforces a DAG between the functions requiring
  67             // the auto trait bounds in question.
  68             Ok(vec![tcx.bound_type_of(def_id).subst(tcx, substs)])
  69         }
  70     }
  71 }
  72
  73 pub(super) fn instantiate_constituent_tys_for_sized_trait<'tcx>(
  74     infcx: &InferCtxt<'tcx>,
  75     ty: Ty<'tcx>,
  76 ) -> Result<Vec<Ty<'tcx>>, NoSolution> {
  77     match *ty.kind() {
  78         ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
  79         | ty::Uint(_)
  80         | ty::Int(_)
  81         | ty::Bool
  82         | ty::Float(_)
  83         | ty::FnDef(..)
  84         | ty::FnPtr(_)
  85         | ty::RawPtr(..)
  86         | ty::Char
  87         | ty::Ref(..)
  88         | ty::Generator(..)
  89         | ty::GeneratorWitness(..)
  90         | ty::Array(..)
  91         | ty::Closure(..)
  92         | ty::Never
  93         | ty::Dynamic(_, _, ty::DynStar)
  94         | ty::Error(_) => Ok(vec![]),
  95
  96         ty::Str
  97         | ty::Slice(_)
  98         | ty::Dynamic(..)
  99         | ty::Foreign(..)
 100         | ty::Alias(..)
 101         | ty::Param(_)
 102         | ty::Infer(ty::TyVar(_)) => Err(NoSolution),
 103
 104         ty::Placeholder(..)
 105         | ty::Bound(..)
 106         | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => bug!(),
 107
 108         ty::Tuple(tys) => Ok(tys.to_vec()),
 109
 110         ty::Adt(def, substs) => {
 111             let sized_crit = def.sized_constraint(infcx.tcx);
 112             Ok(sized_crit
 113                 .0
 114                 .iter()
 115                 .map(|ty| sized_crit.rebind(*ty).subst(infcx.tcx, substs))
 116                 .collect())
 117         }
 118     }
 119 }
 120
 121 pub(super) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>(
 122     infcx: &InferCtxt<'tcx>,
 123     ty: Ty<'tcx>,
 124 ) -> Result<Vec<Ty<'tcx>>, NoSolution> {
 125     match *ty.kind() {
 126         ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
 127         | ty::FnDef(..)
 128         | ty::FnPtr(_)
 129         | ty::Error(_) => Ok(vec![]),
 130
 131         // Implementations are provided in core
 132         ty::Uint(_)
 133         | ty::Int(_)
 134         | ty::Bool
 135         | ty::Float(_)
 136         | ty::Char
 137         | ty::RawPtr(..)
 138         | ty::Never
 139         | ty::Ref(_, _, Mutability::Not)
 140         | ty::Array(..) => Err(NoSolution),
 141
 142         ty::Dynamic(..)
 143         | ty::Str
 144         | ty::Slice(_)
 145         | ty::Generator(_, _, Movability::Static)
 146         | ty::Foreign(..)
 147         | ty::Ref(_, _, Mutability::Mut)
 148         | ty::Adt(_, _)
 149         | ty::Alias(_, _)
 150         | ty::Param(_)
 151         | ty::Infer(ty::TyVar(_)) => Err(NoSolution),
 152
 153         ty::Placeholder(..)
 154         | ty::Bound(..)
 155         | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => bug!(),
 156
 157         ty::Tuple(tys) => Ok(tys.to_vec()),
 158
 159         ty::Closure(_, substs) => Ok(vec![substs.as_closure().tupled_upvars_ty()]),
 160
 161         ty::Generator(_, substs, Movability::Movable) => {
 162             if infcx.tcx.features().generator_clone {
 163                 let generator = substs.as_generator();
 164                 Ok(vec![generator.tupled_upvars_ty(), generator.witness()])
 165             } else {
 166                 Err(NoSolution)
 167             }
 168         }
 169
 170         ty::GeneratorWitness(types) => {
 171             Ok(infcx.replace_bound_vars_with_placeholders(types).to_vec())
 172         }
 173     }
 174 }
 175
 176 pub(crate) fn extract_tupled_inputs_and_output_from_callable<'tcx>(
 177     tcx: TyCtxt<'tcx>,
 178     self_ty: Ty<'tcx>,
 179     goal_kind: ty::ClosureKind,
 180 ) -> Result<Option<ty::Binder<'tcx, (Ty<'tcx>, Ty<'tcx>)>>, NoSolution> {
 181     match *self_ty.kind() {
 182         ty::FnDef(def_id, substs) => Ok(Some(
 183             tcx.bound_fn_sig(def_id)
 184                 .subst(tcx, substs)
 185                 .map_bound(|sig| (tcx.mk_tup(sig.inputs().iter()), sig.output())),
 186         )),
 187         ty::FnPtr(sig) => {
 188             Ok(Some(sig.map_bound(|sig| (tcx.mk_tup(sig.inputs().iter()), sig.output()))))
 189         }
 190         ty::Closure(_, substs) => {
 191             let closure_substs = substs.as_closure();
 192             match closure_substs.kind_ty().to_opt_closure_kind() {
 193                 Some(closure_kind) if closure_kind.extends(goal_kind) => {}
 194                 None => return Ok(None),
 195                 _ => return Err(NoSolution),
 196             }
 197             Ok(Some(closure_substs.sig().map_bound(|sig| (sig.inputs()[0], sig.output()))))
 198         }
 199         ty::Bool
 200         | ty::Char
 201         | ty::Int(_)
 202         | ty::Uint(_)
 203         | ty::Float(_)
 204         | ty::Adt(_, _)
 205         | ty::Foreign(_)
 206         | ty::Str
 207         | ty::Array(_, _)
 208         | ty::Slice(_)
 209         | ty::RawPtr(_)
 210         | ty::Ref(_, _, _)
 211         | ty::Dynamic(_, _, _)
 212         | ty::Generator(_, _, _)
 213         | ty::GeneratorWitness(_)
 214         | ty::Never
 215         | ty::Tuple(_)
 216         | ty::Alias(_, _)
 217         | ty::Param(_)
 218         | ty::Placeholder(_)
 219         | ty::Bound(_, _)
 220         | ty::Infer(_)
 221         | ty::Error(_) => Err(NoSolution),
 222     }
 223 }