move unique param check into rustc_middle

compiler/rustc_middle/src/ty/util.rs

@@ -5,10 +5,7 @@ use crate::ty::fold::{FallibleTypeFolder, TypeFolder};
 use crate::ty::layout::IntegerExt;
 use crate::ty::query::TyCtxtAt;
 use crate::ty::subst::{GenericArgKind, Subst, SubstsRef};
-use crate::ty::{
-    self, DebruijnIndex, DefIdTree, EarlyBinder, List, ReEarlyBound, Ty, TyCtxt, TyKind::*,
-    TypeFoldable,
-};
+use crate::ty::{self, DefIdTree, Ty, TyCtxt, TypeFoldable};
 use rustc_apfloat::Float as _;
 use rustc_ast as ast;
 use rustc_attr::{self as attr, SignedInt, UnsignedInt};
@@ -18,6 +15,7 @@ use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::def::{CtorOf, DefKind, Res};
 use rustc_hir::def_id::DefId;
+use rustc_index::bit_set::GrowableBitSet;
 use rustc_macros::HashStable;
 use rustc_span::{sym, DUMMY_SP};
 use rustc_target::abi::{Integer, Size, TargetDataLayout};
@@ -32,6 +30,12 @@ pub struct Discr<'tcx> {
     pub ty: Ty<'tcx>,
 }
 
+#[derive(Copy, Clone, Debug)]
+pub enum NotUniqueParam<'tcx> {
+    DuplicateParam(ty::GenericArg<'tcx>),
+    NotParam(ty::GenericArg<'tcx>),
+}
+
 impl<'tcx> fmt::Display for Discr<'tcx> {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         match *self.ty.kind() {
@@ -49,8 +53,8 @@ impl<'tcx> fmt::Display for Discr<'tcx> {
 
 fn int_size_and_signed<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> (Size, bool) {
     let (int, signed) = match *ty.kind() {
-        Int(ity) => (Integer::from_int_ty(&tcx, ity), true),
-        Uint(uty) => (Integer::from_uint_ty(&tcx, uty), false),
+        ty::Int(ity) => (Integer::from_int_ty(&tcx, ity), true),
+        ty::Uint(uty) => (Integer::from_uint_ty(&tcx, uty), false),
         _ => bug!("non integer discriminant"),
     };
     (int.size(), signed)
@@ -176,7 +180,7 @@ impl<'tcx> TyCtxt<'tcx> {
         if let ty::Adt(def, substs) = *ty.kind() {
             for field in def.all_fields() {
                 let field_ty = field.ty(self, substs);
-                if let Error(_) = field_ty.kind() {
+                if let ty::Error(_) = field_ty.kind() {
                     return true;
                 }
             }
@@ -311,7 +315,7 @@ impl<'tcx> TyCtxt<'tcx> {
         let (mut a, mut b) = (source, target);
         loop {
             match (&a.kind(), &b.kind()) {
-                (&Adt(a_def, a_substs), &Adt(b_def, b_substs))
+                (&ty::Adt(a_def, a_substs), &ty::Adt(b_def, b_substs))
                     if a_def == b_def && a_def.is_struct() =>
                 {
                     if let Some(f) = a_def.non_enum_variant().fields.last() {
@@ -321,7 +325,7 @@ impl<'tcx> TyCtxt<'tcx> {
                         break;
                     }
                 }
-                (&Tuple(a_tys), &Tuple(b_tys)) if a_tys.len() == b_tys.len() => {
+                (&ty::Tuple(a_tys), &ty::Tuple(b_tys)) if a_tys.len() == b_tys.len() => {
                     if let Some(&a_last) = a_tys.last() {
                         a = a_last;
                         b = *b_tys.last().unwrap();
@@ -427,7 +431,7 @@ impl<'tcx> TyCtxt<'tcx> {
             .filter(|&(_, k)| {
                 match k.unpack() {
                     GenericArgKind::Lifetime(region) => match region.kind() {
-                        ReEarlyBound(ref ebr) => {
+                        ty::ReEarlyBound(ref ebr) => {
                             !impl_generics.region_param(ebr, self).pure_wrt_drop
                         }
                         // Error: not a region param
@@ -453,6 +457,49 @@ impl<'tcx> TyCtxt<'tcx> {
         result
     }
 
+    /// Checks whether each generic argument is simply a unique generic parameter.
+    pub fn uses_unique_generic_params(
+        self,
+        substs: SubstsRef<'tcx>,
+        ignore_regions: bool,
+    ) -> Result<(), NotUniqueParam<'tcx>> {
+        let mut seen = GrowableBitSet::default();
+        for arg in substs {
+            match arg.unpack() {
+                GenericArgKind::Lifetime(lt) => {
+                    if !ignore_regions {
+                        match lt.kind() {
+                            ty::ReEarlyBound(p) => {
+                                if !seen.insert(p.index) {
+                                    return Err(NotUniqueParam::DuplicateParam(lt.into()));
+                                }
+                            }
+                            _ => return Err(NotUniqueParam::NotParam(lt.into())),
+                        }
+                    }
+                }
+                GenericArgKind::Type(t) => match t.kind() {
+                    ty::Param(p) => {
+                        if !seen.insert(p.index) {
+                            return Err(NotUniqueParam::DuplicateParam(t.into()));
+                        }
+                    }
+                    _ => return Err(NotUniqueParam::NotParam(t.into())),
+                },
+                GenericArgKind::Const(c) => match c.val() {
+                    ty::ConstKind::Param(p) => {
+                        if !seen.insert(p.index) {
+                            return Err(NotUniqueParam::DuplicateParam(c.into()));
+                        }
+                    }
+                    _ => return Err(NotUniqueParam::NotParam(c.into())),
+                },
+            }
+        }
+
+        Ok(())
+    }
+
     /// Returns `true` if `def_id` refers to a closure (e.g., `|x| x * 2`). Note
     /// that closures have a `DefId`, but the closure *expression* also
     /// has a `HirId` that is located within the context where the
@@ -594,30 +641,33 @@ impl<'tcx> TyCtxt<'tcx> {
         if visitor.found_recursion { Err(expanded_type) } else { Ok(expanded_type) }
     }
 
-    pub fn bound_type_of(self, def_id: DefId) -> EarlyBinder<Ty<'tcx>> {
-        EarlyBinder(self.type_of(def_id))
+    pub fn bound_type_of(self, def_id: DefId) -> ty::EarlyBinder<Ty<'tcx>> {
+        ty::EarlyBinder(self.type_of(def_id))
     }
 
-    pub fn bound_fn_sig(self, def_id: DefId) -> EarlyBinder<ty::PolyFnSig<'tcx>> {
-        EarlyBinder(self.fn_sig(def_id))
+    pub fn bound_fn_sig(self, def_id: DefId) -> ty::EarlyBinder<ty::PolyFnSig<'tcx>> {
+        ty::EarlyBinder(self.fn_sig(def_id))
     }
 
-    pub fn bound_impl_trait_ref(self, def_id: DefId) -> Option<EarlyBinder<ty::TraitRef<'tcx>>> {
-        self.impl_trait_ref(def_id).map(|i| EarlyBinder(i))
+    pub fn bound_impl_trait_ref(
+        self,
+        def_id: DefId,
+    ) -> Option<ty::EarlyBinder<ty::TraitRef<'tcx>>> {
+        self.impl_trait_ref(def_id).map(|i| ty::EarlyBinder(i))
     }
 
     pub fn bound_explicit_item_bounds(
         self,
         def_id: DefId,
-    ) -> EarlyBinder<&'tcx [(ty::Predicate<'tcx>, rustc_span::Span)]> {
-        EarlyBinder(self.explicit_item_bounds(def_id))
+    ) -> ty::EarlyBinder<&'tcx [(ty::Predicate<'tcx>, rustc_span::Span)]> {
+        ty::EarlyBinder(self.explicit_item_bounds(def_id))
     }
 
     pub fn bound_item_bounds(
         self,
         def_id: DefId,
-    ) -> EarlyBinder<&'tcx ty::List<ty::Predicate<'tcx>>> {
-        EarlyBinder(self.item_bounds(def_id))
+    ) -> ty::EarlyBinder<&'tcx ty::List<ty::Predicate<'tcx>>> {
+        ty::EarlyBinder(self.item_bounds(def_id))
     }
 }
 
@@ -930,35 +980,40 @@ impl<'tcx> Ty<'tcx> {
     pub fn is_structural_eq_shallow(self, tcx: TyCtxt<'tcx>) -> bool {
         match self.kind() {
             // Look for an impl of both `PartialStructuralEq` and `StructuralEq`.
-            Adt(..) => tcx.has_structural_eq_impls(self),
+            ty::Adt(..) => tcx.has_structural_eq_impls(self),
 
             // Primitive types that satisfy `Eq`.
-            Bool | Char | Int(_) | Uint(_) | Str | Never => true,
+            ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Str | ty::Never => true,
 
             // Composite types that satisfy `Eq` when all of their fields do.
             //
             // Because this function is "shallow", we return `true` for these composites regardless
             // of the type(s) contained within.
-            Ref(..) | Array(..) | Slice(_) | Tuple(..) => true,
+            ty::Ref(..) | ty::Array(..) | ty::Slice(_) | ty::Tuple(..) => true,
 
             // Raw pointers use bitwise comparison.
-            RawPtr(_) | FnPtr(_) => true,
+            ty::RawPtr(_) | ty::FnPtr(_) => true,
 
             // Floating point numbers are not `Eq`.
-            Float(_) => false,
+            ty::Float(_) => false,
 
             // Conservatively return `false` for all others...
 
             // Anonymous function types
-            FnDef(..) | Closure(..) | Dynamic(..) | Generator(..) => false,
+            ty::FnDef(..) | ty::Closure(..) | ty::Dynamic(..) | ty::Generator(..) => false,
 
             // Generic or inferred types
             //
             // FIXME(ecstaticmorse): Maybe we should `bug` here? This should probably only be
             // called for known, fully-monomorphized types.
-            Projection(_) | Opaque(..) | Param(_) | Bound(..) | Placeholder(_) | Infer(_) => false,
+            ty::Projection(_)
+            | ty::Opaque(..)
+            | ty::Param(_)
+            | ty::Bound(..)
+            | ty::Placeholder(_)
+            | ty::Infer(_) => false,
 
-            Foreign(_) | GeneratorWitness(..) | Error(_) => false,
+            ty::Foreign(_) | ty::GeneratorWitness(..) | ty::Error(_) => false,
         }
     }
 
@@ -974,13 +1029,13 @@ impl<'tcx> Ty<'tcx> {
     /// - `&'a *const &'b u8 -> *const &'b u8`
     pub fn peel_refs(self) -> Ty<'tcx> {
         let mut ty = self;
-        while let Ref(_, inner_ty, _) = ty.kind() {
+        while let ty::Ref(_, inner_ty, _) = ty.kind() {
             ty = *inner_ty;
         }
         ty
     }
 
-    pub fn outer_exclusive_binder(self) -> DebruijnIndex {
+    pub fn outer_exclusive_binder(self) -> ty::DebruijnIndex {
         self.0.outer_exclusive_binder
     }
 }
@@ -1177,8 +1232,8 @@ pub struct AlwaysRequiresDrop;
 /// with their underlying types.
 pub fn normalize_opaque_types<'tcx>(
     tcx: TyCtxt<'tcx>,
-    val: &'tcx List<ty::Predicate<'tcx>>,
-) -> &'tcx List<ty::Predicate<'tcx>> {
+    val: &'tcx ty::List<ty::Predicate<'tcx>>,
+) -> &'tcx ty::List<ty::Predicate<'tcx>> {
     let mut visitor = OpaqueTypeExpander {
         seen_opaque_tys: FxHashSet::default(),
         expanded_cache: FxHashMap::default(),