Typecheck dyn* coercions

[rust.git] / compiler / rustc_middle / src / ty / sty.rs

diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 80354a3f8a2260e8f61b39e37a89251470c10a75..6713660ab8fafdcd81da629a61db132bd03f1051 100644 (file)
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -11,6 +11,7 @@
     TypeVisitor,
 };
 use crate::ty::{List, ParamEnv};
+use hir::def::DefKind;
 use polonius_engine::Atom;
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::intern::Interned;
@@ -30,7 +31,7 @@
 
 use rustc_type_ir::sty::TyKind::*;
 use rustc_type_ir::RegionKind as IrRegionKind;
-use rustc_type_ir::TyKind as IrTyKind;
+use rustc_type_ir::{TraitObjectRepresentation, TyKind as IrTyKind};
 
 // Re-export the `TyKind` from `rustc_type_ir` here for convenience
 #[rustc_diagnostic_item = "TyKind"]
@@ -691,6 +692,9 @@ pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
 }
 
 impl<'tcx> Binder<'tcx, ExistentialPredicate<'tcx>> {
+    /// Given an existential predicate like `?Self: PartialEq<u32>` (e.g., derived from `dyn PartialEq<u32>`),
+    /// and a concrete type `self_ty`, returns a full predicate where the existentially quantified variable `?Self`
+    /// has been replaced with `self_ty` (e.g., `self_ty: PartialEq<u32>`, in our example).
     pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
         use crate::ty::ToPredicate;
         match self.skip_binder() {
@@ -849,6 +853,12 @@ pub fn to_poly_trait_predicate_negative_polarity(&self) -> ty::PolyTraitPredicat
     }
 }
 
+impl rustc_errors::IntoDiagnosticArg for PolyTraitRef<'_> {
+    fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
+        self.to_string().into_diagnostic_arg()
+    }
+}
+
 /// An existential reference to a trait, where `Self` is erased.
 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
 /// ```ignore (illustrative)
@@ -1190,7 +1200,9 @@ pub struct ProjectionTy<'tcx> {
 
 impl<'tcx> ProjectionTy<'tcx> {
     pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
-        tcx.parent(self.item_def_id)
+        let parent = tcx.parent(self.item_def_id);
+        assert_eq!(tcx.def_kind(parent), DefKind::Trait);
+        parent
     }
 
     /// Extracts the underlying trait reference and own substs from this projection.
@@ -1505,7 +1517,6 @@ pub fn has_name(self) -> bool {
             ty::ReStatic => true,
             ty::ReVar(..) => false,
             ty::RePlaceholder(placeholder) => placeholder.name.is_named(),
-            ty::ReEmpty(_) => false,
             ty::ReErased => false,
         }
     }
@@ -1530,11 +1541,6 @@ pub fn is_placeholder(self) -> bool {
         matches!(*self, ty::RePlaceholder(..))
     }
 
-    #[inline]
-    pub fn is_empty(self) -> bool {
-        matches!(*self, ty::ReEmpty(..))
-    }
-
     #[inline]
     pub fn bound_at_or_above_binder(self, index: ty::DebruijnIndex) -> bool {
         match *self {
@@ -1566,7 +1572,7 @@ pub fn type_flags(self) -> TypeFlags {
                 flags = flags | TypeFlags::HAS_FREE_REGIONS;
                 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
             }
-            ty::ReEmpty(_) | ty::ReStatic => {
+            ty::ReStatic => {
                 flags = flags | TypeFlags::HAS_FREE_REGIONS;
             }
             ty::ReLateBound(..) => {
@@ -1846,7 +1852,12 @@ pub fn is_floating_point(self) -> bool {
 
     #[inline]
     pub fn is_trait(self) -> bool {
-        matches!(self.kind(), Dynamic(..))
+        matches!(self.kind(), Dynamic(_, _, TraitObjectRepresentation::Unsized))
+    }
+
+    #[inline]
+    pub fn is_dyn_star(self) -> bool {
+        matches!(self.kind(), Dynamic(_, _, TraitObjectRepresentation::Sized))
     }
 
     #[inline]