Push ast::{ItemKind, ImplItemKind}::OpaqueTy hack down into lowering

src/librustc/hir/lowering.rs

@@ -452,7 +452,6 @@ impl<'a> LoweringContext<'a> {
                     | ItemKind::Union(_, ref generics)
                     | ItemKind::Enum(_, ref generics)
                     | ItemKind::TyAlias(_, ref generics)
-                    | ItemKind::OpaqueTy(_, ref generics)
                     | ItemKind::Trait(_, _, ref generics, ..) => {
                         let def_id = self.lctx.resolver.definitions().local_def_id(item.id);
                         let count = generics

src/librustc/hir/lowering/item.rs

@@ -335,20 +335,22 @@ impl LoweringContext<'_> {
             ItemKind::Mod(ref m) => hir::ItemKind::Mod(self.lower_mod(m)),
             ItemKind::ForeignMod(ref nm) => hir::ItemKind::ForeignMod(self.lower_foreign_mod(nm)),
             ItemKind::GlobalAsm(ref ga) => hir::ItemKind::GlobalAsm(self.lower_global_asm(ga)),
-            ItemKind::TyAlias(ref t, ref generics) => hir::ItemKind::TyAlias(
-                self.lower_ty(t, ImplTraitContext::disallowed()),
-                self.lower_generics(generics, ImplTraitContext::disallowed()),
-            ),
-            ItemKind::OpaqueTy(ref b, ref generics) => hir::ItemKind::OpaqueTy(
-                hir::OpaqueTy {
-                    generics: self.lower_generics(generics,
-                        ImplTraitContext::OpaqueTy(None)),
-                    bounds: self.lower_param_bounds(b,
-                        ImplTraitContext::OpaqueTy(None)),
-                    impl_trait_fn: None,
-                    origin: hir::OpaqueTyOrigin::TypeAlias,
+            ItemKind::TyAlias(ref ty, ref generics) => match ty.kind.opaque_top_hack() {
+                None => {
+                    let ty = self.lower_ty(ty, ImplTraitContext::disallowed());
+                    let generics = self.lower_generics(generics, ImplTraitContext::disallowed());
+                    hir::ItemKind::TyAlias(ty, generics)
                 },
-            ),
+                Some(bounds) => {
+                    let ty = hir::OpaqueTy {
+                        generics: self.lower_generics(generics, ImplTraitContext::OpaqueTy(None)),
+                        bounds: self.lower_param_bounds(bounds, ImplTraitContext::OpaqueTy(None)),
+                        impl_trait_fn: None,
+                        origin: hir::OpaqueTyOrigin::TypeAlias,
+                    };
+                    hir::ItemKind::OpaqueTy(ty)
+                }
+            }
             ItemKind::Enum(ref enum_definition, ref generics) => {
                 hir::ItemKind::Enum(
                     hir::EnumDef {
@@ -914,16 +916,20 @@ impl LoweringContext<'_> {
 
                 (generics, hir::ImplItemKind::Method(sig, body_id))
             }
-            ImplItemKind::TyAlias(ref ty) => (
-                self.lower_generics(&i.generics, ImplTraitContext::disallowed()),
-                hir::ImplItemKind::TyAlias(self.lower_ty(ty, ImplTraitContext::disallowed())),
-            ),
-            ImplItemKind::OpaqueTy(ref bounds) => (
-                self.lower_generics(&i.generics, ImplTraitContext::disallowed()),
-                hir::ImplItemKind::OpaqueTy(
-                    self.lower_param_bounds(bounds, ImplTraitContext::disallowed()),
-                ),
-            ),
+            ImplItemKind::TyAlias(ref ty) => {
+                let generics = self.lower_generics(&i.generics, ImplTraitContext::disallowed());
+                let kind = match ty.kind.opaque_top_hack() {
+                    None => {
+                        let ty = self.lower_ty(ty, ImplTraitContext::disallowed());
+                        hir::ImplItemKind::TyAlias(ty)
+                    }
+                    Some(bs) => {
+                        let bounds = self.lower_param_bounds(bs, ImplTraitContext::disallowed());
+                        hir::ImplItemKind::OpaqueTy(bounds)
+                    }
+                };
+                (generics, kind)
+            },
             ImplItemKind::Macro(..) => bug!("`TyMac` should have been expanded by now"),
         };
 
@@ -948,11 +954,13 @@ impl LoweringContext<'_> {
             span: i.span,
             vis: self.lower_visibility(&i.vis, Some(i.id)),
             defaultness: self.lower_defaultness(i.defaultness, true /* [1] */),
-            kind: match i.kind {
+            kind: match &i.kind {
                 ImplItemKind::Const(..) => hir::AssocItemKind::Const,
-                ImplItemKind::TyAlias(..) => hir::AssocItemKind::Type,
-                ImplItemKind::OpaqueTy(..) => hir::AssocItemKind::OpaqueTy,
-                ImplItemKind::Method(ref sig, _) => hir::AssocItemKind::Method {
+                ImplItemKind::TyAlias(ty) => match ty.kind.opaque_top_hack() {
+                    None => hir::AssocItemKind::Type,
+                    Some(_) => hir::AssocItemKind::OpaqueTy,
+                },
+                ImplItemKind::Method(sig, _) => hir::AssocItemKind::Method {
                     has_self: sig.decl.has_self(),
                 },
                 ImplItemKind::Macro(..) => unimplemented!(),

src/librustc/hir/map/def_collector.rs

@@ -107,7 +107,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
             }
             ItemKind::Mod(..) | ItemKind::Trait(..) | ItemKind::TraitAlias(..) |
             ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) |
-            ItemKind::OpaqueTy(..) | ItemKind::ExternCrate(..) | ItemKind::ForeignMod(..) |
+            ItemKind::ExternCrate(..) | ItemKind::ForeignMod(..) |
             ItemKind::TyAlias(..) => DefPathData::TypeNs(i.ident.name),
             ItemKind::Fn(sig, generics, body) if sig.header.asyncness.node.is_async() => {
                 return self.visit_async_fn(
@@ -239,8 +239,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
             }
             ImplItemKind::Method(..) |
             ImplItemKind::Const(..) => DefPathData::ValueNs(ii.ident.name),
-            ImplItemKind::TyAlias(..) |
-            ImplItemKind::OpaqueTy(..) => DefPathData::TypeNs(ii.ident.name),
+            ImplItemKind::TyAlias(..) => DefPathData::TypeNs(ii.ident.name),
             ImplItemKind::Macro(..) => return self.visit_macro_invoc(ii.id),
         };
 

src/librustc_parse/parser/item.rs

@@ -7,7 +7,7 @@ use syntax::ast::{self, Abi, DUMMY_NODE_ID, Ident, Attribute, AttrKind, AttrStyl
 use syntax::ast::{ItemKind, ImplItem, ImplItemKind, TraitItem, TraitItemKind, UseTree, UseTreeKind};
 use syntax::ast::{PathSegment, IsAuto, Constness, IsAsync, Unsafety, Defaultness};
 use syntax::ast::{Visibility, VisibilityKind, Mutability, FnHeader, ForeignItem, ForeignItemKind};
-use syntax::ast::{Ty, TyKind, Generics, GenericBounds, TraitRef, EnumDef, VariantData, StructField};
+use syntax::ast::{Ty, TyKind, Generics, TraitRef, EnumDef, VariantData, StructField};
 use syntax::ast::{Mac, MacDelimiter, Block, BindingMode, FnDecl, FnSig, SelfKind, Param};
 use syntax::ptr::P;
 use syntax::ThinVec;
@@ -21,15 +21,6 @@ use log::debug;
 use std::mem;
 use errors::{PResult, Applicability, DiagnosticBuilder, DiagnosticId, StashKey};
 
-/// Whether the type alias or associated type is a concrete type or an opaque type.
-#[derive(Debug)]
-pub(super) enum AliasKind {
-    /// Just a new name for the same type.
-    Weak(P<Ty>),
-    /// Only trait impls of the type will be usable, not the actual type itself.
-    OpaqueTy(GenericBounds),
-}
-
 pub(super) type ItemInfo = (Ident, ItemKind, Option<Vec<Attribute>>);
 
 impl<'a> Parser<'a> {
@@ -266,15 +257,11 @@ impl<'a> Parser<'a> {
             return self.mk_item_with_info(attrs, lo, vis, info);
         }
 
-        if let Some(type_) = self.eat_type() {
-            let (ident, alias, generics) = type_?;
+        if self.eat_keyword(kw::Type) {
             // TYPE ITEM
-            let item_ = match alias {
-                AliasKind::Weak(ty) => ItemKind::TyAlias(ty, generics),
-                AliasKind::OpaqueTy(bounds) => ItemKind::OpaqueTy(bounds, generics),
-            };
-            let span = lo.to(self.prev_span);
-            return Ok(Some(self.mk_item(span, ident, item_, vis, attrs)));
+            let (ident, ty, generics) = self.parse_type_alias()?;
+            let kind = ItemKind::TyAlias(ty, generics);
+            return self.mk_item_with_info(attrs, lo, vis, (ident, kind, None));
         }
 
         if self.eat_keyword(kw::Enum) {
@@ -708,13 +695,9 @@ impl<'a> Parser<'a> {
         let lo = self.token.span;
         let vis = self.parse_visibility(false)?;
         let defaultness = self.parse_defaultness();
-        let (name, kind, generics) = if let Some(type_) = self.eat_type() {
-            let (name, alias, generics) = type_?;
-            let kind = match alias {
-                AliasKind::Weak(typ) => ast::ImplItemKind::TyAlias(typ),
-                AliasKind::OpaqueTy(bounds) => ast::ImplItemKind::OpaqueTy(bounds),
-            };
-            (name, kind, generics)
+        let (name, kind, generics) = if self.eat_keyword(kw::Type) {
+            let (name, ty, generics) = self.parse_type_alias()?;
+            (name, ast::ImplItemKind::TyAlias(ty), generics)
         } else if self.is_const_item() {
             self.parse_impl_const()?
         } else if let Some(mac) = self.parse_assoc_macro_invoc("impl", Some(&vis), at_end)? {
@@ -1318,34 +1301,16 @@ impl<'a> Parser<'a> {
         })
     }
 
-    /// Parses `type Foo = Bar;` or returns `None`
-    /// without modifying the parser state.
-    fn eat_type(&mut self) -> Option<PResult<'a, (Ident, AliasKind, Generics)>> {
-        // This parses the grammar:
-        //     Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
-        if self.eat_keyword(kw::Type) {
-            Some(self.parse_type_alias())
-        } else {
-            None
-        }
-    }
-
-    /// Parses a type alias or opaque type.
-    fn parse_type_alias(&mut self) -> PResult<'a, (Ident, AliasKind, Generics)> {
+    /// Parses the grammar:
+    ///     Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
+    fn parse_type_alias(&mut self) -> PResult<'a, (Ident, P<Ty>, Generics)> {
         let ident = self.parse_ident()?;
         let mut tps = self.parse_generics()?;
         tps.where_clause = self.parse_where_clause()?;
         self.expect(&token::Eq)?;
-        let alias = if self.check_keyword(kw::Impl) {
-            self.bump();
-            let bounds = self.parse_generic_bounds(Some(self.prev_span))?;
-            AliasKind::OpaqueTy(bounds)
-        } else {
-            let ty = self.parse_ty()?;
-            AliasKind::Weak(ty)
-        };
+        let ty = self.parse_ty()?;
         self.expect_semi()?;
-        Ok((ident, alias, tps))
+        Ok((ident, ty, tps))
     }
 
     /// Parses an enum declaration.

src/librustc_passes/ast_validation.rs

@@ -20,7 +20,7 @@ use syntax::source_map::Spanned;
 use syntax::symbol::{kw, sym};
 use syntax::visit::{self, Visitor};
 use syntax::{span_err, struct_span_err, walk_list};
-use syntax_pos::{Span, MultiSpan};
+use syntax_pos::Span;
 use errors::{Applicability, FatalError};
 
 struct AstValidator<'a> {
@@ -584,14 +584,6 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                                                 "unions cannot have zero fields");
                 }
             }
-            ItemKind::OpaqueTy(ref bounds, _) => {
-                if !bounds.iter()
-                          .any(|b| if let GenericBound::Trait(..) = *b { true } else { false }) {
-                    let msp = MultiSpan::from_spans(bounds.iter()
-                        .map(|bound| bound.span()).collect());
-                    self.err_handler().span_err(msp, "at least one trait must be specified");
-                }
-            }
             _ => {}
         }
 

src/librustc_resolve/build_reduced_graph.rs

@@ -699,13 +699,12 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
             }
 
             // These items live in the type namespace.
-            ItemKind::TyAlias(..) => {
-                let res = Res::Def(DefKind::TyAlias, self.r.definitions.local_def_id(item.id));
-                self.r.define(parent, ident, TypeNS, (res, vis, sp, expansion));
-            }
-
-            ItemKind::OpaqueTy(_, _) => {
-                let res = Res::Def(DefKind::OpaqueTy, self.r.definitions.local_def_id(item.id));
+            ItemKind::TyAlias(ref ty, _) => {
+                let def_kind = match ty.kind.opaque_top_hack() {
+                    None => DefKind::TyAlias,
+                    Some(_) => DefKind::OpaqueTy,
+                };
+                let res = Res::Def(def_kind, self.r.definitions.local_def_id(item.id));
                 self.r.define(parent, ident, TypeNS, (res, vis, sp, expansion));
             }
 

src/librustc_resolve/late.rs

@@ -730,7 +730,6 @@ impl<'a, 'b> LateResolutionVisitor<'a, '_> {
 
         match item.kind {
             ItemKind::TyAlias(_, ref generics) |
-            ItemKind::OpaqueTy(_, ref generics) |
             ItemKind::Fn(_, ref generics, _) => {
                 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes),
                                             |this| visit::walk_item(this, item));
@@ -1085,18 +1084,6 @@ impl<'a, 'b> LateResolutionVisitor<'a, '_> {
 
                                                 this.visit_ty(ty);
                                             }
-                                            ImplItemKind::OpaqueTy(ref bounds) => {
-                                                // If this is a trait impl, ensure the type
-                                                // exists in trait
-                                                this.check_trait_item(impl_item.ident,
-                                                                      TypeNS,
-                                                                      impl_item.span,
-                                                    |n, s| TypeNotMemberOfTrait(n, s));
-
-                                                for bound in bounds {
-                                                    this.visit_param_bound(bound);
-                                                }
-                                            }
                                             ImplItemKind::Macro(_) =>
                                                 panic!("unexpanded macro in resolve!"),
                                         }

src/librustc_save_analysis/dump_visitor.rs

@@ -1133,12 +1133,6 @@ impl<'l, 'tcx> DumpVisitor<'l, 'tcx> {
                 // trait.
                 self.visit_ty(ty)
             }
-            ast::ImplItemKind::OpaqueTy(ref bounds) => {
-                // FIXME: uses of the assoc type should ideally point to this
-                // 'def' and the name here should be a ref to the def in the
-                // trait.
-                self.process_bounds(&bounds);
-            }
             ast::ImplItemKind::Macro(_) => {}
         }
     }
@@ -1384,38 +1378,6 @@ impl<'l, 'tcx> Visitor<'l> for DumpVisitor<'l, 'tcx> {
                 self.visit_ty(&ty);
                 self.process_generic_params(ty_params, &qualname, item.id);
             }
-            OpaqueTy(ref bounds, ref ty_params) => {
-                let qualname = format!("::{}",
-                    self.tcx.def_path_str(self.tcx.hir().local_def_id_from_node_id(item.id)));
-
-                let value = String::new();
-                if !self.span.filter_generated(item.ident.span) {
-                    let span = self.span_from_span(item.ident.span);
-                    let id = id_from_node_id(item.id, &self.save_ctxt);
-                    let hir_id = self.tcx.hir().node_to_hir_id(item.id);
-
-                    self.dumper.dump_def(
-                        &access_from!(self.save_ctxt, item, hir_id),
-                        Def {
-                            kind: DefKind::Type,
-                            id,
-                            span,
-                            name: item.ident.to_string(),
-                            qualname: qualname.clone(),
-                            value,
-                            parent: None,
-                            children: vec![],
-                            decl_id: None,
-                            docs: self.save_ctxt.docs_for_attrs(&item.attrs),
-                            sig: sig::item_signature(item, &self.save_ctxt),
-                            attributes: lower_attributes(item.attrs.clone(), &self.save_ctxt),
-                        },
-                    );
-                }
-
-                self.process_bounds(bounds);
-                self.process_generic_params(ty_params, &qualname, item.id);
-            }
             Mac(_) => (),
             _ => visit::walk_item(self, item),
         }

src/librustc_save_analysis/sig.rs

@@ -447,16 +447,6 @@ impl Sig for ast::Item {
 
                 Ok(merge_sigs(sig.text.clone(), vec![sig, ty]))
             }
-            ast::ItemKind::OpaqueTy(ref bounds, ref generics) => {
-                let text = "type ".to_owned();
-                let mut sig = name_and_generics(text, offset, generics, self.id, self.ident, scx)?;
-
-                sig.text.push_str(" = impl ");
-                sig.text.push_str(&pprust::bounds_to_string(bounds));
-                sig.text.push(';');
-
-                Ok(sig)
-            }
             ast::ItemKind::Enum(_, ref generics) => {
                 let text = "enum ".to_owned();
                 let mut sig = name_and_generics(text, offset, generics, self.id, self.ident, scx)?;

src/libsyntax/ast.rs

@@ -1579,7 +1579,6 @@ pub enum ImplItemKind {
     Const(P<Ty>, P<Expr>),
     Method(FnSig, P<Block>),
     TyAlias(P<Ty>),
-    OpaqueTy(GenericBounds),
     Macro(Mac),
 }
 
@@ -1816,6 +1815,15 @@ impl TyKind {
             false
         }
     }
+
+    /// HACK(type_alias_impl_trait, Centril): A temporary crutch used
+    /// in lowering to avoid making larger changes there and beyond.
+    pub fn opaque_top_hack(&self) -> Option<&GenericBounds> {
+        match self {
+            Self::ImplTrait(_, bounds) => Some(bounds),
+            _ => None,
+        }
+    }
 }
 
 /// Syntax used to declare a trait object.
@@ -2483,10 +2491,6 @@ pub enum ItemKind {
     ///
     /// E.g., `type Foo = Bar<u8>;`.
     TyAlias(P<Ty>, Generics),
-    /// An opaque `impl Trait` type alias.
-    ///
-    /// E.g., `type Foo = impl Bar + Boo;`.
-    OpaqueTy(GenericBounds, Generics),
     /// An enum definition (`enum`).
     ///
     /// E.g., `enum Foo<A, B> { C<A>, D<B> }`.
@@ -2540,7 +2544,6 @@ impl ItemKind {
             ItemKind::ForeignMod(..) => "foreign module",
             ItemKind::GlobalAsm(..) => "global asm",
             ItemKind::TyAlias(..) => "type alias",
-            ItemKind::OpaqueTy(..) => "opaque type",
             ItemKind::Enum(..) => "enum",
             ItemKind::Struct(..) => "struct",
             ItemKind::Union(..) => "union",

src/libsyntax/feature_gate/check.rs

@@ -318,6 +318,27 @@ impl<'a> PostExpansionVisitor<'a> {
             );
         }
     }
+
+    /// Feature gate `impl Trait` inside `type Alias = $type_expr;`.
+    fn check_impl_trait(&self, ty: &ast::Ty) {
+        struct ImplTraitVisitor<'a> {
+            vis: &'a PostExpansionVisitor<'a>,
+        }
+        impl Visitor<'_> for ImplTraitVisitor<'_> {
+            fn visit_ty(&mut self, ty: &ast::Ty) {
+                if let ast::TyKind::ImplTrait(..) = ty.kind {
+                    gate_feature_post!(
+                        &self.vis,
+                        type_alias_impl_trait,
+                        ty.span,
+                        "`impl Trait` in type aliases is unstable"
+                    );
+                }
+                visit::walk_ty(self, ty);
+            }
+        }
+        ImplTraitVisitor { vis: self }.visit_ty(ty);
+    }
 }
 
 impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
@@ -452,14 +473,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 gate_feature_post!(&self, decl_macro, i.span, msg);
             }
 
-            ast::ItemKind::OpaqueTy(..) => {
-                gate_feature_post!(
-                    &self,
-                    type_alias_impl_trait,
-                    i.span,
-                    "`impl Trait` in type aliases is unstable"
-                );
-            }
+            ast::ItemKind::TyAlias(ref ty, ..) => self.check_impl_trait(&ty),
 
             _ => {}
         }
@@ -633,9 +647,8 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 }
             }
             ast::TraitItemKind::Type(_, ref default) => {
-                // We use three if statements instead of something like match guards so that all
-                // of these errors can be emitted if all cases apply.
-                if default.is_some() {
+                if let Some(ty) = default {
+                    self.check_impl_trait(ty);
                     gate_feature_post!(&self, associated_type_defaults, ti.span,
                                        "associated type defaults are unstable");
                 }
@@ -660,15 +673,8 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                                        "C-variadic functions are unstable");
                 }
             }
-            ast::ImplItemKind::OpaqueTy(..) => {
-                gate_feature_post!(
-                    &self,
-                    type_alias_impl_trait,
-                    ii.span,
-                    "`impl Trait` in type aliases is unstable"
-                );
-            }
-            ast::ImplItemKind::TyAlias(_) => {
+            ast::ImplItemKind::TyAlias(ref ty) => {
+                self.check_impl_trait(ty);
                 self.check_gat(&ii.generics, ii.span);
             }
             _ => {}

src/libsyntax/mut_visit.rs

@@ -887,10 +887,6 @@ pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
             vis.visit_ty(ty);
             vis.visit_generics(generics);
         }
-        ItemKind::OpaqueTy(bounds, generics) => {
-            visit_bounds(bounds, vis);
-            vis.visit_generics(generics);
-        }
         ItemKind::Enum(EnumDef { variants }, generics) => {
             variants.flat_map_in_place(|variant| vis.flat_map_variant(variant));
             vis.visit_generics(generics);
@@ -970,7 +966,6 @@ pub fn noop_flat_map_impl_item<T: MutVisitor>(mut item: ImplItem, visitor: &mut
             visitor.visit_block(body);
         }
         ImplItemKind::TyAlias(ty) => visitor.visit_ty(ty),
-        ImplItemKind::OpaqueTy(bounds) => visit_bounds(bounds, visitor),
         ImplItemKind::Macro(mac) => visitor.visit_mac(mac),
     }
     visitor.visit_span(span);

src/libsyntax/print/pprust.rs

@@ -1255,19 +1255,6 @@ impl<'a> State<'a> {
                 self.s.word(";");
                 self.end(); // end the outer ibox
             }
-            ast::ItemKind::OpaqueTy(ref bounds, ref generics) => {
-                self.head(visibility_qualified(&item.vis, "type"));
-                self.print_ident(item.ident);
-                self.word_space("= impl");
-                self.print_generic_params(&generics.params);
-                self.end(); // end the inner ibox
-
-                self.print_where_clause(&generics.where_clause);
-                self.s.space();
-                self.print_type_bounds(":", bounds);
-                self.s.word(";");
-                self.end(); // end the outer ibox
-            }
             ast::ItemKind::Enum(ref enum_definition, ref params) => {
                 self.print_enum_def(
                     enum_definition,
@@ -1620,13 +1607,6 @@ impl<'a> State<'a> {
             ast::ImplItemKind::TyAlias(ref ty) => {
                 self.print_associated_type(ii.ident, None, Some(ty));
             }
-            ast::ImplItemKind::OpaqueTy(ref bounds) => {
-                self.word_space("type");
-                self.print_ident(ii.ident);
-                self.word_space("= impl");
-                self.print_type_bounds(":", bounds);
-                self.s.word(";");
-            }
             ast::ImplItemKind::Macro(ref mac) => {
                 self.print_mac(mac);
                 match mac.delim {

src/libsyntax/visit.rs

@@ -263,10 +263,6 @@ pub fn walk_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a Item) {
             visitor.visit_ty(typ);
             visitor.visit_generics(generics)
         }
-        ItemKind::OpaqueTy(ref bounds, ref generics) => {
-            walk_list!(visitor, visit_param_bound, bounds);
-            visitor.visit_generics(generics)
-        }
         ItemKind::Enum(ref enum_definition, ref generics) => {
             visitor.visit_generics(generics);
             visitor.visit_enum_def(enum_definition, generics, item.id, item.span)
@@ -628,9 +624,6 @@ pub fn walk_impl_item<'a, V: Visitor<'a>>(visitor: &mut V, impl_item: &'a ImplIt
         ImplItemKind::TyAlias(ref ty) => {
             visitor.visit_ty(ty);
         }
-        ImplItemKind::OpaqueTy(ref bounds) => {
-            walk_list!(visitor, visit_param_bound, bounds);
-        }
         ImplItemKind::Macro(ref mac) => {
             visitor.visit_mac(mac);
         }

src/test/ui/feature-gates/feature-gate-type_alias_impl_trait.rs

@@ -1,15 +1,45 @@
-type Foo = impl std::fmt::Debug; //~ ERROR `impl Trait` in type aliases is unstable
+use std::fmt::Debug;
+
+type Foo = impl Debug; //~ ERROR `impl Trait` in type aliases is unstable
 
 trait Bar {
-    type Baa: std::fmt::Debug;
+    type Baa: Debug;
     fn define() -> Self::Baa;
 }
 
 impl Bar for () {
-    type Baa = impl std::fmt::Debug; //~ ERROR `impl Trait` in type aliases is unstable
+    type Baa = impl Debug; //~ ERROR `impl Trait` in type aliases is unstable
     fn define() -> Self::Baa { 0 }
 }
 
 fn define() -> Foo { 0 }
 
+trait TraitWithDefault {
+    type Assoc = impl Debug;
+    //~^ ERROR associated type defaults are unstable
+    //~| ERROR `impl Trait` not allowed outside of function
+    //~| ERROR `impl Trait` in type aliases is unstable
+}
+
+type NestedFree = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+//~^ ERROR `impl Trait` in type aliases is unstable
+//~| ERROR `impl Trait` in type aliases is unstable
+//~| ERROR `impl Trait` in type aliases is unstable
+//~| ERROR `impl Trait` in type aliases is unstable
+//~| ERROR `impl Trait` not allowed outside of function
+//~| ERROR `impl Trait` not allowed outside of function
+//~| ERROR `impl Trait` not allowed outside of function
+
+impl Bar for u8 {
+    type Baa = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+    //~^ ERROR `impl Trait` in type aliases is unstable
+    //~| ERROR `impl Trait` in type aliases is unstable
+    //~| ERROR `impl Trait` in type aliases is unstable
+    //~| ERROR `impl Trait` in type aliases is unstable
+    //~| ERROR `impl Trait` not allowed outside of function
+    //~| ERROR `impl Trait` not allowed outside of function
+    //~| ERROR `impl Trait` not allowed outside of function
+    fn define() -> Self::Baa { (vec![true], 0u8, 0i32..1) }
+}
+
 fn main() {}

src/test/ui/feature-gates/feature-gate-type_alias_impl_trait.stderr

@@ -1,21 +1,154 @@
 error[E0658]: `impl Trait` in type aliases is unstable
-  --> $DIR/feature-gate-type_alias_impl_trait.rs:1:1
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:3:12
    |
-LL | type Foo = impl std::fmt::Debug;
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | type Foo = impl Debug;
+   |            ^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/63063
    = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
 
 error[E0658]: `impl Trait` in type aliases is unstable
-  --> $DIR/feature-gate-type_alias_impl_trait.rs:9:5
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:11:16
    |
-LL |     type Baa = impl std::fmt::Debug;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     type Baa = impl Debug;
+   |                ^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/63063
    = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
 
-error: aborting due to 2 previous errors
+error[E0658]: `impl Trait` in type aliases is unstable
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:18:18
+   |
+LL |     type Assoc = impl Debug;
+   |                  ^^^^^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/63063
+   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
+
+error[E0658]: associated type defaults are unstable
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:18:5
+   |
+LL |     type Assoc = impl Debug;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/29661
+   = help: add `#![feature(associated_type_defaults)]` to the crate attributes to enable
+
+error[E0658]: `impl Trait` in type aliases is unstable
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:24:24
+   |
+LL | type NestedFree = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                        ^^^^^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/63063
+   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
+
+error[E0658]: `impl Trait` in type aliases is unstable
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:24:37
+   |
+LL | type NestedFree = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                                     ^^^^^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/63063
+   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
+
+error[E0658]: `impl Trait` in type aliases is unstable
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:24:49
+   |
+LL | type NestedFree = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/63063
+   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
+
+error[E0658]: `impl Trait` in type aliases is unstable
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:24:70
+   |
+LL | type NestedFree = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                                                                      ^^^^^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/63063
+   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
+
+error[E0658]: `impl Trait` in type aliases is unstable
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:34:21
+   |
+LL |     type Baa = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                     ^^^^^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/63063
+   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
+
+error[E0658]: `impl Trait` in type aliases is unstable
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:34:34
+   |
+LL |     type Baa = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                                  ^^^^^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/63063
+   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
+
+error[E0658]: `impl Trait` in type aliases is unstable
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:34:46
+   |
+LL |     type Baa = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/63063
+   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
+
+error[E0658]: `impl Trait` in type aliases is unstable
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:34:67
+   |
+LL |     type Baa = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                                                                   ^^^^^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/63063
+   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
+
+error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:18:18
+   |
+LL |     type Assoc = impl Debug;
+   |                  ^^^^^^^^^^
+
+error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:24:24
+   |
+LL | type NestedFree = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                        ^^^^^^^^^^
+
+error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:24:37
+   |
+LL | type NestedFree = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                                     ^^^^^^^^^^
+
+error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:24:49
+   |
+LL | type NestedFree = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:34:21
+   |
+LL |     type Baa = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                     ^^^^^^^^^^
+
+error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:34:34
+   |
+LL |     type Baa = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                                  ^^^^^^^^^^
+
+error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
+  --> $DIR/feature-gate-type_alias_impl_trait.rs:34:46
+   |
+LL |     type Baa = (Vec<impl Debug>, impl Debug, impl Iterator<Item = impl Debug>);
+   |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 19 previous errors
 
-For more information about this error, try `rustc --explain E0658`.
+Some errors have detailed explanations: E0562, E0658.
+For more information about an error, try `rustc --explain E0562`.

src/test/ui/impl-trait/where-allowed.rs

@@ -163,6 +163,7 @@ type InTypeAlias<R> = impl Debug;
 
 type InReturnInTypeAlias<R> = fn() -> impl Debug;
 //~^ ERROR `impl Trait` not allowed outside of function and inherent method return types
+//~| ERROR `impl Trait` in type aliases is unstable
 
 // Disallowed in impl headers
 impl PartialEq<impl Debug> for () {

src/test/ui/impl-trait/where-allowed.stderr

@@ -17,19 +17,28 @@ LL | fn in_impl_Fn_parameter_in_return() -> &'static impl Fn(impl Debug) { panic
    |                                                 outer `impl Trait`
 
 error[E0658]: `impl Trait` in type aliases is unstable
-  --> $DIR/where-allowed.rs:124:5
+  --> $DIR/where-allowed.rs:124:16
    |
 LL |     type Out = impl Debug;
-   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |                ^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/63063
    = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
 
 error[E0658]: `impl Trait` in type aliases is unstable
-  --> $DIR/where-allowed.rs:160:1
+  --> $DIR/where-allowed.rs:160:23
    |
 LL | type InTypeAlias<R> = impl Debug;
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                       ^^^^^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/63063
+   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
+
+error[E0658]: `impl Trait` in type aliases is unstable
+  --> $DIR/where-allowed.rs:164:39
+   |
+LL | type InReturnInTypeAlias<R> = fn() -> impl Debug;
+   |                                       ^^^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/63063
    = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
@@ -179,69 +188,69 @@ LL | type InReturnInTypeAlias<R> = fn() -> impl Debug;
    |                                       ^^^^^^^^^^
 
 error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
-  --> $DIR/where-allowed.rs:168:16
+  --> $DIR/where-allowed.rs:169:16
    |
 LL | impl PartialEq<impl Debug> for () {
    |                ^^^^^^^^^^
 
 error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
-  --> $DIR/where-allowed.rs:173:24
+  --> $DIR/where-allowed.rs:174:24
    |
 LL | impl PartialEq<()> for impl Debug {
    |                        ^^^^^^^^^^
 
 error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
-  --> $DIR/where-allowed.rs:178:6
+  --> $DIR/where-allowed.rs:179:6
    |
 LL | impl impl Debug {
    |      ^^^^^^^^^^
 
 error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
-  --> $DIR/where-allowed.rs:184:24
+  --> $DIR/where-allowed.rs:185:24
    |
 LL | impl InInherentImplAdt<impl Debug> {
    |                        ^^^^^^^^^^
 
 error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
-  --> $DIR/where-allowed.rs:190:11
+  --> $DIR/where-allowed.rs:191:11
    |
 LL |     where impl Debug: Debug
    |           ^^^^^^^^^^
 
 error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
-  --> $DIR/where-allowed.rs:197:15
+  --> $DIR/where-allowed.rs:198:15
    |
 LL |     where Vec<impl Debug>: Debug
    |               ^^^^^^^^^^
 
 error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
-  --> $DIR/where-allowed.rs:204:24
+  --> $DIR/where-allowed.rs:205:24
    |
 LL |     where T: PartialEq<impl Debug>
    |                        ^^^^^^^^^^
 
 error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
-  --> $DIR/where-allowed.rs:211:17
+  --> $DIR/where-allowed.rs:212:17
    |
 LL |     where T: Fn(impl Debug)
    |                 ^^^^^^^^^^
 
 error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
-  --> $DIR/where-allowed.rs:218:22
+  --> $DIR/where-allowed.rs:219:22
    |
 LL |     where T: Fn() -> impl Debug
    |                      ^^^^^^^^^^
 
 error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
-  --> $DIR/where-allowed.rs:224:29
+  --> $DIR/where-allowed.rs:225:29
    |
 LL |     let _in_local_variable: impl Fn() = || {};
    |                             ^^^^^^^^^
    |
    = help: add `#![feature(impl_trait_in_bindings)]` to the crate attributes to enable
 
 error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
-  --> $DIR/where-allowed.rs:226:46
+  --> $DIR/where-allowed.rs:227:46
    |
 LL |     let _in_return_in_local_variable = || -> impl Fn() { || {} };
    |                                              ^^^^^^^^^
@@ -270,7 +279,7 @@ error: could not find defining uses
 LL |     type Out = impl Debug;
    |     ^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 43 previous errors
+error: aborting due to 44 previous errors
 
 Some errors have detailed explanations: E0282, E0562, E0658, E0666.
 For more information about an error, try `rustc --explain E0282`.

src/test/ui/type-alias-impl-trait/generic_nondefining_use.stderr

@@ -1,8 +1,8 @@
 error: at least one trait must be specified
-  --> $DIR/generic_nondefining_use.rs:5:20
+  --> $DIR/generic_nondefining_use.rs:5:15
    |
 LL | type Cmp<T> = impl 'static;
-   |                    ^^^^^^^
+   |               ^^^^^^^^^^^^
 
 error: defining opaque type use does not fully define opaque type
   --> $DIR/generic_nondefining_use.rs:11:1

src/test/ui/type-alias-impl-trait/generic_not_used.stderr

@@ -1,8 +1,8 @@
 error: at least one trait must be specified
-  --> $DIR/generic_not_used.rs:5:38
+  --> $DIR/generic_not_used.rs:5:33
    |
 LL | type WrongGeneric<T: 'static> = impl 'static;
-   |                                      ^^^^^^^
+   |                                 ^^^^^^^^^^^^
 
 error: type parameter `V` is part of concrete type but not used in parameter list for the `impl Trait` type alias
   --> $DIR/generic_not_used.rs:8:73

src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.nll.stderr

@@ -1,8 +1,8 @@
 error: at least one trait must be specified
-  --> $DIR/generic_type_does_not_live_long_enough.rs:9:29
+  --> $DIR/generic_type_does_not_live_long_enough.rs:9:24
    |
 LL | type WrongGeneric<T> = impl 'static;
-   |                             ^^^^^^^
+   |                        ^^^^^^^^^^^^
 
 error[E0308]: mismatched types
   --> $DIR/generic_type_does_not_live_long_enough.rs:6:18

src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.stderr

@@ -1,8 +1,8 @@
 error: at least one trait must be specified
-  --> $DIR/generic_type_does_not_live_long_enough.rs:9:29
+  --> $DIR/generic_type_does_not_live_long_enough.rs:9:24
    |
 LL | type WrongGeneric<T> = impl 'static;
-   |                             ^^^^^^^
+   |                        ^^^^^^^^^^^^
 
 error[E0308]: mismatched types
   --> $DIR/generic_type_does_not_live_long_enough.rs:6:18

src/test/ui/type-alias-impl-trait/generic_underconstrained.stderr

@@ -1,8 +1,8 @@
 error: at least one trait must be specified
-  --> $DIR/generic_underconstrained.rs:6:40
+  --> $DIR/generic_underconstrained.rs:6:35
    |
 LL | type Underconstrained<T: Trait> = impl 'static;
-   |                                        ^^^^^^^
+   |                                   ^^^^^^^^^^^^
 
 error[E0277]: the trait bound `T: Trait` is not satisfied
   --> $DIR/generic_underconstrained.rs:6:1

src/test/ui/type-alias-impl-trait/generic_underconstrained2.stderr

@@ -1,14 +1,14 @@
 error: at least one trait must be specified
-  --> $DIR/generic_underconstrained2.rs:5:50
+  --> $DIR/generic_underconstrained2.rs:5:45
    |
 LL | type Underconstrained<T: std::fmt::Debug> = impl 'static;
-   |                                                  ^^^^^^^
+   |                                             ^^^^^^^^^^^^
 
 error: at least one trait must be specified
-  --> $DIR/generic_underconstrained2.rs:14:51
+  --> $DIR/generic_underconstrained2.rs:14:46
    |
 LL | type Underconstrained2<T: std::fmt::Debug> = impl 'static;
-   |                                                   ^^^^^^^
+   |                                              ^^^^^^^^^^^^
 
 error[E0277]: `U` doesn't implement `std::fmt::Debug`
   --> $DIR/generic_underconstrained2.rs:5:1

src/test/ui/type-alias-impl-trait/issue-60371.stderr

@@ -1,8 +1,8 @@
 error[E0658]: `impl Trait` in type aliases is unstable
-  --> $DIR/issue-60371.rs:8:5
+  --> $DIR/issue-60371.rs:8:17
    |
 LL |     type Item = impl Bug;
-   |     ^^^^^^^^^^^^^^^^^^^^^
+   |                 ^^^^^^^^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/63063
    = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable

src/test/ui/type-alias-impl-trait/type-alias-impl-trait-with-no-traits.stderr

@@ -1,8 +1,8 @@
 error: at least one trait must be specified
-  --> $DIR/type-alias-impl-trait-with-no-traits.rs:3:17
+  --> $DIR/type-alias-impl-trait-with-no-traits.rs:3:12
    |
 LL | type Foo = impl 'static;
-   |                 ^^^^^^^
+   |            ^^^^^^^^^^^^
 
 error: at least one trait must be specified
   --> $DIR/type-alias-impl-trait-with-no-traits.rs:10:13

src/test/ui/type-alias-impl-trait/unused_generic_param.stderr

@@ -1,14 +1,14 @@
 error: at least one trait must be specified
-  --> $DIR/unused_generic_param.rs:6:33
+  --> $DIR/unused_generic_param.rs:6:28
    |
 LL | type PartiallyDefined<T> = impl 'static;
-   |                                 ^^^^^^^
+   |                            ^^^^^^^^^^^^
 
 error: at least one trait must be specified
-  --> $DIR/unused_generic_param.rs:13:34
+  --> $DIR/unused_generic_param.rs:13:29
    |
 LL | type PartiallyDefined2<T> = impl 'static;
-   |                                  ^^^^^^^
+   |                             ^^^^^^^^^^^^
 
 error: aborting due to 2 previous errors