Print opaque types from type aliases via their path

1 files changed, 15 insertions, 19 deletions

diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 11a3ee53629..6521957ec94 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -644,18 +644,23 @@ pub trait PrettyPrinter<'tcx>:
                     return Ok(self);
                 }
 
-                let def_key = self.tcx().def_key(def_id);
-                if let Some(name) = def_key.disambiguated_data.data.get_opt_name() {
-                    p!(write("{}", name));
-                    // FIXME(eddyb) print this with `print_def_path`.
-                    if !substs.is_empty() {
-                        p!("::");
-                        p!(generic_delimiters(|cx| cx.comma_sep(substs.iter())));
+                let parent = self.tcx().parent(def_id).expect("opaque types always have a parent");
+                match self.tcx().def_kind(parent) {
+                    DefKind::TyAlias | DefKind::AssocTy => {
+                        if let ty::Opaque(d, _) = *self.tcx().type_of(parent).kind() {
+                            if d == def_id {
+                                // If the type alias directly starts with the `impl` of the
+                                // opaque type we're printing, then skip the `::{opaque#1}`.
+                                p!(print_def_path(parent, substs));
+                                return Ok(self);
+                            }
+                        }
+                        // Complex opaque type, e.g. `type Foo = (i32, impl Debug);`
+                        p!(print_def_path(def_id, substs));
+                        return Ok(self);
                     }
-                    return Ok(self);
+                    _ => return self.pretty_print_opaque_impl_type(def_id, substs),
                 }
-
-                return self.pretty_print_opaque_impl_type(def_id, substs);
             }
             ty::Str => p!("str"),
             ty::Generator(did, substs, movability) => {
@@ -898,15 +903,6 @@ pub trait PrettyPrinter<'tcx>:
                     if !first {
                         p!(", ");
                     }
-                    if let GenericArgKind::Type(ty) = ty.unpack() {
-                        if let ty::Opaque(d, substs) = *ty.kind() {
-                            if d == def_id {
-                                p!(print_def_path(d, substs));
-                                first = false;
-                                continue;
-                            }
-                        }
-                    }
                     p!(print(trait_ref.rebind(*ty)));
                     first = false;
                 }