Adjust pretty printing of RPITITs

5 files changed, 31 insertions, 11 deletions

diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index 0196bd26217..95a36dd8a56 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -61,6 +61,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_errors::{pluralize, struct_span_err, Diagnostic, ErrorGuaranteed, IntoDiagnosticArg};
 use rustc_errors::{Applicability, DiagnosticBuilder, DiagnosticStyledString, MultiSpan};
 use rustc_hir as hir;
+use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::Node;
@@ -1682,6 +1683,19 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                                 pos.col.to_usize() + 1,
                             )
                         }
+                        (true, ty::Projection(proj))
+                            if self.tcx.def_kind(proj.item_def_id)
+                                == DefKind::ImplTraitPlaceholder =>
+                        {
+                            let sm = self.tcx.sess.source_map();
+                            let pos = sm.lookup_char_pos(self.tcx.def_span(proj.item_def_id).lo());
+                            format!(
+                                " (trait associated opaque type at <{}:{}:{}>)",
+                                sm.filename_for_diagnostics(&pos.file.name),
+                                pos.line,
+                                pos.col.to_usize() + 1,
+                            )
+                        }
                         (true, _) => format!(" ({})", ty.sort_string(self.tcx)),
                         (false, _) => "".to_string(),
                     };
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 1ae3063dae4..f134e2cd1bc 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -632,7 +632,13 @@ pub trait PrettyPrinter<'tcx>:
             ty::Foreign(def_id) => {
                 p!(print_def_path(def_id, &[]));
             }
-            ty::Projection(ref data) => p!(print(data)),
+            ty::Projection(ref data) => {
+                if self.tcx().def_kind(data.item_def_id) == DefKind::ImplTraitPlaceholder {
+                    return self.pretty_print_opaque_impl_type(data.item_def_id, data.substs);
+                } else {
+                    p!(print(data))
+                }
+            }
             ty::Placeholder(placeholder) => p!(write("Placeholder({:?})", placeholder)),
             ty::Opaque(def_id, substs) => {
                 // FIXME(eddyb) print this with `print_def_path`.
diff --git a/src/test/ui/async-await/async-trait-fn.stderr b/src/test/ui/async-await/async-trait-fn.stderr
index 6c17077d90b..e5c584e31e8 100644
--- a/src/test/ui/async-await/async-trait-fn.stderr
+++ b/src/test/ui/async-await/async-trait-fn.stderr
@@ -48,8 +48,8 @@ LL |     async fn foo() {}
 LL | pub const fn from_generator<T>(gen: T) -> impl Future<Output = T::Return>
    |                                           ------------------------------- the found opaque type
    |
-   = note: expected associated type `<Self as T>::foo::{opaque#0}`
-                  found opaque type `impl Future<Output = ()>`
+   = note: expected associated type `impl Future<Output = ()>` (trait associated opaque type at <$DIR/async-trait-fn.rs:3:20>)
+                  found opaque type `impl Future<Output = ()>` (opaque type at <$SRC_DIR/core/src/future/mod.rs:LL:COL>)
 
 error[E0308]: mismatched types
   --> $DIR/async-trait-fn.rs:5:25
@@ -62,8 +62,8 @@ LL |     async fn bar(&self) {}
 LL | pub const fn from_generator<T>(gen: T) -> impl Future<Output = T::Return>
    |                                           ------------------------------- the found opaque type
    |
-   = note: expected associated type `<Self as T>::bar::{opaque#0}<'_>`
-                  found opaque type `impl Future<Output = ()>`
+   = note: expected associated type `impl Future<Output = ()>` (trait associated opaque type at <$DIR/async-trait-fn.rs:5:25>)
+                  found opaque type `impl Future<Output = ()>` (opaque type at <$SRC_DIR/core/src/future/mod.rs:LL:COL>)
 
 error[E0308]: mismatched types
   --> $DIR/async-trait-fn.rs:7:20
@@ -81,8 +81,8 @@ LL | |     }
 LL |   pub const fn from_generator<T>(gen: T) -> impl Future<Output = T::Return>
    |                                             ------------------------------- the found opaque type
    |
-   = note: expected associated type `<Self as T>::baz::{opaque#0}`
-                  found opaque type `impl Future<Output = ()>`
+   = note: expected associated type `impl Future<Output = ()>` (trait associated opaque type at <$DIR/async-trait-fn.rs:7:20>)
+                  found opaque type `impl Future<Output = ()>` (opaque type at <$SRC_DIR/core/src/future/mod.rs:LL:COL>)
 
 error: aborting due to 6 previous errors
 
diff --git a/src/test/ui/async-await/edition-deny-async-fns-2015.stderr b/src/test/ui/async-await/edition-deny-async-fns-2015.stderr
index 2f40ef1ccbb..8c2902d9b00 100644
--- a/src/test/ui/async-await/edition-deny-async-fns-2015.stderr
+++ b/src/test/ui/async-await/edition-deny-async-fns-2015.stderr
@@ -103,8 +103,8 @@ LL |     async fn foo() {}
 LL | pub const fn from_generator<T>(gen: T) -> impl Future<Output = T::Return>
    |                                           ------------------------------- the found opaque type
    |
-   = note: expected associated type `<Self as Bar>::foo::{opaque#0}`
-                  found opaque type `impl Future<Output = ()>`
+   = note: expected associated type `impl Future<Output = ()>` (trait associated opaque type at <$DIR/edition-deny-async-fns-2015.rs:18:20>)
+                  found opaque type `impl Future<Output = ()>` (opaque type at <$SRC_DIR/core/src/future/mod.rs:LL:COL>)
 
 error: aborting due to 11 previous errors
 
diff --git a/src/test/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.stderr b/src/test/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.stderr
index 9819f650137..3814c568e72 100644
--- a/src/test/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.stderr
+++ b/src/test/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.stderr
@@ -85,8 +85,8 @@ LL | trait C{async fn new(val: T) {}
 LL | pub const fn from_generator<T>(gen: T) -> impl Future<Output = T::Return>
    |                                           ------------------------------- the found opaque type
    |
-   = note: expected associated type `<Self as C>::new::{opaque#0}`
-                  found opaque type `impl Future<Output = ()>`
+   = note: expected associated type `impl Future<Output = ()>` (trait associated opaque type at <$DIR/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.rs:13:30>)
+                  found opaque type `impl Future<Output = ()>` (opaque type at <$SRC_DIR/core/src/future/mod.rs:LL:COL>)
 
 warning: changes to closure capture in Rust 2021 will affect drop order
   --> $DIR/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.rs:13:30