Add an opt-out in pretty printing for RTN rendering

Author: compiler-errors

compiler/rustc_hir_analysis/src/check/mod.rs

@@ -84,6 +84,7 @@ use rustc_infer::infer::{self, TyCtxtInferExt as _};
 use rustc_infer::traits::ObligationCause;
 use rustc_middle::query::Providers;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
+use rustc_middle::ty::print::with_types_for_suggestion;
 use rustc_middle::ty::{self, GenericArgs, GenericArgsRef, Ty, TyCtxt, TypingMode};
 use rustc_middle::{bug, span_bug};
 use rustc_session::parse::feature_err;
@@ -240,11 +241,11 @@ fn missing_items_err(
         (Vec::new(), Vec::new(), Vec::new());
 
     for &trait_item in missing_items {
-        let snippet = suggestion_signature(
+        let snippet = with_types_for_suggestion!(suggestion_signature(
             tcx,
             trait_item,
             tcx.impl_trait_ref(impl_def_id).unwrap().instantiate_identity(),
-        );
+        ));
         let code = format!("{padding}{snippet}\n{padding}");
         if let Some(span) = tcx.hir().span_if_local(trait_item.def_id) {
             missing_trait_item_label

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -63,6 +63,7 @@ thread_local! {
     static FORCE_TRIMMED_PATH: Cell<bool> = const { Cell::new(false) };
     static REDUCED_QUERIES: Cell<bool> = const { Cell::new(false) };
     static NO_VISIBLE_PATH: Cell<bool> = const { Cell::new(false) };
+    static TYPE_FOR_SUGGESTION: Cell<bool> = const { Cell::new(false) };
 }
 
 macro_rules! define_helper {
@@ -122,6 +123,11 @@ define_helper!(
     /// Prevent selection of visible paths. `Display` impl of DefId will prefer
     /// visible (public) reexports of types as paths.
     fn with_no_visible_paths(NoVisibleGuard, NO_VISIBLE_PATH);
+    /// Render a type for the purposes of a suggestion, rather than for diagnostic
+    /// clarity. Right now, this suppresses the "{{ path::to::Trait::method(..) }}"
+    /// for RPITITs, but it could be used to render more friendly representations
+    /// for things like `FnDef`, too.
+    fn with_types_for_suggestion(TypeForSuggestionGuard, TYPE_FOR_SUGGESTION);
 );
 
 /// Avoids running any queries during prints.
@@ -1224,6 +1230,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
         }
 
         if self.tcx().features().return_type_notation()
+            && !with_types_for_suggestion()
             && let Some(ty::ImplTraitInTraitData::Trait { fn_def_id, .. }) =
                 self.tcx().opt_rpitit_info(def_id)
             && let ty::Alias(_, alias_ty) =

tests/ui/associated-type-bounds/return-type-notation/rendering.fixed

@@ -0,0 +1,15 @@
+//@ run-rustfix
+
+#![allow(unused)]
+#![feature(return_type_notation)]
+
+trait Foo {
+    fn missing() -> impl Sized;
+}
+
+impl Foo for () {
+    //~^ ERROR not all trait items implemented, missing: `missing`
+fn missing() -> impl Sized { todo!() }
+}
+
+fn main() {}

tests/ui/associated-type-bounds/return-type-notation/rendering.rs

@@ -0,0 +1,14 @@
+//@ run-rustfix
+
+#![allow(unused)]
+#![feature(return_type_notation)]
+
+trait Foo {
+    fn missing() -> impl Sized;
+}
+
+impl Foo for () {
+    //~^ ERROR not all trait items implemented, missing: `missing`
+}
+
+fn main() {}

tests/ui/associated-type-bounds/return-type-notation/rendering.stderr

@@ -0,0 +1,12 @@
+error[E0046]: not all trait items implemented, missing: `missing`
+  --> $DIR/rendering.rs:10:1
+   |
+LL |     fn missing() -> impl Sized;
+   |     --------------------------- `missing` from trait
+...
+LL | impl Foo for () {
+   | ^^^^^^^^^^^^^^^ missing `missing` in implementation
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0046`.