From f93aa75426ef42d31deacbe145db50d5f5d75a17 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Thu, 26 Oct 2023 19:03:29 +0000
Subject: [PATCH] address review comments

---
 .../src/traits/error_reporting/suggestions.rs | 48 ++++++++-----------
 .../sealed-traits/sealed-trait-local.stderr   | 13 +++--
 2 files changed, 26 insertions(+), 35 deletions(-)

diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 8232eef9451c4..67a13de0062b1 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -2682,35 +2682,27 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                                 .flatten()
                                 .chain(impls_of.blanket_impls().iter())
                                 .collect::<Vec<_>>();
-                            match &impls[..] {
-                                [] => {}
-                                [only] => {
-                                    err.help(with_no_trimmed_paths!(format!(
-                                        "type `{}` implements the trait",
-                                        tcx.type_of(*only).instantiate_identity(),
-                                    )));
-                                }
-                                impls => {
-                                    let mut types = impls.iter()
-                                        .map(|t| with_no_trimmed_paths!(format!(
-                                            " - {}\n",
-                                            tcx.type_of(*t).instantiate_identity(),
-                                        )))
-                                        .collect::<Vec<_>>();
-                                    let post = if types.len() > 9 {
-                                        let len = types.len();
-                                        types.truncate(8);
-                                        format!("and {} others", len - 8)
-                                    } else {
-                                        String::new()
-                                    };
-                                    err.help(format!(
-                                        "the following types implement the trait:\n{}{post}",
-                                        types.join(""),
-                                    ));
-                                }
+                            if !impls.is_empty() {
+                                let len = impls.len();
+                                let mut types = impls.iter()
+                                    .map(|t| with_no_trimmed_paths!(format!(
+                                        "  {}",
+                                        tcx.type_of(*t).instantiate_identity(),
+                                    )))
+                                    .collect::<Vec<_>>();
+                                let post = if types.len() > 9 {
+                                    types.truncate(8);
+                                    format!("\nand {} others", len - 8)
+                                } else {
+                                    String::new()
+                                };
+                                err.help(format!(
+                                    "the following type{} implement{} the trait:\n{}{post}",
+                                    pluralize!(len),
+                                    if len == 1 { "s" } else { "" },
+                                    types.join("\n"),
+                                ));
                             }
-
                         }
                     }
                 } else {
diff --git a/tests/ui/privacy/sealed-traits/sealed-trait-local.stderr b/tests/ui/privacy/sealed-traits/sealed-trait-local.stderr
index 6f9777be9b61d..a7f77a1c0c020 100644
--- a/tests/ui/privacy/sealed-traits/sealed-trait-local.stderr
+++ b/tests/ui/privacy/sealed-traits/sealed-trait-local.stderr
@@ -10,7 +10,8 @@ note: required by a bound in `a::Sealed`
 LL |     pub trait Sealed: self::b::Hidden {
    |                       ^^^^^^^^^^^^^^^ required by this bound in `Sealed`
    = note: `Sealed` is a "sealed trait", because to implement it you also need to implement `a::b::Hidden`, which is not accessible; this is usually done to force you to use one of the provided types that already implement it
-   = help: type `a::X` implements the trait
+   = help: the following type implements the trait:
+             a::X
 
 error[E0277]: the trait bound `S: d::Hidden` is not satisfied
   --> $DIR/sealed-trait-local.rs:53:20
@@ -25,9 +26,8 @@ LL |     pub trait Sealed: self::d::Hidden {
    |                       ^^^^^^^^^^^^^^^ required by this bound in `Sealed`
    = note: `Sealed` is a "sealed trait", because to implement it you also need to implement `c::d::Hidden`, which is not accessible; this is usually done to force you to use one of the provided types that already implement it
    = help: the following types implement the trait:
-            - c::X
-            - c::Y
-           
+             c::X
+             c::Y
 
 error[E0277]: the trait bound `S: f::Hidden` is not satisfied
   --> $DIR/sealed-trait-local.rs:54:20
@@ -42,9 +42,8 @@ LL |     pub trait Sealed: self::f::Hidden {
    |                       ^^^^^^^^^^^^^^^ required by this bound in `Sealed`
    = note: `Sealed` is a "sealed trait", because to implement it you also need to implement `e::f::Hidden`, which is not accessible; this is usually done to force you to use one of the provided types that already implement it
    = help: the following types implement the trait:
-            - e::X
-            - e::Y
-           
+             e::X
+             e::Y
 
 error: aborting due to 3 previous errors