sort suggestions for object diagnostic

Author: compiler-errors

compiler/rustc_infer/src/traits/error_reporting/mod.rs

@@ -178,12 +178,13 @@ pub fn report_object_safety_error<'tcx>(
             )));
         }
         impls => {
-            let types = impls
+            let mut types = impls
                 .iter()
                 .map(|t| {
                     with_no_trimmed_paths!(format!("  {}", tcx.type_of(*t).instantiate_identity(),))
                 })
                 .collect::<Vec<_>>();
+            types.sort();
             err.help(format!(
                 "the following types implement the trait, consider defining an enum where each \
                  variant holds one of these types, implementing `{}` for this new enum and using \

tests/ui/generic-associated-types/gat-in-trait-path.base.stderr

@@ -13,8 +13,8 @@ LL |     type A<'a> where Self: 'a;
    |          ^ ...because it contains the generic associated type `A`
    = help: consider moving `A` to another trait
    = help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `Foo` for this new enum and using it instead:
-             Fooy
              Fooer<T>
+             Fooy
 
 error: aborting due to 1 previous error
 

tests/ui/generic-associated-types/issue-79422.base.stderr

@@ -29,8 +29,8 @@ LL |     type VRefCont<'a>: RefCont<'a, V> where Self: 'a;
    |          ^^^^^^^^ ...because it contains the generic associated type `VRefCont`
    = help: consider moving `VRefCont` to another trait
    = help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `MapLike` for this new enum and using it instead:
-             std::collections::BTreeMap<K, V>
              Source
+             std::collections::BTreeMap<K, V>
 
 error[E0038]: the trait `MapLike` cannot be made into an object
   --> $DIR/issue-79422.rs:44:13
@@ -47,8 +47,8 @@ LL |     type VRefCont<'a>: RefCont<'a, V> where Self: 'a;
    |          ^^^^^^^^ ...because it contains the generic associated type `VRefCont`
    = help: consider moving `VRefCont` to another trait
    = help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `MapLike` for this new enum and using it instead:
-             std::collections::BTreeMap<K, V>
              Source
+             std::collections::BTreeMap<K, V>
    = note: required for the cast from `Box<BTreeMap<u8, u8>>` to `Box<dyn MapLike<u8, u8, VRefCont = (dyn RefCont<'_, u8> + 'static)>>`
 
 error: aborting due to 3 previous errors

tests/ui/wf/wf-unsafe-trait-obj-match.stderr

@@ -30,8 +30,8 @@ LL | trait Trait: Sized {}
    |       |
    |       this trait cannot be made into an object...
    = help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `Trait` for this new enum and using it instead:
-             S
              R
+             S
    = note: required for the cast from `&S` to `&dyn Trait`
 
 error[E0038]: the trait `Trait` cannot be made into an object
@@ -52,8 +52,8 @@ LL | trait Trait: Sized {}
    |       |
    |       this trait cannot be made into an object...
    = help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `Trait` for this new enum and using it instead:
-             S
              R
+             S
    = note: required for the cast from `&R` to `&dyn Trait`
 
 error: aborting due to 3 previous errors