Rollup merge of #141580 - oli-obk:early-dyn-catches-the-incompat, r=compiler-errors

Use more detailed spans in dyn compat errors within bodies

Within bodies we can employ the full dyn compat check query instead of only doing the minimal hir ty lowerer one. This in turn gives us better spans and also silences many follow-up duplicate or bogus errors.

alternative to https://github.com/rust-lang/rust/pull/141439, tho I think I could turn the delayed bug from that one into a bug now instead of having an error code path.

r? `@compiler-errors`
cc `@fmease`

45 files changed, 205 insertions, 206 deletions

diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index f5206d9a015..8a2edd843f2 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -31,7 +31,7 @@ use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::intravisit::{self, InferKind, Visitor, VisitorExt, walk_generics};
 use rustc_hir::{self as hir, GenericParamKind, HirId, Node, PreciseCapturingArgKind};
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
-use rustc_infer::traits::ObligationCause;
+use rustc_infer::traits::{DynCompatibilityViolation, ObligationCause};
 use rustc_middle::hir::nested_filter;
 use rustc_middle::query::Providers;
 use rustc_middle::ty::util::{Discr, IntTypeExt};
@@ -40,7 +40,7 @@ use rustc_middle::{bug, span_bug};
 use rustc_span::{DUMMY_SP, Ident, Span, Symbol, kw, sym};
 use rustc_trait_selection::error_reporting::traits::suggestions::NextTypeParamName;
 use rustc_trait_selection::infer::InferCtxtExt;
-use rustc_trait_selection::traits::ObligationCtxt;
+use rustc_trait_selection::traits::{ObligationCtxt, hir_ty_lowering_dyn_compatibility_violations};
 use tracing::{debug, instrument};
 
 use crate::errors;
@@ -625,6 +625,10 @@ impl<'tcx> HirTyLowerer<'tcx> for ItemCtxt<'tcx> {
 
         (input_tys, output_ty)
     }
+
+    fn dyn_compatibility_violations(&self, trait_def_id: DefId) -> Vec<DynCompatibilityViolation> {
+        hir_ty_lowering_dyn_compatibility_violations(self.tcx, trait_def_id)
+    }
 }
 
 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs
index 9e44b645aca..fb65c9a8929 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs
@@ -11,7 +11,7 @@ use rustc_middle::ty::{
 };
 use rustc_span::{ErrorGuaranteed, Span};
 use rustc_trait_selection::error_reporting::traits::report_dyn_incompatibility;
-use rustc_trait_selection::traits::{self, hir_ty_lowering_dyn_compatibility_violations};
+use rustc_trait_selection::traits;
 use smallvec::{SmallVec, smallvec};
 use tracing::{debug, instrument};
 
@@ -97,8 +97,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         // to avoid ICEs.
         for (clause, span) in user_written_bounds {
             if let Some(trait_pred) = clause.as_trait_clause() {
-                let violations =
-                    hir_ty_lowering_dyn_compatibility_violations(tcx, trait_pred.def_id());
+                let violations = self.dyn_compatibility_violations(trait_pred.def_id());
                 if !violations.is_empty() {
                     let reported = report_dyn_incompatibility(
                         tcx,
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
index 6b21bbbfcd8..a5dd17b4d63 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
@@ -33,7 +33,7 @@ use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::{self as hir, AnonConst, GenericArg, GenericArgs, HirId};
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
-use rustc_infer::traits::ObligationCause;
+use rustc_infer::traits::{DynCompatibilityViolation, ObligationCause};
 use rustc_middle::middle::stability::AllowUnstable;
 use rustc_middle::mir::interpret::LitToConstInput;
 use rustc_middle::ty::print::PrintPolyTraitRefExt as _;
@@ -200,6 +200,10 @@ pub trait HirTyLowerer<'tcx> {
     {
         self
     }
+
+    /// Performs minimalistic dyn compat checks outside of bodies, but full within bodies.
+    /// Outside of bodies we could end up in cycles, so we delay most checks to later phases.
+    fn dyn_compatibility_violations(&self, trait_def_id: DefId) -> Vec<DynCompatibilityViolation>;
 }
 
 /// The "qualified self" of an associated item path.
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
index ea0adf16b1a..cfb25deac0e 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
@@ -14,7 +14,7 @@ use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::{self as hir, HirId, ItemLocalMap};
 use rustc_hir_analysis::hir_ty_lowering::{HirTyLowerer, RegionInferReason};
 use rustc_infer::infer;
-use rustc_infer::traits::Obligation;
+use rustc_infer::traits::{DynCompatibilityViolation, Obligation};
 use rustc_middle::ty::{self, Const, Ty, TyCtxt, TypeVisitableExt};
 use rustc_session::Session;
 use rustc_span::{self, DUMMY_SP, ErrorGuaranteed, Ident, Span, sym};
@@ -388,6 +388,10 @@ impl<'tcx> HirTyLowerer<'tcx> for FnCtxt<'_, 'tcx> {
         };
         (input_tys, output_ty)
     }
+
+    fn dyn_compatibility_violations(&self, trait_def_id: DefId) -> Vec<DynCompatibilityViolation> {
+        self.tcx.dyn_compatibility_violations(trait_def_id).to_vec()
+    }
 }
 
 /// The `ty` representation of a user-provided type. Depending on the use-site
diff --git a/tests/ui/async-await/dyn/mut-is-pointer-like.stderr b/tests/ui/async-await/dyn/mut-is-pointer-like.stderr
index 9b818a15c29..6689539ff45 100644
--- a/tests/ui/async-await/dyn/mut-is-pointer-like.stderr
+++ b/tests/ui/async-await/dyn/mut-is-pointer-like.stderr
@@ -8,10 +8,10 @@ LL | #![feature(async_fn_in_dyn_trait)]
    = note: `#[warn(incomplete_features)]` on by default
 
 error[E0038]: the trait `AsyncTrait` is not dyn compatible
-  --> $DIR/mut-is-pointer-like.rs:35:16
+  --> $DIR/mut-is-pointer-like.rs:35:29
    |
 LL |         let x: Pin<&mut dyn AsyncTrait<Output = ()>> = f;
-   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
+   |                             ^^^^^^^^^^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/async-await/dyn/works.stderr b/tests/ui/async-await/dyn/works.stderr
index 5d2cc385cbd..338479d8b70 100644
--- a/tests/ui/async-await/dyn/works.stderr
+++ b/tests/ui/async-await/dyn/works.stderr
@@ -8,10 +8,10 @@ LL | #![feature(async_fn_in_dyn_trait)]
    = note: `#[warn(incomplete_features)]` on by default
 
 error[E0038]: the trait `AsyncTrait` is not dyn compatible
-  --> $DIR/works.rs:27:16
+  --> $DIR/works.rs:27:21
    |
 LL |         let x: &dyn AsyncTrait = &"hello, world!";
-   |                ^^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
+   |                     ^^^^^^^^^^ `AsyncTrait` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/async-await/dyn/wrong-size.stderr b/tests/ui/async-await/dyn/wrong-size.stderr
index 930ca571417..a465f91f62a 100644
--- a/tests/ui/async-await/dyn/wrong-size.stderr
+++ b/tests/ui/async-await/dyn/wrong-size.stderr
@@ -8,10 +8,10 @@ LL | #![feature(async_fn_in_dyn_trait)]
    = note: `#[warn(incomplete_features)]` on by default
 
 error[E0038]: the trait `AsyncTrait` is not dyn compatible
-  --> $DIR/wrong-size.rs:21:12
+  --> $DIR/wrong-size.rs:21:17
    |
 LL |     let x: &dyn AsyncTrait = &"hello, world!";
-   |            ^^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
+   |                 ^^^^^^^^^^ `AsyncTrait` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/async-await/in-trait/dyn-compatibility.stderr b/tests/ui/async-await/in-trait/dyn-compatibility.stderr
index 553bcbf89d5..f0c5dc53478 100644
--- a/tests/ui/async-await/in-trait/dyn-compatibility.stderr
+++ b/tests/ui/async-await/in-trait/dyn-compatibility.stderr
@@ -1,8 +1,8 @@
 error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/dyn-compatibility.rs:9:12
+  --> $DIR/dyn-compatibility.rs:9:17
    |
 LL |     let x: &dyn Foo = todo!();
-   |            ^^^^^^^^ `Foo` is not dyn compatible
+   |                 ^^^ `Foo` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/did_you_mean/trait-object-reference-without-parens-suggestion.rs b/tests/ui/did_you_mean/trait-object-reference-without-parens-suggestion.rs
index 9cd32ffeb6d..b7470864a30 100644
--- a/tests/ui/did_you_mean/trait-object-reference-without-parens-suggestion.rs
+++ b/tests/ui/did_you_mean/trait-object-reference-without-parens-suggestion.rs
@@ -4,4 +4,5 @@ fn main() {
     let _: &Copy + 'static; //~ ERROR expected a path
     //~^ ERROR is not dyn compatible
     let _: &'static Copy + 'static; //~ ERROR expected a path
+    //~^ ERROR is not dyn compatible
 }
diff --git a/tests/ui/did_you_mean/trait-object-reference-without-parens-suggestion.stderr b/tests/ui/did_you_mean/trait-object-reference-without-parens-suggestion.stderr
index 762b37b9e9d..57dbc79a0fd 100644
--- a/tests/ui/did_you_mean/trait-object-reference-without-parens-suggestion.stderr
+++ b/tests/ui/did_you_mean/trait-object-reference-without-parens-suggestion.stderr
@@ -21,16 +21,26 @@ LL |     let _: &'static (Copy + 'static);
    |                     +              +
 
 error[E0038]: the trait `Copy` is not dyn compatible
-  --> $DIR/trait-object-reference-without-parens-suggestion.rs:4:12
+  --> $DIR/trait-object-reference-without-parens-suggestion.rs:4:13
    |
 LL |     let _: &Copy + 'static;
-   |            ^^^^^ `Copy` is not dyn compatible
+   |             ^^^^ `Copy` is not dyn compatible
+   |
+   = note: the trait is not dyn compatible because it requires `Self: Sized`
+   = note: for a trait to be dyn compatible it needs to allow building a vtable
+           for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
+
+error[E0038]: the trait `Copy` is not dyn compatible
+  --> $DIR/trait-object-reference-without-parens-suggestion.rs:6:21
+   |
+LL |     let _: &'static Copy + 'static;
+   |                     ^^^^ `Copy` is not dyn compatible
    |
    = note: the trait is not dyn compatible because it requires `Self: Sized`
    = note: for a trait to be dyn compatible it needs to allow building a vtable
            for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
 
-error: aborting due to 3 previous errors
+error: aborting due to 4 previous errors
 
 Some errors have detailed explanations: E0038, E0178.
 For more information about an error, try `rustc --explain E0038`.
diff --git a/tests/ui/dyn-compatibility/almost-supertrait-associated-type.stderr b/tests/ui/dyn-compatibility/almost-supertrait-associated-type.stderr
index d3022b5d8cd..acd6dbe7b2c 100644
--- a/tests/ui/dyn-compatibility/almost-supertrait-associated-type.stderr
+++ b/tests/ui/dyn-compatibility/almost-supertrait-associated-type.stderr
@@ -16,10 +16,10 @@ LL |     fn transmute(&self, t: T) -> <Self as Super<NotActuallySuper>>::Assoc;
    = help: consider moving `transmute` to another trait
 
 error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/almost-supertrait-associated-type.rs:7:27
+  --> $DIR/almost-supertrait-associated-type.rs:7:32
    |
 LL |     (&PhantomData::<T> as &dyn Foo<T, U>).transmute(t)
-   |                           ^^^^^^^^^^^^^^ `Foo` is not dyn compatible
+   |                                ^^^^^^^^^ `Foo` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/dyn-compatibility/generics.stderr b/tests/ui/dyn-compatibility/generics.stderr
index aec51970ebb..79dccc42244 100644
--- a/tests/ui/dyn-compatibility/generics.stderr
+++ b/tests/ui/dyn-compatibility/generics.stderr
@@ -31,10 +31,10 @@ LL |     fn bar<T>(&self, t: T);
    = help: consider moving `bar` to another trait
 
 error[E0038]: the trait `Bar` is not dyn compatible
-  --> $DIR/generics.rs:22:10
+  --> $DIR/generics.rs:22:15
    |
 LL |     t as &dyn Bar
-   |          ^^^^^^^^ `Bar` is not dyn compatible
+   |               ^^^ `Bar` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/dyn-compatibility/mention-correct-dyn-incompatible-trait.stderr b/tests/ui/dyn-compatibility/mention-correct-dyn-incompatible-trait.stderr
index 5bc1847ebde..dd7b31a70c5 100644
--- a/tests/ui/dyn-compatibility/mention-correct-dyn-incompatible-trait.stderr
+++ b/tests/ui/dyn-compatibility/mention-correct-dyn-incompatible-trait.stderr
@@ -1,8 +1,8 @@
 error[E0038]: the trait `Bar` is not dyn compatible
-  --> $DIR/mention-correct-dyn-incompatible-trait.rs:19:15
+  --> $DIR/mention-correct-dyn-incompatible-trait.rs:19:24
    |
 LL |     let test: &mut dyn Bar = &mut thing;
-   |               ^^^^^^^^^^^^ `Bar` is not dyn compatible
+   |                        ^^^ `Bar` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/dyn-compatibility/no-static.stderr b/tests/ui/dyn-compatibility/no-static.stderr
index 8e4f109c97d..c1d5dd6f562 100644
--- a/tests/ui/dyn-compatibility/no-static.stderr
+++ b/tests/ui/dyn-compatibility/no-static.stderr
@@ -23,10 +23,10 @@ LL |     fn foo() where Self: Sized {}
    |              +++++++++++++++++
 
 error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/no-static.rs:18:12
+  --> $DIR/no-static.rs:18:20
    |
 LL |     let b: Box<dyn Foo> = Box::new(Bar);
-   |            ^^^^^^^^^^^^ `Foo` is not dyn compatible
+   |                    ^^^ `Foo` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/feature-gates/feature-gate-dispatch-from-dyn-missing-impl.stderr b/tests/ui/feature-gates/feature-gate-dispatch-from-dyn-missing-impl.stderr
index 18b99d24083..c70ab65aa90 100644
--- a/tests/ui/feature-gates/feature-gate-dispatch-from-dyn-missing-impl.stderr
+++ b/tests/ui/feature-gates/feature-gate-dispatch-from-dyn-missing-impl.stderr
@@ -1,11 +1,11 @@
 error[E0038]: the trait `Trait` is not dyn compatible
-  --> $DIR/feature-gate-dispatch-from-dyn-missing-impl.rs:32:25
+  --> $DIR/feature-gate-dispatch-from-dyn-missing-impl.rs:32:33
    |
 LL |     fn ptr(self: Ptr<Self>);
    |                  --------- help: consider changing method `ptr`'s `self` parameter to be `&self`: `&Self`
 ...
 LL |     Ptr(Box::new(4)) as Ptr<dyn Trait>;
-   |                         ^^^^^^^^^^^^^^ `Trait` is not dyn compatible
+   |                                 ^^^^^ `Trait` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/generic-associated-types/issue-76535.stderr b/tests/ui/generic-associated-types/issue-76535.stderr
index 9bac3318948..2daf9d817bb 100644
--- a/tests/ui/generic-associated-types/issue-76535.stderr
+++ b/tests/ui/generic-associated-types/issue-76535.stderr
@@ -15,10 +15,10 @@ LL |     let sub: Box<dyn SuperTrait<SubType<'a> = SubStruct>> = Box::new(SuperS
    |                                        ++++
 
 error[E0038]: the trait `SuperTrait` is not dyn compatible
-  --> $DIR/issue-76535.rs:34:14
+  --> $DIR/issue-76535.rs:34:22
    |
 LL |     let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `SuperTrait` is not dyn compatible
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `SuperTrait` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/generic-associated-types/issue-78671.stderr b/tests/ui/generic-associated-types/issue-78671.stderr
index c6da137672d..fff061a8ada 100644
--- a/tests/ui/generic-associated-types/issue-78671.stderr
+++ b/tests/ui/generic-associated-types/issue-78671.stderr
@@ -15,10 +15,10 @@ LL |     Box::new(Family) as &dyn CollectionFamily<Member<T>=usize>
    |                                                     +++
 
 error[E0038]: the trait `CollectionFamily` is not dyn compatible
-  --> $DIR/issue-78671.rs:5:25
+  --> $DIR/issue-78671.rs:5:30
    |
 LL |     Box::new(Family) as &dyn CollectionFamily<Member=usize>
-   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `CollectionFamily` is not dyn compatible
+   |                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `CollectionFamily` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/generic-associated-types/issue-79422.stderr b/tests/ui/generic-associated-types/issue-79422.stderr
index 403cb67adb4..dcf3a9008de 100644
--- a/tests/ui/generic-associated-types/issue-79422.stderr
+++ b/tests/ui/generic-associated-types/issue-79422.stderr
@@ -15,10 +15,10 @@ LL |         as Box<dyn MapLike<u8, u8, VRefCont<'a> = dyn RefCont<'_, u8>>>;
    |                                            ++++
 
 error[E0038]: the trait `MapLike` is not dyn compatible
-  --> $DIR/issue-79422.rs:45:12
+  --> $DIR/issue-79422.rs:45:20
    |
 LL |         as Box<dyn MapLike<u8, u8, VRefCont = dyn RefCont<'_, u8>>>;
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `MapLike` is not dyn compatible
+   |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `MapLike` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/higher-ranked/trait-bounds/span-bug-issue-121597.rs b/tests/ui/higher-ranked/trait-bounds/span-bug-issue-121597.rs
index 949c49a820b..cc813430468 100644
--- a/tests/ui/higher-ranked/trait-bounds/span-bug-issue-121597.rs
+++ b/tests/ui/higher-ranked/trait-bounds/span-bug-issue-121597.rs
@@ -15,5 +15,4 @@ fn main() {
     //~^ ERROR the trait `Foo` is not dyn compatible
 
     needs_bar(x);
-    //~^ ERROR mismatched types
 }
diff --git a/tests/ui/higher-ranked/trait-bounds/span-bug-issue-121597.stderr b/tests/ui/higher-ranked/trait-bounds/span-bug-issue-121597.stderr
index 10a9e2c8d24..d35394a4f66 100644
--- a/tests/ui/higher-ranked/trait-bounds/span-bug-issue-121597.stderr
+++ b/tests/ui/higher-ranked/trait-bounds/span-bug-issue-121597.stderr
@@ -1,8 +1,8 @@
 error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/span-bug-issue-121597.rs:14:12
+  --> $DIR/span-bug-issue-121597.rs:14:17
    |
 LL |     let x: &dyn Foo = &();
-   |            ^^^^^^^^ `Foo` is not dyn compatible
+   |                 ^^^ `Foo` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
@@ -13,23 +13,6 @@ LL | trait Foo: for<T> Bar<T> {}
    |       |
    |       this trait is not dyn compatible...
 
-error[E0308]: mismatched types
-  --> $DIR/span-bug-issue-121597.rs:17:15
-   |
-LL |     needs_bar(x);
-   |     --------- ^ types differ in mutability
-   |     |
-   |     arguments to this function are incorrect
-   |
-   = note: expected raw pointer `*mut Type2`
-                found reference `&dyn Foo`
-note: function defined here
-  --> $DIR/span-bug-issue-121597.rs:11:4
-   |
-LL | fn needs_bar(_: *mut Type2) {}
-   |    ^^^^^^^^^ -------------
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
-Some errors have detailed explanations: E0038, E0308.
-For more information about an error, try `rustc --explain E0038`.
+For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/impl-trait/dyn-incompatible-trait-in-return-position-dyn-trait.rs b/tests/ui/impl-trait/dyn-incompatible-trait-in-return-position-dyn-trait.rs
index c3dc417b187..accd173ce23 100644
--- a/tests/ui/impl-trait/dyn-incompatible-trait-in-return-position-dyn-trait.rs
+++ b/tests/ui/impl-trait/dyn-incompatible-trait-in-return-position-dyn-trait.rs
@@ -21,6 +21,8 @@ impl DynIncompatible for B {
 
 fn car() -> dyn DynIncompatible { //~ ERROR the trait `DynIncompatible` is not dyn compatible
 //~^ ERROR return type cannot be a trait object without pointer indirection
+//~| ERROR the trait `DynIncompatible` is not dyn compatible
+//~| ERROR the trait `DynIncompatible` is not dyn compatible
     if true {
         return A;
     }
diff --git a/tests/ui/impl-trait/dyn-incompatible-trait-in-return-position-dyn-trait.stderr b/tests/ui/impl-trait/dyn-incompatible-trait-in-return-position-dyn-trait.stderr
index a230090eb00..a8787a01a6f 100644
--- a/tests/ui/impl-trait/dyn-incompatible-trait-in-return-position-dyn-trait.stderr
+++ b/tests/ui/impl-trait/dyn-incompatible-trait-in-return-position-dyn-trait.stderr
@@ -41,6 +41,7 @@ help: alternatively, box the return type, and wrap all of the returned values in
    |
 LL ~ fn car() -> Box<dyn DynIncompatible> {
 LL |
+...
 LL |     if true {
 LL ~         return Box::new(A);
 LL |     }
@@ -48,7 +49,7 @@ LL ~     Box::new(B)
    |
 
 error[E0038]: the trait `DynIncompatible` is not dyn compatible
-  --> $DIR/dyn-incompatible-trait-in-return-position-dyn-trait.rs:30:17
+  --> $DIR/dyn-incompatible-trait-in-return-position-dyn-trait.rs:32:17
    |
 LL | fn cat() -> Box<dyn DynIncompatible> {
    |                 ^^^^^^^^^^^^^^^^^^^ `DynIncompatible` is not dyn compatible
@@ -75,7 +76,74 @@ help: alternatively, consider constraining `foo` so it does not apply to trait o
 LL |     fn foo() -> Self where Self: Sized;
    |                      +++++++++++++++++
 
-error: aborting due to 3 previous errors
+error[E0038]: the trait `DynIncompatible` is not dyn compatible
+  --> $DIR/dyn-incompatible-trait-in-return-position-dyn-trait.rs:22:17
+   |
+LL | fn car() -> dyn DynIncompatible {
+   |                 ^^^^^^^^^^^^^^^ `DynIncompatible` is not dyn compatible
+   |
+note: for a trait to be dyn compatible it needs to allow building a vtable
+      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
+  --> $DIR/dyn-incompatible-trait-in-return-position-dyn-trait.rs:4:8
+   |
+LL | trait DynIncompatible {
+   |       --------------- this trait is not dyn compatible...
+LL |     fn foo() -> Self;
+   |        ^^^ ...because associated function `foo` has no `self` parameter
+   = help: the following types implement `DynIncompatible`:
+             A
+             B
+           consider defining an enum where each variant holds one of these types,
+           implementing `DynIncompatible` for this new enum and using it instead
+help: consider using an opaque type instead
+   |
+LL - fn car() -> dyn DynIncompatible {
+LL + fn car() -> impl DynIncompatible {
+   |
+help: consider turning `foo` into a method by giving it a `&self` argument
+   |
+LL |     fn foo(&self) -> Self;
+   |            +++++
+help: alternatively, consider constraining `foo` so it does not apply to trait objects
+   |
+LL |     fn foo() -> Self where Self: Sized;
+   |                      +++++++++++++++++
+
+error[E0038]: the trait `DynIncompatible` is not dyn compatible
+  --> $DIR/dyn-incompatible-trait-in-return-position-dyn-trait.rs:22:17
+   |
+LL | fn car() -> dyn DynIncompatible {
+   |                 ^^^^^^^^^^^^^^^ `DynIncompatible` is not dyn compatible
+   |
+note: for a trait to be dyn compatible it needs to allow building a vtable
+      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
+  --> $DIR/dyn-incompatible-trait-in-return-position-dyn-trait.rs:4:8
+   |
+LL | trait DynIncompatible {
+   |       --------------- this trait is not dyn compatible...
+LL |     fn foo() -> Self;
+   |        ^^^ ...because associated function `foo` has no `self` parameter
+   = help: the following types implement `DynIncompatible`:
+             A
+             B
+           consider defining an enum where each variant holds one of these types,
+           implementing `DynIncompatible` for this new enum and using it instead
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+help: consider using an opaque type instead
+   |
+LL - fn car() -> dyn DynIncompatible {
+LL + fn car() -> impl DynIncompatible {
+   |
+help: consider turning `foo` into a method by giving it a `&self` argument
+   |
+LL |     fn foo(&self) -> Self;
+   |            +++++
+help: alternatively, consider constraining `foo` so it does not apply to trait objects
+   |
+LL |     fn foo() -> Self where Self: Sized;
+   |                      +++++++++++++++++
+
+error: aborting due to 5 previous errors
 
 Some errors have detailed explanations: E0038, E0746.
 For more information about an error, try `rustc --explain E0038`.
diff --git a/tests/ui/impl-trait/in-trait/dyn-compatibility.stderr b/tests/ui/impl-trait/in-trait/dyn-compatibility.stderr
index d65ed6bbcda..8cdb3808533 100644
--- a/tests/ui/impl-trait/in-trait/dyn-compatibility.stderr
+++ b/tests/ui/impl-trait/in-trait/dyn-compatibility.stderr
@@ -1,8 +1,8 @@
 error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/dyn-compatibility.rs:14:33
+  --> $DIR/dyn-compatibility.rs:14:41
    |
 LL |     let i = Box::new(42_u32) as Box<dyn Foo>;
-   |                                 ^^^^^^^^^^^^ `Foo` is not dyn compatible
+   |                                         ^^^ `Foo` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/impl-trait/in-trait/foreign-dyn-error.stderr b/tests/ui/impl-trait/in-trait/foreign-dyn-error.stderr
index 29235ca78a5..68ac765a3c1 100644
--- a/tests/ui/impl-trait/in-trait/foreign-dyn-error.stderr
+++ b/tests/ui/impl-trait/in-trait/foreign-dyn-error.stderr
@@ -1,8 +1,8 @@
 error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/foreign-dyn-error.rs:6:12
+  --> $DIR/foreign-dyn-error.rs:6:17
    |
 LL |     let _: &dyn rpitit::Foo = todo!();
-   |            ^^^^^^^^^^^^^^^^ `Foo` is not dyn compatible
+   |                 ^^^^^^^^^^^ `Foo` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/issues/issue-18959.rs b/tests/ui/issues/issue-18959.rs
index 4fe669adcda..415fe818f53 100644
--- a/tests/ui/issues/issue-18959.rs
+++ b/tests/ui/issues/issue-18959.rs
@@ -18,4 +18,5 @@ fn main() {
     let test: &dyn Bar = &mut thing;
     //~^ ERROR E0038
     foo(test);
+    //~^ ERROR E0038
 }
diff --git a/tests/ui/issues/issue-18959.stderr b/tests/ui/issues/issue-18959.stderr
index 5345046ba6d..df47d50a019 100644
--- a/tests/ui/issues/issue-18959.stderr
+++ b/tests/ui/issues/issue-18959.stderr
@@ -15,10 +15,10 @@ LL | pub trait Bar: Foo { }
    = help: consider moving `foo` to another trait
 
 error[E0038]: the trait `Bar` is not dyn compatible
-  --> $DIR/issue-18959.rs:18:15
+  --> $DIR/issue-18959.rs:18:20
    |
 LL |     let test: &dyn Bar = &mut thing;
-   |               ^^^^^^^^ `Bar` is not dyn compatible
+   |                    ^^^ `Bar` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
@@ -30,6 +30,22 @@ LL | pub trait Bar: Foo { }
    |           --- this trait is not dyn compatible...
    = help: consider moving `foo` to another trait
 
-error: aborting due to 2 previous errors
+error[E0038]: the trait `Bar` is not dyn compatible
+  --> $DIR/issue-18959.rs:20:9
+   |
+LL |     foo(test);
+   |         ^^^^ `Bar` is not dyn compatible
+   |
+note: for a trait to be dyn compatible it needs to allow building a vtable
+      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
+  --> $DIR/issue-18959.rs:1:20
+   |
+LL | pub trait Foo { fn foo<T>(&self, ext_thing: &T); }
+   |                    ^^^ ...because method `foo` has generic type parameters
+LL | pub trait Bar: Foo { }
+   |           --- this trait is not dyn compatible...
+   = help: consider moving `foo` to another trait
+
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/issues/issue-50781.stderr b/tests/ui/issues/issue-50781.stderr
index be6519429a5..4ba3166b6c5 100644
--- a/tests/ui/issues/issue-50781.stderr
+++ b/tests/ui/issues/issue-50781.stderr
@@ -16,10 +16,10 @@ LL |     fn foo(&self) where Self: Trait;
    = help: only type `()` implements `X`; consider using it directly instead.
 
 error[E0038]: the trait `X` is not dyn compatible
-  --> $DIR/issue-50781.rs:16:6
+  --> $DIR/issue-50781.rs:16:10
    |
 LL |     <dyn X as X>::foo(&());
-   |      ^^^^^ `X` is not dyn compatible
+   |          ^ `X` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/issues/issue-58734.rs b/tests/ui/issues/issue-58734.rs
index ee23be87b6b..e5b371f5530 100644
--- a/tests/ui/issues/issue-58734.rs
+++ b/tests/ui/issues/issue-58734.rs
@@ -18,8 +18,7 @@ fn main() {
     Trait::exists(());
     // no dyn-compatibility error
     Trait::nonexistent(());
-    //~^ ERROR no function or associated item named `nonexistent` found
-    //~| WARN trait objects without an explicit `dyn` are deprecated
+    //~^ WARN trait objects without an explicit `dyn` are deprecated
     //~| WARN this is accepted in the current edition
     //~| ERROR the trait `Trait` is not dyn compatible
 }
diff --git a/tests/ui/issues/issue-58734.stderr b/tests/ui/issues/issue-58734.stderr
index c4624cecc62..e5dad000b51 100644
--- a/tests/ui/issues/issue-58734.stderr
+++ b/tests/ui/issues/issue-58734.stderr
@@ -37,13 +37,6 @@ help: alternatively, consider constraining `dyn_incompatible` so it does not app
 LL |     fn dyn_incompatible() -> Self where Self: Sized;
    |                                   +++++++++++++++++
 
-error[E0599]: no function or associated item named `nonexistent` found for trait object `dyn Trait` in the current scope
-  --> $DIR/issue-58734.rs:20:12
-   |
-LL |     Trait::nonexistent(());
-   |            ^^^^^^^^^^^ function or associated item not found in `dyn Trait`
-
-error: aborting due to 2 previous errors; 1 warning emitted
+error: aborting due to 1 previous error; 1 warning emitted
 
-Some errors have detailed explanations: E0038, E0599.
-For more information about an error, try `rustc --explain E0038`.
+For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/kindck/kindck-inherited-copy-bound.stderr b/tests/ui/kindck/kindck-inherited-copy-bound.stderr
index 05d31f48f47..c15aabacddd 100644
--- a/tests/ui/kindck/kindck-inherited-copy-bound.stderr
+++ b/tests/ui/kindck/kindck-inherited-copy-bound.stderr
@@ -20,10 +20,10 @@ LL | fn take_param<T:Foo>(foo: &T) { }
    |                 ^^^ required by this bound in `take_param`
 
 error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/kindck-inherited-copy-bound.rs:23:19
+  --> $DIR/kindck-inherited-copy-bound.rs:23:24
    |
 LL |     let z = &x as &dyn Foo;
-   |                   ^^^^^^^^ `Foo` is not dyn compatible
+   |                        ^^^ `Foo` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/self/arbitrary-self-types-dyn-incompatible.stderr b/tests/ui/self/arbitrary-self-types-dyn-incompatible.stderr
index 977ccecea06..fe4802c9b3a 100644
--- a/tests/ui/self/arbitrary-self-types-dyn-incompatible.stderr
+++ b/tests/ui/self/arbitrary-self-types-dyn-incompatible.stderr
@@ -1,11 +1,11 @@
 error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/arbitrary-self-types-dyn-incompatible.rs:29:32
+  --> $DIR/arbitrary-self-types-dyn-incompatible.rs:29:39
    |
 LL |     fn foo(self: &Rc<Self>) -> usize;
    |                  --------- help: consider changing method `foo`'s `self` parameter to be `&self`: `&Self`
 ...
 LL |     let x = Rc::new(5usize) as Rc<dyn Foo>;
-   |                                ^^^^^^^^^^^ `Foo` is not dyn compatible
+   |                                       ^^^ `Foo` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/traits/issue-20692.stderr b/tests/ui/traits/issue-20692.stderr
index e902a582cc7..d4a18899dcb 100644
--- a/tests/ui/traits/issue-20692.stderr
+++ b/tests/ui/traits/issue-20692.stderr
@@ -1,8 +1,8 @@
 error[E0038]: the trait `Array` is not dyn compatible
-  --> $DIR/issue-20692.rs:6:5
+  --> $DIR/issue-20692.rs:6:10
    |
 LL |     &dyn Array;
-   |     ^^^^^^^^^^ `Array` is not dyn compatible
+   |          ^^^^^ `Array` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/traits/issue-38604.stderr b/tests/ui/traits/issue-38604.stderr
index 0455230b1aa..0f39dc536eb 100644
--- a/tests/ui/traits/issue-38604.stderr
+++ b/tests/ui/traits/issue-38604.stderr
@@ -1,8 +1,8 @@
 error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/issue-38604.rs:14:13
+  --> $DIR/issue-38604.rs:14:21
    |
 LL |     let _f: Box<dyn Foo> =
-   |             ^^^^^^^^^^^^ `Foo` is not dyn compatible
+   |                     ^^^ `Foo` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/traits/item-privacy.rs b/tests/ui/traits/item-privacy.rs
index cdfd667a6f1..9f75e6e4c12 100644
--- a/tests/ui/traits/item-privacy.rs
+++ b/tests/ui/traits/item-privacy.rs
@@ -99,9 +99,7 @@ fn check_assoc_const() {
     S::C; // OK
     // A, B, C are resolved as inherent items, their traits don't need to be in scope
     <dyn C>::A;
-    //~^ ERROR associated constant `A` is private
-    //~| ERROR the trait `assoc_const::C` is not dyn compatible
-    //~| ERROR the trait `assoc_const::C` is not dyn compatible
+    //~^ ERROR the trait `assoc_const::C` is not dyn compatible
     <dyn C>::B;
     //~^ ERROR the trait `assoc_const::C` is not dyn compatible
     C::C; // OK
diff --git a/tests/ui/traits/item-privacy.stderr b/tests/ui/traits/item-privacy.stderr
index 1d3d8cb9843..bf59cd079a5 100644
--- a/tests/ui/traits/item-privacy.stderr
+++ b/tests/ui/traits/item-privacy.stderr
@@ -131,44 +131,10 @@ LL + use assoc_const::B;
    |
 
 error[E0038]: the trait `assoc_const::C` is not dyn compatible
-  --> $DIR/item-privacy.rs:101:6
+  --> $DIR/item-privacy.rs:101:10
    |
 LL |     <dyn C>::A;
-   |      ^^^^^ `assoc_const::C` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/item-privacy.rs:25:15
-   |
-LL |         const A: u8 = 0;
-   |               ^ ...because it contains this associated `const`
-...
-LL |         const B: u8 = 0;
-   |               ^ ...because it contains this associated `const`
-...
-LL |     pub trait C: A + B {
-   |               - this trait is not dyn compatible...
-LL |         const C: u8 = 0;
-   |               ^ ...because it contains this associated `const`
-   = help: consider moving `C` to another trait
-   = help: consider moving `A` to another trait
-   = help: consider moving `B` to another trait
-   = help: only type `S` implements `assoc_const::C`; consider using it directly instead.
-
-error[E0624]: associated constant `A` is private
-  --> $DIR/item-privacy.rs:101:14
-   |
-LL |         const A: u8 = 0;
-   |         ----------- private associated constant defined here
-...
-LL |     <dyn C>::A;
-   |              ^ private associated constant
-
-error[E0038]: the trait `assoc_const::C` is not dyn compatible
-  --> $DIR/item-privacy.rs:101:5
-   |
-LL |     <dyn C>::A;
-   |     ^^^^^^^^^^ `assoc_const::C` is not dyn compatible
+   |          ^ `assoc_const::C` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
@@ -190,10 +156,10 @@ LL |         const C: u8 = 0;
    = help: only type `S` implements `assoc_const::C`; consider using it directly instead.
 
 error[E0038]: the trait `assoc_const::C` is not dyn compatible
-  --> $DIR/item-privacy.rs:105:5
+  --> $DIR/item-privacy.rs:103:10
    |
 LL |     <dyn C>::B;
-   |     ^^^^^^^^^^ `assoc_const::C` is not dyn compatible
+   |          ^ `assoc_const::C` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
@@ -215,7 +181,7 @@ LL |         const C: u8 = 0;
    = help: only type `S` implements `assoc_const::C`; consider using it directly instead.
 
 error[E0223]: ambiguous associated type
-  --> $DIR/item-privacy.rs:118:12
+  --> $DIR/item-privacy.rs:116:12
    |
 LL |     let _: S::A;
    |            ^^^^
@@ -227,7 +193,7 @@ LL +     let _: <S as Example>::A;
    |
 
 error[E0223]: ambiguous associated type
-  --> $DIR/item-privacy.rs:119:12
+  --> $DIR/item-privacy.rs:117:12
    |
 LL |     let _: S::B;
    |            ^^^^
@@ -239,7 +205,7 @@ LL +     let _: <S as assoc_ty::B>::B;
    |
 
 error[E0223]: ambiguous associated type
-  --> $DIR/item-privacy.rs:120:12
+  --> $DIR/item-privacy.rs:118:12
    |
 LL |     let _: S::C;
    |            ^^^^
@@ -251,7 +217,7 @@ LL +     let _: <S as assoc_ty::C>::C;
    |
 
 error[E0624]: associated type `A` is private
-  --> $DIR/item-privacy.rs:122:12
+  --> $DIR/item-privacy.rs:120:12
    |
 LL |         type A = u8;
    |         ------ the associated type is defined here
@@ -260,7 +226,7 @@ LL |     let _: T::A;
    |            ^^^^ private associated type
 
 error[E0624]: associated type `A` is private
-  --> $DIR/item-privacy.rs:131:9
+  --> $DIR/item-privacy.rs:129:9
    |
 LL |         type A = u8;
    |         ------ the associated type is defined here
@@ -268,7 +234,7 @@ LL |         type A = u8;
 LL |         A = u8,
    |         ^^^^^^ private associated type
 
-error: aborting due to 17 previous errors
+error: aborting due to 15 previous errors
 
 Some errors have detailed explanations: E0038, E0223, E0599, E0624.
 For more information about an error, try `rustc --explain E0038`.
diff --git a/tests/ui/traits/non_lifetime_binders/supertrait-dyn-compatibility.rs b/tests/ui/traits/non_lifetime_binders/supertrait-dyn-compatibility.rs
index 2945b28eec3..96345732f0f 100644
--- a/tests/ui/traits/non_lifetime_binders/supertrait-dyn-compatibility.rs
+++ b/tests/ui/traits/non_lifetime_binders/supertrait-dyn-compatibility.rs
@@ -19,5 +19,4 @@ fn main() {
     let x: &dyn Foo = &();
     //~^ ERROR the trait `Foo` is not dyn compatible
     needs_bar(x);
-    //~^ ERROR the trait `Foo` is not dyn compatible
 }
diff --git a/tests/ui/traits/non_lifetime_binders/supertrait-dyn-compatibility.stderr b/tests/ui/traits/non_lifetime_binders/supertrait-dyn-compatibility.stderr
index 2cf6329d0a1..aead19c4527 100644
--- a/tests/ui/traits/non_lifetime_binders/supertrait-dyn-compatibility.stderr
+++ b/tests/ui/traits/non_lifetime_binders/supertrait-dyn-compatibility.stderr
@@ -8,10 +8,10 @@ LL | #![feature(non_lifetime_binders)]
    = note: `#[warn(incomplete_features)]` on by default
 
 error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/supertrait-dyn-compatibility.rs:19:12
+  --> $DIR/supertrait-dyn-compatibility.rs:19:17
    |
 LL |     let x: &dyn Foo = &();
-   |            ^^^^^^^^ `Foo` is not dyn compatible
+   |                 ^^^ `Foo` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
@@ -23,22 +23,6 @@ LL | trait Foo: for<T> Bar<T> {}
    |       this trait is not dyn compatible...
    = help: only type `()` implements `Foo`; consider using it directly instead.
 
-error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/supertrait-dyn-compatibility.rs:21:5
-   |
-LL |     needs_bar(x);
-   |     ^^^^^^^^^ `Foo` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/supertrait-dyn-compatibility.rs:4:12
-   |
-LL | trait Foo: for<T> Bar<T> {}
-   |       ---  ^^^^^^^^^^^^^ ...because where clause cannot reference non-lifetime `for<...>` variables
-   |       |
-   |       this trait is not dyn compatible...
-   = help: only type `()` implements `Foo`; consider using it directly instead.
-
-error: aborting due to 2 previous errors; 1 warning emitted
+error: aborting due to 1 previous error; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/traits/object/canonicalize-fresh-infer-vars-issue-103626.rs b/tests/ui/traits/object/canonicalize-fresh-infer-vars-issue-103626.rs
index 415b050b9d6..9ac3b84dc12 100644
--- a/tests/ui/traits/object/canonicalize-fresh-infer-vars-issue-103626.rs
+++ b/tests/ui/traits/object/canonicalize-fresh-infer-vars-issue-103626.rs
@@ -9,7 +9,6 @@ trait Try {
 fn w<'a, T: 'a, F: Fn(&'a T)>() {
     let b: &dyn FromResidual = &();
     //~^ ERROR: the trait `FromResidual` is not dyn compatible
-    //~| ERROR the type parameter `R` must be explicitly specified
 }
 
 fn main() {}
diff --git a/tests/ui/traits/object/canonicalize-fresh-infer-vars-issue-103626.stderr b/tests/ui/traits/object/canonicalize-fresh-infer-vars-issue-103626.stderr
index 0f872dfba5d..707aa9e9713 100644
--- a/tests/ui/traits/object/canonicalize-fresh-infer-vars-issue-103626.stderr
+++ b/tests/ui/traits/object/canonicalize-fresh-infer-vars-issue-103626.stderr
@@ -1,23 +1,8 @@
-error[E0393]: the type parameter `R` must be explicitly specified
-  --> $DIR/canonicalize-fresh-infer-vars-issue-103626.rs:10:17
-   |
-LL | trait FromResidual<R = <Self as Try>::Residual> {
-   | ----------------------------------------------- type parameter `R` must be specified for this
-...
-LL |     let b: &dyn FromResidual = &();
-   |                 ^^^^^^^^^^^^
-   |
-   = note: because the parameter default references `Self`, the parameter must be specified on the object type
-help: set the type parameter to the desired type
-   |
-LL |     let b: &dyn FromResidual<R> = &();
-   |                             +++
-
 error[E0038]: the trait `FromResidual` is not dyn compatible
-  --> $DIR/canonicalize-fresh-infer-vars-issue-103626.rs:10:12
+  --> $DIR/canonicalize-fresh-infer-vars-issue-103626.rs:10:17
    |
 LL |     let b: &dyn FromResidual = &();
-   |            ^^^^^^^^^^^^^^^^^ `FromResidual` is not dyn compatible
+   |                 ^^^^^^^^^^^^ `FromResidual` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
@@ -36,7 +21,6 @@ help: alternatively, consider constraining `from_residual` so it does not apply
 LL |     fn from_residual(residual: R) -> Self where Self: Sized;
    |                                           +++++++++++++++++
 
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
-Some errors have detailed explanations: E0038, E0393.
-For more information about an error, try `rustc --explain E0038`.
+For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/traits/object/macro-matcher.stderr b/tests/ui/traits/object/macro-matcher.stderr
index 3c668ce99c7..94d5c189a43 100644
--- a/tests/ui/traits/object/macro-matcher.stderr
+++ b/tests/ui/traits/object/macro-matcher.stderr
@@ -1,19 +1,19 @@
-error[E0224]: at least one trait is required for an object type
-  --> $DIR/macro-matcher.rs:11:8
-   |
-LL |     m!(dyn 'static +);
-   |        ^^^^^^^^^^^^^
-
 error[E0038]: the trait `Copy` is not dyn compatible
-  --> $DIR/macro-matcher.rs:8:8
+  --> $DIR/macro-matcher.rs:8:12
    |
 LL |     m!(dyn Copy + Send + 'static);
-   |        ^^^^^^^^^^^^^^^^^^^^^^^^^ `Copy` is not dyn compatible
+   |            ^^^^ `Copy` is not dyn compatible
    |
    = note: the trait is not dyn compatible because it requires `Self: Sized`
    = note: for a trait to be dyn compatible it needs to allow building a vtable
            for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
 
+error[E0224]: at least one trait is required for an object type
+  --> $DIR/macro-matcher.rs:11:8
+   |
+LL |     m!(dyn 'static +);
+   |        ^^^^^^^^^^^^^
+
 error: aborting due to 2 previous errors
 
 Some errors have detailed explanations: E0038, E0224.
diff --git a/tests/ui/traits/object/safety.stderr b/tests/ui/traits/object/safety.stderr
index a3671d90d28..c5637b43526 100644
--- a/tests/ui/traits/object/safety.stderr
+++ b/tests/ui/traits/object/safety.stderr
@@ -1,8 +1,8 @@
 error[E0038]: the trait `Tr` is not dyn compatible
-  --> $DIR/safety.rs:15:12
+  --> $DIR/safety.rs:15:17
    |
 LL |     let _: &dyn Tr = &St;
-   |            ^^^^^^^ `Tr` is not dyn compatible
+   |                 ^^ `Tr` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/traits/test-2.stderr b/tests/ui/traits/test-2.stderr
index e4e39e9194c..6a8109281a8 100644
--- a/tests/ui/traits/test-2.stderr
+++ b/tests/ui/traits/test-2.stderr
@@ -27,10 +27,10 @@ LL | trait bar { fn dup(&self) -> Self; fn blah<X>(&self); }
    |                                       ^^^^ -
 
 error[E0038]: the trait `bar` is not dyn compatible
-  --> $DIR/test-2.rs:13:22
+  --> $DIR/test-2.rs:13:30
    |
 LL |     (Box::new(10) as Box<dyn bar>).dup();
-   |                      ^^^^^^^^^^^^ `bar` is not dyn compatible
+   |                              ^^^ `bar` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
diff --git a/tests/ui/type/type-parameter-defaults-referencing-Self-ppaux.rs b/tests/ui/type/type-parameter-defaults-referencing-Self-ppaux.rs
index 444453dc694..b877ef569f6 100644
--- a/tests/ui/type/type-parameter-defaults-referencing-Self-ppaux.rs
+++ b/tests/ui/type/type-parameter-defaults-referencing-Self-ppaux.rs
@@ -13,5 +13,4 @@ fn main() {
     let x: i32 = 5;
     let y = x as dyn MyAdd<i32>;
     //~^ ERROR E0038
-    //~| ERROR cast to unsized type: `i32` as `dyn MyAdd<i32>`
 }
diff --git a/tests/ui/type/type-parameter-defaults-referencing-Self-ppaux.stderr b/tests/ui/type/type-parameter-defaults-referencing-Self-ppaux.stderr
index eea2e75a238..33478740d65 100644
--- a/tests/ui/type/type-parameter-defaults-referencing-Self-ppaux.stderr
+++ b/tests/ui/type/type-parameter-defaults-referencing-Self-ppaux.stderr
@@ -1,20 +1,8 @@
-error[E0620]: cast to unsized type: `i32` as `dyn MyAdd<i32>`
-  --> $DIR/type-parameter-defaults-referencing-Self-ppaux.rs:14:13
-   |
-LL |     let y = x as dyn MyAdd<i32>;
-   |             ^^^^^^^^^^^^^^^^^^^
-   |
-help: consider using a box or reference as appropriate
-  --> $DIR/type-parameter-defaults-referencing-Self-ppaux.rs:14:13
-   |
-LL |     let y = x as dyn MyAdd<i32>;
-   |             ^
-
 error[E0038]: the trait `MyAdd` is not dyn compatible
-  --> $DIR/type-parameter-defaults-referencing-Self-ppaux.rs:14:18
+  --> $DIR/type-parameter-defaults-referencing-Self-ppaux.rs:14:22
    |
 LL |     let y = x as dyn MyAdd<i32>;
-   |                  ^^^^^^^^^^^^^^ `MyAdd` is not dyn compatible
+   |                      ^^^^^^^^^^ `MyAdd` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
@@ -25,7 +13,6 @@ LL | trait MyAdd<Rhs=Self> { fn add(&self, other: &Rhs) -> Self; }
    = help: consider moving `add` to another trait
    = help: only type `i32` implements `MyAdd`; consider using it directly instead.
 
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
-Some errors have detailed explanations: E0038, E0620.
-For more information about an error, try `rustc --explain E0038`.
+For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/wf/wf-dyn-incompatible.stderr b/tests/ui/wf/wf-dyn-incompatible.stderr
index e61b37d9293..2ba17b7aaef 100644
--- a/tests/ui/wf/wf-dyn-incompatible.stderr
+++ b/tests/ui/wf/wf-dyn-incompatible.stderr
@@ -1,8 +1,8 @@
 error[E0038]: the trait `A` is not dyn compatible
-  --> $DIR/wf-dyn-incompatible.rs:9:13
+  --> $DIR/wf-dyn-incompatible.rs:9:18
    |
 LL |     let _x: &dyn A;
-   |             ^^^^^^ `A` is not dyn compatible
+   |                  ^ `A` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>