Account for object unsafe impl Trait on dyn Trait {}

Author: estebank

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

@@ -6,7 +6,7 @@ use rustc_errors::{struct_span_err, DiagnosticBuilder, ErrorGuaranteed, MultiSpa
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::ty::print::with_no_trimmed_paths;
-use rustc_middle::ty::TyCtxt;
+use rustc_middle::ty::{self, TyCtxt};
 use rustc_span::Span;
 use std::fmt;
 use std::iter;
@@ -112,7 +112,14 @@ pub fn report_object_safety_error<'tcx>(
 
     let impls_of = tcx.trait_impls_of(trait_def_id);
     let impls = if impls_of.blanket_impls().is_empty() {
-        impls_of.non_blanket_impls().values().flatten().collect::<Vec<_>>()
+        impls_of
+            .non_blanket_impls()
+            .values()
+            .flatten()
+            .filter(|def_id| {
+                !matches!(tcx.type_of(*def_id).instantiate_identity().kind(), ty::Dynamic(..))
+            })
+            .collect::<Vec<_>>()
     } else {
         vec![]
     };

tests/ui/coherence/coherence-impl-trait-for-trait-object-safe.stderr

@@ -12,7 +12,6 @@ LL | trait NotObjectSafe { fn eq(&self, other: Self); }
    |       |
    |       this trait cannot be made into an object...
    = help: consider moving `eq` to another trait
-   = help: only type `(dyn NotObjectSafe + 'static)` implements the trait, consider using it directly instead
 
 error: aborting due to previous error