Rollup merge of #118727 - compiler-errors:lint-decorate, r=WaffleLapkin

Don't pass lint back out of lint decorator

Change the decorator function in the signature of the `emit_lint`/`span_lint`/etc family of methods from `impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>) -> &'b mut DiagnosticBuilder<'a, ()>` to `impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>)`. I consider it easier to read this way, especially when there's control flow involved.

r? nnethercote though feel free to reassign

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -273,7 +273,6 @@ fn overlap<'tcx>(
                                     causing the impls to overlap",
                                 infcx.resolve_vars_if_possible(failing_obligation.predicate)
                             ));
-                            lint
                         },
                     );
                 }

compiler/rustc_trait_selection/src/traits/object_safety.rs

@@ -194,7 +194,6 @@ fn lint_object_unsafe_trait(
                 // Only provide the help if its a local trait, otherwise it's not
                 violation.solution().add_to(err);
             }
-            err
         },
     );
 }

compiler/rustc_trait_selection/src/traits/specialize/mod.rs

@@ -450,7 +450,6 @@ fn report_conflicting_impls<'tcx>(
                 msg,
                 |err| {
                     decorate(tcx, &overlap, impl_span, err);
-                    err
                 },
             );
         }