Fix ICE in diagnostic_hir_wf_check

src/test/ui/wf/issue-87495.rs

@@ -0,0 +1,8 @@
+// Regression test for the ICE described in #87495.
+
+trait T {
+    const CONST: (bool, dyn T);
+    //~^ ERROR: the trait `T` cannot be made into an object [E0038]
+}
+
+fn main() {}

src/test/ui/wf/issue-87495.stderr

@@ -0,0 +1,18 @@
+error[E0038]: the trait `T` cannot be made into an object
+  --> $DIR/issue-87495.rs:4:25
+   |
+LL |     const CONST: (bool, dyn T);
+   |                         ^^^^^ `T` cannot be made into an object
+   |
+   = help: consider moving `CONST` to another trait
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/issue-87495.rs:4:11
+   |
+LL | trait T {
+   |       - this trait cannot be made into an object...
+LL |     const CONST: (bool, dyn T);
+   |           ^^^^^ ...because it contains this associated `const`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0038`.