Special-case alias ty in try_from_lit

Author: Jaic1

compiler/rustc_middle/src/ty/consts.rs

@@ -305,7 +305,16 @@ impl<'tcx> Const<'tcx> {
             // mir.
             match tcx.at(expr.span).lit_to_const(lit_input) {
                 Ok(c) => return Some(c),
-                Err(_) => return None,
+                Err(_) if lit_input.ty.has_aliases() => {
+                    // allow the `ty`` to be an alias type, though we cannot handle it here
+                    return None
+                },
+                Err(e) => {
+                    tcx.dcx().span_delayed_bug(
+                        expr.span,
+                        format!("Const::from_anon_const: couldn't lit_to_const {e:?}"),
+                    );
+                }
             }
         }