Always enlarge resolved constant types

Author: muglug

src/code_info/ttype/type_expander.rs

@@ -343,7 +343,15 @@ fn expand_atomic(
                 FxHashSet::default(),
             );
 
-            if let Some(const_type) = const_type {
+            if let Some(mut const_type) = const_type {
+                expand_union(
+                    codebase,
+                    interner,
+                    &mut const_type,
+                    options,
+                    data_flow_graph,
+                );
+
                 new_return_type_parts.extend(const_type.types);
             } else {
                 new_return_type_parts.push(TAtomic::TMixed);

tests/inference/Constant/classConstantIndirection/input.hack

@@ -0,0 +1,17 @@
+enum M: int as int {
+	A = 0;
+	B = 1;
+	C = 2;
+	D = 3;
+	E = 4;
+}
+
+const keyset<M> FOO = Bar::FOO;
+
+final class Bar {
+    const keyset<M> FOO = keyset[M::A, M::C, M::E];
+}
+
+function baz(M $i): void {
+    if (C\contains(FOO, $i)) {}
+}