[NominalFuzzing] Don't compare nominal types in the fuzzer (#4603)

The same module will have a different type after some transformations, even
though that is not observable, like --roundtrip. Basically, we should not be
comparing types between separate modules, which is what the fuzzer does.

1 files changed, 8 insertions, 3 deletions

diff --git a/src/tools/execution-results.h b/src/tools/execution-results.h
index 5f2e772f0..10e243287 100644
--- a/src/tools/execution-results.h
+++ b/src/tools/execution-results.h
@@ -151,9 +151,14 @@ struct ExecutionResults {
   bool areEqual(Literal a, Literal b) {
     // We allow nulls to have different types (as they compare equal regardless)
     // but anything else must have an identical type.
-    if (a.type != b.type && !(a.isNull() && b.isNull())) {
-      std::cout << "types not identical! " << a << " != " << b << '\n';
-      return false;
+    // We cannot do this in nominal typing, however, as different modules will
+    // have different types in general. We could perhaps compare the entire
+    // graph structurally TODO
+    if (getTypeSystem() != TypeSystem::Nominal) {
+      if (a.type != b.type && !(a.isNull() && b.isNull())) {
+        std::cout << "types not identical! " << a << " != " << b << '\n';
+        return false;
+      }
     }
     if (a.type.isRef()) {
       // Don't compare references - only their types. There are several issues