Remove RTTs (#4848)

RTTs were removed from the GC spec and if they are added back in in the future,
they will be heap types rather than value types as in our implementation.
Updating our implementation to have RTTs be heap types would have been more work
than deleting them for questionable benefit since we don't know how long it will
be before they are specced again.

1 files changed, 5 insertions, 6 deletions

diff --git a/src/tools/fuzzing.h b/src/tools/fuzzing.h
index d0c92690a..47d55cfef 100644
--- a/src/tools/fuzzing.h
+++ b/src/tools/fuzzing.h
@@ -181,11 +181,11 @@ private:
 
   // Recombination and mutation can replace a node with another node of the same
   // type, but should not do so for certain types that are dangerous. For
-  // example, it would be bad to add an RTT in a tuple, as that would force us
-  // to use temporary locals for the tuple, but RTTs are not defaultable.
-  // Also, 'pop' pseudo instruction for EH is supposed to exist only at the
-  // beginning of a 'catch' block, so it shouldn't be moved around or deleted
-  // freely.
+  // example, it would be bad to add a non-nullable reference to a tuple, as
+  // that would force us to use temporary locals for the tuple, but non-nullable
+  // references cannot always be stored in locals. Also, the 'pop' pseudo
+  // instruction for EH is supposed to exist only at the beginning of a 'catch'
+  // block, so it shouldn't be moved around or deleted freely.
   bool canBeArbitrarilyReplaced(Expression* curr) {
     return curr->type.isDefaultable() &&
            !EHUtils::containsValidDanglingPop(curr);
@@ -312,7 +312,6 @@ private:
   bool isLoggableType(Type type);
   Nullability getSubType(Nullability nullability);
   HeapType getSubType(HeapType type);
-  Rtt getSubType(Rtt rtt);
   Type getSubType(Type type);
 
   // Utilities