Make listing/mapping typecasts more PE-friendly (#1837)

This rewrites the listing/mapping typecast nodes to be more friendly
to partial-evaluation.

This is because the compiler bails out of deeply recursive calls.

pkl-core/src/main/java/org/pkl/core/ast/member/ElementOrEntryNode.java

@@ -51,7 +51,7 @@ public abstract class ElementOrEntryNode extends RegularMemberNode {
       @Cached("create()") @Shared("callNode") IndirectCallNode callNode) {
     var result = bodyNode.executeGeneric(frame);
     return VmUtils.shouldRunTypeCheck(frame)
-        ? receiver.executeTypeCasts(result, VmUtils.getOwner(frame), callNode, null, null)
+        ? receiver.executeTypeCasts(result, VmUtils.getOwner(frame), callNode, null)
         : result;
   }
 
@@ -62,7 +62,7 @@ public abstract class ElementOrEntryNode extends RegularMemberNode {
       @Cached("create()") @Shared("callNode") IndirectCallNode callNode) {
     var result = bodyNode.executeGeneric(frame);
     return VmUtils.shouldRunTypeCheck(frame)
-        ? receiver.executeTypeCasts(result, VmUtils.getOwner(frame), callNode, null, null)
+        ? receiver.executeTypeCasts(result, VmUtils.getOwner(frame), callNode, null)
         : result;
   }
 

pkl-core/src/main/java/org/pkl/core/runtime/VmListingOrMapping.java

@@ -55,30 +55,24 @@ public abstract class VmListingOrMapping extends VmObject {
     this.typeCheckOwner = typeCheckOwner;
   }
 
-  // Recursively executes type casts between `owner` and `this` and returns the resulting value.
+  // Executes type casts for every parent between `owner` and `this` and returns the resulting
+  // value.
   public final Object executeTypeCasts(
       Object value,
       VmObjectLike owner,
       IndirectCallNode callNode,
       // if non-null, a stack frame for this member is inserted if a type cast fails
-      @Nullable ObjectMember member,
+      @Nullable ObjectMember member) {
-      // Next type cast to be performed by the caller.
+    var result = value;
-      // Avoids repeating the same type cast in some cases.
+    VmObject parent = this;
-      @Nullable ListingOrMappingTypeCastNode nextTypeCastNode) {
+    ListingOrMappingTypeCastNode prevTypeCastNode = null;
-    var newNextTypeCastNode = typeCastNode != null ? typeCastNode : nextTypeCastNode;
+    while (parent != null && parent != owner) {
-    Object result;
+      var obj = (VmListingOrMapping) parent;
-    if (this == owner) {
+      if (obj.typeCastNode != null && obj.typeCastNode != prevTypeCastNode) {
-      result = value;
+        var callTarget = obj.typeCastNode.getCallTarget();
-    } else {
-      assert parent != null;
-      result =
-          ((VmListingOrMapping) parent)
-              .executeTypeCasts(value, owner, callNode, member, newNextTypeCastNode);
-    }
-    if (typeCastNode == null || typeCastNode == nextTypeCastNode) return result;
-    var callTarget = typeCastNode.getCallTarget();
         try {
-      return callNode.call(callTarget, typeCheckReceiver, typeCheckOwner, result);
+          result = callNode.call(callTarget, obj.typeCheckReceiver, obj.typeCheckOwner, result);
+          prevTypeCastNode = obj.typeCastNode;
         } catch (VmException e) {
           CompilerDirectives.transferToInterpreter();
           if (member != null) {
@@ -87,6 +81,10 @@ public abstract class VmListingOrMapping extends VmObject {
           throw e;
         }
       }
+      parent = parent.parent;
+    }
+    return result;
+  }
 
   @Override
   @TruffleBoundary

pkl-core/src/main/java/org/pkl/core/runtime/VmUtils.java

@@ -396,7 +396,7 @@ public final class VmUtils {
           && owner instanceof VmListingOrMapping) {
         // `owner instanceof VmListingOrMapping` guards against
         // PropertiesRenderer amending VmDynamic with VmListing (hack?)
-        result = listingOrMapping.executeTypeCasts(constantValue, owner, callNode, member, null);
+        result = listingOrMapping.executeTypeCasts(constantValue, owner, callNode, member);
       }
 
       receiver.setCachedValue(memberKey, result);