Set up correct findTypeSubscription function

Author: erthalion

src/backend/commands/typecmds.c

@@ -94,6 +94,7 @@ static Oid	findTypeSendFunction(List *procname, Oid typeOid);
 static Oid	findTypeTypmodinFunction(List *procname);
 static Oid	findTypeTypmodoutFunction(List *procname);
 static Oid	findTypeAnalyzeFunction(List *procname, Oid typeOid);
+static Oid	findTypeSubscriptionFunction(List *procname, Oid typeOid);
 static Oid	findRangeSubOpclass(List *opcname, Oid subtype);
 static Oid	findRangeCanonicalFunction(List *procname, Oid typeOid);
 static Oid	findRangeSubtypeDiffFunction(List *procname, Oid subtype);
@@ -520,7 +521,7 @@ DefineType(List *names, List *parameters)
 		analyzeOid = findTypeAnalyzeFunction(analyzeName, typoid);
 
 	if (subscriptionName)
-		subscriptionOid = findTypeAnalyzeFunction(subscriptionName, typoid);
+		subscriptionOid = findTypeSubscriptionFunction(subscriptionName, typoid);
 
 	/*
 	 * Check permissions on functions.  We choose to require the creator/owner
@@ -1916,6 +1917,33 @@ findTypeAnalyzeFunction(List *procname, Oid typeOid)
 	return procOid;
 }
 
+static Oid
+findTypeSubscriptionFunction(List *procname, Oid typeOid)
+{
+	Oid			argList[1];
+	Oid			procOid;
+
+	/*
+	 * Analyze functions always take one INTERNAL argument and return INTERNAL.
+	 */
+	argList[0] = INTERNALOID;
+
+	procOid = LookupFuncName(procname, 1, argList, true);
+	if (!OidIsValid(procOid))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_FUNCTION),
+				 errmsg("function %s does not exist",
+						func_signature_string(procname, 1, NIL, argList))));
+
+	if (get_func_rettype(procOid) != INTERNALOID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+				 errmsg("type subscription function %s must return type %s",
+						NameListToString(procname), "internal")));
+
+	return procOid;
+}
+
 /*
  * Find suitable support functions and opclasses for a range type.
  */