Duplicate var in :find and :with throws ArrayIndexOutOfBoundsException

Question

Environment

• com.datomic/client-cloud "1.0.119"
• com.datomic/dev-local 1.0.242

History

(def client (d/client {:server-type :dev-local
                         :storage-dir :mem
                         :system      "test"}))
=> #'user/client
(d/create-database client {:db-name "a"})
=> true
(def conn (d/connect client {:db-name "a"}))
=> #'user/conn
(d/q '[:find ?e
         :where
         [?e :db/ident :db/cardinality]
         :with ?e]
    (d/db conn))
Execution error (ArrayIndexOutOfBoundsException) at datomic.core.datalog/fn$project (datalog.clj:560).
Index 1 out of bounds for length 1

If you remove the duplicate binding from :with, the exception will not be thrown.

(d/q '[:find ?e
         :where [?e :db/ident :db/cardinality]]
    (d/db conn))
=> [[41]]

Expectation

A duplicate var in :find and :with returns the same result as no duplicate.

Actual

A duplicate var in :find and :with throws an ArrayIndexOutOfBoundsException.

Evidence

Full stacktrace:

#error{:cause "Index 1 out of bounds for length 1",
       :via [{:type clojure.lang.ExceptionInfo,
              :message "processing clause: [?e :db/ident :db/cardinality], message: java.lang.ArrayIndexOutOfBoundsException: Index 1 out of bounds for length 1",
              :data #:cognitect.anomalies{:category :cognitect.anomalies/incorrect,
                                          :message "processing clause: [?e :db/ident :db/cardinality], message: java.lang.ArrayIndexOutOfBoundsException: Index 1 out of bounds for length 1"},
              :at [datomic.core.datalog$throw_query_ex_BANG_ invokeStatic "datalog.clj" 50]}
             {:type java.lang.ArrayIndexOutOfBoundsException,
              :message "Index 1 out of bounds for length 1",
              :at [clojure.lang.RT aset "RT.java" 2381]}],
       :trace [[clojure.lang.RT aset "RT.java" 2381]
               [datomic.core.datalog$fn__24749$project__24832 invoke "datalog.clj" 560]
               [datomic.core.datalog$fn__24749$join__24850 invoke "datalog.clj" 659]
               [datomic.core.datalog$fn__24749$fn__24853 invoke "datalog.clj" 666]
               [datomic.core.common$pooled_mapv$fn__24505$fn__24506 invoke "common.clj" 490]
               [clojure.lang.AFn applyToHelper "AFn.java" 152]
               [clojure.lang.AFn applyTo "AFn.java" 144]
               [clojure.core$apply invokeStatic "core.clj" 667]
               [clojure.core$with_bindings_STAR_ invokeStatic "core.clj" 1990]
               [clojure.core$with_bindings_STAR_ doInvoke "core.clj" 1990]
               [clojure.lang.RestFn invoke "RestFn.java" 425]
               [clojure.lang.AFn applyToHelper "AFn.java" 156]
               [clojure.lang.RestFn applyTo "RestFn.java" 132]
               [clojure.core$apply invokeStatic "core.clj" 671]
               [clojure.core$bound_fn_STAR_$fn__5818 doInvoke "core.clj" 2020]
               [clojure.lang.RestFn invoke "RestFn.java" 397]
               [clojure.lang.AFn call "AFn.java" 18]
               [java.util.concurrent.FutureTask run "FutureTask.java" 264]
               [java.util.concurrent.ThreadPoolExecutor runWorker "ThreadPoolExecutor.java" 1128]
               [java.util.concurrent.ThreadPoolExecutor$Worker run "ThreadPoolExecutor.java" 628]
               [java.lang.Thread run "Thread.java" 829]]}

Impact

Programmatically built queries that always add a :with clause need to detect and remove duplicates prior to issuing the query. This results in extra code and unknown edge cases surfacing.

Answer 1

(Not an answer, but another example of the scope of this bug.)

I think the same underlying error can be provoked when using pull and not using with.

(d/q {:query '[:find ?c (pull ?c [*])

                   :where 
                   , [?c :ansi.fips/state-numeric "51"]
                   , [?c :usps/state-name ?sn]]
          :args [db]})

That ^ provokes the IndexOutOfBoundsException but it can be resolved by removing either the pull or the bare ?c from the find expression. This is frustrating for automated query construction.

(And I've given up trying to get the code sample to format correctly... the embedded quote in the code wreaks havoc with this site's formatter....)