Cannot perform operation: String + womLong(x) in config

[DavyCats]

Cromwell 37 errors when the backend submit configuration contains an expression like:
${"-l h_vmem=" + memory + "G"}:

error message

cromwell.core.CromwellFatalException: common.exception.AggregatedMessageException: Error(s):
Could not evaluate expression: "-l h_vmem=" + memory + "G": Cannot perform operation: -l h_vmem= + WomLong(4)
        at cromwell.core.retry.Retry$$anonfun$withRetry$1.applyOrElse(Retry.scala:47)
        at cromwell.core.retry.Retry$$anonfun$withRetry$1.applyOrElse(Retry.scala:38)
        at scala.concurrent.Future.$anonfun$recoverWith$1(Future.scala:413)
        at scala.concurrent.impl.Promise.$anonfun$transformWith$1(Promise.scala:37)
        at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:60)
        at akka.dispatch.BatchingExecutor$AbstractBatch.processBatch(BatchingExecutor.scala:55)
        at akka.dispatch.BatchingExecutor$BlockableBatch.$anonfun$run$1(BatchingExecutor.scala:91)
        at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
        at scala.concurrent.BlockContext$.withBlockContext(BlockContext.scala:81)
        at akka.dispatch.BatchingExecutor$BlockableBatch.run(BatchingExecutor.scala:91)
        at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:40)
        at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(ForkJoinExecutorConfigurator.scala:44)
        at akka.dispatch.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
        at akka.dispatch.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
        at akka.dispatch.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
        at akka.dispatch.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
Caused by: common.exception.AggregatedMessageException: Error(s):
Could not evaluate expression: "-l h_vmem=" + memory + "G": Cannot perform operation: -l h_vmem= + WomLong(4)
        at common.validation.Validation$ValidationTry$.toTry$extension1(Validation.scala:77)
        at common.validation.Validation$ValidationTry$.toTry$extension0(Validation.scala:73)
        at cromwell.backend.impl.sfs.config.ConfigAsyncJobExecutionActor.writeTaskScript(ConfigAsyncJobExecutionActor.scala:107)
        at cromwell.backend.impl.sfs.config.ConfigAsyncJobExecutionActor.writeTaskScript$(ConfigAsyncJobExecutionActor.scala:55)
        at cromwell.backend.impl.sfs.config.DispatchedConfigAsyncJobExecutionActor.writeTaskScript(ConfigAsyncJobExecutionActor.scala:211)
        at cromwell.backend.impl.sfs.config.ConfigAsyncJobExecutionActor.processArgs(ConfigAsyncJobExecutionActor.scala:43)
        at cromwell.backend.impl.sfs.config.ConfigAsyncJobExecutionActor.processArgs$(ConfigAsyncJobExecutionActor.scala:39)
        at cromwell.backend.impl.sfs.config.DispatchedConfigAsyncJobExecutionActor.processArgs$lzycompute(ConfigAsyncJobExecutionActor.scala:211)
        at cromwell.backend.impl.sfs.config.DispatchedConfigAsyncJobExecutionActor.processArgs(ConfigAsyncJobExecutionActor.scala:211)
        at cromwell.backend.sfs.SharedFileSystemAsyncJobExecutionActor.makeProcessRunner(SharedFileSystemAsyncJobExecutionActor.scala:174)
        at cromwell.backend.sfs.SharedFileSystemAsyncJobExecutionActor.makeProcessRunner$(SharedFileSystemAsyncJobExecutionActor.scala:171)
        at cromwell.backend.impl.sfs.config.DispatchedConfigAsyncJobExecutionActor.makeProcessRunner(ConfigAsyncJobExecutionActor.scala:211)
        at cromwell.backend.sfs.SharedFileSystemAsyncJobExecutionActor.$anonfun$execute$2(SharedFileSystemAsyncJobExecutionActor.scala:145)
        at scala.util.Either.fold(Either.scala:188)
        at cromwell.backend.sfs.SharedFileSystemAsyncJobExecutionActor.execute(SharedFileSystemAsyncJobExecutionActor.scala:144)
        at cromwell.backend.sfs.SharedFileSystemAsyncJobExecutionActor.execute$(SharedFileSystemAsyncJobExecutionActor.scala:139)
        at cromwell.backend.impl.sfs.config.DispatchedConfigAsyncJobExecutionActor.execute(ConfigAsyncJobExecutionActor.scala:211)
        at cromwell.backend.standard.StandardAsyncExecutionActor.$anonfun$executeAsync$1(StandardAsyncExecutionActor.scala:637)
        at scala.util.Try$.apply(Try.scala:209)
        at cromwell.backend.standard.StandardAsyncExecutionActor.executeAsync(StandardAsyncExecutionActor.scala:637)
        at cromwell.backend.standard.StandardAsyncExecutionActor.executeAsync$(StandardAsyncExecutionActor.scala:637)
        at cromwell.backend.impl.sfs.config.DispatchedConfigAsyncJobExecutionActor.executeAsync(ConfigAsyncJobExecutionActor.scala:211)
        at cromwell.backend.standard.StandardAsyncExecutionActor.executeOrRecover(StandardAsyncExecutionActor.scala:952)
        at cromwell.backend.standard.StandardAsyncExecutionActor.executeOrRecover$(StandardAsyncExecutionActor.scala:944)
        at cromwell.backend.impl.sfs.config.DispatchedConfigAsyncJobExecutionActor.executeOrRecover(ConfigAsyncJobExecutionActor.scala:211)
        at cromwell.backend.async.AsyncBackendJobExecutionActor.$anonfun$robustExecuteOrRecover$1(AsyncBackendJobExecutionActor.scala:65)
        at cromwell.core.retry.Retry$.withRetry(Retry.scala:38)
        at cromwell.core.retry.Retry$$anonfun$withRetry$1.$anonfun$applyOrElse$3(Retry.scala:45)
        at akka.pattern.FutureTimeoutSupport.liftedTree1$1(FutureTimeoutSupport.scala:26)
        at akka.pattern.FutureTimeoutSupport.$anonfun$after$1(FutureTimeoutSupport.scala:26)
        at akka.actor.Scheduler$$anon$4.run(Scheduler.scala:205)
        ... 6 more

This is a minimal example of a config which gets such an error:
Could not evaluate expression: "echo " + memory: Cannot perform operation: echo + WomLong(4)

include required(classpath("application"))
webservice {
  port = 8000
}
backend {
  default="Local"
  providers {
    Local {
      actor-factory = "cromwell.backend.impl.sfs.config.ConfigBackendLifecycleActorFactory"
      config {
        runtime-attributes = """
        Int? memory
        String? docker
        String? docker_user
        """
        submit = """
        bash ${script}
        ${"echo " + memory}
        """
      }
    }
  }
} 

This means that the launch command given in the cromwell docs here will not work.

A current workaround would be to use an expression like this instead:
${true="echo" false="" defined(memory)} ${memory}

[myourshaw]

I am getting this bug in Cromwell 44.

Could not evaluate expression: "--mem-per-cpu=" + memory_mb: Cannot perform operation: --mem-per-cpu= + WomLong(1024)

[jaredbancroft]

This works as expected in Cromwell 36 so the behavior changed between 36 and 37.

[leepc12]

This still persists in Cromwell 47. I think +op is not defined between WomString and WomLong while + between WomString and WomInteger is defined?

[EugeneEA]

still persist in cromwell 75.
Also in my case I'd like to configure docker memory usage and docker reqiers suffix "g" or "m" after the number, so the @DavyCats trick does not work here