[JENKINS-68646] Delegate of cloned closure cannot be modified

I experienced a rather strange and, as far as I can tell, erroneous behavior when cloning a closure. To reproduce, create a Pipeline job with the following simple Pipeline script:

node {

    Closure c1 = { echo "someValue: ${someValue}" }

    c1.delegate = [someValue:1]

    c1.call()

    Closure c2 = c1.clone()

    c2.delegate = [someValue:2]

    c2.call()

} 

Closure c1 refers to variable someValue which is resolved through its delegate. However, cloning c1 and setting a different delegate produces the same output:

```
Started by user admin
[Pipeline] Start of Pipeline
[Pipeline] node
Running on Jenkins in /var/jenkins_home/workspace/ClosureClone
[Pipeline] {
[Pipeline] echo
someValue: 1
[Pipeline] echo
someValue: 1
[Pipeline] }
[Pipeline] // node
[Pipeline] End of Pipeline
Finished: SUCCESS
```

Running this code directly with Groovy (versions >= 2.x) produces the correct result, which is why I assume that it must be caused by Jenkins:

```
someValue: 1
someValue: 2
```

---
Originally reported by p9r, imported from: Delegate of cloned closure cannot be modified

• status: Open
  
• priority: Minor
  
• component(s): workflow-cps-plugin
  
• resolution: Unresolved
  
• votes: 0
  
• watchers: 2
  
• imported: 2025-12-07
  

Raw content of original issue

I experienced a rather strange and, as far as I can tell, erroneous behavior when cloning a closure. To reproduce, create a Pipeline job with the following simple Pipeline script:



node {

    Closure c1 = { echo "someValue: ${someValue}" }

    c1.delegate = [someValue:1]

    c1.call()

    Closure c2 = c1.clone()

    c2.delegate = [someValue:2]

    c2.call()

} 



Closure c1 refers to variable someValue which is resolved through its delegate. However, cloning c1 and setting a different delegate produces the same output:



Started by user admin

[Pipeline] Start of Pipeline

[Pipeline] node

Running on Jenkins in /var/jenkins_home/workspace/ClosureClone

[Pipeline] {

[Pipeline] echo

someValue: 1

[Pipeline] echo

someValue: 1

[Pipeline] }

[Pipeline] // node

[Pipeline] End of Pipeline

Finished: SUCCESS



Running this code directly with Groovy (versions >= 2.x) produces the correct result, which is why I assume that it must be caused by Jenkins:



someValue: 1

someValue: 2

environment

```
Jenkins: 2.349 (installed via Docker Hub)

OS: Linux - 4.14.276-211.499.amzn2.x86_64

---

ace-editor:1.1

antisamy-markup-formatter:2.7

apache-httpcomponents-client-4-api:4.5.13-1.0

bootstrap5-api:5.1.3-7

bouncycastle-api:2.26

branch-api:2.1046.v0ca_37783ecc5

build-timeout:1.21

caffeine-api:2.9.3-65.v6a_47d0f4d1fe

checks-api:1.7.4

cloudbees-folder:6.722.v8165b_a_cf25e9

command-launcher:84.v4a_97f2027398

credentials:1129.vef26f5df883c

credentials-binding:523.vd859a_4b_122e6

display-url-api:2.3.6

durable-task:496.va67c6f9eefa7

echarts-api:5.3.2-2

font-awesome-api:6.1.1-1

git-client:3.11.0

handlebars:3.0.8

jackson2-api:2.13.3-285.vc03c0256d517

javax-activation-api:1.2.0-3

javax-mail-api:1.6.2-6

jaxb:2.3.6-1

jdk-tool:1.5

jquery3-api:3.6.0-4

jsch:0.1.55.2

junit:1119.va_a_5e9068da_d7

mailer:414.vcc4c33714601

matrix-auth:3.1.2

matrix-project:771.v574584b_39e60

momentjs:1.1.1

pam-auth:1.8

pipeline-build-step:2.18

pipeline-graph-analysis:195.v5812d95a_a_2f9

pipeline-groovy-lib:591.v3a_7f422b_d058

pipeline-input-step:448.v37cea_9a_10a_70

pipeline-milestone-step:101.vd572fef9d926

pipeline-model-api:2.2086.v12b_420f036e5

pipeline-model-definition:2.2086.v12b_420f036e5

pipeline-model-extensions:2.2086.v12b_420f036e5

pipeline-rest-api:2.24

pipeline-stage-step:293.v200037eefcd5

pipeline-stage-tags-metadata:2.2086.v12b_420f036e5

pipeline-stage-view:2.24

plain-credentials:1.8

plugin-util-api:2.17.0

popper2-api:2.11.5-2

resource-disposer:0.19

scm-api:608.vfa_f971c5a_a_e9

script-security:1175.v4b_d517d6db_f0

snakeyaml-api:1.30.1

ssh-credentials:277.v95c2fec1c047

sshd:3.237.v883d165a_c1d3

structs:318.va_f3ccb_729b_71

timestamper:1.17

token-macro:293.v283932a_0a_b_49

trilead-api:1.57.v6e90e07157e1

variant:1.4

workflow-aggregator:581.v0c46fa_697ffd

workflow-api:1153.vb_912c0e47fb_a_

workflow-basic-steps:948.v2c72a_091b_b_68

workflow-cps:2706.v71dd22b_c5a_a_2

workflow-durable-task-step:1139.v252a_e12e8463

workflow-job:1182.v60a_e6279b_579

workflow-multibranch:716.vc692a_e52371b_

workflow-scm-step:400.v6b_89a_1317c9a_

workflow-step-api:625.vd896b_f445a_f8

workflow-support:820.vd1a_6cc65ef33

ws-cleanup:0.42
```

Start by reproducing the behavior with the Pipeline script in the issue and compare it with the direct Groovy result. Then trace the workflow-cps implementation responsible for cloned closures and delegate resolution; done means the cloned closure uses its newly assigned delegate and the reproduction prints someValue: 1 followed by someValue: 2.

Written by the indexing model from the issue text.