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[SR-6422] Encountering "Constant strings cannot be deallocated" in Linux foundation #3785

mbrandonw opened this issue Nov 17, 2017 · 2 comments


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mbrandonw commented Nov 17, 2017

Previous ID SR-6422
Radar None
Original Reporter @mbrandonw
Type Bug
Status Resolved
Resolution Duplicate
Additional Detail from JIRA
Votes 0
Component/s Foundation
Labels Bug, RunTimeCrash
Assignee None
Priority Medium

md5: 591e29ee8530d7b357e7037d4dee4824


  • SR-6398 Constant strings cannot be deallocated: file Foundation/NSCFString.swift, line 118

Issue Description:

Hello! I have a test case that when run on Linux somehow encounters the "Constant strings cannot be deallocated” fatal error thrown in NSCFString.swift, as seen here:

The test that does it is here:

Now there’s a lot to unravel here and I haven’t been able to find a minimal test case yet, but I thought I would at least file this for now and can update if I find the minimal test case.

I have also raised this issue not he corelibs-dev mailing list:


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mbrandonw commented Nov 30, 2017

Hello! After some investigation we were able to find that most of these crashes have something to do with `URLQueryItem`s. In fact, it seems that it has to do with duplicate keys in a query string, as demonstrated here:


You can see the failure on this Travis CI output:

At the bottom we have:
fatal error: Constant strings cannot be deallocated: file Foundation/NSCFString.swift, line 118

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parkera commented Dec 1, 2017

I think we've tracked this down. We'll fix with SR-6398.

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
@shahmishal shahmishal transferred this issue from apple/swift May 5, 2022
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