[SR-392] Creating a String from an object of type ErrorType segfaults #43009
Comments
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Comment by Austin Zheng (JIRA) A bit of context: I'm rewriting _dump() to not use _Reflectable, which means I can't rely upon _MirrorType's 'summary' property. A natural alternative is to ask the instance to describe itself, via debugDescription, description, etc, which is where the String(reflecting: ) constructor comes in. |
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Comment by Austin Zheng (JIRA) After doing some more testing, it appears that the crash happens as early as "let b : ErrorType = a". Also, I occasionally get the following error: Assertion failed: (newval + quantum >= RC_ONE && "releasing reference with a refcount of zero"), function doDecrementShouldDeallocate, file /Users/austinzheng/Developer/Swift/swift/include/swift/Runtime/../../../stdlib/public/SwiftShims/RefCount.h, line 207. |
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Comment by Jesse Rusak (JIRA) I ran a git bisect on this last night and it identified the following commit as causing this regression: Reverting that commit on top of master seems to fix the issue. I'm guessing the issue has to do with the |
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Comment by Austin Zheng (JIRA) Thanks for looking into this, I really appreciate it. Is this something you'd like to pursue further, or would you prefer to hand it off to someone else? |
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Comment by Jesse Rusak (JIRA) Yes, I'll try to put something together for this; just wanted to finish up a couple other things before taking it on. |
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Comment by Jesse Rusak (JIRA) I've put up a PR for this here: #861 |
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Comment by Jesse Rusak (JIRA) PR was merged here: 35448a1 |
Environment
OS X 10.11.2, running development version built from source (SHA: 3d0b77c). I made sure all dependencies were updated and ran the build script with the --clean flag.
Additional Detail from JIRA
md5: 665c561a48400ef5cc296a7e706545e5
blocks:
relates to:
Issue Description:
A variable of type 'ErrorType' causes a segfault if a program attempts to construct a String from it, either using the "String(a)" or "String(reflecting: a)" initializers.
As an example, the following code, whether run in the REPL or compiled into a Swift program, causes a segmentation fault when executed:
class MyErrorClass : ErrorType { }
let a = MyErrorClass()
// These are fine
print("(String(reflecting: a))")
print("(String(a))")
let b : ErrorType = a
// Either of these cause a segfault
print("(String(reflecting: b))")
print("(String(b))")
Note that this does NOT happen when using the version of swiftc bundled with Xcode 7.2. It seems like a regression.
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