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[SR-2170] Linux Linker error when deriving a class from NSURL #4454

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swift-ci opened this issue Jul 26, 2016 · 5 comments
Closed

[SR-2170] Linux Linker error when deriving a class from NSURL #4454

swift-ci opened this issue Jul 26, 2016 · 5 comments
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bug Foundation Linux

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@swift-ci
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Previous ID SR-2170
Radar None
Original Reporter dsperling (JIRA User)
Type Bug
Status Resolved
Resolution Done
Environment

Linux Toolchain 0620 or Preview 2

Additional Detail from JIRA
Votes 2
Component/s Foundation
Labels Bug, Linux
Assignee None
Priority Medium

md5: a5a07129f728b6f25484e450eb46d70d

relates to:

  • SR-1901 Linker error "hidden symbol" on subclassing Thread

Issue Description:

The following code compiles but fails to link on Linux. Mac works OK.

import Foundation

public class URLParser : NSURL {

    public init(url: NSData) {
#if os(Linux)
        super.init(string: String(data: url, encoding: NSUTF8StringEncoding) ?? "", relativeToURL: nil)!
#else
        super.init(string: String(data: url as Data, encoding: String.Encoding.utf8) ?? "", relativeTo: nil)!
#endif
    }

    // NSURL required initializers
    required convenience public init(fileReferenceLiteralResourceName path: String) {
        fatalError("init(fileReferenceLiteralResourceName:) has not been implemented")
    }
    required public init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

let _ = URLParser(url: "https://swift.org".data(using: NSUTF8StringEncoding)!)

The linker errors with:

/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLg5_baseVS_7_CFInfo' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLs5_baseVS_7_CFInfo' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLm5_baseVS_7_CFInfo' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLg6_flagsVs6UInt32' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLs6_flagsVs6UInt32' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLm6_flagsVs6UInt32' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLg9_encodingVs6UInt32' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLs9_encodingVs6UInt32' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLm9_encodingVs6UInt32' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLg7_stringGSqGSpCSo8CFString__' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLs7_stringGSqGSpCSo8CFString__' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLm7_stringGSqGSpCSo8CFString__' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLg8_baseURLGSqGSpCSo5CFURL__' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLs8_baseURLGSqGSpCSo5CFURL__' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLm8_baseURLGSqGSpCSo5CFURL__' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLg6_extraGSqVs13OpaquePointer_' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLs6_extraGSqVs13OpaquePointer_' is not defined locally
/usr/bin/ld: error: hidden symbol '_TFC10Foundation5NSURLm6_extraGSqVs13OpaquePointer_' is not defined locally

...
@swift-ci
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Comment by Dave Sperling (JIRA)

The problem persists with the Linux 0725 toolchain.

import Foundation

public class URLParser : NSURL {

    public init(url: Data) {
        super.init(string: String(data: url, encoding: String.Encoding.utf8) ?? "", relativeTo: nil)!
    }

    // NSURL required initializers
    required convenience public init(fileReferenceLiteralResourceName path: String) {
        fatalError("init(fileReferenceLiteralResourceName:) has not been implemented")
    }
    required public init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

let _ = URLParser(url: "https://swift.org".data(using: String.Encoding.utf8)!)

@swift-ci
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swift-ci commented Sep 1, 2016

Comment by David Grove (JIRA)

Problem still present with Linux 0830 toolchain. Updated test case below:

import Foundation

public class URLParser : NSURL {

    public init(url: Data) {
        super.init(string: String(data: url, encoding: String.Encoding.utf8) ?? "", relativeTo: nil)!
    }

    // NSURL required initializers
    required convenience public init(fileReferenceLiteralResourceName path: String) {
        fatalError("init(fileReferenceLiteralResourceName:) has not been implemented")
    }
    required public init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

let _ = URLParser(url: "https://swift.org".data(using: String.Encoding.utf8)!)

@swift-ci
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swift-ci commented Sep 1, 2016

Comment by David Grove (JIRA)

This is a general problem with subclassing an open class with internal members external to the defining library. For example, the code below also fails with linker errors:

import Foundation

public class MyOperation : Operation {
}

let o = MyOperation()

@modocache
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Mannequin

modocache mannequin commented Sep 21, 2016

Another example of this affecting corelibs API: #651

@spevans
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spevans commented Mar 5, 2020

These now compile and link under recent versions of swift - the NSURL subclassing fails for other reasons internal to the implenetation of NSURL - but the link issue is now resolved.

@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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