[SR-138] Foundation objects are not bridged on Linux as they are on OS X.

[swift-ci]

Previous ID	SR-138
Radar	None
Original Reporter	babt (JIRA User)
Type	Bug
Status	Resolved
Resolution	Done

Environment

OS X 10.11.1, Ubuntu 15.10

Additional Detail from JIRA

Votes	6
Component/s	Compiler, Foundation
Labels	Bug
Assignee	@millenomi
Priority	Medium

md5: fd4610a64cf6030b8952ae7fa9bfb6ba

is duplicated by:

• SR-309 Unable to coerce String -> NSString
• SR-5160 NSMutableCharacterSet cannot be coerced to CharacterSet under Linux
• SR-5404 Linux: Cannot cast NSData to Data

Issue Description:

Foundation in this build does include NSString but there's lots a caveats associated with it. It's not bridged to String as it is on OS X yet and I suspect (but haven't verified yet,) that most other Foundation objects that are bridged on OS X are not yet bridged on Linux. So casting as in the example below will fail:

3> let foo: NSString = "foo"
 foo: Foundation.NSString = \{
 Foundation.NSObject = \{}
 _cfinfo =

\{ info = 1920 pad = 0 }

_storage = "foo"
 }
 4> let bar = foo as String
 repl.swift:4:11: error: cannot convert value of type 'NSString' to type 'String' in coercion
 let bar = foo as String
 ^~~

While on OS X, it will do as expected:

3> let foo:NSString = "foo"
 foo: NSString = "foo"
 4> let bar = foo as String
 bar: String = "foo"

In order for the Linux version of Swift-repl to recognize Foundation, it needs to be invoked as follows:

%: swift -lFoundation <rest of the parameters>

This tells Swift that you're using Foundation and to link (-l) with the Foundation shared library. However, this is not needed on OS X.

Feel free to contact me if you have any questions,

[parkera]

Adding the lldb component as well, for the REPL issue.

The lack of bridging is a (very unfortunate) known issue.

[swift-ci]

Comment by Kate Stone (JIRA)

To avoid derailing the bridging issue I'm removing LLDB for Swift from this issue. I've filed <rdar://problem/23902940> internally to track the notion that the broader notion that the REPL should respect a more inclusive notion of a default Swift "SDK" on Linux. What that should look like is a distinct and interesting question that probably deserves discussion on Swift.org, and it's definitely not REPL-specific.

[spevans]

Bridging is now fixed in 4.2

$ cat sr_138.swift 
import Foundation

let foo: NSString = "foo"
let bar = foo as String
print("bar:", bar)

$ ~/swift-4.2-CONVERGENCE-ubuntu16.04/usr/bin/swift sr_138.swift 
bar: foo