[GitHub] csantanapr opened a new issue #60: Swift 4.1 issue discovered around Structs with two Strings

[GitBox <gi...@apache.org>]

csantanapr opened a new issue #60: Swift 4.1 issue discovered around Structs with two Strings
URL: https://github.com/apache/incubator-openwhisk-runtime-swift/issues/60
 
 
   @eweiter commented on [Fri May 11 2018](https://github.com/apache/incubator-openwhisk/issues/3646)
   
   It was reported that the Swift 4.1 runtime was exhibiting a strange behavior.  The behavior in question occurs when a Struct has multiple Strings and those Strings are being initialized directly from static Strings. 
   
   For instance, the following piece of code will work:
   ```
   struct Output: Codable {
       let greeting: String
       let group: String
   }
   func main(completion: (Output?, Error?) -> Void) -> Void {
       let name = "MyName"
       let result = Output(greeting: "Hello \(name)", group: "Greetings")
       print("Log greeting:\(result.greeting)")
       completion(result, nil)
   }
   ```
   However the following code will not:
   ```
   struct Output: Codable {
       let greeting: String
       let group: String
   }
   func main(completion: (Output?, Error?) -> Void) -> Void {
       let result = Output(greeting: "Hello Name", group: "bummer")
       print("Log greeting:\(result.greeting)")
       completion(result, nil)
   }
   ```
   
   It appears to be a bug within Swift itself. 
   We have discovered that if the code is compiled with the compiler flag to turn off optimizations then the compiling will work.  This compile flag is `-Xswiftc -Onone`
   
   ---
   
   @eweiter commented on [Sun May 13 2018](https://github.com/apache/incubator-openwhisk/issues/3646#issuecomment-388636175)
   
   PR https://github.com/apache/incubator-openwhisk/pull/3647 was merged as a temp fix until the issue is addressed in the Swift Docker image. 
   
   ---
   
   @eweiter commented on [Mon May 14 2018](https://github.com/apache/incubator-openwhisk/issues/3646#issuecomment-389001553)
   
   I believe I have narrowed down the reasoning for this issue as coming from the use of the "@escaping" syntax in here https://github.com/apache/incubator-openwhisk-runtime-swift/blob/master/core/swift41Action/epilogue.swift#L98
   
   I have stripped down this code the mainly the essentials (non-whisk related) items and when the "@escaping" option is present the code will throw a compiler error, however when I remove the statement the code will compile fine and execute successfully.
   
   I will be opening an issue against the Swift Docker image tomorrow and will link that here when I do. 
   
   ---
   
   @csantanapr commented on [Mon May 14 2018](https://github.com/apache/incubator-openwhisk/issues/3646#issuecomment-389012394)
   
   leaving open until we get a fix from swift team
   
   

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