Swift similar generic functions runtime crash

Originator:keithbsmiley
Number:rdar://23718676 Date Originated:01-Dec-2015 09:02 PM
Status:Open Resolved:
Product:Developer Tools Product Version:Swift 2.1
Classification:Other Bug Reproducible:Always
 
Summary:

When you have multiple swift functions with very similar generic
signatures, the compiler crashes, especially when using the nil
coalescing operator.

Steps to reproduce:

1. Attempt to run the attached script with
  `swift GenericFunctionCrash.swift`

Expected results:

Everything runs correctly.

Actual results:

It crashes at runtime with this error:

```
Could not cast value of type 'Swift.String' to 'Swift.Optional<Swift.String>'
```

Notes:

- Doing `"foo" as! String?` should work fine (as seen in the repl)
- If you comment out the fallback using the `??` operator, it runs fine
- If you comment out the similar generic function, it runs fine

Comments

https://github.com/keith/radars/tree/master/GenericFunctionCrash

By keithbsmiley at Dec. 2, 2015, 5:04 a.m. (reply...)

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