Object reference not set to an instance of an object in compiling random test code

Elements Silver
1

In trying to replicate another issue I found that this code crashes the compiler:


open class SynchronizedDictionary
{
	var dict: Dictionary

	public init()
	{
		self.dict = Dictionary()
	}

	// many wrappers ommitted

	open func getAndUpdate( forKey key: Key, _ updateFunc: @escaping (Value?) -> (Value?) ) -> Value?
	{
		// locking omitted
		let current = dict[key]
		let newVal = updateFunc(current)
		dict[key] = newVal
		return newVal
	}
}
 
open class Subscription
{
	var msg = "hello"
}


let m = SynchronizedDictionary<Int64, Subscription>()

print(m.dict[0])

m.getAndUpdate(forKey: 0)
{
	currentVal in
	return Subscription()
}

print(m.dict[0])

In Fire 2151 Gives
: error E0: Internal error: Object reference not set to an instance of an object

2

So if you change the getAndUpdate func to this, you can replace the NRE with a type error:

image.png765×134 16.5 KB

This is incorrect behaviour as assigning nil to a dictionary should remove the value from the dictionary:


‘If you assign nil as the value for the given key, the dictionary removes that key and its associated value.’

3

I just found that I got different results and the NRE went away if I typed dict as Swift.Dictionary<Key,Value> instead of Dictionary<Key,Value> - that was kind of unexpected…
Something to do with the new RTL?

4

Thanks, logged as bugs://77988

5

Hi,

I can’t reproduce this with latest beta, tried on .NET Java and Cocoa.

6

bugs://77988 got closed with status cannotrepro.