Swift: Generic metadata deadlock when initializing generic, indirectly recursive struct

Originator:rix.rob
Number:rdar://19320857 Date Originated:21-Dec-2014 01:17 PM
Status:Open Resolved:
Product:Developer Tools Product Version:Xcode 6.1.1 (6A2008a)
Classification:Crash/Hang/Data Loss Reproducible:Always
 
Summary:



Steps to Reproduce:
1. Compile & run this:

struct RoseTree<T> {
	let value: T
	let branches: [RoseTree]
}

RoseTree(value: 1, branches: [])


Expected Results:
I expected it to compile & run.


Actual Results:
It compiles, but deadlocks as soon as it hits the last line (which constructs a RoseTree).


Regression:
It doesn’t deadlock if you remove the branches.
It doesn’t deadlock if the struct is not generic.
It doesn’t deadlock if the generic value is placed in an array.
It does deadlock if you use Box instead of arrays and make it a binary tree, cf https://github.com/robrix/Box/issues/12


Notes:
h/t https://github.com/regexident for finding this: https://github.com/robrix/Box/issues/12

Comments


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