[SR-13062] Using Typealias + Generics leads to an EXC_BAD_ACCESS crash

[swift-ci]

Previous ID	SR-13062
Radar	None
Original Reporter	AKhilik (JIRA User)
Type	Bug

Additional Detail from JIRA

Votes	0
Component/s
Labels	Bug
Assignee	None
Priority	Medium

md5: f51dcd8dca6e6fbd3947e42192a82c9a

Issue Description:

During migration from Xcode 11.2.1 to 11.4.1 we noticed that the following usage of typealiases and generics started to lead to an EXC_BAD_ACCESS crash:

Obj-c code:

• ObjcClass

• ObjcProtocol

Swift code:

typealias SomeType = ObjcClass & ObjcProtocol
class TestClass<T: SomeType> {

}

// An attempt to initialize TestClass with SomeType:
_ = TestClass<SomeType>() // EXC_BAD_ACCESS
 

I simplified this example as much as I could. This crash also is possible to reproduce with Xcode 11.5 and 11.6-beta