[SR-14160] Runtime crash on passing functions with incompatible representations

[LucianoPAlmeida]

Previous ID	SR-14160
Radar	rdar://problem/74110413
Original Reporter	@LucianoPAlmeida
Type	Sub-task

Attachment: Download

Environment

Xcode 12.3 (12C33)

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Sub-task
Assignee	None
Priority	Medium

md5: d343b7970380688af4185c9df548b637

Parent-Task:

• SR-14169 ☂️ Compiler/runtime issues while converting functions with incompatible representations

relates to:

• SR-14058 Trying to coerce regular function to @convention(c) traps

Issue Description:

Both compiles fine, but crashes at runtime because of thick-to-thin conversion
Note: Removing @convention(thin) this executes fine

I think the compiler should emit a conversion mismatch diagnostic.

func a<K: Hashable, V>(d: [K: V], p: @convention(thin) (K, V) -> Void) {
  //_ = d.lazy.map(p) // Runtime crash
  p(d.first!.key, d.first!.value) // Also runtime crash.
}

let v = [1: "1"]

a(d: v, p: { _,_  in })


[LucianoPAlmeida]

cc theindigamer (JIRA User)

[LucianoPAlmeida]

I don't understand why, but if we constraint the generic arguments to objc convertible it runs fine, so maybe is just a runtime issue?

import Foundation

func a<K: NSObject, V: NSObject>(d: [K: V], p: @convention(thin) (K, V) -> Void) {
  _ = d.lazy.map(p) // NO crash
  p(d.first!.key, d.first!.value) // No crash.
}

let v = [1 as NSNumber: "1" as NSString]

a(d: v, p: { _,_  in })

print("finished")

[typesanitizer]

I think this might be the same problem as https://bugs.swift.org/browse/SR-14058 , we should be emitting a compile-time error.

[typesanitizer]

Maybe we should create an umbrella task for conversions between function conventions. Then this JIRA, SR-14058 and SR-14060 would all be sub-tasks of that.

[LucianoPAlmeida]

I like the idea of creating an umbrella task =]

[LucianoPAlmeida]

theindigamer (JIRA User) Here it is https://bugs.swift.org/browse/SR-14169

[typesanitizer]

@swift-ci create