[SR-7426] Segmentation fault when building with -Osize

[ChristopherRogers]

Previous ID	SR-7426
Radar	rdar://problem/39414272
Original Reporter	@ChristopherRogers
Type	Bug

Environment

Xcode 9.3, Swift 4.1

Swift 4.2 master (5ea4848)

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, CompilerCrash, OptimizedOnly
Assignee	@aschwaighofer
Priority	Medium

md5: 9dfe97cde2c14b3c4990b74e565d74af

Issue Description:

Compiling the code below with -Osize should trigger a segfault (or assertion failure). It can be worked around by forcing the type of "resource" to be Optional.

I tried to dig in to the code for this. As far as I could see the error occurs in the Outliner pass in -Osize, where ti's is creating an outline for the Obj-C method call for bundle.path(forResource:ofType🙂. Both of its parameters take Optional<String> (or Optional<NSString>) but it generates a non-optional String parameter type and it causes a type mismatch.

import Foundation

func foo() -> String? {
    let bundle = Bundle.main
    let resource = "common parameter" // add "as String?" for workaround

    return bundle.path(forResource: resource, ofType: "png")
        ?? bundle.path(forResource: resource, ofType: "apng")
}

print(foo() ?? "nope")

[belkadan]

aschwaighofer@apple.com (JIRA User), is this a dup?

[aschwaighofer]

@swift-ci create

[aschwaighofer]

Fails on master

[aschwaighofer]

#15920