Comment by Trent Nadeau (JIRA)

There is no arc4random function in glibc. That function only exists in BSD distros and the Bionic libc used in Android.

Comment by Michael Thomas (JIRA)

I created a modulemap of libbsd to get arc4random on Linux, see here.

Comment by Jay Buffington (JIRA)

        #if os(Linux)
            return Int(random() % (max + 1))
        #else
            return Int(arc4random_uniform(UInt32(max)))
        #endif

Comment by Johannes Schriewer (JIRA)

It may look absurd, but this actually works:

$ swift -Xcc -fmodule-map-file=libbsd.modulemap
Welcome to Swift version 3.0-dev (LLVM 699a786c15, Clang 77080f2c03, Swift d22638766e). Type :help for assistance.
  1> import BSD
  2> print(arc4random())
2257500811

When there is a module map file for libbsd with these contents:

module BSD [system] {
        header "/usr/include/bsd/bsd.h"
        link "bsd"
        export *
}

Please, never apply Jay Buffington workaround, as it would mislead people on Linux and potentially create threats.

What should happen to this bug since SE-0202 (in Swift 4.2) encourages the new `Int.random(in: Range)` etc. instead?

I vote to close wontfix, as I don't need it in 4.2. Feel free to speak up if you still do

I think that's correct. We also now have the SwiftPM module map packages, in case someone wants to use Johannes' solution.

Resolving because both the reporter (@drewcrawford) and @belkadan commented that it is "resolved" as "Won't Fix".