[swift-dev] Failed to launch REPL process

[Alex Blewitt]

> On 24 Oct 2017, at 17:00, Ron Olson via swift-dev <swift-dev at swift.org> wrote:
> 
> Hi all-
> 
> I am able to build Swift 4 on Fedora 26 Linux (https://github.com/tachoknight/swift-rpm) and while it can compile and run Swift code just fine, the REPL does not start because of:
> 
> error: failed to launch REPL process: process launch failed: 'A' packet returned an error: -1

This occurs when you are running the docker image without a --privileged flag, or without a --cap-add=SYS_PTRACE flag. You are not able to debug any running program, and since the Swift REPL is implemented as a front-end to an lldb debugging instance, it follows that the Swift REPL will not work without the container being launched without either of those flags.

Alex