[swift-corelibs-dev] libdispatch on Linux, or C++ std::async?

Chris Bailey BAILEYC at uk.ibm.com
Mon May 30 11:19:33 CDT 2016

The missing reference is to 'pthread_workqueue_signal_np()' which was 
added to libpwq via PR #10:

I suspect that you don't have the libpwq submodule checked out in 
swift-corelibs-libdispatch. Is there any contents in 

If not, running:
        git submodule init
        git submodule update
from the swift-corelibs-libdispatch directory should fix it.


From:   Brian Gesiak <modocache at gmail.com>
To:     Chris Bailey/UK/IBM at IBMGB
Cc:     Rob Allen <rob at akrabat.com>, Swift Core Libs 
<swift-corelibs-dev at swift.org>
Date:   30/05/2016 16:51
Subject:        Re: [swift-corelibs-dev] libdispatch on Linux, or C++ 

Thanks for the quick responses!

I had tried the experimental/foundation branch as well, with no luck. 
Here's the full output from a clean build I just attempted: 

Prior to the build I removed my entire build directory (which included 
both libdispatch-linux-x86_64 and swift-linux-x86_64) and removed all 
build artifacts from my libdispatch directory (I used `git clean -fxd` -- 
Make tells me there's no target `distclean`).

Looking at the build failure, it appears to be the same one that was 
reported in https://bugs.swift.org/browse/SR-1242. The author of that 
report indicates that 
https://github.com/apple/swift-corelibs-libdispatch/pull/64 fixes the 
problem. My checkout includes the commits from that pull request, but the 
problem remains.

In any case, thanks for all your help! I'll keep trying. Any and all 
advice would be much appreciated!

- Brian Gesiak

On Mon, May 30, 2016 at 10:22 AM, Chris Bailey <BAILEYC at uk.ibm.com> wrote:
I'd certainly recommend picking up the experimental/foundation branch as 
Rob recommends. Its where we've been doing some additional work to get 
properly built into the Swift toolchain and to open up some internal APIs 
needed by Foundation. 

Whilst I've been building Dispatch either independently or as part of a 
full toolchain using the buildbot_linux preset (with dispatch and 
install-dispatch added), I've just checked your build line and its working 
fine for me. It might be worth cleaning out any partial build you might 
have of libdispatch in your build directory, and running 'make distclean' 
from your libdispatch source directory. 

FYI, we've got some further changes to the experimental/foundation branch 
of libdispatch with should land in the next couple of days. This fixes 
some issues with the Swift overlay, and resolves a crash that we've found 
in the underlying libkqueue implementation. 


From:        Rob Allen via swift-corelibs-dev <
swift-corelibs-dev at swift.org> 
To:        Brian Gesiak <modocache at gmail.com> 
Cc:        Swift Core Libs <swift-corelibs-dev at swift.org> 
Date:        30/05/2016 08:08 
Subject:        Re: [swift-corelibs-dev] libdispatch on Linux, or C++ 
Sent by:        swift-corelibs-dev-bounces at swift.org 


For what it's worth, I can't get the master branch to build either, but I 
can get the experimental/foundation branch to build. 



On 30 May 2016, at 05:28, Brian Gesiak via swift-corelibs-dev <
swift-corelibs-dev at swift.org> wrote: 

Hello all! 

I'm working on https://bugs.swift.org/browse/SR-710, which involves 
porting SourceKit to Linux. SourceKit contains a handful of references to 
libdispatch symbols.

I have two questions:

1. Could someone share a set of instructions to build 
swift-corelibs-libdispatch on Linux? I'm using Ubuntu 15.10 and have 
installed [the dependencies listed here](
). I have tried using both `swift/utils/build-script --libdispatch` as 
well as the instructions in the swift-corelibs-libdispatch `INSTALL` file. 
Both fail with the [same errors](
https://gist.github.com/modocache/8389d5d64e39ca5a4281500f84e9ce11). Any 

2. I don't know much about C++, but from what I understand the C++ stdlib 
provides tools for asynchronous programming. I list SourceKit's uses of 
libdispatch in a comment on https://bugs.swift.org/browse/SR-1639. For 
those familiar with both C++ and libdispatch: do you think it's a good 
idea to migrate to C++, at least for now? 

Any advice would be appreciated. Thanks!! 

- Brian Gesiak 

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