[swift-users] [swift-build-dev] Importing C system libraries

[Ankit Aggarwal]

Hi,

Apologies for not replying to this earlier.

You can have multiple targets in a single package. Each target can either
be Swift or C-family. The type of target is determined by the sources
contained in it (*.c/*.cpp etc means C target, *.swift means Swift target).
So if you want to create multiple C targets, this layout should work:

Package.swift
Sources/
    Bitmap
    Cubify
    Cairo/anchor.c <---- This is just an empty file to tell SwiftPM that
this is a C target.
    Cairo/include/Cairo.h
    Cairo/include/module.modulemap
    GLFW/anchor.c
    GLFW/include/GLFW.h
    GLFW/include/module.modulemap

The modulemap is automatically generated, if not provided. This is a
package which contains two targets (one C and one Swift):
https://github.com/jpsim/Yams

If you need to pass a bunch of compiler flags, you can use SwiftPM's
pkgConfig feature but that will require you to have a separate repository
for Cario and GLFW. You can experiment without creating tags using the edit
feature
<https://github.com/apple/swift-package-manager/blob/master/Documentation/Usage.md#editable-packages>
.

PS: You can join SwiftPM slack channel for quicker turn around time:
https://lists.swift.org/pipermail/swift-build-dev/Week-of-Mon-20160530/000497.html

Thanks,
Ankit


On Wed, Mar 29, 2017 at 6:06 AM, Michael Ilseman via swift-build-dev <
swift-build-dev at swift.org> wrote:

> This is into uncharted territory for me, but it seems you’re building with
> SwiftPM. You’ll probably want to configure extra compiler flags if that’s
> possible. You could also bite the bullet and build your C libraries with
> SwiftPM as well. Hopefully someone on swift-build-dev can help you out.
>
> CC-ing Ankit
>
>
> On Mar 28, 2017, at 5:09 PM, Kelvin Ma <kelvinsthirteen at gmail.com> wrote:
>
> How do I compile a project with many modules? My tree looks like this:
>
> <Selection_001.png>
> ​
>
> On Tue, Mar 28, 2017 at 12:47 PM, Michael Ilseman <milseman at apple.com>
> wrote:
>
>> Sure! In this example, I have built libgit2. I have a directory called
>> Git, and inside that I have the following module map:
>>
>> module Git [system] {
>>        header "<my path>/libgit2/include/git2.h"
>>        export *
>> }
>>
>> When I run, I use:
>>
>> swift -I <path-to-“Git”-directory> -L <path-to-built-libgit2> -lgit2
>> foo.swift
>>
>> inside foo.swift I can:
>>
>> import Git
>> // … use libGit2
>>
>>
>> Read more about how to write a more appropriate module.map file for your
>> purposes at https://clang.llvm.org/docs/Modules.html. For example, you
>> might be able to define link flags inside the module.map, use umbrella
>> directories, submodules, etc.
>>
>>
>>
>> On Mar 28, 2017, at 6:27 AM, Kelvin Ma <kelvinsthirteen at gmail.com> wrote:
>>
>> Can you give an example?
>>
>> On Mon, Mar 27, 2017 at 3:59 PM, Michael Ilseman <milseman at apple.com>
>> wrote:
>>
>>> Sure. At a low level, you can create a module.map file and use -L/-l
>>> flags in your invocation of Swift. If you want to do so at a higher level,
>>> then perhaps SwiftPM can. CCing swift-build-dev for the SwiftPM part.
>>>
>>>
>>> > On Mar 26, 2017, at 3:20 PM, Kelvin Ma via swift-users <
>>> swift-users at swift.org> wrote:
>>> >
>>> > Idk if this has been asked before, but is there a way to import C
>>> libraries into a Swift project without creating a local git repo?
>>> Preferably something similar to C where you can just `#include` headers and
>>> then specify the link flags (in Package.swift?)
>>> >
>>> > It’s getting very cumbersome to make a bunch of empty git repos just
>>> to use libglfw or libcairo.
>>> > _______________________________________________
>>> > swift-users mailing list
>>> > swift-users at swift.org
>>> > https://lists.swift.org/mailman/listinfo/swift-users
>>>
>>>
>>
>>
>
>
> _______________________________________________
> swift-build-dev mailing list
> swift-build-dev at swift.org
> https://lists.swift.org/mailman/listinfo/swift-build-dev
>
>
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