[swift-evolution] Draft Proposal SwiftPM System Module Search Paths

[Max Howell]

> Thanks for sending out this proposal. I admit I’m somewhat ignorant of the current state of SwiftPM so feel free to point me at existing resources if I’m missing basic things.
> 
> You don’t cover it in your proposal, but does this mean pkg-config is now a dependency for SwiftPM? I may be mistaken but it doesn’t seem as though pkg-config is installed on the base OS X system. (This leads me to assume it’s an optional dependency.)

This is a good point, I’ll revise the proposal.

My intentions were: if available, use it, if not, then things may not build. Long term we could parse pkg-config files ourselves since the format is very basic which would be preferable since “your package graph *may* or *may not* build” is hardly fun.

> Your proposal suggests the set of supported package mangers will be closed. What about folks using new, or non-standard package managers?

They can add their package manager to the supported list via a Pull Request.

> What about packages that are installed system-wide without a package manager (e.g. with ./configure && make && make install)? 

Such packages should come with a .pc file.

> This may be covered elsewhere, but about the case of a C package that is normally system-wide but is currently being hacked on by the user? (For example to while debugging it, or writing bindings for it.)

There is no convenient way to do this at this time, but proposals are welcome. It *is* possible currently, you can make a local module map package that encapsulates the C library, or if it is simple enough our C-target support may be sufficient.