Linking a GUI-using app in a nix-shell, via
ghc, I suddenly started getting these errors:
Undefined symbols for architecture x86_64: "_OBJC_CLASS_$_NSData", referenced from: objc-class-ref in libfltk.a(Fl_MacOS_Sys_Menu_Bar.o) "_NSDefaultRunLoopMode", referenced from: Fl_Cocoa_Screen_Driver::ready() in libfltk.a(Fl_cocoa.o) Fl_Cocoa_Screen_Driver::wait(double) in libfltk.a(Fl_cocoa.o) Fl_Cocoa_Screen_Driver::open_display_platform() in libfltk.a(Fl_cocoa.o) [ etc ]
After a bunch of poking about with verbose flags, the problem seems to be that
darwin.CF) winds up as a -F flag. Actually very many -F flags show up, many of them repeated, which I assume is down to using bash for stdenv and is usually harmless… except when it’s not. I wind up with both the swift-corefoundation and
darwin.cf-private). It seems to work if I have neither -F flags, or if I have both but but apple-framework comes last. If I have just swift, or swift comes after apple-framework, then link failure. They both have a CoreFoundation.framework, so presumably you don’t want to find the wrong one… or either of them? Strange. To be clear, I’m not doing anything to do with swift, it’s just along for the ride for some reason.
When trying to track down how it winds up on the ghc link line, it turns out it’s always there regardless of any env vars, and I suspect it’s because all hackage package.conf files have acquired a
framework-dirs: /nix/store/blahblah-swift-etc. I assume this is somehow due to it winding up in some env var, perhaps due to it going in defaultBuildInputs, which seems to be undocumented and I can’t quite trace where it goes.
This all seems to be related to rstudio: issues with darwin frameworks · Issue #24237 · NixOS/nixpkgs · GitHub, and I must have stumbled across this a while back because I had the
-F/System/Library/Frameworks hack in there… and now after updating nixpkgs it’s no longer working. There are about a zillion flags on and being in the wrong order is fatal so no surprise if it’s brittle.
Anyway, my thought is to try to get that swift thing out of
framework-dirs, but before I put another evening into trying to see how it gets in there… does anyone have any clues? Is there a better way to debug this? Why are there multiple CoreFoundations? What is each one for? Why would I not have the link error if I don’t link any of them, but get it if I have both but in the wrong order? Also, this is just about
-F flags, which is about the paths… I’m not directly linking CoreFoundation. However, I do link Cocoa and maybe they pull each other in. What is defaultBuildInputs, and what effect does it have? How does an apparently swift library wind up in all haskell packages?
Oh, and this is intel, not aarch64, if it makes a difference.
Thanks in advance!