Patching svgcairo on nixpkgs with this commit fixed the linux build but removing one of the flags broke it for darwin. I don't think it's a nixpkgs issue and after some investigation I found similar issues on Github. It seems like we need to retain the -D__attribute__(A)= flag, so this adds it back with a if os(darwin) conditonal.
This builds on https://github.com/gtk2hs/svgcairo/pull/10/commits/df6c6172b52ecbd32007529d86ba9913ba001306.
Patching
svgcairoon nixpkgs with this commit fixed the linux build but removing one of the flags broke it for darwin. I don't think it's a nixpkgs issue and after some investigation I found similar issues on Github. It seems like we need to retain the-D__attribute__(A)=flag, so this adds it back with aif os(darwin)conditonal.