Adjust rpath in cabal-cache artifacts

[AlexeyRaga]

Problem:

[ 9 of 29] Compiling App.Options.Lens ( src/App/Options/Lens.hs, /Users/david/src/arbor/mayhem/banner-commander/dist-newstyle/build/x86_64-osx/ghc-8.6.5/banner-commander-0.0.1/build/App/Options/Lens.o ) [Control.Lens changed]
<command line>: can't load .so/.DLL for: /Users/david/.cabal/store/ghc-8.6.5/lib/libHSrndm-shffl-0.0.4-63f5dfd2-ghc8.6.5.dylib (dlopen(/Users/david/.cabal/store/ghc-8.6.5/lib/libHSrndm-shffl-0.0.4-63f5dfd2-ghc8.6.5.dylib, 5): Library not loaded: /usr/local/opt/ghc/lib/ghc-8.6.5/base-4.12.0.0/libHSbase-4.12.0.0-ghc8.6.5.dylib
  Referenced from: /Users/david/.cabal/store/ghc-8.6.5/lib/libHSrndm-shffl-0.0.4-63f5dfd2-ghc8.6.5.dylib
  Reason: image not found)

sometimes an .so is pushed that has a full path to a base library.

otool -L lib/libHSrndm-shffl-0.0.4-63f5dfd2-ghc8.6.5.dylib 
lib/libHSrndm-shffl-0.0.4-63f5dfd2-ghc8.6.5.dylib:
        @rpath/libHSrndm-shffl-0.0.4-63f5dfd2-ghc8.6.5.dylib (compatibility version 0.0.0, current version 0.0.0)
        @rpath/libHSrndm-1.1-46d8c4d3-ghc8.6.5.dylib (compatibility version 0.0.0, current version 0.0.0)
        /usr/local/opt/ghc/lib/ghc-8.6.5/base-4.12.0.0/libHSbase-4.12.0.0-ghc8.6.5.dylib (compatibility version 0.0.0, current version 0.0.0)
        /usr/local/opt/ghc/lib/ghc-8.6.5/integer-gmp-1.0.2.0/libHSinteger-gmp-1.0.2.0-ghc8.6.5.dylib (compatibility version 0.0.0, current version 0.0.0)
        /usr/local/opt/ghc/lib/ghc-8.6.5/ghc-prim-0.5.3/libHSghc-prim-0.5.3-ghc8.6.5.dylib (compatibility version 0.0.0, current version 0.0.0)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1252.250.1)

They should all be relative to @rpath:

ghc-8.6.5/lib/libHSBln-0.2.4-a71178c6-ghc8.6.5.dylib:
        @rpath/libHSBln-0.2.4-a71178c6-ghc8.6.5.dylib (compatibility version 0.0.0, current version 0.0.0)
        @rpath/libHSbase-4.12.0.0-ghc8.6.5.dylib (compatibility version 0.0.0, current version 0.0.0)
        @rpath/libHSinteger-gmp-1.0.2.0-ghc8.6.5.dylib (compatibility version 0.0.0, current version 0.0.0)
        @rpath/libHSghc-prim-0.5.3-ghc8.6.5.dylib (compatibility version 0.0.0, current version 0.0.0)

[newhoggy]

Is this a cabal-cache problem or a cabal/ghc problem?

[AlexeyRaga]

AFAIK it is just how GHC works: it writes absolute paths in binary artifacts making them much harder to re-distribute.
cabal-cache may help here by re-writing these paths so that they work fine in a target location.

[newhoggy]

Might be worth creating an issue on ghc or cabal too.

[AlexeyRaga]

I don't think they see it as an issue. It is a very well known thing, maybe there is a ticket somewhere.
And a very well known solution too. For example nix does exactly that for cached binaries.