Doctests new build

[phadej]

No description provided.

[ekmett]

Can you add a preamble to the Setup.lhs like:

#ifndef MIN_VERSION_Cabal
#define MIN_VERSION_Cabal(X,Y,Z) 0
#endif

This way when run on older cabal versions it'll be more robust.

[phadej]

@ekmett, I did. Let's see what travis says. I guess setup-depends: Cabal >= 1.24 is ok, as it really helps if people move to recent cabal.

Tested locally: can run doctests with GHC-7.8.4 and GHC-8.0.1 when using cabal-install-head new-build

[RyanGlScott]

Thanks for doing this, @phadej! Since there's a number of other packages that use a similar Setup.hs script (and since we don't yet have cabal doctest), I'd like to adapt this for other packages. Some questions I have after skimming the changes:

1. Does this really require cabal-install-head as the minimum?
2. Is there any logic here that's lens-specific that couldn't just be copy-pasted into something like, say, distributive's Setup.hs?

[phadej]

@RyanGlScott For 2: The lens diagram copying code is something none of other packages need: https://github.com/ekmett/lens/blob/master/Setup.lhs#L42-L44

For 1: I'm not sure, it might work with cabal-install-1.24 new-build too, too lazy to check what https://github.com/haskell/cabal/blame/675d4f1625edc6e3d3a68448cbc72a7931a590ea/cabal-install/Distribution/Client/SetupWrapper.hs#L810-L821 looks like.

But anyhow, cabal-install-1.24 new-build is/was a technology preview, and I wouldn't use it if I can pick HEAD (with HVR's ppa repo it's easy, if you are on Ubuntu; I'm also planning to provide nightly OSX builds of cabal, but run out of time setting that up: now I said it publicly, so I guess it will happen sooner ;) )

[RyanGlScott]

1. Oh, I didn't read the new-build part of the title. But lens's Travis script isn't currently using new-build, right? It's still using configure/build/test for the moment. So as long as you stick to the old-style build process, does it matter what version of cabal-install you use?

2. Good point, I'll make sure not to use the diagram-copying part elsewhere.

[bennofs]

@phadej does this work with older cabal-install versions? I'd assume it requires a cabal-install that knows about custom-setup, or parsing of the cabal file will fail.

[phadej]

parsing doesn't fail, cabal just says "unknown section". You can see it e.g. from https://travis-ci.org/ekmett/distributive/builds/197339532

[bennofs]

Oh cool, I had assumed that this was less backwards-compatible than it actually is. This is nice, thanks!