Look for install includes in buildpref as well

[angerman]

When installing a lirbary, we should look for it's headers in it's 'build' preference first, then relative to the current path.

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[angerman]

Alright, so ideally we'd look into the relative directories from the cabal file. This will work when the CWD is the folder containing the cabal file. However if it is not, and the generic package description in passed in, we have no handle on the location of the cabal file. Or do we?

However, Looking for the include headers in the build directory, prior to trying to locate them relative to the current path seems like a sensible change to me.

[23Skidoo]

Should say what the default build preference dir is, i.e.:

... will look for include headers in the build preference dir ('dist/build/...' by default) as well.

[23Skidoo]

When installing a lirbary, we should look for it's headers in it's 'build' preference first, then relative to the current path.

That's because custom setup scripts can put stuff there? OK, makes sense.

/cc @dcoutts

[hvr]

Can you explain the motivation and/or the problem this solving?

[angerman]

scratch that.

[angerman]

Can you explain the motivation and/or the problem this solving?

Alright, so you end up "generating" your headers. And they end up in the build directory, however your cabal file does addresses them relative.

[angerman]

To clarify why I called this "build preference". This is due wo the variable naming of buildPref in the source.

[23Skidoo]

@angerman To the users it's either dist/build/... or --builddir.

[hvr]

Oh I see; one thing though, for *-modules we have autogen-modules, in order to be explicit about what is autogenerated and which things cabal is supposed to warn us about.

I think we should have the corresponding facility also for installed headers, so we can have cabal warn at sdist time properly, when you specify a header that doesn't exist yet (because it will (not) be autogenerated)

[angerman]

@23Skidoo I'll update the change log to reflect that better.

[angerman]

To better understand where I'm coming from. I'm currently trying to roll ghc-cabal into hadrian. And all these issues crop up while doing so.

[23Skidoo]

Merged, thanks!