Upgrade the Setup.hs harness to use cabal-doctest.

This upgrades the `Setup.hs` harness to use `cabal-doctest`,
making it compatible with `Cabal-1.25` (shipped with GHC 8.2).
See ekmett/lens#709

Make sure to add a dependency on bits in the doctests test-suite
to avoid haskellari/cabal-doctest#5

CHANGELOG.markdown

@@ -1,3 +1,9 @@
+next
+----
+* Revamp `Setup.hs` to use `cabal-doctest`. This makes it build
+  with `Cabal-1.25`, and makes the `doctest`s work with `cabal new-build` and
+  sandboxes.
+
 4.3.2.1
 -----
 * GHC 8 support

Setup.lhs

@@ -1,48 +1,182 @@
-#!/usr/bin/runhaskell
 \begin{code}
-{-# OPTIONS_GHC -Wall #-}
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE OverloadedStrings #-}
 module Main (main) where
 
+#ifndef MIN_VERSION_cabal_doctest
+#define MIN_VERSION_cabal_doctest(x,y,z) 0
+#endif
+
+
+#if MIN_VERSION_cabal_doctest(1,0,0)
+import Distribution.Extra.Doctest ( defaultMainWithDoctests )
+#else
+
+-- Otherwise we provide a shim
+
+#ifndef MIN_VERSION_Cabal
+#define MIN_VERSION_Cabal(x,y,z) 0
+#endif
+#ifndef MIN_VERSION_directory
+#define MIN_VERSION_directory(x,y,z) 0
+#endif
+#if MIN_VERSION_Cabal(1,24,0)
+#define InstalledPackageId UnitId
+#endif
+
+import Control.Monad ( when )
 import Data.List ( nub )
-import Data.Version ( showVersion )
-import Distribution.Package ( PackageName(PackageName), PackageId, InstalledPackageId, packageVersion, packageName )
-import Distribution.PackageDescription ( PackageDescription(), TestSuite(..) )
+import Data.String ( fromString )
+import Distribution.Package ( InstalledPackageId )
+import Distribution.Package ( PackageId, Package (..), packageVersion )
+import Distribution.PackageDescription ( PackageDescription(), TestSuite(..) , Library (..), BuildInfo (..))
 import Distribution.Simple ( defaultMainWithHooks, UserHooks(..), simpleUserHooks )
 import Distribution.Simple.Utils ( rewriteFile, createDirectoryIfMissingVerbose )
 import Distribution.Simple.BuildPaths ( autogenModulesDir )
-import Distribution.Simple.Setup ( BuildFlags(buildVerbosity), fromFlag )
-import Distribution.Simple.LocalBuildInfo ( withLibLBI, withTestLBI, LocalBuildInfo(), ComponentLocalBuildInfo(componentPackageDeps) )
-import Distribution.Verbosity ( Verbosity )
+import Distribution.Simple.Setup ( BuildFlags(buildDistPref, buildVerbosity), fromFlag)
+import Distribution.Simple.LocalBuildInfo ( withPackageDB, withLibLBI, withTestLBI, LocalBuildInfo(), ComponentLocalBuildInfo(componentPackageDeps), compiler )
+import Distribution.Simple.Compiler ( showCompilerId , PackageDB (..))
+import Distribution.Text ( display , simpleParse )
 import System.FilePath ( (</>) )
 
-main :: IO ()
-main = defaultMainWithHooks simpleUserHooks
-  { buildHook = \pkg lbi hooks flags -> do
-     generateBuildModule (fromFlag (buildVerbosity flags)) pkg lbi
-     buildHook simpleUserHooks pkg lbi hooks flags
-  }
+#if MIN_VERSION_Cabal(1,25,0)
+import Distribution.Simple.BuildPaths ( autogenComponentModulesDir )
+#endif
+
+#if MIN_VERSION_directory(1,2,2)
+import System.Directory (makeAbsolute)
+#else
+import System.Directory (getCurrentDirectory)
+import System.FilePath (isAbsolute)
+
+makeAbsolute :: FilePath -> IO FilePath
+makeAbsolute p | isAbsolute p = return p
+               | otherwise    = do
+    cwd <- getCurrentDirectory
+    return $ cwd </> p
+#endif
+
+generateBuildModule :: String -> BuildFlags -> PackageDescription -> LocalBuildInfo -> IO ()
+generateBuildModule testsuiteName flags pkg lbi = do
+  let verbosity = fromFlag (buildVerbosity flags)
+  let distPref = fromFlag (buildDistPref flags)
+
+  -- Package DBs
+  let dbStack = withPackageDB lbi ++ [ SpecificPackageDB $ distPref </> "package.conf.inplace" ]
+  let dbFlags = "-hide-all-packages" : packageDbArgs dbStack
+
+  withLibLBI pkg lbi $ \lib libcfg -> do
+    let libBI = libBuildInfo lib
+
+    -- modules
+    let modules = exposedModules lib ++ otherModules libBI
+    -- it seems that doctest is happy to take in module names, not actual files!
+    let module_sources = modules
+
+    -- We need the directory with library's cabal_macros.h!
+#if MIN_VERSION_Cabal(1,25,0)
+    let libAutogenDir = autogenComponentModulesDir lbi libcfg
+#else
+    let libAutogenDir = autogenModulesDir lbi
+#endif
 
-generateBuildModule :: Verbosity -> PackageDescription -> LocalBuildInfo -> IO ()
-generateBuildModule verbosity pkg lbi = do
-  let dir = autogenModulesDir lbi
-  createDirectoryIfMissingVerbose verbosity True dir
-  withLibLBI pkg lbi $ \_ libcfg -> do
-    withTestLBI pkg lbi $ \suite suitecfg -> do
-      rewriteFile (dir </> "Build_" ++ testName suite ++ ".hs") $ unlines
-        [ "module Build_" ++ testName suite ++ " where"
+    -- Lib sources and includes
+    iArgs <- mapM (fmap ("-i"++) . makeAbsolute) $ libAutogenDir : hsSourceDirs libBI
+    includeArgs <- mapM (fmap ("-I"++) . makeAbsolute) $ includeDirs libBI
+
+    -- CPP includes, i.e. include cabal_macros.h
+    let cppFlags = map ("-optP"++) $
+            [ "-include", libAutogenDir ++ "/cabal_macros.h" ]
+            ++ cppOptions libBI
+
+    withTestLBI pkg lbi $ \suite suitecfg -> when (testName suite == fromString testsuiteName) $ do
+
+      -- get and create autogen dir
+#if MIN_VERSION_Cabal(1,25,0)
+      let testAutogenDir = autogenComponentModulesDir lbi suitecfg
+#else
+      let testAutogenDir = autogenModulesDir lbi
+#endif
+      createDirectoryIfMissingVerbose verbosity True testAutogenDir
+
+      -- write autogen'd file
+      rewriteFile (testAutogenDir </> "Build_doctests.hs") $ unlines
+        [ "module Build_doctests where"
         , ""
-        , "autogen_dir :: String"
-        , "autogen_dir = " ++ show dir
+        -- -package-id etc. flags
+        , "pkgs :: [String]"
+        , "pkgs = " ++ (show $ formatDeps $ testDeps libcfg suitecfg)
         , ""
-        , "deps :: [String]"
-        , "deps = " ++ (show $ formatdeps (testDeps libcfg suitecfg))
+        , "flags :: [String]"
+        , "flags = " ++ show (iArgs ++ includeArgs ++ dbFlags ++ cppFlags)
+        , ""
+        , "module_sources :: [String]"
+        , "module_sources = " ++ show (map display module_sources)
         ]
   where
-    formatdeps = map (formatone . snd)
-    formatone p = case packageName p of
-      PackageName n -> n ++ "-" ++ showVersion (packageVersion p)
+    -- we do this check in Setup, as then doctests don't need to depend on Cabal
+    isOldCompiler = maybe False id $ do
+      a <- simpleParse $ showCompilerId $ compiler lbi
+      b <- simpleParse "7.5"
+      return $ packageVersion (a :: PackageId) < b
+
+    formatDeps = map formatOne
+    formatOne (installedPkgId, pkgId)
+      -- The problem is how different cabal executables handle package databases
+      -- when doctests depend on the library
+      | packageId pkg == pkgId = "-package=" ++ display pkgId
+      | otherwise              = "-package-id=" ++ display installedPkgId
+
+    -- From Distribution.Simple.Program.GHC
+    packageDbArgs :: [PackageDB] -> [String]
+    packageDbArgs | isOldCompiler = packageDbArgsConf
+                  | otherwise     = packageDbArgsDb
+
+    -- GHC <7.6 uses '-package-conf' instead of '-package-db'.
+    packageDbArgsConf :: [PackageDB] -> [String]
+    packageDbArgsConf dbstack = case dbstack of
+      (GlobalPackageDB:UserPackageDB:dbs) -> concatMap specific dbs
+      (GlobalPackageDB:dbs)               -> ("-no-user-package-conf")
+                                           : concatMap specific dbs
+      _ -> ierror
+      where
+        specific (SpecificPackageDB db) = [ "-package-conf=" ++ db ]
+        specific _                      = ierror
+        ierror = error $ "internal error: unexpected package db stack: "
+                      ++ show dbstack
+
+    -- GHC >= 7.6 uses the '-package-db' flag. See
+    -- https://ghc.haskell.org/trac/ghc/ticket/5977.
+    packageDbArgsDb :: [PackageDB] -> [String]
+    -- special cases to make arguments prettier in common scenarios
+    packageDbArgsDb dbstack = case dbstack of
+      (GlobalPackageDB:UserPackageDB:dbs)
+        | all isSpecific dbs              -> concatMap single dbs
+      (GlobalPackageDB:dbs)
+        | all isSpecific dbs              -> "-no-user-package-db"
+                                           : concatMap single dbs
+      dbs                                 -> "-clear-package-db"
+                                           : concatMap single dbs
+     where
+       single (SpecificPackageDB db) = [ "-package-db=" ++ db ]
+       single GlobalPackageDB        = [ "-global-package-db" ]
+       single UserPackageDB          = [ "-user-package-db" ]
+       isSpecific (SpecificPackageDB _) = True
+       isSpecific _                     = False
 
 testDeps :: ComponentLocalBuildInfo -> ComponentLocalBuildInfo -> [(InstalledPackageId, PackageId)]
 testDeps xs ys = nub $ componentPackageDeps xs ++ componentPackageDeps ys
 
+defaultMainWithDoctests :: String -> IO ()
+defaultMainWithDoctests testSuiteName = defaultMainWithHooks simpleUserHooks
+  { buildHook = \pkg lbi hooks flags -> do
+     generateBuildModule testSuiteName flags pkg lbi
+     buildHook simpleUserHooks pkg lbi hooks flags
+  }
+
+#endif
+
+main :: IO ()
+main = defaultMainWithDoctests "doctests"
+
 \end{code}

ad.cabal

@@ -81,6 +81,12 @@ flag herbie
   default: False
   manual: True
 
+custom-setup
+  setup-depends:
+    base          >= 4.3 && <5,
+    Cabal         >= 1.10,
+    cabal-doctest >= 1 && <1.1
+
 library
   hs-source-dirs: src
   include-dirs: include

tests/doctests.hs

@@ -1,32 +1,25 @@
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Main (doctests)
+-- Copyright   :  (C) 2012-14 Edward Kmett
+-- License     :  BSD-style (see the file LICENSE)
+-- Maintainer  :  Edward Kmett <ekmett@gmail.com>
+-- Stability   :  provisional
+-- Portability :  portable
+--
+-- This module provides doctests for a project based on the actual versions
+-- of the packages it was built with. It requires a corresponding Setup.lhs
+-- to be added to the project
+-----------------------------------------------------------------------------
 module Main where
 
-import Build_doctests (autogen_dir, deps)
-import Control.Applicative
-import Control.Monad
-import Data.List
-import System.Directory
-import System.FilePath
+import Build_doctests (flags, pkgs, module_sources)
+import Data.Foldable (traverse_)
 import Test.DocTest
 
 main :: IO ()
-main = getSources >>= \sources -> doctest $
-    "-isrc"
-  : ("-i" ++ autogen_dir)
-  : "-optP-include"
-  : ("-optP" ++ autogen_dir ++ "/cabal_macros.h")
-  : "-optP-I"
-  : "-optPinclude"
-  : "-hide-all-packages"
-  : map ("-package="++) deps ++ sources
-
-getSources :: IO [FilePath]
-getSources = filter (isSuffixOf ".hs") <$> go "src"
+main = do
+    traverse_ putStrLn args
+    doctest args
   where
-    go dir = do
-      (dirs, files) <- getFilesAndDirectories dir
-      (files ++) . concat <$> mapM go dirs
-
-getFilesAndDirectories :: FilePath -> IO ([FilePath], [FilePath])
-getFilesAndDirectories dir = do
-  c <- map (dir </>) . filter (`notElem` ["..", "."]) <$> getDirectoryContents dir
-  (,) <$> filterM doesDirectoryExist c <*> filterM doesFileExist c
+    args = flags ++ pkgs ++ module_sources