From e11c78c0ceb801db2b2904a693565924417da672 Mon Sep 17 00:00:00 2001
From: Mathieu Boespflug <m@tweag.io>
Date: Sat, 4 Jun 2016 23:48:46 +0200
Subject: [PATCH] Support .buildinfo files in stack ghci.

`Distribution.Simple` based `Setup.hs` sometimes create
`<package>.buildinfo` files as an artifact of the configure phase.
This is the case in particular when using the autoconf hooks. Since
this is an internal detail private to any given package's `Setup.hs`,
Stack shouldn't (and doesn't) need to care or be aware of this. But
`stack ghci` does, since in that use case we're not using Cabal to
build - we're taking care of the build ourselves. In particular,
ignoring the `<package.buildinfo` file can mean that a successful
build using `stack build` can't be replicated using `stack ghci`.

E.g. in the case of the `network` package, the set of C files to build
is decided at configure time, based on the current platform. So the
`c-files` stanza in the .cabal file is not complete. This in turn
means `stack ghci` isn't aware of all object files it has to link in,
leading to obscure link errors (see #1239).

See [1] for more on .buildinfo files.

Fixes #2239.

[1]: https://www.haskell.org/cabal/users-guide/developing-packages.html#system-dependent-parameters
---
 src/Stack/Ghci.hs    | 25 +++++++++++++++++++++----
 src/Stack/Package.hs | 12 ++++++++++++
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/src/Stack/Ghci.hs b/src/Stack/Ghci.hs
index b9856548d6..bf244ea0d8 100644
--- a/src/Stack/Ghci.hs
+++ b/src/Stack/Ghci.hs
@@ -18,12 +18,12 @@ module Stack.Ghci
 
 import           Control.Applicative
 import           Control.Exception.Enclosed (tryAny)
-import           Control.Monad
+import           Control.Monad hiding (forM)
 import           Control.Monad.Catch
 import           Control.Monad.IO.Class
 import           Control.Monad.Logger
-import           Control.Monad.RWS.Strict
-import           Control.Monad.State.Strict
+import           Control.Monad.State.Strict (State, execState, get, modify)
+import           Control.Monad.Reader (MonadReader, asks)
 import           Control.Monad.Trans.Unlift (MonadBaseUnlift)
 import qualified Data.ByteString.Char8 as S8
 import           Data.Either
@@ -35,12 +35,15 @@ import           Data.Map.Strict (Map)
 import qualified Data.Map.Strict as M
 import           Data.Maybe
 import           Data.Maybe.Extra (forMaybeM)
+import           Data.Monoid
 import           Data.Set (Set)
 import qualified Data.Set as S
+import           Data.Traversable (forM)
 import           Data.Text (Text)
 import qualified Data.Text as T
 import           Data.Typeable (Typeable)
 import           Distribution.ModuleName (ModuleName)
+import           Distribution.PackageDescription (updatePackageDescription)
 import           Distribution.Text (display)
 import           Network.HTTP.Client.Conduit
 import           Path
@@ -379,7 +382,21 @@ makeGhciPkgInfo boptsCli sourceMap installedMap locals addPkgs name cabalfp targ
             , packageConfigCompilerVersion = envConfigCompilerVersion econfig
             , packageConfigPlatform = configPlatform (getConfig bconfig)
             }
-    (warnings,pkg) <- readPackage config cabalfp
+    (warnings,gpkgdesc) <- readPackageUnresolved cabalfp
+
+    -- Source the package's *.buildinfo file created by configure if any. See
+    -- https://www.haskell.org/cabal/users-guide/developing-packages.html#system-dependent-parameters
+    buildinfofp <- parseRelFile (T.unpack (packageNameText name) ++ ".buildinfo")
+    hasDotBuildinfo <- doesFileExist (parent cabalfp </> buildinfofp)
+    let mbuildinfofp
+          | hasDotBuildinfo = Just (parent cabalfp </> buildinfofp)
+          | otherwise = Nothing
+    mbuildinfo <- forM mbuildinfofp readDotBuildinfo
+    let pkg =
+            packageFromPackageDescription config gpkgdesc $
+            maybe id (updatePackageDescription) mbuildinfo $
+            resolvePackageDescription config gpkgdesc
+
     mapM_ (printCabalFileWarning cabalfp) warnings
     (mods,files,opts) <- getPackageOpts (packageOpts pkg) sourceMap installedMap locals addPkgs cabalfp
     let filteredOpts = filterWanted opts
diff --git a/src/Stack/Package.hs b/src/Stack/Package.hs
index 62b69a3801..b96addbde8 100644
--- a/src/Stack/Package.hs
+++ b/src/Stack/Package.hs
@@ -18,6 +18,7 @@ module Stack.Package
   (readPackage
   ,readPackageBS
   ,readPackageDescriptionDir
+  ,readDotBuildinfo
   ,readPackageUnresolved
   ,readPackageUnresolvedBS
   ,resolvePackage
@@ -147,6 +148,17 @@ readPackageDescriptionDir config pkgDir = do
     gdesc   <- liftM snd (readPackageUnresolved cabalfp)
     return (gdesc, resolvePackageDescription config gdesc)
 
+-- | Read @<package>.buildinfo@ ancillary files produced by some Setup.hs hooks.
+-- The file includes Cabal file syntax to be merged into the package description
+-- derived from the package's .cabal file.
+--
+-- NOTE: not to be confused with BuildInfo, an Stack-internal datatype.
+readDotBuildinfo :: MonadIO m
+                 => Path Abs File
+                 -> m HookedBuildInfo
+readDotBuildinfo buildinfofp =
+    liftIO $ readHookedBuildInfo D.silent (toFilePath buildinfofp)
+
 -- | Print cabal file warnings.
 printCabalFileWarning
     :: (MonadLogger m)