Squashed 'hadrian/' changes from fa3771fe6b..4499b294e4

4499b294e4 Follow GHC changes
8fd68186b2 Add ways to build hadrian using nix
e5c7a29c23 Do not depend on the in-tree filepath library
9dd7ad2acc Fix dependencies
497184390e Bring mtl dependency back
6c5f5c9bd9 Minor clean up of Hadrian dependencies
9aff81d424 Fix Windows build
fa95caa8df Unbreak `cabal new-build`

git-subtree-dir: hadrian
git-subtree-split: 4499b294e4a53f71f8808d6eb55a7dd0b341cfb8

12 files changed, 135 insertions, 37 deletions

diff --git a/README.md b/README.md
index 916edc21a1..d188a4a054 100644
--- a/README.md
+++ b/README.md
@@ -41,8 +41,8 @@ Notes:
 on Cabal sandboxes (`build.cabal.*`), Stack (`build.stack.*`) or the global package database
 (`build.global-db.*`). Also see [instructions for building GHC on Windows using Stack][windows-build].
 
-* Hadrian is written in Haskell and depends on the following packages:
-`ansi-terminal extra mtl quickcheck shake`.
+* Hadrian is written in Haskell and depends on `shake` (plus a few packages that `shake` depends on),
+`ansi-terminal`, `mtl`, `quickcheck`, and GHC core libraries.
 
 * If you have never built GHC before, start with the [preparation guide][ghc-preparation].
 
diff --git a/build.nix.sh b/build.nix.sh
new file mode 100755
index 0000000000..4b03ea8418
--- /dev/null
+++ b/build.nix.sh
@@ -0,0 +1,35 @@
+#!/usr/bin/env nix-shell
+#! nix-shell -i bash shell.nix
+
+# This script sets up the build environment by invoking nix-shell shell.nix
+# and then runs the hadrian executable.
+
+function rl {
+    TARGET_FILE="$1"
+
+    cd "$(dirname "$TARGET_FILE")"
+    TARGET_FILE="$(basename "$TARGET_FILE")"
+
+    # Iterate down a (possible) chain of symlinks
+    while [ -L "$TARGET_FILE" ]
+    do
+        TARGET_FILE="$(readlink "$TARGET_FILE")"
+        cd "$(dirname "$TARGET_FILE")"
+        TARGET_FILE="$(basename "$TARGET_FILE")"
+    done
+
+    # Compute the canonicalized name by finding the physical path
+    # for the directory we're in and appending the target file.
+    PHYS_DIR="$(pwd -P)"
+    RESULT="$PHYS_DIR/$TARGET_FILE"
+    echo "$RESULT"
+}
+
+absoluteRoot="$(dirname "$(rl "$0")")"
+echo $absoluteRoot
+cd "$absoluteRoot"
+
+hadrian         \
+  --lint                         \
+  --directory="$absoluteRoot/.." \
+  "$@"
diff --git a/cabal.project b/cabal.project
index 317094fb74..0d2b509daa 100644
--- a/cabal.project
+++ b/cabal.project
@@ -1,6 +1,5 @@
 packages: ./
           ../libraries/Cabal/Cabal/
-          ../libraries/filepath/
-          ../libraries/text/
           ../libraries/hpc/
           ../libraries/parsec/
+          ../libraries/text/
diff --git a/hadrian.cabal b/hadrian.cabal
index 389f5530c1..9c170bcd16 100644
--- a/hadrian.cabal
+++ b/hadrian.cabal
@@ -116,17 +116,17 @@ executable hadrian
                        , TupleSections
     other-extensions:    MultiParamTypeClasses
                        , TypeFamilies
-    build-depends:       base >= 4.8 && < 5
+    build-depends:       base                 >= 4.8     && < 5
                        , ansi-terminal        == 0.6.*
                        , Cabal                >= 2.0.0.2 && < 2.2
                        , containers           == 0.5.*
-                       , directory            >= 1.2 && < 1.4
+                       , directory            >= 1.2     && < 1.4
                        , extra                >= 1.4.7
                        , mtl                  == 2.2.*
-                       , QuickCheck           >= 2.6 && < 2.10
+                       , QuickCheck           >= 2.6     && < 2.10
                        , shake                == 0.16.*
-                       , transformers         >= 0.4 && < 0.6
-                       , unordered-containers == 0.2.*
+                       , transformers         >= 0.4     && < 0.6
+                       , unordered-containers >= 0.2.1   && < 0.3
     build-tools:         alex  >= 3.1
                        , happy >= 1.19.4
     ghc-options:       -Wall
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 0000000000..e9a5ecc88e
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1,61 @@
+# Invoking nix-shell sets up an environment where we can build ghc
+# by only invoking hadrian.
+
+
+{ nixpkgs ? import <nixpkgs> {} }:
+
+let
+  haskellPackages = nixpkgs.haskell.packages.ghc821;
+
+  removeBuild = path: type:
+    let baseName = baseNameOf (toString path);
+    in
+        ! (baseName == "_build"
+           || baseName == "dist"
+           || baseName == "dist-newstyle"
+           || baseName == ".stack-work"
+           || baseName == "config.log"
+           || baseName == "config.status"
+           || nixpkgs.lib.hasSuffix ".sh" baseName
+           || !(nixpkgs.lib.cleanSourceFilter path type)) ;
+
+  filterSrc = path: builtins.filterSource removeBuild path;
+
+
+  hadrianPackages = nixpkgs.haskell.packages.ghc821.override {
+    overrides = self: super: let
+        localPackage = name: path: self.callCabal2nix name (filterSrc path) {};
+      in {
+        hadrian = localPackage "hadrian" ./. ;
+        shake = self.callHackage "shake" "0.16" {};
+        Cabal = localPackage "Cabal" ./../libraries/Cabal/Cabal ;
+        filepath = localPackage "filepath" ./../libraries/filepath ;
+        text = localPackage "text" ./../libraries/text  ;
+        hpc = localPackage"hpc" ./../libraries/hpc ;
+        parsec = localPackage "parsec" ./../libraries/parsec ;
+        HUnit = nixpkgs.haskell.lib.dontCheck (self.callHackage "HUnit" "1.3.1.2" {});
+        process = localPackage "process" ./../libraries/process ;
+        directory = localPackage "directory" ./../libraries/directory ;
+      }; };
+
+in
+
+  nixpkgs.stdenv.mkDerivation {
+    name = "ghc-dev";
+    buildInputs = [
+                    hadrianPackages.hadrian
+                    nixpkgs.haskell.compiler.ghc821
+                    haskellPackages.alex
+                    haskellPackages.happy
+                    nixpkgs.python3
+                    nixpkgs.git
+                    nixpkgs.autoconf
+                    nixpkgs.automake
+                    nixpkgs.perl
+                    nixpkgs.gcc
+                    nixpkgs.python3Packages.sphinx
+                    nixpkgs.ncurses
+                    nixpkgs.m4
+                    nixpkgs.gmp
+                    nixpkgs.file ];
+  }
diff --git a/src/Rules/Compile.hs b/src/Rules/Compile.hs
index a4b1278660..b7f3bc8447 100644
--- a/src/Rules/Compile.hs
+++ b/src/Rules/Compile.hs
@@ -22,8 +22,6 @@ compilePackage rs context@Context {..} = do
             path <- buildPath context
             (src, deps) <- lookupDependencies (path -/- ".dependencies") obj
             need $ src : deps
-            when (isLibrary package) $ need =<< return <$> pkgConfFile context
-            needLibrary =<< contextDependencies context
             buildWithResources rs $ target context (Ghc CompileHs stage) [src] [obj]
 
     priority 2.0 $ do
diff --git a/src/Rules/Dependencies.hs b/src/Rules/Dependencies.hs
index f27ef0d912..f9d17e93d8 100644
--- a/src/Rules/Dependencies.hs
+++ b/src/Rules/Dependencies.hs
@@ -19,11 +19,11 @@ buildPackageDependencies rs context@Context {..} =
         orderOnly =<< interpretInContext context generatedDependencies
         let mk = deps <.> "mk"
         if null srcs
-        then writeFileChanged mk ""
+        then writeFile' mk ""
         else buildWithResources rs $
             target context (Ghc FindHsDependencies stage) srcs [mk]
         removeFile $ mk <.> "bak"
-        mkDeps <- readFile' mk
+        mkDeps <- liftIO $ readFile mk
         writeFileChanged deps . unlines
                               . map (\(src, deps) -> unwords $ src : deps)
                               . map (bimap unifyPath (map unifyPath))
diff --git a/src/Rules/Program.hs b/src/Rules/Program.hs
index ba4dab0442..dca177f879 100644
--- a/src/Rules/Program.hs
+++ b/src/Rules/Program.hs
@@ -92,7 +92,6 @@ buildWrapper context@Context {..} wrapper wrapperPath wrapped = do
     putSuccess $ "| Successfully created wrapper for " ++
         quote (pkgName package) ++ " (" ++ show stage ++ ")."
 
--- TODO: Get rid of the Paths_hsc2hs.o hack.
 buildBinary :: [(Resource, Int)] -> FilePath -> Context -> Action ()
 buildBinary rs bin context@Context {..} = do
     binDeps <- if stage == Stage0 && package == ghcCabal
@@ -107,8 +106,6 @@ buildBinary rs bin context@Context {..} = do
             cObjs  <- mapM (objectPath context) cSrcs
             hsObjs <- hsObjects context
             return $ cObjs ++ hsObjs
-                  ++ [ path -/- "Paths_hsc2hs.o"  | package == hsc2hs  ]
-                  ++ [ path -/- "Paths_haddock.o" | package == haddock ]
     need binDeps
     buildWithResources rs $ target context (Ghc LinkHs stage) binDeps [bin]
     synopsis <- traverse pkgSynopsis (pkgCabalFile package)
diff --git a/src/Settings/Builders/Ghc.hs b/src/Settings/Builders/Ghc.hs
index a975e7e799..af78b74637 100644
--- a/src/Settings/Builders/Ghc.hs
+++ b/src/Settings/Builders/Ghc.hs
@@ -87,10 +87,10 @@ haddockGhcArgs = mconcat [ commonGhcArgs, getPkgDataList HsArgs ]
 -- Used in ghcBuilderArgs, ghcCBuilderArgs, ghcMBuilderArgs and haddockGhcArgs.
 commonGhcArgs :: Args
 commonGhcArgs = do
-    way     <- getWay
-    path    <- getBuildPath
-    pkg     <- getPackage
-    when (isLibrary pkg) $ do
+    way  <- getWay
+    path <- getBuildPath
+    pkg  <- getPackage
+    when (pkg == rts) $ do
         context <- getContext
         conf <- expr $ pkgConfFile context
         expr $ need [conf]
diff --git a/src/Settings/Packages/GhcCabal.hs b/src/Settings/Packages/GhcCabal.hs
index 0e915b3ea6..c88617b97f 100644
--- a/src/Settings/Packages/GhcCabal.hs
+++ b/src/Settings/Packages/GhcCabal.hs
@@ -8,10 +8,11 @@ import Utilities
 
 ghcCabalPackageArgs :: Args
 ghcCabalPackageArgs = stage0 ? package ghcCabal ? builder Ghc ? do
-    cabalDeps    <- expr $ stage1Dependencies cabal
+    cabalDeps <- expr $ stage1Dependencies cabal
+    let bootDeps = cabalDeps \\ [integerGmp, integerSimple, mtl, parsec, text]
     cabalVersion <- expr $ pkgVersion (unsafePkgCabalFile cabal) -- TODO: improve
     mconcat
-        [ pure [ "-package " ++ pkgName pkg | pkg <- cabalDeps \\ [parsec, mtl] ]
+        [ pure [ "-package " ++ pkgName pkg | pkg <- bootDeps ]
         , arg "--make"
         , arg "-j"
         , pure ["-Wall", "-fno-warn-unused-imports", "-fno-warn-warnings-deprecations"]
diff --git a/src/Utilities.hs b/src/Utilities.hs
index 3c61daecfd..fc898c35b9 100644
--- a/src/Utilities.hs
+++ b/src/Utilities.hs
@@ -24,21 +24,29 @@ buildWithResources rs target = H.buildWithResources rs target getArgs
 buildWithCmdOptions :: [CmdOption] -> Target -> Action ()
 buildWithCmdOptions opts target = H.buildWithCmdOptions opts target getArgs
 
--- | Given a 'Context' this 'Action' look up the package dependencies and wrap
+-- TODO: Cache the computation.
+-- | Given a 'Context' this 'Action' looks up the package dependencies and wraps
 -- the results in appropriate contexts. The only subtlety here is that we never
 -- depend on packages built in 'Stage2' or later, therefore the stage of the
 -- resulting dependencies is bounded from above at 'Stage1'. To compute package
--- dependencies we scan package @.cabal@ files, see 'pkgDependencies' defined
--- in "Hadrian.Haskell.Cabal".
+-- dependencies we transitively scan @.cabal@ files using 'pkgDependencies'
+-- defined in "Hadrian.Haskell.Cabal".
 contextDependencies :: Context -> Action [Context]
-contextDependencies Context {..} = case pkgCabalFile package of
-    Nothing        -> return [] -- Non-Cabal packages have no dependencies.
-    Just cabalFile -> do
-        let depStage   = min stage Stage1
-            depContext = \pkg -> Context depStage pkg way
-        deps <- pkgDependencies cabalFile
-        pkgs <- sort <$> stagePackages depStage
-        return . map depContext $ intersectOrd (compare . pkgName) pkgs deps
+contextDependencies Context {..} = do
+    depPkgs <- go [package]
+    return [ Context depStage pkg way | pkg <- depPkgs, pkg /= package ]
+  where
+    depStage = min stage Stage1
+    go pkgs  = do
+        deps <- concatMapM step pkgs
+        let newPkgs = nubOrd $ sort (deps ++ pkgs)
+        if pkgs == newPkgs then return pkgs else go newPkgs
+    step pkg   = case pkgCabalFile pkg of
+        Nothing        -> return [] -- Non-Cabal packages have no dependencies.
+        Just cabalFile -> do
+            deps   <- pkgDependencies cabalFile
+            active <- sort <$> stagePackages depStage
+            return $ intersectOrd (compare . pkgName) active deps
 
 -- | Lookup dependencies of a 'Package' in the vanilla Stage1 context.
 stage1Dependencies :: Package -> Action [Package]
diff --git a/stack.yaml b/stack.yaml
index a1b7413474..1d3f6e3b38 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -7,10 +7,9 @@ resolver: lts-9.0
 packages:
 - '.'
 - '../libraries/Cabal/Cabal'
-- '../libraries/filepath/'
-- '../libraries/text/'
-- '../libraries/hpc/'
-- '../libraries/parsec/'
+- '../libraries/hpc'
+- '../libraries/parsec'
+- '../libraries/text'
 
 extra-deps:
 - shake-0.16