Per-component new-build support (no Custom support yet).

A bit of a megapatch.  Here's what's in it:

* First, a few miscellaneous utility functions and reexports
  in Cabal.  I could have split these into a separate commit
  but I was too lazy to.

* Distribution.Client.Install got refactored:
  instead of using PackageFixedDeps, it uses PackageInstalled
  instead.  That's because the install plan was NOT using
  ComponentDeps in any nontrivial way. And it shouldn't.
  So use a more specific type-class.  I also removed the
  invariant checking and error reporting because it was
  being annoying (we check the invariants already in
  SolverInstallPlan).

* Look at Distribution.Client.ProjectPlanning.Types.
  This contains the primary type change: ElaboratedConfiguredPackage
  is now EITHER a monolithic ElaboratedPackage, or a per-component
  ElaboratedComponent (it should get renamed but I didn't do that
  in this patch.)  These are what we're going to store in our
  plans: if a package we're building has a Setup script which supports
  per-component builds, we'll explode it into a component.  Otherwise
  we'll keep it as a package.  We'll see codepaths for both
  throughout.

* OK, so the expansion happens in ProjectPlanning, mostly in
  'elaborateAndExpandSolverPackage'.  You should review the
  package hash computation code closely.  When we can separate
  components, we compute a hash for each INDEPENDENTLY.  This
  is good: we get more sharing.

* We need to adjust the target resolution and pruning code
  in ProjectOrchestration and ProjectPlanning.  I did a dumb
  but easy idea: if a user mentions 'packagename' in a
  target name, I spray the PackageTarget on every
  possibly relevant IPID in buildTargets', and then pare
  it down later.

* And of course there's code in ProjectBuilding to actual
  do a configure and then build.

Custom doesn't work yet because I need to give them their own
separate component, and teach Cabal how to build them specially.

Signed-off-by: Edward Z. Yang <[email protected]>

Cabal/Distribution/Package.hs

@@ -27,6 +27,7 @@ module Distribution.Package (
         UnitId(..),
         mkUnitId,
         mkLegacyUnitId,
+        unitIdComponentId,
         getHSLibraryName,
         InstalledPackageId, -- backwards compat
 
@@ -176,6 +177,10 @@ mkUnitId = SimpleUnitId . ComponentId
 mkLegacyUnitId :: PackageId -> UnitId
 mkLegacyUnitId = SimpleUnitId . ComponentId . display
 
+-- | Extract 'ComponentId' from 'UnitId'.
+unitIdComponentId :: UnitId -> ComponentId
+unitIdComponentId (SimpleUnitId cid) = cid
+
 -- ------------------------------------------------------------
 -- * Package source dependencies
 -- ------------------------------------------------------------

Cabal/Distribution/Simple/Configure.hs

@@ -35,6 +35,8 @@ module Distribution.Simple.Configure (configure,
                                       tryGetPersistBuildConfig,
                                       maybeGetPersistBuildConfig,
                                       findDistPref, findDistPrefOrDefault,
+                                      mkComponentsGraph,
+                                      getInternalPackages,
                                       computeComponentId,
                                       computeCompatPackageKey,
                                       computeCompatPackageName,

Cabal/Distribution/Types/PackageDescription.hs

@@ -43,6 +43,7 @@ module Distribution.Types.PackageDescription (
     updatePackageDescription,
     pkgComponents,
     pkgBuildableComponents,
+    enabledComponents,
     lookupComponent,
     getComponent,
   ) where
@@ -57,6 +58,7 @@ import Distribution.Types.Benchmark
 
 import Distribution.Types.Component
 import Distribution.Types.ComponentName
+import Distribution.Types.ComponentEnabledSpec
 import Distribution.Types.SetupBuildInfo
 import Distribution.Types.BuildInfo
 import Distribution.Types.BuildType
@@ -346,6 +348,13 @@ pkgComponents pkg =
 pkgBuildableComponents :: PackageDescription -> [Component]
 pkgBuildableComponents = filter componentBuildable . pkgComponents
 
+-- | A list of all components in the package that are enabled.
+--
+-- @since 2.0.0.0
+--
+enabledComponents :: PackageDescription -> ComponentEnabledSpec -> [Component]
+enabledComponents pkg enabled = filter (componentEnabled enabled) $ pkgBuildableComponents pkg
+
 lookupComponent :: PackageDescription -> ComponentName -> Maybe Component
 lookupComponent pkg CLibName = fmap CLib (library pkg)
 lookupComponent pkg (CSubLibName name) =

cabal-install/Distribution/Client/CmdBuild.hs

@@ -65,6 +65,7 @@ buildAction (configFlags, configExFlags, installFlags, haddockFlags)
     -- repl targets (as opposed to say repl or haddock targets).
     selectBuildTargets =
       selectTargets
+        verbosity
         BuildDefaultComponents
         BuildSpecificComponent
 

cabal-install/Distribution/Client/CmdFreeze.hs

@@ -7,13 +7,11 @@ module Distribution.Client.CmdFreeze (
   ) where
 
 import Distribution.Client.ProjectPlanning
-         ( ElaboratedInstallPlan, rebuildInstallPlan )
 import Distribution.Client.ProjectConfig
          ( ProjectConfig(..), ProjectConfigShared(..)
          , commandLineFlagsToProjectConfig, writeProjectLocalFreezeConfig
          , findProjectRoot )
 import Distribution.Client.ProjectPlanning.Types
-         ( ElaboratedConfiguredPackage(..) )
 import Distribution.Client.Targets
          ( UserConstraint(..) )
 import Distribution.Solver.Types.ConstraintSource
@@ -149,16 +147,18 @@ projectFreezeConstraints plan =
     flagAssignments =
       Map.fromList
         [ (pkgname, flags)
-        | InstallPlan.Configured pkg <- InstallPlan.toList plan
-        , let flags   = pkgFlagAssignment pkg
+        | InstallPlan.Configured pkg_or_comp <- InstallPlan.toList plan
+        , let pkg     = getElaboratedPackage pkg_or_comp
+              flags   = pkgFlagAssignment pkg
               pkgname = packageName pkg
         , not (null flags) ]
 
     localPackages :: Map PackageName ()
     localPackages =
       Map.fromList
         [ (packageName pkg, ())
-        | InstallPlan.Configured pkg <- InstallPlan.toList plan
+        | InstallPlan.Configured pkg_or_comp <- InstallPlan.toList plan
+        , let pkg = getElaboratedPackage pkg_or_comp
         , pkgLocalToProject pkg
         ]
 

cabal-install/Distribution/Client/CmdRepl.hs

@@ -69,6 +69,7 @@ replAction (configFlags, configExFlags, installFlags, haddockFlags)
     -- repl targets (as opposed to say build or haddock targets).
     selectReplTargets =
       selectTargets
+        verbosity
         ReplDefaultComponent
         ReplSpecificComponent
 

cabal-install/Distribution/Client/Install.hs

@@ -114,7 +114,6 @@ import           Distribution.Solver.Types.ConstraintSource
 import           Distribution.Solver.Types.LabeledPackageConstraint
 import           Distribution.Solver.Types.OptionalStanza
 import qualified Distribution.Solver.Types.PackageIndex as SourcePackageIndex
-import           Distribution.Solver.Types.PackageFixedDeps
 import           Distribution.Solver.Types.PkgConfigDb
                    ( PkgConfigDb, readPkgConfigDb )
 import           Distribution.Solver.Types.SourcePackage as SourcePackage
@@ -612,12 +611,12 @@ packageStatus installedPkgIndex cpkg =
     changes :: Installed.InstalledPackageInfo
             -> ReadyPackage
             -> [MergeResult PackageIdentifier PackageIdentifier]
-    changes pkg pkg' = filter changed $
+    changes pkg (ReadyPackage pkg') = filter changed $
       mergeBy (comparing packageName)
         -- deps of installed pkg
         (resolveInstalledIds $ Installed.depends pkg)
         -- deps of configured pkg
-        (resolveInstalledIds $ CD.nonSetupDeps (depends pkg'))
+        (resolveInstalledIds $ map confInstId (CD.nonSetupDeps (confPkgDeps pkg')))
 
     -- convert to source pkg ids via index
     resolveInstalledIds :: [UnitId] -> [PackageIdentifier]