Properly assign component ID/build dir for LibV09 test libraries

When building a LibV09 test library, Cabal previously dumped
it into the same directory as the library proper.  This means
that if there are any module name conflicts, they'd override
each other. Bad!

The way to fix this is to build test libraries in different
directories.  We need to teach Cabal that not all libraries
are the main library.  This patch is a minimal patch to make
this work for GHC; doubtless refactoring can make this
generalize to all other backends (and make it hard to get
wrong.)

This follows the reserved namespace as per haskell#3017.

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

Author: ezyang

Cabal/Distribution/Simple/Build.hs

@@ -35,15 +35,14 @@ import qualified Distribution.Simple.Build.PathsModule as Build.PathsModule
 
 import Distribution.Package
          ( Package(..), PackageName(..), PackageIdentifier(..)
-         , Dependency(..), thisPackageVersion, packageName
-         , ComponentId(..), ComponentId(..) )
+         , Dependency(..), thisPackageVersion )
 import Distribution.Simple.Compiler
          ( Compiler, CompilerFlavor(..), compilerFlavor
          , PackageDB(..), PackageDBStack )
 import Distribution.PackageDescription
          ( PackageDescription(..), BuildInfo(..), Library(..), Executable(..)
          , TestSuite(..), TestSuiteInterface(..), Benchmark(..)
-         , BenchmarkInterface(..), allBuildInfo, defaultRenaming )
+         , BenchmarkInterface(..), allBuildInfo )
 import qualified Distribution.InstalledPackageInfo as IPI
 import qualified Distribution.ModuleName as ModuleName
 import Distribution.ModuleName (ModuleName)
@@ -55,7 +54,7 @@ import Distribution.Simple.BuildTarget
 import Distribution.Simple.PreProcess
          ( preprocessComponent, preprocessExtras, PPSuffixHandler )
 import Distribution.Simple.LocalBuildInfo
-         ( LocalBuildInfo(compiler, buildDir, withPackageDB, withPrograms)
+         ( LocalBuildInfo(compiler, buildDir, withPackageDB, withPrograms, flagAssignment)
          , Component(..), componentName, getComponent, componentBuildInfo
          , ComponentLocalBuildInfo(..), pkgEnabledComponents
          , withComponentsInBuildOrder, componentsInBuildOrder
@@ -65,6 +64,7 @@ import Distribution.Simple.Program.Types
 import Distribution.Simple.Program.Db
 import Distribution.Simple.BuildPaths
          ( autogenModulesDir, autogenModuleName, cppHeaderName, exeExtension )
+import Distribution.Simple.Configure (computeComponentId, computeCompatPackageKey)
 import Distribution.Simple.Register
          ( registerPackage, inplaceInstalledPackageInfo
          , doesPackageDBExist, deletePackageDB, createPackageDB )
@@ -249,7 +249,10 @@ buildComponent verbosity numJobs pkg_descr lbi0 suffixes
     extras <- preprocessExtras comp lbi
     info verbosity $ "Building test suite " ++ testName test ++ "..."
     buildLib verbosity numJobs pkg lbi lib libClbi
-    registerPackage verbosity (compiler lbi) (withPrograms lbi) False
+    -- NB: need to enable multiple instances here, because on 7.10+
+    -- the package name is the same as the library, and we still
+    -- want the registration to go through.
+    registerPackage verbosity (compiler lbi) (withPrograms lbi) True
                     (withPackageDB lbi) ipi
     let ebi = buildInfo exe
         exe' = exe { buildInfo = addExtraCSources ebi extras }
@@ -401,17 +404,22 @@ testSuiteLibV09AsLibAndExe pkg_descr
             libExposed     = True,
             libBuildInfo   = bi
           }
+    cid = computeComponentId (package pkg_descr)
+                             (CTestName (testName test))
+                             (map fst (componentPackageDeps clbi))
+                             (flagAssignment lbi)
+    (pkg_name, compat_key) = computeCompatPackageKey
+                                (compiler lbi) (package pkg_descr)
+                                (CTestName (testName test)) cid
     libClbi = LibComponentLocalBuildInfo
                 { componentPackageDeps = componentPackageDeps clbi
                 , componentPackageRenaming = componentPackageRenaming clbi
-                , componentId = ComponentId $ display (packageId pkg)
-                , componentCompatPackageKey = ComponentId $ display (packageId pkg)
+                , componentId = cid
+                , componentCompatPackageKey = compat_key
                 , componentExposedModules = [IPI.ExposedModule m Nothing Nothing]
                 }
     pkg = pkg_descr {
-            package      = (package pkg_descr) {
-                             pkgName = PackageName (testName test)
-                           }
+            package      = (package pkg_descr) { pkgName = pkg_name }
           , buildDepends = targetBuildDepends $ testBuildInfo test
           , executables  = []
           , testSuites   = []
@@ -439,9 +447,7 @@ testSuiteLibV09AsLibAndExe pkg_descr
                   : (filter (\(_, x) -> let PackageName name = pkgName x
                                         in name == "Cabal" || name == "base")
                             (componentPackageDeps clbi)),
-                componentPackageRenaming =
-                    Map.insert (packageName ipi) defaultRenaming
-                               (componentPackageRenaming clbi)
+                componentPackageRenaming = Map.empty
               }
 testSuiteLibV09AsLibAndExe _ TestSuite{} _ _ _ _ = error "testSuiteLibV09AsLibAndExe: wrong kind"