More nix-local-build merging: solver and setup wrapper features

cabal-install/Distribution/Client/Configure.hs

@@ -182,6 +182,7 @@ configureSetupScript packageDBs
                      mpkg
   = SetupScriptOptions {
       useCabalVersion   = cabalVersion
+    , useCabalSpecVersion = Nothing
     , useCompiler       = Just comp
     , usePlatform       = Just platform
     , usePackageDB      = packageDBs'
@@ -201,6 +202,7 @@ configureSetupScript packageDBs
       -- Therefore, for now, we just leave this blank.
     , useDependencies          = fromMaybe [] explicitSetupDeps
     , useDependenciesExclusive = isJust explicitSetupDeps
+    , useVersionMacros         = isJust explicitSetupDeps
     }
   where
     -- When we are compiling a legacy setup script without an explicit

cabal-install/Distribution/Client/Dependency.hs

@@ -56,7 +56,8 @@ module Distribution.Client.Dependency (
     hideInstalledPackagesSpecificByUnitId,
     hideInstalledPackagesSpecificBySourcePackageId,
     hideInstalledPackagesAllVersions,
-    removeUpperBounds
+    removeUpperBounds,
+    addDefaultSetupDependencies,
   ) where
 
 import Distribution.Client.Dependency.TopDown
@@ -356,13 +357,14 @@ hideBrokenInstalledPackages params =
 
 -- | Remove upper bounds in dependencies using the policy specified by the
 -- 'AllowNewer' argument (all/some/none).
+--
+-- Note: It's important to apply 'removeUpperBounds' after
+-- 'addSourcePackages'. Otherwise, the packages inserted by
+-- 'addSourcePackages' won't have upper bounds in dependencies relaxed.
+--
 removeUpperBounds :: AllowNewer -> DepResolverParams -> DepResolverParams
 removeUpperBounds allowNewer params =
     params {
-      -- NB: It's important to apply 'removeUpperBounds' after
-      -- 'addSourcePackages'. Otherwise, the packages inserted by
-      -- 'addSourcePackages' won't have upper bounds in dependencies relaxed.
-
       depResolverSourcePkgIndex = sourcePkgIndex'
     }
   where
@@ -437,6 +439,39 @@ removeUpperBounds allowNewer params =
         onCondTree g = mapCondTree g (map f) id
 
 
+-- | Supply defaults for packages without explicit Setup dependencies
+--
+-- Note: It's important to apply 'addDefaultSetupDepends' after
+-- 'addSourcePackages'. Otherwise, the packages inserted by
+-- 'addSourcePackages' won't have upper bounds in dependencies relaxed.
+--
+addDefaultSetupDependencies :: (SourcePackage -> [Dependency])
+                            -> DepResolverParams -> DepResolverParams
+addDefaultSetupDependencies defaultSetupDeps params =
+    params {
+      depResolverSourcePkgIndex =
+        fmap applyDefaultSetupDeps (depResolverSourcePkgIndex params)
+    }
+  where
+    applyDefaultSetupDeps :: SourcePackage -> SourcePackage
+    applyDefaultSetupDeps srcpkg =
+        srcpkg {
+          packageDescription = gpkgdesc {
+            PD.packageDescription = pkgdesc {
+              PD.setupBuildInfo =
+                case PD.setupBuildInfo pkgdesc of
+                  Just sbi -> Just sbi
+                  Nothing  -> Just PD.SetupBuildInfo {
+                                PD.setupDepends = defaultSetupDeps srcpkg
+                              }
+            }
+          }
+        }
+      where
+        gpkgdesc = packageDescription srcpkg
+        pkgdesc  = PD.packageDescription gpkgdesc
+
+
 upgradeDependencies :: DepResolverParams -> DepResolverParams
 upgradeDependencies = setPreferenceDefault PreferAllLatest
 

cabal-install/Distribution/Client/Dependency/Modular/Preference.hs

@@ -324,9 +324,12 @@ deferWeakFlagChoices = trav go
     go (GoalChoiceF xs) = GoalChoiceF (P.sortBy defer xs)
     go x                = x
 
+    -- weak flags go very last, weak stanzas second last
     defer :: Tree a -> Tree a -> Ordering
     defer (FChoice _ _ True _ _) _ = GT
     defer _ (FChoice _ _ True _ _) = LT
+    defer (SChoice _ _ True _) _   = GT
+    defer _ (SChoice _ _ True _)   = LT
     defer _ _                      = EQ
 
 -- Transformation that sorts choice nodes so that

cabal-install/Distribution/Client/Freeze.hs

@@ -170,10 +170,8 @@ planPackages verbosity comp platform mSandboxPkgInfo freezeFlags
 
     logMsg message rest = debug verbosity message >> rest
 
-    stanzas = concat
-        [ if testsEnabled      then [TestStanzas]  else []
-        , if benchmarksEnabled then [BenchStanzas] else []
-        ]
+    stanzas = [ TestStanzas | testsEnabled ]
+           ++ [ BenchStanzas | benchmarksEnabled ]
     testsEnabled      = fromFlagOrDefault False $ freezeTests freezeFlags
     benchmarksEnabled = fromFlagOrDefault False $ freezeBenchmarks freezeFlags
 

cabal-install/Distribution/Client/Install.hs

@@ -402,11 +402,9 @@ planPackages comp platform mSandboxPkgInfo solver
       $ standardInstallPolicy
         installedPkgIndex sourcePkgDb pkgSpecifiers
 
-    stanzas = concat
-        [ if testsEnabled then [TestStanzas] else []
-        , if benchmarksEnabled then [BenchStanzas] else []
-        ]
-    testsEnabled = fromFlagOrDefault False $ configTests configFlags
+    stanzas           = [ TestStanzas | testsEnabled ]
+                     ++ [ BenchStanzas | benchmarksEnabled ]
+    testsEnabled      = fromFlagOrDefault False $ configTests configFlags
     benchmarksEnabled = fromFlagOrDefault False $ configBenchmarks configFlags
 
     reinstall        = fromFlag (installOverrideReinstall installFlags) ||

cabal-install/Distribution/Client/SetupWrapper.hs

@@ -120,8 +120,37 @@ import System.Directory    ( doesDirectoryExist )
 import qualified System.Win32 as Win32
 #endif
 
+--TODO: The 'setupWrapper' and 'SetupScriptOptions' should be split into two
+-- parts: one that has no policy and just does as it's told with all the
+-- explicit options, and an optional initial part that applies certain
+-- policies (like if we should add the Cabal lib as a dep, and if so which
+-- version). This could be structured as an action that returns a fully
+-- elaborated 'SetupScriptOptions' containing no remaining policy choices.
+--
+-- See also the discussion at https://github.com/haskell/cabal/pull/3094
+
 data SetupScriptOptions = SetupScriptOptions {
+    -- | The version of the Cabal library to use (if 'useDependenciesExclusive'
+    -- is not set). A suitable version of the Cabal library must be installed
+    -- (or for some build-types be the one cabal-install was built with).
+    --
+    -- The version found also determines the version of the Cabal specification
+    -- that we us for talking to the Setup.hs, unless overridden by
+    -- 'useCabalSpecVersion'.
+    --
     useCabalVersion          :: VersionRange,
+
+    -- | This is the version of the Cabal specification that we believe that
+    -- this package uses. This affects the semantics and in particular the
+    -- Setup command line interface.
+    --
+    -- This is similar to 'useCabalVersion' but instead of probing the system
+    -- for a version of the /Cabal library/ you just say exactly which version
+    -- of the /spec/ we will use. Using this also avoid adding the Cabal
+    -- library as an additional dependency, so add it to 'useDependencies'
+    -- if needed.
+    --
+    useCabalSpecVersion      :: Maybe Version,
     useCompiler              :: Maybe Compiler,
     usePlatform              :: Maybe Platform,
     usePackageDB             :: PackageDBStack,
@@ -137,14 +166,25 @@ data SetupScriptOptions = SetupScriptOptions {
 
     -- | Is the list of setup dependencies exclusive?
     --
-    -- This is here for legacy reasons. Before the introduction of the explicit
-    -- setup stanza in .cabal files we compiled Setup.hs scripts with all
-    -- packages in the environment visible, but we will needed to restrict
-    -- _some_ packages; in particular, we need to restrict the version of Cabal
-    -- that the setup script gets linked against (this was the only "dependency
-    -- constraint" that we had previously for Setup scripts).
+    -- When this is @False@, if we compile the Setup.hs script we do so with
+    -- the list in 'useDependencies' but all other packages in the environment
+    -- are also visible. Additionally, a suitable version of @Cabal@ library
+    -- is added to the list of dependencies (see 'useCabalVersion').
+    --
+    -- When @True@, only the 'useDependencies' packages are used, with other
+    -- packages in the environment hidden.
+    --
+    -- This feature is here to support the setup stanza in .cabal files that
+    -- specifies explicit (and exclusive) dependencies, as well as the old
+    -- style with no dependencies.
     useDependenciesExclusive :: Bool,
 
+    -- | Should we build the Setup.hs with CPP version macros available?
+    -- We turn this on when we have a setup stanza in .cabal that declares
+    -- explicit setup dependencies.
+    --
+    useVersionMacros         :: Bool,
+
     -- Used only by 'cabal clean' on Windows.
     --
     -- Note: win32 clean hack
@@ -174,12 +214,14 @@ data SetupScriptOptions = SetupScriptOptions {
 defaultSetupScriptOptions :: SetupScriptOptions
 defaultSetupScriptOptions = SetupScriptOptions {
     useCabalVersion          = anyVersion,
+    useCabalSpecVersion      = Nothing,
     useCompiler              = Nothing,
     usePlatform              = Nothing,
     usePackageDB             = [GlobalPackageDB, UserPackageDB],
     usePackageIndex          = Nothing,
     useDependencies          = [],
     useDependenciesExclusive = False,
+    useVersionMacros         = False,
     useProgramConfig         = emptyProgramConfiguration,
     useDistPref              = defaultDistPref,
     useLoggingHandle         = Nothing,
@@ -235,7 +277,9 @@ determineSetupMethod options buildType'
     -- between the self and internal setup methods, which are
     -- consistent with each other.
   | buildType' == Custom             = externalSetupMethod
-  | not (cabalVersion `withinRange`
+  | maybe False (cabalVersion /=)
+        (useCabalSpecVersion options)
+ || not (cabalVersion `withinRange`
          useCabalVersion options)    = externalSetupMethod
   | isJust (useLoggingHandle options)
     -- Forcing is done to use an external process e.g. due to parallel
@@ -338,18 +382,24 @@ externalSetupMethod verbosity options pkg bt mkargs = do
 
   cabalLibVersionToUse :: IO (Version, (Maybe UnitId)
                              ,SetupScriptOptions)
-  cabalLibVersionToUse = do
-    savedVer <- savedVersion
-    case savedVer of
-      Just version | version `withinRange` useCabalVersion options
-        -> do updateSetupScript version bt
-              -- Does the previously compiled setup executable still exist and
-              -- is it up-to date?
-              useExisting <- canUseExistingSetup version
-              if useExisting
-                then return (version, Nothing, options)
-                else installedVersion
-      _ -> installedVersion
+  cabalLibVersionToUse =
+    case useCabalSpecVersion options of
+      Just version -> do
+        updateSetupScript version bt
+        writeFile setupVersionFile (show version ++ "\n")
+        return (version, Nothing, options)
+      Nothing  -> do
+        savedVer <- savedVersion
+        case savedVer of
+          Just version | version `withinRange` useCabalVersion options
+            -> do updateSetupScript version bt
+                  -- Does the previously compiled setup executable still exist
+                  -- and is it up-to date?
+                  useExisting <- canUseExistingSetup version
+                  if useExisting
+                    then return (version, Nothing, options)
+                    else installedVersion
+          _ -> installedVersion
     where
       -- This check duplicates the checks in 'getCachedSetupExecutable' /
       -- 'compileSetupExecutable'. Unfortunately, we have to perform it twice
@@ -551,13 +601,19 @@ externalSetupMethod verbosity options pkg bt mkargs = do
           cabalDep = maybe [] (\ipkgid -> [(ipkgid, cabalPkgid)])
                               maybeCabalLibInstalledPkgId
 
-          -- We do a few things differently once packages opt-in and declare
-          -- a custom-settup stanza. In particular we then enforce the deps
-          -- specified, but also let the Setup.hs use the version macros.
-          newPedanticDeps     = useDependenciesExclusive options'
-          selectedDeps
-            | newPedanticDeps = useDependencies options'
-            | otherwise       = useDependencies options' ++ cabalDep
+          -- With 'useDependenciesExclusive' we enforce the deps specified,
+          -- so only the given ones can be used. Otherwise we allow the use
+          -- of packages in the ambient environment, and add on a dep on the
+          -- Cabal library.
+          --
+          -- With 'useVersionMacros' we use a version CPP macros .h file.
+          --
+          -- Both of these options should be enabled for packages that have
+          -- opted-in and declared a custom-settup stanza.
+          --
+          selectedDeps | useDependenciesExclusive options'
+                                   = useDependencies options'
+                       | otherwise = useDependencies options' ++ cabalDep
           addRenaming (ipid, pid) = (ipid, pid, defaultRenaming)
           cppMacrosFile = setupDir </> "setup_macros.h"
           ghcOptions = mempty {
@@ -570,15 +626,15 @@ externalSetupMethod verbosity options pkg bt mkargs = do
             , ghcOptSourcePathClear = Flag True
             , ghcOptSourcePath      = toNubListR [workingDir]
             , ghcOptPackageDBs      = usePackageDB options''
-            , ghcOptHideAllPackages = Flag newPedanticDeps
-            , ghcOptCabal           = Flag newPedanticDeps
+            , ghcOptHideAllPackages = Flag (useDependenciesExclusive options')
+            , ghcOptCabal           = Flag (useDependenciesExclusive options')
             , ghcOptPackages        = toNubListR $ map addRenaming selectedDeps
             , ghcOptCppIncludes     = toNubListR [ cppMacrosFile
-                                                 | newPedanticDeps ]
+                                                 | useVersionMacros options' ]
             , ghcOptExtra           = toNubListR extraOpts
             }
       let ghcCmdLine = renderGhcOptions compiler ghcOptions
-      when newPedanticDeps $
+      when (useVersionMacros options') $
         rewriteFile cppMacrosFile (generatePackageVersionMacros
                                      [ pid | (_ipid, pid) <- selectedDeps ])
       case useLoggingHandle options of