Force Cabal >= 1.24 dep when there's no custom-setup stanza.

Fixes #3199.

Cabal/Distribution/PackageDescription.hs

@@ -111,7 +111,7 @@ module Distribution.PackageDescription (
 
 import Distribution.Compat.Binary
 import qualified Distribution.Compat.Semigroup as Semi ((<>))
-import Distribution.Compat.Semigroup as Semi (Monoid(..), Semigroup, gmempty, gmappend)
+import Distribution.Compat.Semigroup as Semi (Monoid(..), Semigroup, gmempty)
 import qualified Distribution.Compat.ReadP as Parse
 import Distribution.Compat.ReadP   ((<++))
 import Distribution.Package
@@ -308,18 +308,22 @@ instance Text BuildType where
 -- options authors can specify to just Haskell package dependencies.
 
 data SetupBuildInfo = SetupBuildInfo {
-        setupDepends :: [Dependency]
+        setupDepends        :: [Dependency],
+        defaultSetupDepends :: Bool
+        -- ^ Is this a default 'custom-setup' section added by the cabal-install
+        -- code (as opposed to user-provided)? See #3199.
     }
     deriving (Generic, Show, Eq, Read, Typeable, Data)
 
 instance Binary SetupBuildInfo
 
 instance Semi.Monoid SetupBuildInfo where
-  mempty = gmempty
+  mempty  = SetupBuildInfo [] False
   mappend = (Semi.<>)
 
 instance Semigroup SetupBuildInfo where
-  (<>) = gmappend
+  a <> b = SetupBuildInfo (setupDepends a Semi.<> setupDepends b)
+           (defaultSetupDepends a || defaultSetupDepends b)
 
 -- ---------------------------------------------------------------------------
 -- Module renaming

cabal-install/Distribution/Client/Configure.hs

@@ -184,18 +184,19 @@ configureSetupScript packageDBs
                      index
                      mpkg
   = SetupScriptOptions {
-      useCabalVersion   = cabalVersion
-    , useCabalSpecVersion = Nothing
-    , useCompiler       = Just comp
-    , usePlatform       = Just platform
-    , usePackageDB      = packageDBs'
-    , usePackageIndex   = index'
-    , useProgramConfig  = conf
-    , useDistPref       = distPref
-    , useLoggingHandle  = Nothing
-    , useWorkingDir     = Nothing
-    , setupCacheLock    = lock
-    , useWin32CleanHack = False
+      useCabalVersion          = cabalVersion
+    , noDefaultCabalDep        = defaultSetupDeps
+    , useCabalSpecVersion      = Nothing
+    , useCompiler              = Just comp
+    , usePlatform              = Just platform
+    , usePackageDB             = packageDBs'
+    , usePackageIndex          = index'
+    , useProgramConfig         = conf
+    , useDistPref              = distPref
+    , useLoggingHandle         = Nothing
+    , useWorkingDir            = Nothing
+    , setupCacheLock           = lock
+    , useWin32CleanHack        = False
     , forceExternalSetupMethod = forceExternal
       -- If we have explicit setup dependencies, list them; otherwise, we give
       -- the empty list of dependencies; ideally, we would fix the version of
@@ -204,8 +205,8 @@ configureSetupScript packageDBs
       -- know the version of Cabal at this point, but only find this there.
       -- Therefore, for now, we just leave this blank.
     , useDependencies          = fromMaybe [] explicitSetupDeps
-    , useDependenciesExclusive = isJust explicitSetupDeps
-    , useVersionMacros         = isJust explicitSetupDeps
+    , useDependenciesExclusive = not defaultSetupDeps && isJust explicitSetupDeps
+    , useVersionMacros         = not defaultSetupDeps && isJust explicitSetupDeps
     }
   where
     -- When we are compiling a legacy setup script without an explicit
@@ -223,13 +224,24 @@ configureSetupScript packageDBs
         -- but if the user is using an odd db stack, don't touch it
         _otherwise -> (packageDBs, Just index)
 
+    maybeSetupBuildInfo :: Maybe PkgDesc.SetupBuildInfo
+    maybeSetupBuildInfo = do
+      ReadyPackage (ConfiguredPackage (SourcePackage _ gpkg _ _) _ _ _) _
+                 <- mpkg
+      PkgDesc.setupBuildInfo (PkgDesc.packageDescription gpkg)
+
+    -- Was a default 'custom-setup' stanza added by 'cabal-install' itself? If
+    -- so, 'setup-depends' must not be exclusive. See #3199.
+    defaultSetupDeps :: Bool
+    defaultSetupDeps = maybe False PkgDesc.defaultSetupDepends
+                       maybeSetupBuildInfo
+
     explicitSetupDeps :: Maybe [(UnitId, PackageId)]
     explicitSetupDeps = do
-      ReadyPackage (ConfiguredPackage (SourcePackage _ gpkg _ _) _ _ _) deps
-                 <- mpkg
-      -- Check if there is an explicit setup stanza
-      _buildInfo <- PkgDesc.setupBuildInfo (PkgDesc.packageDescription gpkg)
+      -- Check if there is an explicit setup stanza.
+      _buildInfo <- maybeSetupBuildInfo
       -- Return the setup dependencies computed by the solver
+      ReadyPackage _ deps <- mpkg
       return [ ( Installed.installedUnitId deppkg
                , Installed.sourcePackageId    deppkg
                )

cabal-install/Distribution/Client/Dependency.hs

@@ -100,8 +100,8 @@ import Distribution.PackageDescription.Configuration
 import Distribution.Client.PackageUtils
          ( externalBuildDepends )
 import Distribution.Version
-         ( VersionRange, anyVersion, thisVersion, withinRange
-         , simplifyVersionRange )
+         ( VersionRange, Version(..), anyVersion, orLaterVersion, thisVersion
+         , withinRange, simplifyVersionRange )
 import Distribution.Compiler
          ( CompilerInfo(..) )
 import Distribution.System
@@ -122,7 +122,7 @@ import Distribution.Verbosity
 import Data.List
          ( foldl', sort, sortBy, nubBy, maximumBy, intercalate, nub )
 import Data.Function (on)
-import Data.Maybe (fromMaybe)
+import Data.Maybe  (fromMaybe)
 import qualified Data.Map as Map
 import qualified Data.Set as Set
 import Data.Set (Set)
@@ -409,7 +409,8 @@ addDefaultSetupDependencies defaultSetupDeps params =
                 -- NB: moving build-type check out kills performance.
                 case (PD.setupBuildInfo pkgdesc, bt) of
                   (Nothing, PD.Custom)  -> Just PD.SetupBuildInfo {
-                    PD.setupDepends = defaultSetupDeps srcpkg
+                    PD.setupDepends        = defaultSetupDeps srcpkg,
+                    PD.defaultSetupDepends = True
                     }
                   (maybeSBI, _)         -> maybeSBI
             }
@@ -451,6 +452,10 @@ standardInstallPolicy
   . hideInstalledPackagesSpecificBySourcePackageId
       [ packageId pkg | SpecificSourcePackage pkg <- pkgSpecifiers ]
 
+  . addDefaultSetupDependencies
+      (const [Dependency (PackageName "Cabal")
+              (orLaterVersion $ Version [1,24] [])])
+
   . addSourcePackages
       [ pkg  | SpecificSourcePackage pkg <- pkgSpecifiers ]
 

cabal-install/Distribution/Client/ProjectPlanning.hs

@@ -1754,6 +1754,7 @@ setupHsScriptOptions (ReadyPackage ElaboratedConfiguredPackage{..} deps)
       useDependencies          = [ (installedPackageId ipkg, packageId ipkg)
                                  | ipkg <- CD.setupDeps deps ],
       useDependenciesExclusive = True,
+      noDefaultCabalDep        = False,
       useVersionMacros         = pkgSetupScriptStyle == SetupCustomExplicitDeps,
       useProgramConfig         = pkgConfigCompilerProgs,
       useDistPref              = builddir,

cabal-install/Distribution/Client/SetupWrapper.hs

@@ -131,8 +131,9 @@ import qualified System.Win32 as Win32
 
 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).
+    -- or 'noDefaultCabalDep' 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
@@ -166,10 +167,11 @@ data SetupScriptOptions = SetupScriptOptions {
 
     -- | Is the list of setup dependencies exclusive?
     --
-    -- 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 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. Unless 'noDefaultCabalDep' is @True@, a suitable version of
+    -- @Cabal@ library is also added to the list of dependencies (see
+    -- 'useCabalVersion').
     --
     -- When @True@, only the 'useDependencies' packages are used, with other
     -- packages in the environment hidden.
@@ -179,6 +181,13 @@ data SetupScriptOptions = SetupScriptOptions {
     -- style with no dependencies.
     useDependenciesExclusive :: Bool,
 
+    -- | Don't add a default dependency on Cabal even if
+    -- 'useDependenciesExclusive' is @False@. Assume that it is provided via
+    -- 'useDependencies'. This is turned on (in conjunction with
+    -- useDependenciesExclusive = False) when a default setup dependencies
+    -- stanza is added by cabal-install itself. See #3199.
+    noDefaultCabalDep :: 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.
@@ -221,6 +230,7 @@ defaultSetupScriptOptions = SetupScriptOptions {
     usePackageIndex          = Nothing,
     useDependencies          = [],
     useDependenciesExclusive = False,
+    noDefaultCabalDep        = False,
     useVersionMacros         = False,
     useProgramConfig         = emptyProgramConfiguration,
     useDistPref              = defaultDistPref,
@@ -604,7 +614,7 @@ externalSetupMethod verbosity options pkg bt mkargs = do
           -- 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.
+          -- Cabal library (unless 'noDefaultCabalDep' is specified).
           --
           -- With 'useVersionMacros' we use a version CPP macros .h file.
           --
@@ -613,7 +623,9 @@ externalSetupMethod verbosity options pkg bt mkargs = do
           --
           selectedDeps | useDependenciesExclusive options'
                                    = useDependencies options'
-                       | otherwise = useDependencies options' ++ cabalDep
+                       | otherwise = useDependencies options' ++
+                                     if noDefaultCabalDep options'
+                                     then [] else cabalDep
           addRenaming (ipid, pid) = (ipid, pid, defaultRenaming)
           cppMacrosFile = setupDir </> "setup_macros.h"
           ghcOptions = mempty {

cabal-install/tests/UnitTests/Distribution/Client/Dependency/Modular/DSL.hs

@@ -168,7 +168,8 @@ exAvSrcPkg ex =
                  , C.benchmarks     = error "not yet configured: benchmarks"
                  , C.buildDepends   = error "not yet configured: buildDepends"
                  , C.setupBuildInfo = Just C.SetupBuildInfo {
-                       C.setupDepends = mkSetupDeps (CD.setupDeps (exAvDeps ex))
+                       C.setupDepends = mkSetupDeps (CD.setupDeps (exAvDeps ex)),
+                       C.defaultSetupDepends = False
                      }
                  }
              , C.genPackageFlags = nub $ concatMap extractFlags