Add new 'user-config' subcommand 'init'.

'cabal user-config init' creates a default config file if it doesn't already
exist.

If '--config-file' is set, then that file will be written.

If '-f' or '--force' is used, then the file will be overwritten if it already
exists.

cabal-install/Distribution/Client/Config.hs

@@ -37,7 +37,8 @@ module Distribution.Client.Config (
     withProgramsFields,
     withProgramOptionsFields,
     userConfigDiff,
-    userConfigUpdate
+    userConfigUpdate,
+    createDefaultConfigFile
   ) where
 
 import Distribution.Client.Types
@@ -526,11 +527,8 @@ loadConfig verbosity configFileFlag = addBaseConf $ do
     Nothing -> do
       notice verbosity $ "Config file path source is " ++ sourceMsg source ++ "."
       notice verbosity $ "Config file " ++ configFile ++ " not found."
-      notice verbosity $ "Writing default configuration to " ++ configFile
-      commentConf <- commentSavedConfig
-      initialConf <- initialSavedConfig
-      writeConfigFile configFile commentConf initialConf
-      return initialConf
+      createDefaultConfigFile verbosity configFile
+      loadConfig verbosity configFileFlag
     Just (ParseOk ws conf) -> do
       unless (null ws) $ warn verbosity $
         unlines (map (showPWarning configFile) ws)
@@ -579,6 +577,13 @@ readConfigFile initial file = handleNotExists $
         then return Nothing
         else ioError ioe
 
+createDefaultConfigFile :: Verbosity -> FilePath -> IO ()
+createDefaultConfigFile verbosity filePath = do
+  commentConf <- commentSavedConfig
+  initialConf <- initialSavedConfig
+  notice verbosity $ "Writing default configuration to " ++ filePath
+  writeConfigFile filePath commentConf initialConf
+
 writeConfigFile :: FilePath -> SavedConfig -> SavedConfig -> IO ()
 writeConfigFile file comments vals = do
   let tmpFile = file <.> "tmp"

cabal-install/Distribution/Client/Setup.hs

@@ -2112,15 +2112,18 @@ instance Monoid ExecFlags where
 -- ------------------------------------------------------------
 
 data UserConfigFlags = UserConfigFlags {
-  userConfigVerbosity :: Flag Verbosity
+  userConfigVerbosity :: Flag Verbosity,
+  userConfigForce     :: Flag Bool
 }
 
 instance Monoid UserConfigFlags where
   mempty = UserConfigFlags {
-    userConfigVerbosity = toFlag normal
+    userConfigVerbosity = toFlag normal,
+    userConfigForce     = toFlag False
     }
   mappend a b = UserConfigFlags {
-    userConfigVerbosity = combine userConfigVerbosity
+    userConfigVerbosity = combine userConfigVerbosity,
+    userConfigForce     = combine userConfigForce
     }
     where combine field = field a `mappend` field b
 
@@ -2135,6 +2138,9 @@ userConfigCommand = CommandUI {
     ++ " (i.e. all bindings that are actually defined and not commented out)"
     ++ " and the default config of the new version.\n"
     ++ "\n"
+    ++ "init: Creates a new config file at either ~/.cabal/config or as"
+    ++ " specified by --config-file, if given. An existing file won't be "
+    ++ " overwritten unless -f or --force is given.\n"
     ++ "diff: Shows a pseudo-diff of the user's ~/.cabal/config file and"
     ++ " the default configuration that would be created by cabal if the"
     ++ " config file did not exist.\n"
@@ -2142,10 +2148,14 @@ userConfigCommand = CommandUI {
     ++ " created by default, and write the result back to ~/.cabal/config.",
 
   commandNotes        = Nothing,
-  commandUsage        = usageAlternatives "user-config" ["diff", "update"],
+  commandUsage        = usageAlternatives "user-config" ["init", "diff", "update"],
   commandDefaultFlags = mempty,
   commandOptions      = \ _ -> [
    optionVerbosity userConfigVerbosity (\v flags -> flags { userConfigVerbosity = v })
+ , option ['f'] ["force"]
+     "Overwrite the config file if it already exists."
+     userConfigForce (\v flags -> flags { userConfigForce = v })
+     trueArg
    ]
   }
 

cabal-install/Main.hs

@@ -60,7 +60,7 @@ import Distribution.Client.SetupWrapper
          ( setupWrapper, SetupScriptOptions(..), defaultSetupScriptOptions )
 import Distribution.Client.Config
          ( SavedConfig(..), loadConfig, defaultConfigFile, userConfigDiff
-         , userConfigUpdate )
+         , userConfigUpdate, createDefaultConfigFile )
 import Distribution.Client.Targets
          ( readUserTargets )
 import qualified Distribution.Client.List as List
@@ -1224,13 +1224,22 @@ execAction execFlags extraArgs globalFlags = do
 userConfigAction :: UserConfigFlags -> [String] -> Action
 userConfigAction ucflags extraArgs globalFlags = do
   let verbosity = fromFlag (userConfigVerbosity ucflags)
+      force     = fromFlag (userConfigForce ucflags)
   case extraArgs of
+    ("init":_) -> do
+      path       <- configFile
+      fileExists <- doesFileExist path
+      if (not fileExists || (fileExists && force))
+      then createDefaultConfigFile verbosity path
+      else die $ path ++ " already exists."
     ("diff":_) -> mapM_ putStrLn =<< userConfigDiff globalFlags
     ("update":_) -> userConfigUpdate verbosity globalFlags
     -- Error handling.
     [] -> die $ "Please specify a subcommand (see 'help user-config')"
     _  -> die $ "Unknown 'user-config' subcommand: " ++ unwords extraArgs
-
+  where configFile = do
+          defaultFile <- defaultConfigFile
+          return $ fromFlagOrDefault defaultFile (globalConfigFile globalFlags)
 
 -- | See 'Distribution.Client.Install.withWin32SelfUpgrade' for details.
 --

cabal-install/changelog

@@ -37,6 +37,9 @@
 	* Support for secure repos using hackage-security (#2983).
 	* Added a log file message similar to one printed by 'make' when
 	building in another directory (#2642).
+	* Added new subcommand 'init' to 'cabal user-config'. This
+	subcommand creates a cabal configuration file in either the
+	default location or as specified by --config-file (#2553).
 
 1.22.0.0 Johan Tibell <johan.tibell@gmail.com> January 2015
 	* New command: user-config (#2159).

cabal-install/tests/IntegrationTests/user-config/common.sh

+# Helper to run Cabal
+cabal() {
+    $CABAL $CABAL_ARGS "$@"
+}
+
+die() {
+    echo "die: $@"
+    exit 1
+}

cabal-install/tests/IntegrationTests/user-config/should_fail/doesnt_overwrite_without_f.err

+cabal: ./cabal-config already exists.

cabal-install/tests/IntegrationTests/user-config/should_fail/doesnt_overwrite_without_f.sh

+. ../common.sh
+
+rm -f ./cabal-config
+cabal --config-file=./cabal-config user-config init > /dev/null
+cabal --config-file=./cabal-config user-config init
+rm -f ./cabal-config

cabal-install/tests/IntegrationTests/user-config/should_run/cabal-config

+-- This is the configuration file for the 'cabal' command line tool.
+
+-- The available configuration options are listed below.
+-- Some of them have default values listed.
+
+-- Lines (like this one) beginning with '--' are comments.
+-- Be careful with spaces and indentation because they are
+-- used to indicate layout for nested sections.
+
+-- Cabal library version: 1.23.1.0
+-- cabal-install version: 1.23.0.0
+
+
+repository hackage.haskell.org
+  url: http://hackage.haskell.org/
+
+-- default-user-config:
+-- require-sandbox: False
+-- ignore-sandbox: False
+-- ignore-expiry: False
+-- http-transport:
+remote-repo-cache: /home/gman/.cabal/packages
+-- local-repo:
+-- logs-dir:
+world-file: /home/gman/.cabal/world
+-- verbose: 1
+-- compiler: ghc
+-- with-compiler:
+-- with-hc-pkg:
+-- program-prefix: 
+-- program-suffix: 
+-- library-vanilla: True
+-- library-profiling:
+-- shared:
+-- executable-dynamic: False
+-- profiling:
+-- executable-profiling:
+-- profiling-detail:
+-- library-profiling-detail:
+-- optimization: True
+-- debug-info: False
+-- library-for-ghci:
+-- split-objs: False
+-- executable-stripping: True
+-- library-stripping: True
+-- configure-option:
+-- user-install: True
+-- package-db:
+-- flags:
+-- extra-include-dirs:
+-- extra-lib-dirs:
+extra-prog-path: /home/gman/.cabal/bin
+-- tests: False
+-- coverage: False
+-- library-coverage:
+-- exact-configuration: False
+-- benchmarks: False
+-- relocatable: False
+-- cabal-lib-version:
+-- constraint:
+-- preference:
+-- solver: choose
+-- allow-newer: False
+-- documentation: False
+-- doc-index-file: $datadir/doc/$arch-$os-$compiler/index.html
+-- max-backjumps: 2000
+-- reorder-goals: False
+-- shadow-installed-packages: False
+-- strong-flags: False
+-- reinstall: False
+-- avoid-reinstalls: False
+-- force-reinstalls: False
+-- upgrade-dependencies: False
+-- root-cmd:
+-- symlink-bindir:
+build-summary: /home/gman/.cabal/logs/build.log
+-- build-log:
+remote-build-reporting: anonymous
+-- report-planning-failure: False
+-- one-shot: False
+-- run-tests:
+jobs: $ncpus
+-- offline: False
+-- username:
+-- password:
+-- password-command:
+-- builddir:
+
+haddock
+  -- keep-temp-files: False
+  -- hoogle: False
+  -- html: False
+  -- html-location:
+  -- for-hackage: False
+  -- executables: False
+  -- tests: False
+  -- benchmarks: False
+  -- all:
+  -- internal: False
+  -- css:
+  -- hyperlink-source: False
+  -- hscolour-css:
+  -- contents-location:
+
+install-dirs user
+  -- prefix: /home/gman/.cabal
+  -- bindir: $prefix/bin
+  -- libdir: $prefix/lib
+  -- libsubdir: $abi/$libname
+  -- libexecdir: $prefix/libexec
+  -- datadir: $prefix/share
+  -- datasubdir: $abi/$pkgid
+  -- docdir: $datadir/doc/$abi/$pkgid
+  -- htmldir: $docdir/html
+  -- haddockdir: $htmldir
+  -- sysconfdir: $prefix/etc
+
+install-dirs global
+  -- prefix: /usr/local
+  -- bindir: $prefix/bin
+  -- libdir: $prefix/lib
+  -- libsubdir: $abi/$libname
+  -- libexecdir: $prefix/libexec
+  -- datadir: $prefix/share
+  -- datasubdir: $abi/$pkgid
+  -- docdir: $datadir/doc/$abi/$pkgid
+  -- htmldir: $docdir/html
+  -- haddockdir: $htmldir
+  -- sysconfdir: $prefix/etc
+
+program-locations
+  -- alex-location:
+  -- ar-location:
+  -- c2hs-location:
+  -- cpphs-location:
+  -- gcc-location:
+  -- ghc-location:
+  -- ghc-pkg-location:
+  -- ghcjs-location:
+  -- ghcjs-pkg-location:
+  -- greencard-location:
+  -- haddock-location:
+  -- happy-location:
+  -- haskell-suite-location:
+  -- haskell-suite-pkg-location:
+  -- hmake-location:
+  -- hpc-location:
+  -- hsc2hs-location:
+  -- hscolour-location:
+  -- jhc-location:
+  -- ld-location:
+  -- lhc-location:
+  -- lhc-pkg-location:
+  -- pkg-config-location:
+  -- strip-location:
+  -- tar-location:
+  -- uhc-location:
+
+program-default-options
+  -- alex-options:
+  -- ar-options:
+  -- c2hs-options:
+  -- cpphs-options:
+  -- gcc-options:
+  -- ghc-options:
+  -- ghc-pkg-options:
+  -- ghcjs-options:
+  -- ghcjs-pkg-options:
+  -- greencard-options:
+  -- haddock-options:
+  -- happy-options:
+  -- haskell-suite-options:
+  -- haskell-suite-pkg-options:
+  -- hmake-options:
+  -- hpc-options:
+  -- hsc2hs-options:
+  -- hscolour-options:
+  -- jhc-options:
+  -- ld-options:
+  -- lhc-options:
+  -- lhc-pkg-options:
+  -- pkg-config-options:
+  -- strip-options:
+  -- tar-options:
+  -- uhc-options:

cabal-install/tests/IntegrationTests/user-config/should_run/overwrites_with_f.out

+Writing default configuration to ./cabal-config
+Writing default configuration to ./cabal-config

cabal-install/tests/IntegrationTests/user-config/should_run/overwrites_with_f.sh

+. ../common.sh
+
+rm -f ./cabal-config
+cabal --config-file=./cabal-config user-config init \
+    || die "Couldn't create config file"
+cabal --config-file=./cabal-config user-config -f init \
+    || die "Couldn't create config file"
+test -e ./cabal-config || die "Config file doesn't exist"
+rm -f ./cabal-config

cabal-install/tests/IntegrationTests/user-config/should_run/runs_without_error.out

+Writing default configuration to ./cabal-config

cabal-install/tests/IntegrationTests/user-config/should_run/runs_without_error.sh

+. ../common.sh
+
+rm -f ./cabal-config
+cabal --config-file=./cabal-config user-config init \
+    || die "Couldn't create config file"
+test -e ./cabal-config || die "Config file doesn't exist"
+rm -f ./cabal-config

cabal-install/tests/UnitTests/Distribution/Client/UserConfig.hs

@@ -9,7 +9,8 @@ import Data.List (sort, nub)
 #if !MIN_VERSION_base(4,8,0)
 import Data.Monoid
 #endif
-import System.Directory (getCurrentDirectory)
+import System.Directory (doesFileExist,
+                         getCurrentDirectory, getTemporaryDirectory)
 import System.FilePath ((</>))
 
 import Test.Tasty
@@ -20,6 +21,7 @@ import Distribution.Utils.NubList (fromNubList)
 import Distribution.Client.Setup (GlobalFlags (..), InstallFlags (..))
 import Distribution.Client.Utils (removeExistingFile)
 import Distribution.Simple.Setup (Flag (..), ConfigFlags (..), fromFlag)
+import Distribution.Simple.Utils (withTempDirectory)
 import Distribution.Verbosity (silent)
 
 tests :: [TestTree]
@@ -27,6 +29,7 @@ tests = [ testCase "nullDiffOnCreate" nullDiffOnCreateTest
         , testCase "canDetectDifference" canDetectDifference
         , testCase "canUpdateConfig" canUpdateConfig
         , testCase "doubleUpdateConfig" doubleUpdateConfig
+        , testCase "newDefaultConfig" newDefaultConfig
         ]
 
 nullDiffOnCreateTest :: Assertion
@@ -77,6 +80,16 @@ doubleUpdateConfig = bracketTest $ \configFile -> do
         listUnique (map show . fromNubList . installSummaryFile $ savedInstallFlags updated)
 
 
+newDefaultConfig :: Assertion
+newDefaultConfig = do
+    sysTmpDir <- getTemporaryDirectory
+    withTempDirectory silent sysTmpDir "cabal-test" $ \tmpDir -> do
+        let configFile  = tmpDir </> "tmp.config"
+        createDefaultConfigFile silent configFile
+        exists <- doesFileExist configFile
+        assertBool ("Config file should be written to " ++ configFile) exists
+
+
 globalFlags :: FilePath -> GlobalFlags
 globalFlags configFile = mempty { globalConfigFile = Flag configFile }