Add future-proof aliases for new- commands

Cabal/doc/nix-local-build-overview.rst

@@ -8,7 +8,11 @@ names are only temporary until Nix-style local builds become the default.
 This is expected to happen soon. For those who do not wish to use the new
 functionality, the classic project style will not be removed immediately,
 but these legacy commands will require the usage of the ``v1-`` prefix as of
-Cabal 3.0 and will be removed in a future release.
+Cabal 3.0 and will be removed in a future release. For a future-proof
+way to use these commands in a script or tutorial that anticipates the
+possibility of another UI paradigm being devised in the future, there
+are also ``v2-`` prefixed versions that will reference the same functionality
+until such a point as it is completely removed from Cabal.
 
 Nix-style local builds combine the best of non-sandboxed and sandboxed Cabal:
 

cabal-install/Distribution/Client/CmdLegacy.hs

@@ -2,7 +2,7 @@
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE ViewPatterns #-}
-module Distribution.Client.CmdLegacy ( legacyCmd, legacyWrapperCmd ) where
+module Distribution.Client.CmdLegacy ( legacyCmd, legacyWrapperCmd, newCmd ) where
 
 import Prelude ()
 import Distribution.Client.Compat.Prelude
@@ -159,3 +159,15 @@ legacyCmd ui action = toLegacyCmd (regularCmd ui action)
 
 legacyWrapperCmd :: Monoid flags => CommandUI flags -> (flags -> Setup.Flag Verbosity) -> (flags -> Setup.Flag String) -> [CommandSpec (Client.GlobalFlags -> IO ())]
 legacyWrapperCmd ui verbosity' distPref = toLegacyCmd (wrapperCmd ui verbosity' distPref)
+
+newCmd :: CommandUI flags -> (flags -> [String] -> globals -> IO action) -> [CommandSpec (globals -> IO action)]
+newCmd origUi@CommandUI{..} action = [cmd v2Ui, cmd origUi]
+    where
+        cmd ui = CommandSpec ui (flip commandAddAction action) NormalCommand
+        v2Msg = T.unpack . T.replace "new-" "v2-" . T.pack
+        v2Ui = origUi 
+            { commandName = v2Msg commandName
+            , commandUsage = v2Msg . commandUsage
+            , commandDescription = (v2Msg .) <$> commandDescription
+            , commandNotes = (v2Msg .) <$> commandDescription
+            }

cabal-install/Distribution/Client/Setup.hs

@@ -203,6 +203,7 @@ globalCommand commands = CommandUI {
           , "new-install"
           , "new-clean"
           , "new-sdist"
+          -- v1 commands, stateful style
           , "v1-build"
           , "v1-configure"
           , "v1-repl"
@@ -221,6 +222,20 @@ globalCommand commands = CommandUI {
           , "v1-register"
           , "v1-reconfigure"
           , "v1-sandbox"
+          -- v2 commands, nix-style
+          , "v2-build"
+          , "v2-configure"
+          , "v2-repl"
+          , "v2-freeze"
+          , "v2-run"
+          , "v2-test"
+          , "v2-bench"
+          , "v2-haddock"
+          , "v2-exec"
+          , "v2-update"
+          , "v2-install"
+          , "v2-clean"
+          , "v2-sdist"
           ]
         maxlen    = maximum $ [length name | (name, _) <- cmdDescs]
         align str = str ++ replicate (maxlen - length str) ' '
@@ -294,6 +309,21 @@ globalCommand commands = CommandUI {
         , addCmd "new-clean"
         , addCmd "new-sdist"
         , par
+        , startGroup "new-style projects (forwards-compatible aliases)"
+        , addCmd "v2-build"
+        , addCmd "v2-configure"
+        , addCmd "v2-repl"
+        , addCmd "v2-run"
+        , addCmd "v2-test"
+        , addCmd "v2-bench"
+        , addCmd "v2-freeze"
+        , addCmd "v2-haddock"
+        , addCmd "v2-exec"
+        , addCmd "v2-update"
+        , addCmd "v2-install"
+        , addCmd "v2-clean"
+        , addCmd "v2-sdist"
+        , par
         , startGroup "legacy command aliases"
         , addCmd "v1-build"
         , addCmd "v1-configure"

cabal-install/changelog

@@ -1,9 +1,12 @@
 -*-change-log-*-
 
 2.4.0.0 (current development version)
-        * 'outdated' now accepts '--project-file FILE', which will look for bounds
-          from the new-style freeze file named FILE.freeze. This is only
-          available when `--new-freeze-file` has been passed.
+	* Add aliases for the "new-" commands that won't change when they
+	  lose their prefix or are eventually replaced by a third UI
+	  paradigm in the future. (#5429)
+	* 'outdated' now accepts '--project-file FILE', which will look for bounds
+	  from the new-style freeze file named FILE.freeze. This is only
+	  available when `--new-freeze-file` has been passed.
 	* 'new-repl' now accepts a '--build-depends' flag which accepts the
 	  same syntax as is used in .cabal files to add additional dependencies
 	  to the environment when developing in the REPL. It is now usable outside

cabal-install/main/Main.hs

@@ -303,21 +303,22 @@ mainWorker args = topHandler $
       , hiddenCmd  actAsSetupCommand actAsSetupAction
       , hiddenCmd  manpageCommand (manpageAction commandSpecs)
 
-      , regularCmd  CmdConfigure.configureCommand CmdConfigure.configureAction
-      , regularCmd  CmdUpdate.updateCommand       CmdUpdate.updateAction
-      , regularCmd  CmdBuild.buildCommand         CmdBuild.buildAction
-      , regularCmd  CmdRepl.replCommand           CmdRepl.replAction
-      , regularCmd  CmdFreeze.freezeCommand       CmdFreeze.freezeAction
-      , regularCmd  CmdHaddock.haddockCommand     CmdHaddock.haddockAction
-      , regularCmd  CmdInstall.installCommand     CmdInstall.installAction
-      , regularCmd  CmdRun.runCommand             CmdRun.runAction
-      , regularCmd  CmdTest.testCommand           CmdTest.testAction
-      , regularCmd  CmdBench.benchCommand         CmdBench.benchAction
-      , regularCmd  CmdExec.execCommand           CmdExec.execAction
-      , regularCmd  CmdClean.cleanCommand         CmdClean.cleanAction 
-      , regularCmd  CmdSdist.sdistCommand         CmdSdist.sdistAction
       ] ++ concat
-      [ legacyCmd configureExCommand configureAction
+      [ newCmd  CmdConfigure.configureCommand CmdConfigure.configureAction
+      , newCmd  CmdUpdate.updateCommand       CmdUpdate.updateAction
+      , newCmd  CmdBuild.buildCommand         CmdBuild.buildAction
+      , newCmd  CmdRepl.replCommand           CmdRepl.replAction
+      , newCmd  CmdFreeze.freezeCommand       CmdFreeze.freezeAction
+      , newCmd  CmdHaddock.haddockCommand     CmdHaddock.haddockAction
+      , newCmd  CmdInstall.installCommand     CmdInstall.installAction
+      , newCmd  CmdRun.runCommand             CmdRun.runAction
+      , newCmd  CmdTest.testCommand           CmdTest.testAction
+      , newCmd  CmdBench.benchCommand         CmdBench.benchAction
+      , newCmd  CmdExec.execCommand           CmdExec.execAction
+      , newCmd  CmdClean.cleanCommand         CmdClean.cleanAction 
+      , newCmd  CmdSdist.sdistCommand         CmdSdist.sdistAction
+
+      , legacyCmd configureExCommand configureAction
       , legacyCmd updateCommand updateAction
       , legacyCmd buildCommand buildAction
       , legacyCmd replCommand replAction