add entry for 3.0 to init script

cabal-install/Distribution/Client/Init.hs

@@ -194,6 +194,7 @@ displayCabalVersion v = case versionNumbers v of
   [2,0]  -> "2.0    (+ support for Backpack, internal sub-libs, '^>=' operator)"
   [2,2]  -> "2.2    (+ support for 'common', 'elif', redundant commas, SPDX)"
   [2,4]  -> "2.4    (+ support for '**' globbing)"
+  [3,0]  -> "3.0    (+ support for set-notation syntax for '==' and '^>=')"
   _      -> display v
 
 -- | Ask if a simple project with sensible defaults should be created.
@@ -221,12 +222,20 @@ getCabalVersion flags = do
   cabVer <-     return (flagToMaybe $ cabalVersion flags)
             ?>> maybePrompt flags (either (const defaultCabalVersion) id `fmap`
                                   promptList "Please choose version of the Cabal specification to use"
-                                  [mkVersion [1,10], mkVersion [2,0], mkVersion [2,2], mkVersion [2,4]]
+                                  versionList
                                   (Just defaultCabalVersion) displayCabalVersion False)
             ?>> return (Just defaultCabalVersion)
 
   return $  flags { cabalVersion = maybeToFlag cabVer }
 
+  where
+    versionList = fmap mkVersion
+      [ [1,10]
+      , [2,0]
+      , [2,2]
+      , [2,4]
+      , [3,0]
+      ]
 
 -- | Get the package name: use the package directory (supplied, or the current
 --   directory by default) as a guess. It looks at the SourcePackageDb to avoid

cabal-install/changelog

@@ -1,7 +1,7 @@
 -*-change-log-*-
 
 3.1.0.0 (current development version)
-	* TODO
+	* Add entry for cabal version 3.0 to `cabal init`
 
 3.0.0.0 Mikhail Glushenkov <[email protected]> August 2019
 	* Parse comma-separated lists for extra-prog-path, extra-lib-dirs, extra-framework-dirs,