Add changelog and move utility function

cabal-install/src/Distribution/Client/CmdRun.hs

@@ -64,8 +64,10 @@ import Distribution.Types.UnitId
          ( UnitId )
 import Distribution.Client.ScriptUtils
          ( AcceptNoTargets(..), withContextAndSelectors, updateContextAndWriteProjectFile, TargetContext(..) )
+import Distribution.Client.Utils
+         ( occursOnlyOrBefore )
 
-import Data.List (elemIndex, group)
+import Data.List ( group )
 import qualified Data.Set as Set
 
 import GHC.Environment
@@ -473,10 +475,3 @@ renderRunProblem (TargetProblemNoExes targetSelector) =
  ++ " because "
  ++ plural (targetSelectorPluralPkgs targetSelector) "it does" "they do"
  ++ " not contain any executables."
-
--- True if x occurs before y
-occursOnlyOrBefore :: (Eq a) => [a] -> a -> a -> Bool
-occursOnlyOrBefore xs x y = case (elemIndex x xs, elemIndex y xs) of
-                       (Just i, Just j) -> i < j
-                       (Just _, _) -> True
-                       _ -> False

cabal-install/src/Distribution/Client/Utils.hs

@@ -29,6 +29,7 @@ module Distribution.Client.Utils
   , listFilesInside
   , safeRead
   , hasElem
+  , occursOnlyOrBefore
   ) where
 
 import Prelude ()
@@ -47,7 +48,7 @@ import System.FilePath
 import Control.Monad
          ( zipWithM_ )
 import Data.List
-         ( groupBy )
+         ( groupBy, elemIndex )
 import qualified Control.Exception as Exception
          ( finally )
 import qualified Control.Exception.Safe as Safe
@@ -488,3 +489,10 @@ safeRead s
 --   This is [Agda.Utils.List.hasElem](https://hackage.haskell.org/package/Agda-2.6.2.2/docs/Agda-Utils-List.html#v:hasElem).
 hasElem :: Ord a => [a] -> a -> Bool
 hasElem xs = (`Set.member` Set.fromList xs)
+
+-- True if x occurs before y
+occursOnlyOrBefore :: (Eq a) => [a] -> a -> a -> Bool
+occursOnlyOrBefore xs x y = case (elemIndex x xs, elemIndex y xs) of
+                       (Just i, Just j) -> i < j
+                       (Just _, _) -> True
+                       _ -> False

changelog.d/pr-8709

+synopsis: Add warning for running cabal run with +RTS flag
+packages: cabal-install
+prs: #8709
+
+description: {
+
+This adds a warning when 'cabal run +RTS' is run,
+as this passes the +RTS options to cabal instead of the program.
+More often, users want to use 'cabal run -- +RTS'
+
+}