Allow to run 'cabal update' automatically before the HLS build

app/ghcup/GHCup/OptParse/Compile.hs

@@ -85,6 +85,7 @@ data HLSCompileOptions = HLSCompileOptions
   { targetHLS    :: HLS.HLSVer
   , jobs         :: Maybe Int
   , setCompile   :: Bool
+  , updateCabal  :: Bool
   , ovewrwiteVer :: Either Bool Version
   , isolateDir   :: Maybe FilePath
   , cabalProject :: Maybe (Either FilePath URI)
@@ -152,8 +153,8 @@ Examples:
   These need to be available in PATH prior to compilation.
 
 Examples:
-  # compile 1.7.0.0 from hackage for 8.10.7
-  ghcup compile hls --hackage-version 1.7.0.0 --ghc 8.10.7
+  # compile 1.7.0.0 from hackage for 8.10.7, running 'cabal update' before the build
+  ghcup compile hls --hackage-version 1.7.0.0 --ghc 8.10.7 --cabal-update
   # compile 1.7.0.0 from official source dist for ghc 8.10.5 and 8.10.7, passing '--allow-newer' to cabal
   ghcup compile hls -v 1.7.0.0 -j 12 --ghc 8.10.5 --ghc 8.10.7 -- --allow-newer
   # compile from master for ghc 9.2.3 using 'git describe' to name the binary and ignore the pinned index state
@@ -335,6 +336,7 @@ hlsCompileOpts =
             )
           )
     <*> fmap (fromMaybe True) (invertableSwitch "set" Nothing True (help "Don't set as active version after install"))
+    <*> switch (long "cabal-update" <> help "Run 'cabal update' before the build")
     <*>
          (
           (Right <$> option
@@ -524,6 +526,7 @@ compile compileCommand settings Dirs{..} runAppState runLogger = do
                     (maybe GHCupInternal IsolateDir isolateDir)
                     cabalProject
                     cabalProjectLocal
+                    updateCabal
                     patches
                     cabalArgs
         GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo

lib/GHCup/HLS.hs

@@ -337,6 +337,7 @@ compileHLS :: ( MonadMask m
            -> InstallDir
            -> Maybe (Either FilePath URI)
            -> Maybe URI
+           -> Bool
            -> Maybe (Either FilePath [URI])  -- ^ patches
            -> [Text]                   -- ^ additional args to cabal install
            -> Excepts '[ NoDownload
@@ -349,11 +350,14 @@ compileHLS :: ( MonadMask m
                        , BuildFailed
                        , NotInstalled
                        ] m Version
-compileHLS targetHLS ghcs jobs ov installDir cabalProject cabalProjectLocal patches cabalArgs = do
+compileHLS targetHLS ghcs jobs ov installDir cabalProject cabalProjectLocal updateCabal patches cabalArgs = do
   PlatformRequest { .. } <- lift getPlatformReq
   GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
   Dirs { .. } <- lift getDirs
 
+  when updateCabal $ reThrowAll @_ @'[ProcessError] DownloadFailed $ do
+    lift $ logInfo "Updating cabal DB"
+    lEM $ exec "cabal" ["update"] (Just $ fromGHCupPath tmpDir) Nothing
 
   (workdir, tmpUnpack, tver, git_describe) <- case targetHLS of
     -- unpack from version tarball