Add hscTypecheckRenameWithDiagnostics, for HLS (#24996)

Use runHsc' in runHsc so that both functions can't fall out of sync

We're currently copying parts of GHC code to get structured warnings
in HLS, so that we can recreate `hscTypecheckRenameWithDiagnostics`
locally. Once we get this function into GHC we can drop the copied code
in future versions of HLS.

compiler/GHC/Driver/Env.hs

@@ -86,8 +86,8 @@ import qualified Data.Set as Set
 import GHC.Unit.Module.Graph
 
 runHsc :: HscEnv -> Hsc a -> IO a
-runHsc hsc_env (Hsc hsc) = do
-    (a, w) <- hsc hsc_env emptyMessages
+runHsc hsc_env hsc = do
+    (a, w) <- runHsc' hsc_env hsc
     let dflags = hsc_dflags hsc_env
     let !diag_opts = initDiagOpts dflags
         !print_config = initPrintConfig dflags

compiler/GHC/Driver/Main.hs

@@ -64,6 +64,7 @@ module GHC.Driver.Main
     , hscRecompStatus
     , hscParse
     , hscTypecheckRename
+    , hscTypecheckRenameWithDiagnostics
     , hscTypecheckAndGetWarnings
     , hscDesugar
     , makeSimpleDetails
@@ -642,7 +643,14 @@ extract_renamed_stuff mod_summary tc_result = do
 -- | Rename and typecheck a module, additionally returning the renamed syntax
 hscTypecheckRename :: HscEnv -> ModSummary -> HsParsedModule
                    -> IO (TcGblEnv, RenamedStuff)
-hscTypecheckRename hsc_env mod_summary rdr_module = runHsc hsc_env $
+hscTypecheckRename hsc_env mod_summary rdr_module =
+    fst <$> hscTypecheckRenameWithDiagnostics hsc_env mod_summary rdr_module
+
+-- | Rename and typecheck a module, additionally returning the renamed syntax
+-- and the diagnostics produced.
+hscTypecheckRenameWithDiagnostics :: HscEnv -> ModSummary -> HsParsedModule
+                                  -> IO ((TcGblEnv, RenamedStuff), Messages GhcMessage)
+hscTypecheckRenameWithDiagnostics hsc_env mod_summary rdr_module = runHsc' hsc_env $
     hsc_typecheck True mod_summary (Just rdr_module)
 
 -- | Do Typechecking without throwing SourceError exception with -Werror