wip: Thread HostHc into the proper places.

Author: angerman

cabal-install/src/Distribution/Client/ProjectConfig/Legacy.hs

@@ -704,9 +704,6 @@ convertLegacyAllPackageFlags
 convertLegacyAllPackageFlags globalFlags configFlags configExFlags installFlags projectFlags projectConfigMultiRepl =
   ProjectConfigShared{..}
   where
-    projectConfigHostHcFlavor = NoFlag
-    projectConfigHostHcPath = NoFlag
-    projectConfigHostHcPkg = NoFlag
     projectConfigPackageDBs = (fmap . fmap) (interpretPackageDB Nothing) projectConfigPackageDBs_
     projectConfigHookHashes = mempty -- :: Map FilePath HookAccept
     projectConfigDistDir = fmap getSymbolicPath projectConfigAbsoluteDistDir
@@ -744,6 +741,9 @@ convertLegacyAllPackageFlags globalFlags configFlags configExFlags installFlags
       , configAllowNewer = projectConfigAllowNewer
       , configWriteGhcEnvironmentFilesPolicy =
         projectConfigWriteGhcEnvironmentFilesPolicy
+      , configHostHcFlavor = projectConfigHostHcFlavor
+      , configHostHcPath = projectConfigHostHcPath
+      , configHostHcPkg = projectConfigHostHcPkg
       } = configExFlags
 
     InstallFlags

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

@@ -661,7 +661,7 @@ rebuildInstallPlan
                 toolchains <- phaseConfigureToolchain projectConfig
 
                 liftIO $ print ("build compiler", compilerId $ toolchainCompiler $ buildToolchain toolchains)
-                liftIO $ print ("host compiler", compilerId $ toolchainCompiler $ buildToolchain toolchains)
+                liftIO $ print ("host compiler", compilerId $ toolchainCompiler $ hostToolchain toolchains)
 
                 -- _ <- phaseConfigurePrograms projectConfig compilerEtc
                 (solverPlan, pkgConfigDB, totalIndexState, activeRepos) <-
@@ -3864,9 +3864,10 @@ setupHsScriptOptions
             --   - if we commit to a Cabal version, the logic in
               Nothing
             else Just elabSetupScriptCliVersion
-      , useCompiler = Just (toolchainCompiler $ buildToolchain $ pkgConfigToolchains)
-      , usePlatform = Just (toolchainPlatform $ buildToolchain $ pkgConfigToolchains)
-      , useProgramDb = toolchainProgramDb $ buildToolchain $ pkgConfigToolchains
+      , -- for Setup.hs, we _always_ want to use the HOST toolchain.
+        useCompiler = Just (toolchainCompiler $ hostToolchain $ pkgConfigToolchains)
+      , usePlatform = Just (toolchainPlatform $ hostToolchain $ pkgConfigToolchains)
+      , useProgramDb = toolchainProgramDb $ hostToolchain $ pkgConfigToolchains
       , usePackageDB = elabSetupPackageDBStack
       , usePackageIndex = Nothing
       , useDependencies =