Add HomeUnit type

Since Backpack the "home unit" is much more involved than what it was
before (just an identifier obtained with `-this-unit-id`). Now it is
used in conjunction with `-component-id` and `-instantiated-with` to
configure module instantiations and to detect if we are type-checking an
indefinite unit or compiling a definite one.

This patch introduces a new HomeUnit datatype which is much easier to
understand. Moreover to make GHC support several packages in the same
instances, we will need to handle several HomeUnits so having a
dedicated (documented) type is helpful.

Finally in #14335 we will also need to handle the case where we have no
HomeUnit at all because we are only loading existing interfaces for
plugins which live in a different space compared to units used to
produce target code. Several functions will have to be refactored to
accept "Maybe HomeUnit" parameters instead of implicitly querying the
HomeUnit fields in DynFlags. Having a dedicated type will make this
easier.

Bump haddock submodule

1 files changed, 6 insertions, 7 deletions

diff --git a/compiler/GHC/Tc/Module.hs b/compiler/GHC/Tc/Module.hs
index d642a15147..8231955063 100644
--- a/compiler/GHC/Tc/Module.hs
+++ b/compiler/GHC/Tc/Module.hs
@@ -110,7 +110,7 @@ import GHC.Utils.Error
 import GHC.Types.Id as Id
 import GHC.Types.Id.Info( IdDetails(..) )
 import GHC.Types.Var.Env
-import GHC.Unit.Module
+import GHC.Unit
 import GHC.Types.Unique.FM
 import GHC.Types.Name
 import GHC.Types.Name.Env
@@ -181,15 +181,14 @@ tcRnModule hsc_env mod_sum save_rn_syntax
   where
     hsc_src = ms_hsc_src mod_sum
     dflags = hsc_dflags hsc_env
-    err_msg = mkPlainErrMsg (hsc_dflags hsc_env) loc $
+    home_unit = mkHomeUnitFromFlags dflags
+    err_msg = mkPlainErrMsg dflags loc $
               text "Module does not have a RealSrcSpan:" <+> ppr this_mod
 
-    this_pkg = homeUnit (hsc_dflags hsc_env)
-
     pair :: (Module, SrcSpan)
     pair@(this_mod,_)
       | Just (L mod_loc mod) <- hsmodName this_module
-      = (mkModule this_pkg mod, mod_loc)
+      = (mkHomeModule home_unit mod, mod_loc)
 
       | otherwise   -- 'module M where' is omitted
       = (mAIN, srcLocSpan (srcSpanStart loc))
@@ -2839,12 +2838,12 @@ loadUnqualIfaces hsc_env ictxt
   = initIfaceTcRn $ do
     mapM_ (loadSysInterface doc) (moduleSetElts (mkModuleSet unqual_mods))
   where
-    this_pkg = homeUnit (hsc_dflags hsc_env)
+    home_unit = mkHomeUnitFromFlags (hsc_dflags hsc_env)
 
     unqual_mods = [ nameModule name
                   | gre <- globalRdrEnvElts (ic_rn_gbl_env ictxt)
                   , let name = gre_name gre
-                  , nameIsFromExternalPackage this_pkg name
+                  , nameIsFromExternalPackage home_unit name
                   , isTcOcc (nameOccName name)   -- Types and classes only
                   , unQualOK gre ]               -- In scope unqualified
     doc = text "Need interface for module whose export(s) are in scope unqualified"