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

2 files changed, 6 insertions, 5 deletions

diff --git a/compiler/GHC/Runtime/Eval.hs b/compiler/GHC/Runtime/Eval.hs
index 2ee3143f76..7197710cfb 100644
--- a/compiler/GHC/Runtime/Eval.hs
+++ b/compiler/GHC/Runtime/Eval.hs
@@ -85,7 +85,7 @@ import GHC.LanguageExtensions
 import GHC.Types.Unique
 import GHC.Types.Unique.Supply
 import GHC.Utils.Monad
-import GHC.Unit.Module
+import GHC.Unit
 import GHC.Builtin.Names ( toDynName, pretendNameIsInScope )
 import GHC.Builtin.Types ( isCTupleTyConName )
 import GHC.Utils.Panic
@@ -812,7 +812,7 @@ getContext = withSession $ \HscEnv{ hsc_IC=ic } ->
 -- its full top-level scope available.
 moduleIsInterpreted :: GhcMonad m => Module -> m Bool
 moduleIsInterpreted modl = withSession $ \h ->
- if not (isHomeModule (hsc_dflags h) modl)
+ if notHomeModule (mkHomeUnitFromFlags (hsc_dflags h)) modl
         then return False
         else case lookupHpt (hsc_HPT h) (moduleName modl) of
                 Just details       -> return (isJust (mi_globals (hm_iface details)))
diff --git a/compiler/GHC/Runtime/Linker.hs b/compiler/GHC/Runtime/Linker.hs
index 8c05c38c6c..4a3b03e5eb 100644
--- a/compiler/GHC/Runtime/Linker.hs
+++ b/compiler/GHC/Runtime/Linker.hs
@@ -47,6 +47,7 @@ import GHC.Platform.Ways
 import GHC.Types.Name
 import GHC.Types.Name.Env
 import GHC.Unit.Module
+import GHC.Unit.Home
 import GHC.Data.List.SetOps
 import GHC.Runtime.Linker.Types (DynLinker(..), PersistentLinkerState(..))
 import GHC.Driver.Session
@@ -656,7 +657,6 @@ getLinkDeps hsc_env hpt pls replace_osuf span mods
       ; return (lnks_needed, pkgs_needed) }
   where
     dflags = hsc_dflags hsc_env
-    this_pkg = homeUnit dflags
 
         -- The ModIface contains the transitive closure of the module dependencies
         -- within the current package, *except* for boot modules: if we encounter
@@ -682,6 +682,7 @@ getLinkDeps hsc_env hpt pls replace_osuf span mods
           let
             pkg = moduleUnit mod
             deps  = mi_deps iface
+            home_unit = mkHomeUnitFromFlags dflags
 
             pkg_deps = dep_pkgs deps
             (boot_deps, mod_deps) = flip partitionWith (dep_mods deps) $
@@ -694,9 +695,9 @@ getLinkDeps hsc_env hpt pls replace_osuf span mods
             acc_mods'  = addListToUniqDSet acc_mods (moduleName mod : mod_deps)
             acc_pkgs'  = addListToUniqDSet acc_pkgs $ map fst pkg_deps
           --
-          if pkg /= this_pkg
+          if not (isHomeUnit home_unit pkg)
              then follow_deps mods acc_mods (addOneToUniqDSet acc_pkgs' (toUnitId pkg))
-             else follow_deps (map (mkModule this_pkg) boot_deps' ++ mods)
+             else follow_deps (map (mkHomeModule home_unit) boot_deps' ++ mods)
                               acc_mods' acc_pkgs'
         where
             msg = text "need to link module" <+> ppr mod <+>