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, 4 insertions, 5 deletions

diff --git a/compiler/GHC/Tc/TyCl.hs b/compiler/GHC/Tc/TyCl.hs
index ccc23c3930..113fadd20d 100644
--- a/compiler/GHC/Tc/TyCl.hs
+++ b/compiler/GHC/Tc/TyCl.hs
@@ -61,8 +61,7 @@ import GHC.Types.Id
 import GHC.Types.Var
 import GHC.Types.Var.Env
 import GHC.Types.Var.Set
-import GHC.Unit.Module
-import GHC.Unit.State
+import GHC.Unit
 import GHC.Types.Name
 import GHC.Types.Name.Set
 import GHC.Types.Name.Env
@@ -174,8 +173,8 @@ tcTyClGroup (TyClGroup { group_tyclds = tyclds
 
            -- Step 1.5: Make sure we don't have any type synonym cycles
        ; traceTc "Starting synonym cycle check" (ppr tyclss)
-       ; this_uid <- fmap homeUnit getDynFlags
-       ; checkSynCycles this_uid tyclss tyclds
+       ; home_unit <- mkHomeUnitFromFlags <$> getDynFlags
+       ; checkSynCycles (homeUnitAsUnit home_unit) tyclss tyclds
        ; traceTc "Done synonym cycle check" (ppr tyclss)
 
            -- Step 2: Perform the validity check on those types/classes
@@ -4136,7 +4135,7 @@ checkValidDataCon dflags existential_ok tc con
       -- when we actually fill in the abstract type.  As such, don't
       -- warn in this case (it gives users the wrong idea about whether
       -- or not UNPACK on abstract types is supported; it is!)
-      , homeUnitIsDefinite dflags
+      , isHomeUnitDefinite (mkHomeUnitFromFlags dflags)
       = addWarnTc NoReason (bad_bang n (text "Ignoring unusable UNPACK pragma"))
       where
         is_strict = case strict_mark of