Remove transitive information about modules and packages from interface fileswip/ghc-transitive-deps

This commit modifies interface files so that *only* direct information
about modules and packages is stored in the interface file.

* Only direct module and direct package dependencies are stored in the
interface files.
* Trusted packages are now stored separately as they need to be checked
  transitively.
* hs-boot files below the compiled module in the home module are stored
  so that eps_is_boot can be calculated in one-shot mode without loading
  all interface files in the home package.
* The transitive closure of signatures is stored separately

This is important for two reasons

* Less recompilation is needed, as motivated by #16885, a lot of
redundant compilation was triggered when adding new imports deep in the
module tree as all the parent interface files had to be redundantly
updated.
* Checking an interface file is cheaper because you don't have to
perform a transitive traversal to check the dependencies are up-to-date.

In the code, places where we would have used the transitive closure, we
instead compute the necessary transitive closure. The closure is not
computed very often, was already happening in checkDependencies, and
was already happening in getLinkDeps.

Fixes #16885

-------------------------
Metric Decrease:
    MultiLayerModules
    T13701
    T13719
-------------------------

1 files changed, 9 insertions, 11 deletions

diff --git a/compiler/GHC/Tc/Module.hs b/compiler/GHC/Tc/Module.hs
index 5e3f0b3501..b04ab96e43 100644
--- a/compiler/GHC/Tc/Module.hs
+++ b/compiler/GHC/Tc/Module.hs
@@ -366,7 +366,7 @@ tcRnImports hsc_env import_decls
 
         ; this_mod <- getModule
         ; let { dep_mods :: ModuleNameEnv ModuleNameWithIsBoot
-              ; dep_mods = imp_dep_mods imports
+              ; dep_mods = imp_direct_dep_mods imports
 
                 -- We want instance declarations from all home-package
                 -- modules below this one, including boot modules, except
@@ -375,17 +375,15 @@ tcRnImports hsc_env import_decls
                 -- filtering also ensures that we don't see instances from
                 -- modules batch (@--make@) compiled before this one, but
                 -- which are not below this one.
-              ; want_instances :: ModuleName -> Bool
-              ; want_instances mod = mod `elemUFM` dep_mods
-                                   && mod /= moduleName this_mod
-              ; (home_insts, home_fam_insts) = hptInstances hsc_env
-                                                            want_instances
+              ; (home_insts, home_fam_insts) = hptInstancesBelow hsc_env (moduleName this_mod) (eltsUFM dep_mods)
               } ;
 
                 -- Record boot-file info in the EPS, so that it's
                 -- visible to loadHiBootInterface in tcRnSrcDecls,
                 -- and any other incrementally-performed imports
-        ; updateEps_ (\eps -> eps { eps_is_boot = dep_mods }) ;
+              ; when (isOneShot (ghcMode (hsc_dflags hsc_env))) $ do {
+                  updateEps_ $ \eps  -> eps { eps_is_boot = imp_boot_mods imports }
+               }
 
                 -- Update the gbl env
         ; updGblEnv ( \ gbl ->
@@ -399,7 +397,7 @@ tcRnImports hsc_env import_decls
               tcg_hpc          = hpc_info
             }) $ do {
 
-        ; traceRn "rn1" (ppr (imp_dep_mods imports))
+        ; traceRn "rn1" (ppr (imp_direct_dep_mods imports))
                 -- Fail if there are any errors so far
                 -- The error printing (if needed) takes advantage
                 -- of the tcg_env we have now set
@@ -2070,7 +2068,7 @@ runTcInteractive hsc_env thing_inside
 
        ; setEnvs (gbl_env', lcl_env') thing_inside }
   where
-    (home_insts, home_fam_insts) = hptInstances hsc_env (\_ -> True)
+    (home_insts, home_fam_insts) = hptAllInstances hsc_env
 
     icxt                     = hsc_IC hsc_env
     (ic_insts, ic_finsts)    = ic_instances icxt
@@ -2952,9 +2950,9 @@ pprTcGblEnv (TcGblEnv { tcg_type_env  = type_env,
          , ppr_fam_insts fam_insts
          , ppr_rules rules
          , text "Dependent modules:" <+>
-                pprUFM (imp_dep_mods imports) (ppr . sort)
+                pprUFM (imp_direct_dep_mods imports) (ppr . sort)
          , text "Dependent packages:" <+>
-                ppr (S.toList $ imp_dep_pkgs imports)]
+                ppr (S.toList $ imp_dep_direct_pkgs imports)]
                 -- The use of sort is just to reduce unnecessary
                 -- wobbling in testsuite output