Simplify type of ms_srcimps and ms_textual_imps.

Summary:
Previously, we stored an entire ImportDecl, which was pretty
wasteful since all we really cared about was the package qualifier
and the module name.

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Test Plan: validate

Reviewers: bgamari, austin

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1317

5 files changed, 22 insertions, 35 deletions

diff --git a/compiler/iface/MkIface.hs b/compiler/iface/MkIface.hs
index 43e57cdf43..0fc45cc8b9 100644
--- a/compiler/iface/MkIface.hs
+++ b/compiler/iface/MkIface.hs
@@ -1300,8 +1300,8 @@ checkDependencies hsc_env summary iface
 
    this_pkg = thisPackage (hsc_dflags hsc_env)
 
-   dep_missing (L _ (ImportDecl { ideclName = L _ mod, ideclPkgQual = pkg })) = do
-     find_res <- liftIO $ findImportedModule hsc_env mod (fmap sl_fs pkg)
+   dep_missing (mb_pkg, L _ mod) = do
+     find_res <- liftIO $ findImportedModule hsc_env mod (mb_pkg)
      let reason = moduleNameString mod ++ " changed"
      case find_res of
         Found _ mod
diff --git a/compiler/main/DriverMkDepend.hs b/compiler/main/DriverMkDepend.hs
index aae4d0e7c2..1541d95c62 100644
--- a/compiler/main/DriverMkDepend.hs
+++ b/compiler/main/DriverMkDepend.hs
@@ -16,7 +16,6 @@ module DriverMkDepend (
 
 import qualified GHC
 import GhcMonad
-import HsSyn            ( ImportDecl(..) )
 import DynFlags
 import Util
 import HscTypes
@@ -30,7 +29,6 @@ import Panic
 import SrcLoc
 import Data.List
 import FastString
-import BasicTypes ( StringLiteral(..) )
 
 import Exception
 import ErrUtils
@@ -227,9 +225,8 @@ processDeps dflags hsc_env excl_mods root hdl (AcyclicSCC node)
                 -- Emit a dependency for each import
 
         ; let do_imps is_boot idecls = sequence_
-                    [ do_imp loc is_boot (fmap sl_fs $ ideclPkgQual i) mod
-                    | L loc i <- idecls,
-                      let mod = unLoc (ideclName i),
+                    [ do_imp loc is_boot mb_pkg mod
+                    | (mb_pkg, L loc mod) <- idecls,
                       mod `notElem` excl_mods ]
 
         ; do_imps True  (ms_srcimps node)
@@ -379,7 +376,7 @@ pprCycle summaries = pp_group (CyclicSCC summaries)
           pp_ms loop_breaker $$ vcat (map pp_group groups)
         where
           (boot_only, others) = partition is_boot_only mss
-          is_boot_only ms = not (any in_group (map (ideclName.unLoc) (ms_imps ms)))
+          is_boot_only ms = not (any in_group (map snd (ms_imps ms)))
           in_group (L _ m) = m `elem` group_mods
           group_mods = map (moduleName . ms_mod) mss
 
@@ -388,8 +385,8 @@ pprCycle summaries = pp_group (CyclicSCC summaries)
           groups = GHC.topSortModuleGraph True all_others Nothing
 
     pp_ms summary = text mod_str <> text (take (20 - length mod_str) (repeat ' '))
-                       <+> (pp_imps empty (map (ideclName.unLoc) (ms_imps summary)) $$
-                            pp_imps (ptext (sLit "{-# SOURCE #-}")) (map (ideclName.unLoc) (ms_srcimps summary)))
+                       <+> (pp_imps empty (map snd (ms_imps summary)) $$
+                            pp_imps (ptext (sLit "{-# SOURCE #-}")) (map snd (ms_srcimps summary)))
         where
           mod_str = moduleNameString (moduleName (ms_mod summary))
 
diff --git a/compiler/main/GhcMake.hs b/compiler/main/GhcMake.hs
index 3d29b1d38e..123cc9e212 100644
--- a/compiler/main/GhcMake.hs
+++ b/compiler/main/GhcMake.hs
@@ -34,10 +34,8 @@ import ErrUtils
 import Finder
 import GhcMonad
 import HeaderInfo
-import HsSyn
 import HscTypes
 import Module
-import RdrName          ( RdrName )
 import TcIface          ( typecheckIface )
 import TcRnMonad        ( initIfaceCheck )
 
@@ -1720,9 +1718,9 @@ msDeps s =
             then [ (noLoc (moduleName (ms_mod s)), IsBoot) ]
             else []
 
-home_imps :: [Located (ImportDecl RdrName)] -> [Located ModuleName]
-home_imps imps = [ ideclName i |  L _ i <- imps,
-                                  isLocal (fmap sl_fs $ ideclPkgQual i) ]
+home_imps :: [(Maybe FastString, Located ModuleName)] -> [Located ModuleName]
+home_imps imps = [ lmodname |  (mb_pkg, lmodname) <- imps,
+                                  isLocal mb_pkg ]
   where isLocal Nothing = True
         isLocal (Just pkg) | pkg == fsLit "this" = True -- "this" is special
         isLocal _ = False
diff --git a/compiler/main/HeaderInfo.hs b/compiler/main/HeaderInfo.hs
index 3473a4ab88..b4c3f81678 100644
--- a/compiler/main/HeaderInfo.hs
+++ b/compiler/main/HeaderInfo.hs
@@ -37,6 +37,7 @@ import Maybes
 import Bag              ( emptyBag, listToBag, unitBag )
 import MonadUtils
 import Exception
+import BasicTypes
 
 import Control.Monad
 import System.IO
@@ -54,7 +55,9 @@ getImports :: DynFlags
                            --   reporting parse error locations.
            -> FilePath     -- ^ The original source filename (used for locations
                            --   in the function result)
-           -> IO ([Located (ImportDecl RdrName)], [Located (ImportDecl RdrName)], Located ModuleName)
+           -> IO ([(Maybe FastString, Located ModuleName)],
+                  [(Maybe FastString, Located ModuleName)],
+                  Located ModuleName)
               -- ^ The source imports, normal imports, and the module name.
 getImports dflags buf filename source_filename = do
   let loc  = mkRealSrcLoc (mkFastString filename) 1 1
@@ -83,8 +86,11 @@ getImports dflags buf filename source_filename = do
                 implicit_prelude = xopt Opt_ImplicitPrelude dflags
                 implicit_imports = mkPrelImports (unLoc mod) main_loc
                                                  implicit_prelude imps
+                convImport (L _ i) = (fmap sl_fs (ideclPkgQual i), ideclName i)
               in
-              return (src_idecls, implicit_imports ++ ordinary_imps, mod)
+              return (map convImport src_idecls,
+                      map convImport (implicit_imports ++ ordinary_imps),
+                      mod)
 
 mkPrelImports :: ModuleName
               -> SrcSpan    -- Attribute the "import Prelude" to this location
diff --git a/compiler/main/HscTypes.hs b/compiler/main/HscTypes.hs
index ddb4ca160b..2c426d9b36 100644
--- a/compiler/main/HscTypes.hs
+++ b/compiler/main/HscTypes.hs
@@ -2406,9 +2406,9 @@ data ModSummary
           -- ^ Timestamp of hi file, if we *only* are typechecking (it is
           -- 'Nothing' otherwise.
           -- See Note [Recompilation checking when typechecking only] and #9243
-        ms_srcimps      :: [Located (ImportDecl RdrName)],
+        ms_srcimps      :: [(Maybe FastString, Located ModuleName)],
           -- ^ Source imports of the module
-        ms_textual_imps :: [Located (ImportDecl RdrName)],
+        ms_textual_imps :: [(Maybe FastString, Located ModuleName)],
           -- ^ Non-source imports of the module from the module *text*
         ms_merge_imps   :: (Bool, [Module]),
           -- ^ Non-textual imports computed for HsBootMerge
@@ -2424,26 +2424,12 @@ data ModSummary
 ms_mod_name :: ModSummary -> ModuleName
 ms_mod_name = moduleName . ms_mod
 
-ms_imps :: ModSummary -> [Located (ImportDecl RdrName)]
+ms_imps :: ModSummary -> [(Maybe FastString, Located ModuleName)]
 ms_imps ms =
   ms_textual_imps ms ++
   map mk_additional_import (dynFlagDependencies (ms_hspp_opts ms))
   where
-    -- This is a not-entirely-satisfactory means of creating an import
-    -- that corresponds to an import that did not occur in the program
-    -- text, such as those induced by the use of plugins (the -plgFoo
-    -- flag)
-    mk_additional_import mod_nm = noLoc $ ImportDecl {
-      ideclSourceSrc = Nothing,
-      ideclName      = noLoc mod_nm,
-      ideclPkgQual   = Nothing,
-      ideclSource    = False,
-      ideclImplicit  = True, -- Maybe implicit because not "in the program text"
-      ideclQualified = False,
-      ideclAs        = Nothing,
-      ideclHiding    = Nothing,
-      ideclSafe      = False
-    }
+    mk_additional_import mod_nm = (Nothing, noLoc mod_nm)
 
 -- The ModLocation contains both the original source filename and the
 -- filename of the cleaned-up source file after all preprocessing has been