Restore home-package-plugin functionality

6 files changed, 49 insertions, 21 deletions

diff --git a/compiler/main/DriverPipeline.hs b/compiler/main/DriverPipeline.hs
index 112dac0439..aa987d7327 100644
--- a/compiler/main/DriverPipeline.hs
+++ b/compiler/main/DriverPipeline.hs
@@ -934,8 +934,8 @@ runPhase (Hsc src_flavour) input_fn dflags0
                                         ms_location  = location4,
                                         ms_hs_date   = src_timestamp,
                                         ms_obj_date  = Nothing,
-                                        ms_imps      = imps,
-                                        ms_srcimps   = src_imps }
+                                        ms_textual_imps = imps,
+                                        ms_srcimps      = src_imps }
 
   -- run the compiler!
         result <- io $ hscCompileOneShot hsc_env'
diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs
index 9f53666d78..144d6d1fbe 100644
--- a/compiler/main/DynFlags.hs
+++ b/compiler/main/DynFlags.hs
@@ -30,7 +30,7 @@ module DynFlags (
         DynLibLoader(..),
         fFlags, fLangFlags, xFlags,
         DPHBackend(..), dphPackageMaybe,
-        wayNames,
+        wayNames, dynFlagDependencies,
 
         -- ** Safe Haskell
         SafeHaskellMode(..),
@@ -980,6 +980,10 @@ setLanguage l = upd f
                          extensionFlags = flattenExtensionFlags mLang oneoffs
                      }
 
+-- | Some modules have dependencies on others through the DynFlags rather than textual imports
+dynFlagDependencies :: DynFlags -> [ModuleName]
+dynFlagDependencies = pluginModNames
+
 -- | Is the Safe Haskell safe language in use
 safeLanguageOn :: DynFlags -> Bool
 safeLanguageOn dflags = s == Sf_SafeLanguage
diff --git a/compiler/main/GHC.hs b/compiler/main/GHC.hs
index c8ca482784..8f5c894ac2 100644
--- a/compiler/main/GHC.hs
+++ b/compiler/main/GHC.hs
@@ -816,7 +816,7 @@ compileCoreToObj simplify cm@(CoreModule{ cm_module = mName }) = do
          ms_obj_date = Nothing,
          -- Only handling the single-module case for now, so no imports.
          ms_srcimps = [],
-         ms_imps = [],
+         ms_textual_imps = [],
          -- No source file
          ms_hspp_file = "",
          ms_hspp_opts = dflags,
diff --git a/compiler/main/GhcMake.hs b/compiler/main/GhcMake.hs
index 8ccf0a5a81..5dcea1b139 100644
--- a/compiler/main/GhcMake.hs
+++ b/compiler/main/GhcMake.hs
@@ -1254,7 +1254,7 @@ summariseFile hsc_env old_summaries file mb_phase obj_allowed maybe_buf
                              ms_hspp_file = hspp_fn,
                              ms_hspp_opts = dflags',
 			     ms_hspp_buf  = Just buf,
-                             ms_srcimps = srcimps, ms_imps = the_imps,
+                             ms_srcimps = srcimps, ms_textual_imps = the_imps,
 			     ms_hs_date = src_timestamp,
 			     ms_obj_date = obj_timestamp })
 
@@ -1379,8 +1379,8 @@ summariseModule hsc_env old_summary_map is_boot (L loc wanted_mod)
 			      ms_hspp_file = hspp_fn,
                               ms_hspp_opts = dflags',
 			      ms_hspp_buf  = Just buf,
-			      ms_srcimps   = srcimps,
-			      ms_imps      = the_imps,
+			      ms_srcimps      = srcimps,
+			      ms_textual_imps = the_imps,
 			      ms_hs_date   = src_timestamp,
 			      ms_obj_date  = obj_timestamp }))
 
diff --git a/compiler/main/HscTypes.lhs b/compiler/main/HscTypes.lhs
index bc3d02654e..7f43414111 100644
--- a/compiler/main/HscTypes.lhs
+++ b/compiler/main/HscTypes.lhs
@@ -17,7 +17,7 @@ module HscTypes (
         ModGuts(..), CgGuts(..), ForeignStubs(..), appendStubC,
         ImportedMods, ImportedModsVal,
 
-	ModSummary(..), ms_mod_name, showModMsg, isBootSummary,
+	ModSummary(..), ms_imps, ms_mod_name, showModMsg, isBootSummary,
 	msHsFilePath, msHiFilePath, msObjFilePath,
 
         -- * Information about the module being compiled
@@ -131,7 +131,7 @@ import DataCon		( DataCon, dataConImplicitIds, dataConWrapId )
 import PrelNames	( gHC_PRIM )
 import Packages hiding ( Version(..) )
 import DynFlags		( DynFlags(..), isOneShot, HscTarget (..), dopt,
-                          DynFlag(..), SafeHaskellMode(..) )
+                          DynFlag(..), SafeHaskellMode(..), dynFlagDependencies )
 import DriverPhases	( HscSource(..), isHsBoot, hscSourceString, Phase )
 import BasicTypes	( IPName, defaultFixity, WarningTxt(..) )
 import OptimizationFuel	( OptFuelState )
@@ -1656,22 +1656,38 @@ emptyMG = []
 -- * An external-core source module
 data ModSummary
    = ModSummary {
-        ms_mod       :: Module,			-- ^ Identity of the module
-	ms_hsc_src   :: HscSource,		-- ^ The module source either plain Haskell, hs-boot or external core
-        ms_location  :: ModLocation,		-- ^ Location of the various files belonging to the module
-        ms_hs_date   :: ClockTime,		-- ^ Timestamp of source file
-	ms_obj_date  :: Maybe ClockTime,	-- ^ Timestamp of object, if we have one
-        ms_srcimps   :: [Located (ImportDecl RdrName)],	-- ^ Source imports of the module
-        ms_imps      :: [Located (ImportDecl RdrName)],	-- ^ Non-source imports of the module
-        ms_hspp_file :: FilePath,		-- ^ Filename of preprocessed source file
-        ms_hspp_opts :: DynFlags,               -- ^ Cached flags from @OPTIONS@, @INCLUDE@
+        ms_mod          :: Module,		-- ^ Identity of the module
+	ms_hsc_src      :: HscSource,		-- ^ The module source either plain Haskell, hs-boot or external core
+        ms_location     :: ModLocation,		-- ^ Location of the various files belonging to the module
+        ms_hs_date      :: ClockTime,		-- ^ Timestamp of source file
+	ms_obj_date     :: Maybe ClockTime,	-- ^ Timestamp of object, if we have one
+        ms_srcimps      :: [Located (ImportDecl RdrName)],	-- ^ Source imports of the module
+        ms_textual_imps :: [Located (ImportDecl RdrName)],	-- ^ Non-source imports of the module from the module *text*
+        ms_hspp_file    :: FilePath,		-- ^ Filename of preprocessed source file
+        ms_hspp_opts    :: DynFlags,            -- ^ Cached flags from @OPTIONS@, @INCLUDE@
                                                 -- and @LANGUAGE@ pragmas in the modules source code
-	ms_hspp_buf  :: Maybe StringBuffer    	-- ^ The actual preprocessed source, if we have it
+	ms_hspp_buf     :: Maybe StringBuffer   -- ^ The actual preprocessed source, if we have it
      }
 
 ms_mod_name :: ModSummary -> ModuleName
 ms_mod_name = moduleName . ms_mod
 
+ms_imps :: ModSummary -> [Located (ImportDecl RdrName)]
+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 {
+      ideclName = noLoc mod_nm,
+      ideclPkgQual = Nothing,
+      ideclSource = False,
+      ideclQualified = False,
+      ideclAs = Nothing,
+      ideclHiding = Nothing,
+      ideclSafe = False
+    }
+
 -- The ModLocation contains both the original source filename and the
 -- filename of the cleaned-up source file after all preprocessing has been
 -- done.  The point is that the summariser will have to cpp/unlit/whatever
@@ -1697,7 +1713,7 @@ instance Outputable ModSummary where
              nest 3 (sep [text "ms_hs_date = " <> text (show (ms_hs_date ms)),
                           text "ms_mod =" <+> ppr (ms_mod ms) 
 				<> text (hscSourceString (ms_hsc_src ms)) <> comma,
-                          text "ms_imps =" <+> ppr (ms_imps ms),
+                          text "ms_textual_imps =" <+> ppr (ms_textual_imps ms),
                           text "ms_srcimps =" <+> ppr (ms_srcimps ms)]),
              char '}'
             ]
diff --git a/compiler/typecheck/TcRnDriver.lhs b/compiler/typecheck/TcRnDriver.lhs
index 1faa8e6366..1c289f1574 100644
--- a/compiler/typecheck/TcRnDriver.lhs
+++ b/compiler/typecheck/TcRnDriver.lhs
@@ -204,7 +204,15 @@ tcRnImports hsc_env this_mod import_decls
   = do	{ (rn_imports, rdr_env, imports,hpc_info) <- rnImports import_decls ;
 
 	; let { dep_mods :: ModuleNameEnv (ModuleName, IsBootInterface)
-	      ; dep_mods = imp_dep_mods imports
+	        -- Make sure we record the dependencies from the DynFlags in the EPS or we
+	        -- end up hitting the sanity check in LoadIface.loadInterface that
+	        -- checks for unknown home-package modules being loaded. We put
+	        -- these dependencies on the left so their (non-source) imports
+	        -- take precedence over the (possibly-source) imports on the right.
+	        -- We don't add them to any other field (e.g. the imp_dep_mods of
+	        -- imports) because we don't want to load their instances etc.
+	      ; dep_mods = listToUFM [(mod_nm, (mod_nm, False)) | mod_nm <- dynFlagDependencies (hsc_dflags hsc_env)]
+	                        `plusUFM` imp_dep_mods imports
 
 		-- We want instance declarations from all home-package
 		-- modules below this one, including boot modules, except