WIP: Splice importswip/splice-import

20 files changed, 147 insertions, 53 deletions

diff --git a/compiler/GHC.hs b/compiler/GHC.hs
index 9d2d6fb65f..8b1629857a 100644
--- a/compiler/GHC.hs
+++ b/compiler/GHC.hs
@@ -1380,6 +1380,7 @@ availsToGlobalRdrEnv mod_name avails
     imp_spec = ImpSpec { is_decl = decl, is_item = ImpAll}
     decl = ImpDeclSpec { is_mod = mod_name, is_as = mod_name,
                          is_qual = False,
+                         is_splice = False, -- TODO MP
                          is_dloc = srcLocSpan interactiveSrcLoc }
 
 
diff --git a/compiler/GHC/Driver/Session.hs b/compiler/GHC/Driver/Session.hs
index eb14bbc91f..7a5ee744f5 100644
--- a/compiler/GHC/Driver/Session.hs
+++ b/compiler/GHC/Driver/Session.hs
@@ -3510,6 +3510,7 @@ xFlagsDeps = [
   flagSpec "ExistentialQuantification"        LangExt.ExistentialQuantification,
   flagSpec "ExplicitForAll"                   LangExt.ExplicitForAll,
   flagSpec "ExplicitNamespaces"               LangExt.ExplicitNamespaces,
+  flagSpec "ExplicitSpliceImports"            LangExt.ExplicitSpliceImports,
   flagSpec "ExtendedDefaultRules"             LangExt.ExtendedDefaultRules,
   flagSpec "FlexibleContexts"                 LangExt.FlexibleContexts,
   flagSpec "FlexibleInstances"                LangExt.FlexibleInstances,
diff --git a/compiler/GHC/Hs/ImpExp.hs b/compiler/GHC/Hs/ImpExp.hs
index f4c40bd185..70f9da4fb3 100644
--- a/compiler/GHC/Hs/ImpExp.hs
+++ b/compiler/GHC/Hs/ImpExp.hs
@@ -77,6 +77,8 @@ isImportDeclQualified :: ImportDeclQualifiedStyle -> Bool
 isImportDeclQualified NotQualified = False
 isImportDeclQualified _ = True
 
+data IsSpliceImport = SpliceImport | NormalImport deriving (Data, Show, Eq, Ord)
+
 -- | Import Declaration
 --
 -- A single Haskell @import@ declaration.
@@ -90,6 +92,7 @@ data ImportDecl pass
       ideclSource    :: IsBootInterface,      -- ^ IsBoot <=> {-\# SOURCE \#-} import
       ideclSafe      :: Bool,          -- ^ True => safe import
       ideclQualified :: ImportDeclQualifiedStyle, -- ^ If/how the import is qualified.
+      ideclSplice    :: IsSpliceImport, -- ^ Whether the import is a splice import
       ideclImplicit  :: Bool,          -- ^ True => implicit import (of Prelude)
       ideclAs        :: Maybe (XRec pass ModuleName),  -- ^ as Module
       ideclHiding    :: Maybe (Bool, XRec pass [LIE pass])
@@ -147,6 +150,7 @@ simpleImportDecl mn = ImportDecl {
       ideclSafe      = False,
       ideclImplicit  = False,
       ideclQualified = NotQualified,
+      ideclSplice    = NormalImport,
       ideclAs        = Nothing,
       ideclHiding    = Nothing
     }
diff --git a/compiler/GHC/Hs/Stats.hs b/compiler/GHC/Hs/Stats.hs
index bd3e2e6b6d..03d60d2819 100644
--- a/compiler/GHC/Hs/Stats.hs
+++ b/compiler/GHC/Hs/Stats.hs
@@ -36,6 +36,7 @@ ppSourceStats short (L _ (HsModule{ hsmodExports = exports, hsmodImports = impor
              ("  ImpAll         ", imp_all),
              ("  ImpPartial     ", imp_partial),
              ("  ImpHiding      ", imp_hiding),
+             ("  ImpSplices     ", imp_splices),
              ("FixityDecls      ", fixity_sigs),
              ("DefaultDecls     ", default_ds),
              ("TypeDecls        ", type_ds),
@@ -96,8 +97,8 @@ ppSourceStats short (L _ (HsModule{ hsmodExports = exports, hsmodImports = impor
     (val_bind_ds, fn_bind_ds, patsyn_ds)
         = sum3 (map count_bind val_decls)
 
-    (imp_no, imp_safe, imp_qual, imp_as, imp_all, imp_partial, imp_hiding)
-        = sum7 (map import_info imports)
+    (imp_no, imp_safe, imp_qual, imp_as, imp_all, imp_partial, imp_hiding, imp_splices)
+        = sum8 (map import_info imports)
     (data_constrs, data_derivs)
         = sum2 (map data_info tycl_decls)
     (class_method_ds, default_method_ds)
@@ -120,10 +121,11 @@ ppSourceStats short (L _ (HsModule{ hsmodExports = exports, hsmodImports = impor
     sig_info (ClassOpSig {}) = (0,0,0,0,1)
     sig_info _               = (0,0,0,0,0)
 
-    import_info :: LImportDecl GhcPs -> (Int, Int, Int, Int, Int, Int, Int)
+    import_info :: LImportDecl GhcPs -> (Int, Int, Int, Int, Int, Int, Int, Int)
     import_info (L _ (ImportDecl { ideclSafe = safe, ideclQualified = qual
-                                 , ideclAs = as, ideclHiding = spec }))
-        = add7 (1, safe_info safe, qual_info qual, as_info as, 0,0,0) (spec_info spec)
+                                 , ideclAs = as, ideclHiding = spec
+                                 , ideclSplice = sp }))
+        = add8 (1, safe_info safe, qual_info qual, as_info as, 0,0,0, sp_info sp) (spec_info spec)
 
     safe_info False = 0
     safe_info True = 1
@@ -131,9 +133,11 @@ ppSourceStats short (L _ (HsModule{ hsmodExports = exports, hsmodImports = impor
     qual_info _  = 1
     as_info Nothing  = 0
     as_info (Just _) = 1
-    spec_info Nothing           = (0,0,0,0,1,0,0)
-    spec_info (Just (False, _)) = (0,0,0,0,0,1,0)
-    spec_info (Just (True, _))  = (0,0,0,0,0,0,1)
+    spec_info Nothing           = (0,0,0,0,1,0,0,0)
+    spec_info (Just (False, _)) = (0,0,0,0,0,1,0,0)
+    spec_info (Just (True, _))  = (0,0,0,0,0,0,1,0)
+    sp_info SpliceImport = 1
+    sp_info NormalImport = 0
 
     data_info (DataDecl { tcdDataDefn = HsDataDefn
                                           { dd_cons = cs
@@ -169,9 +173,9 @@ ppSourceStats short (L _ (HsModule{ hsmodExports = exports, hsmodImports = impor
     sum2 :: [(Int, Int)] -> (Int, Int)
     sum3 :: [(Int, Int, Int)] -> (Int, Int, Int)
     sum5 :: [(Int, Int, Int, Int, Int)] -> (Int, Int, Int, Int, Int)
-    sum7 :: [(Int, Int, Int, Int, Int, Int, Int)] -> (Int, Int, Int, Int, Int, Int, Int)
-    add7 :: (Int, Int, Int, Int, Int, Int, Int) -> (Int, Int, Int, Int, Int, Int, Int)
-         -> (Int, Int, Int, Int, Int, Int, Int)
+    sum8 :: [(Int, Int, Int, Int, Int, Int, Int, Int)] -> (Int, Int, Int, Int, Int, Int, Int, Int)
+    add8 :: (Int, Int, Int, Int, Int, Int, Int, Int) -> (Int, Int, Int, Int, Int, Int, Int, Int)
+         -> (Int, Int, Int, Int, Int, Int, Int, Int)
 
     addpr (x,y,z) = x+y+z
     sum2 = foldr add2 (0,0)
@@ -183,6 +187,6 @@ ppSourceStats short (L _ (HsModule{ hsmodExports = exports, hsmodImports = impor
     sum5 = foldr add5 (0,0,0,0,0)
       where
         add5 (x1,x2,x3,x4,x5) (y1,y2,y3,y4,y5) = (x1+y1,x2+y2,x3+y3,x4+y4,x5+y5)
-    sum7 = foldr add7 (0,0,0,0,0,0,0)
+    sum8 = foldr add8 (0,0,0,0,0,0,0,0)
 
-    add7 (x1,x2,x3,x4,x5,x6,x7) (y1,y2,y3,y4,y5,y6,y7) = (x1+y1,x2+y2,x3+y3,x4+y4,x5+y5,x6+y6,x7+y7)
+    add8 (x1,x2,x3,x4,x5,x6,x7, x8) (y1,y2,y3,y4,y5,y6,y7,y8) = (x1+y1,x2+y2,x3+y3,x4+y4,x5+y5,x6+y6,x7+y7,x8+y8)
diff --git a/compiler/GHC/Parser.y b/compiler/GHC/Parser.y
index f786940591..31db2761cb 100644
--- a/compiler/GHC/Parser.y
+++ b/compiler/GHC/Parser.y
@@ -58,7 +58,7 @@ import GHC.Unit.Module.Warnings
 import GHC.Data.OrdList
 import GHC.Data.BooleanFormula ( BooleanFormula(..), LBooleanFormula, mkTrue )
 import GHC.Data.FastString
-import GHC.Data.Maybe          ( orElse )
+import GHC.Data.Maybe          ( orElse, isJust )
 
 import GHC.Utils.Outputable
 import GHC.Utils.Misc          ( looksLikePackageName, fstOf3, sndOf3, thdOf3 )
@@ -582,6 +582,7 @@ are the most common patterns, rewritten as regular expressions for clarity:
  'newtype'      { L _ ITnewtype }
  'of'           { L _ ITof }
  'qualified'    { L _ ITqualified }
+ 'splice'       { L _ ITsplice }
  'then'         { L _ ITthen }
  'type'         { L _ ITtype }
  'where'        { L _ ITwhere }
@@ -1085,10 +1086,10 @@ importdecls_semi
         | {- empty -}           { [] }
 
 importdecl :: { LImportDecl GhcPs }
-        : 'import' maybe_src maybe_safe optqualified maybe_pkg modid optqualified maybeas maybeimpspec
+        : 'import' maybe_src maybe_safe optsplice optqualified maybe_pkg modid optqualified maybeas maybeimpspec
                 {% do {
-                  ; let { ; mPreQual = unLoc $4
-                          ; mPostQual = unLoc $7 }
+                  ; let { ; mPreQual = unLoc $5
+                          ; mPostQual = unLoc $8 }
                   ; checkImportDecl mPreQual mPostQual
                   ; let anns
                          = ApiAnnImportDecl
@@ -1096,18 +1097,19 @@ importdecl :: { LImportDecl GhcPs }
                              , importDeclAnnPragma    = fst $ fst $2
                              , importDeclAnnSafe      = fst $3
                              , importDeclAnnQualified = fst $ importDeclQualifiedStyle mPreQual mPostQual
-                             , importDeclAnnPackage   = fst $5
-                             , importDeclAnnAs        = fst $8
+                             , importDeclAnnPackage   = fst $6
+                             , importDeclAnnAs        = fst $9
                              }
-                  ; fmap reLocA $ acs (\cs -> L (comb5 $1 $6 $7 (snd $8) $9) $
+                  ; fmap reLocA $ acs (\cs -> L (comb5 $1 $7 $8 (snd $9) $10) $
                       ImportDecl { ideclExt = ApiAnn (glR $1) anns cs
                                   , ideclSourceSrc = snd $ fst $2
-                                  , ideclName = $6, ideclPkgQual = snd $5
+                                  , ideclName = $7, ideclPkgQual = snd $6
                                   , ideclSource = snd $2, ideclSafe = snd $3
                                   , ideclQualified = snd $ importDeclQualifiedStyle mPreQual mPostQual
+                                  , ideclSplice = if isJust (unLoc $4) then SpliceImport else NormalImport
                                   , ideclImplicit = False
-                                  , ideclAs = unLoc (snd $8)
-                                  , ideclHiding = unLoc $9 })
+                                  , ideclAs = unLoc (snd $9)
+                                  , ideclHiding = unLoc $10 })
                   }
                 }
 
@@ -1132,6 +1134,10 @@ optqualified :: { Located (Maybe AnnAnchor) }
         : 'qualified'                           { sL1 $1 (Just (glAA $1)) }
         | {- empty -}                           { noLoc Nothing }
 
+optsplice :: { Located (Maybe AnnAnchor) }
+        : 'splice'                              { sL1 $1 (Just (glAA $1)) }
+        | {- empty -}                           { noLoc Nothing }
+
 maybeas :: { (Maybe AnnAnchor,Located (Maybe (Located ModuleName))) }
         : 'as' modid                           { (Just (glAA $1)
                                                  ,sLL $1 $> (Just $2)) }
@@ -3761,6 +3767,7 @@ special_id :: { Located FastString }
 special_id
         : 'as'                  { sL1 $1 (fsLit "as") }
         | 'qualified'           { sL1 $1 (fsLit "qualified") }
+        | 'splice'              { sL1 $1 (fsLit "splice") }
         | 'hiding'              { sL1 $1 (fsLit "hiding") }
         | 'export'              { sL1 $1 (fsLit "export") }
         | 'label'               { sL1 $1 (fsLit "label")  }
diff --git a/compiler/GHC/Parser/Header.hs b/compiler/GHC/Parser/Header.hs
index 7b561f2119..28dd2cf792 100644
--- a/compiler/GHC/Parser/Header.hs
+++ b/compiler/GHC/Parser/Header.hs
@@ -127,7 +127,7 @@ mkPrelImports this_mod loc implicit_prelude import_decls
    || explicit_prelude_import
    || not implicit_prelude
   = []
-  | otherwise = [preludeImportDecl]
+  | otherwise = [preludeImportDecl sp_import | sp_import <- [NormalImport, SpliceImport]]
   where
       explicit_prelude_import = any is_prelude_import import_decls
 
@@ -140,8 +140,8 @@ mkPrelImports this_mod loc implicit_prelude import_decls
 
 
       loc' = noAnnSrcSpan loc
-      preludeImportDecl :: LImportDecl GhcPs
-      preludeImportDecl
+      preludeImportDecl :: IsSpliceImport -> LImportDecl GhcPs
+      preludeImportDecl sp_import
         = L loc' $ ImportDecl { ideclExt       = noAnn,
                                 ideclSourceSrc = NoSourceText,
                                 ideclName      = L loc pRELUDE_NAME,
@@ -150,6 +150,7 @@ mkPrelImports this_mod loc implicit_prelude import_decls
                                 ideclSafe      = False,  -- Not a safe import
                                 ideclQualified = NotQualified,
                                 ideclImplicit  = True,   -- Implicit!
+                                ideclSplice    = sp_import,
                                 ideclAs        = Nothing,
                                 ideclHiding    = Nothing  }
 
diff --git a/compiler/GHC/Parser/Lexer.x b/compiler/GHC/Parser/Lexer.x
index bfebbfa411..30eff8ccec 100644
--- a/compiler/GHC/Parser/Lexer.x
+++ b/compiler/GHC/Parser/Lexer.x
@@ -712,6 +712,7 @@ data Token
   | ITnewtype
   | ITof
   | ITqualified
+  | ITsplice
   | ITthen
   | ITtype
   | ITwhere
@@ -968,6 +969,7 @@ reservedWordsFM = listToUFM $
          ( "newtype",        ITnewtype,       0 ),
          ( "of",             ITof,            0 ),
          ( "qualified",      ITqualified,     0 ),
+         ( "splice",         ITsplice,        xbit ExplicitSpliceImportsBit ),
          ( "then",           ITthen,          0 ),
          ( "type",           ITtype,          0 ),
          ( "where",          ITwhere,         0 ),
@@ -2728,6 +2730,7 @@ data ExtBits
   | NoLexicalNegationBit   -- See Note [Why not LexicalNegationBit]
   | OverloadedRecordDotBit
   | OverloadedRecordUpdateBit
+  | ExplicitSpliceImportsBit
 
   -- Flags that are updated once parsing starts
   | InRulePragBit
@@ -2806,6 +2809,7 @@ mkParserOpts warningFlags extensionFlags
       .|. NoLexicalNegationBit        `xoptNotBit` LangExt.LexicalNegation -- See Note [Why not LexicalNegationBit]
       .|. OverloadedRecordDotBit      `xoptBit` LangExt.OverloadedRecordDot
       .|. OverloadedRecordUpdateBit   `xoptBit` LangExt.OverloadedRecordUpdate  -- Enable testing via 'getBit OverloadedRecordUpdateBit' in the parser (RecordDotSyntax parsing uses that information).
+      .|. ExplicitSpliceImportsBit    `xoptBit` LangExt.ExplicitSpliceImports
     optBits =
           HaddockBit        `setBitIf` isHaddock
       .|. RawTokenStreamBit `setBitIf` rawTokStream
diff --git a/compiler/GHC/Rename/Env.hs b/compiler/GHC/Rename/Env.hs
index 68c299a3b0..2b0af26b5c 100644
--- a/compiler/GHC/Rename/Env.hs
+++ b/compiler/GHC/Rename/Env.hs
@@ -1634,7 +1634,7 @@ lookupOneQualifiedNameGHCi fos rdr_name = do
     -- field name multiple times (see
     -- Note [DuplicateRecordFields and -fimplicit-import-qualified]).
     toGRE gname = GRE { gre_name = gname, gre_par = NoParent, gre_lcl = False, gre_imp = [is] }
-    is = ImpSpec { is_decl = ImpDeclSpec { is_mod = mod, is_as = mod, is_qual = True, is_dloc = noSrcSpan }
+    is = ImpSpec { is_decl = ImpDeclSpec { is_mod = mod, is_as = mod, is_qual = True, is_splice = False, is_dloc = noSrcSpan }
                  , is_item = ImpAll }
     -- If -fimplicit-import-qualified succeeded, the name must be qualified.
     (mod, _) = fromMaybe (pprPanic "lookupOneQualifiedNameGHCi" (ppr rdr_name)) (isQual_maybe rdr_name)
diff --git a/compiler/GHC/Rename/Expr.hs b/compiler/GHC/Rename/Expr.hs
index bbf52be2f8..e36747184b 100644
--- a/compiler/GHC/Rename/Expr.hs
+++ b/compiler/GHC/Rename/Expr.hs
@@ -43,7 +43,7 @@ import GHC.Rename.Utils ( HsDocContext(..), bindLocalNamesFV, checkDupNames
                         , warnUnusedLocalBinds, typeAppErr
                         , checkUnusedRecordWildcard )
 import GHC.Rename.Unbound ( reportUnboundName )
-import GHC.Rename.Splice  ( rnBracket, rnSpliceExpr, checkThLocalName )
+import GHC.Rename.Splice  ( rnBracket, rnSpliceExpr, checkThLocalName, checkSpliceImports )
 import GHC.Rename.HsType
 import GHC.Rename.Pat
 import GHC.Driver.Session
@@ -189,14 +189,17 @@ rnLExpr = wrapLocFstMA rnExpr
 
 rnExpr :: HsExpr GhcPs -> RnM (HsExpr GhcRn, FreeVars)
 
-finishHsVar :: LocatedA Name -> RnM (HsExpr GhcRn, FreeVars)
+finishHsVar :: RdrName -> LocatedA Name -> RnM (HsExpr GhcRn, FreeVars)
 -- Separated from rnExpr because it's also used
 -- when renaming infix expressions
-finishHsVar (L l name)
+finishHsVar orig_rdrname (L l name)
  = do { this_mod <- getModule
-      ; when (nameIsLocalOrFrom this_mod name) $
-        checkThLocalName name
-      ; return (HsVar noExtField (L (la2na l) name), unitFV name) }
+      ; splice_import <- xoptM LangExt.ExplicitSpliceImports
+      ; name' <- if (not (nameIsLocalOrFrom this_mod name) && splice_import)
+                  then checkSpliceImports orig_rdrname name
+                  else return name
+      ; when (nameIsLocalOrFrom this_mod name') $ checkThLocalName name'
+      ; return (HsVar noExtField (L (la2na l) name'), unitFV name') }
 
 rnUnboundVar :: RdrName -> RnM (HsExpr GhcRn, FreeVars)
 rnUnboundVar v =
@@ -225,7 +228,7 @@ rnExpr (HsVar _ (L l v))
               -> rnExpr (ExplicitList noAnn [])
 
               | otherwise
-              -> finishHsVar (L (na2la l) name) ;
+              -> finishHsVar v (L (na2la l) name) ;
             Just (UnambiguousGre (FieldGreName fl)) ->
               let sel_name = flSelector fl in
               return ( HsRecFld noExtField (Unambiguous sel_name (L l v) ), unitFV sel_name) ;
diff --git a/compiler/GHC/Rename/Names.hs b/compiler/GHC/Rename/Names.hs
index 6c99bf7b5b..afe47525c5 100644
--- a/compiler/GHC/Rename/Names.hs
+++ b/compiler/GHC/Rename/Names.hs
@@ -290,7 +290,8 @@ rnImportDecl this_mod
                                      , ideclPkgQual = mb_pkg
                                      , ideclSource = want_boot, ideclSafe = mod_safe
                                      , ideclQualified = qual_style, ideclImplicit = implicit
-                                     , ideclAs = as_mod, ideclHiding = imp_details }))
+                                     , ideclAs = as_mod, ideclHiding = imp_details
+                                     , ideclSplice = sp_style }))
   = setSrcSpanA loc $ do
 
     when (isJust mb_pkg) $ do
@@ -298,6 +299,10 @@ rnImportDecl this_mod
         when (not pkg_imports) $ addErr packageImportErr
 
     let qual_only = isImportDeclQualified qual_style
+        splice_only = case sp_style of
+                        SpliceImport -> True
+                        NormalImport  -> False
+        want_compiled = if splice_only then NeededCompiled else NotNeededCompiled
 
     -- If there's an error in loadInterface, (e.g. interface
     -- file not found) we get lots of spurious errors from 'filterImports'
@@ -361,7 +366,8 @@ rnImportDecl this_mod
     let
         qual_mod_name = fmap unLoc as_mod `orElse` imp_mod_name
         imp_spec  = ImpDeclSpec { is_mod = imp_mod_name, is_qual = qual_only,
-                                  is_dloc = locA loc, is_as = qual_mod_name }
+                                  is_dloc = locA loc, is_as = qual_mod_name,
+                                  is_splice = splice_only }
 
     -- filter the imports according to the import declaration
     (new_imp_details, gres) <- filterImports iface imp_spec imp_details
@@ -390,7 +396,7 @@ rnImportDecl this_mod
             , imv_all_exports = potential_gres
             , imv_qualified   = qual_only
             }
-        imports = calculateAvails home_unit iface mod_safe' want_boot (ImportedByUser imv)
+        imports = calculateAvails home_unit iface mod_safe' want_boot want_compiled (ImportedByUser imv)
 
     -- Complain if we import a deprecated module
     whenWOptM Opt_WarnWarningsDeprecations (
@@ -416,9 +422,10 @@ calculateAvails :: HomeUnit
                 -> ModIface
                 -> IsSafeImport
                 -> IsBootInterface
+                -> IsNeededCompiled
                 -> ImportedBy
                 -> ImportAvails
-calculateAvails home_unit iface mod_safe' want_boot imported_by =
+calculateAvails home_unit iface mod_safe' want_boot want_compiled imported_by =
   let imp_mod    = mi_module iface
       imp_sem_mod= mi_semantic_module iface
       orph_iface = mi_orphan (mi_final_exts iface)
@@ -481,7 +488,9 @@ calculateAvails home_unit iface mod_safe' want_boot imported_by =
             -- know if any of them depended on CM.hi-boot, in
             -- which case we should do the hi-boot consistency
             -- check.  See GHC.Iface.Load.loadHiBootInterface
-            ( GWIB { gwib_mod = moduleName imp_mod, gwib_isBoot = want_boot } : dep_mods deps
+            ( GWIB { gwib_mod = moduleName imp_mod
+                   , gwib_isBoot = want_boot
+                   } : dep_mods deps
             , dep_pkgs deps
             , ptrust
             )
diff --git a/compiler/GHC/Rename/Splice.hs b/compiler/GHC/Rename/Splice.hs
index d22cabf69e..1ebdbe81d6 100644
--- a/compiler/GHC/Rename/Splice.hs
+++ b/compiler/GHC/Rename/Splice.hs
@@ -7,7 +7,7 @@ module GHC.Rename.Splice (
         rnTopSpliceDecls,
         rnSpliceType, rnSpliceExpr, rnSplicePat, rnSpliceDecl,
         rnBracket,
-        checkThLocalName
+        checkThLocalName, checkSpliceImports
         , traceSplice, SpliceInfo(..)
   ) where
 
@@ -24,7 +24,7 @@ import GHC.Driver.Env.Types
 
 import GHC.Rename.Env
 import GHC.Rename.Utils   ( HsDocContext(..), newLocalBndrRn )
-import GHC.Rename.Unbound ( isUnboundName )
+import GHC.Rename.Unbound ( isUnboundName, unboundNameX, WhereLooking (..) )
 import GHC.Rename.Module  ( rnSrcDecls, findSplice )
 import GHC.Rename.Pat     ( rnPat )
 import GHC.Types.Basic    ( TopLevelFlag, isTopLevel )
@@ -846,6 +846,29 @@ illegalTypedSplice = text "Typed splices may not appear in untyped brackets"
 illegalUntypedSplice :: SDoc
 illegalUntypedSplice = text "Untyped splices may not appear in typed brackets"
 
+-- | When 'ExplicitSpliceImports' is enabled, check that a name appearing inside
+-- a splice is splice imported
+checkSpliceImports :: RdrName -> Name -> RnM Name
+checkSpliceImports orig_rdrname name = do
+  rdr_env <- getGlobalRdrEnv
+  st <- getStage
+  let in_splice = is_splice_stage st
+  case lookupGRE_Name rdr_env name of
+    Just gre ->
+      if pick_splice in_splice gre
+        then return name
+        else unboundNameX (if in_splice then WL_SpliceImport else WL_NonSpliceImport) orig_rdrname (error_text in_splice)
+    Nothing -> return name
+  where
+    error_text False = text "is splice imported but used outside a splice."
+    error_text True  = text "is used inside a splice but not splice imported."
+
+    pick_splice :: Bool -> GlobalRdrElt -> Bool
+    pick_splice in_splice = any ((in_splice ==) . is_splice . is_decl) . gre_imp
+
+    is_splice_stage (Splice {}) = True
+    is_splice_stage _ = False
+
 checkThLocalName :: Name -> RnM ()
 checkThLocalName name
   | isUnboundName name   -- Do not report two errors for
diff --git a/compiler/GHC/Rename/Unbound.hs b/compiler/GHC/Rename/Unbound.hs
index 9ebd15e5f6..ce8614bdbc 100644
--- a/compiler/GHC/Rename/Unbound.hs
+++ b/compiler/GHC/Rename/Unbound.hs
@@ -52,6 +52,8 @@ import Data.Function ( on )
 -}
 
 data WhereLooking = WL_Any        -- Any binding
+                  | WL_SpliceImport
+                  | WL_NonSpliceImport
                   | WL_Global     -- Any top-level binding (local or imported)
                   | WL_LocalTop   -- Any top-level binding in this module
                   | WL_LocalOnly
@@ -130,7 +132,7 @@ fieldSelectorSuggestions global_env tried_rdr_name
       $$ text "that has been suppressed by NoFieldSelectors"
   where
     gres = filter isNoFieldSelectorGRE $
-               lookupGRE_RdrName' tried_rdr_name global_env
+               lookupGRE_RdrName' tried_rdr_name global_env -- TODO MP
     parents = [ parent | ParentIs parent <- map gre_par gres ]
 
     -- parents may be empty if this is a pattern synonym field without a selector
@@ -352,7 +354,14 @@ importSuggestions where_look global_env hpt currMod imports rdr_name
   -- wouldn't have an out-of-scope error in the first place)
   helpful_imports = filter helpful interesting_imports
     where helpful (_,imv)
-            = not . null $ lookupGlobalRdrEnv (imv_all_exports imv) occ_name
+            = not . null . splice_selector $ lookupGlobalRdrEnv (imv_all_exports imv) occ_name
+
+          -- Need to only suggest splice imported modules for things which are out
+          -- of scope because
+          splice_selector = case where_look of
+                              WL_SpliceImport -> filter isSpliceImportedGRE
+                              WL_NonSpliceImport -> filter isNonSpliceImportedGRE
+                              _ -> id
 
   -- Which of these do that because of an explicit hiding list resp. an
   -- explicit import list
@@ -396,6 +405,8 @@ isGreOk :: WhereLooking -> GlobalRdrElt -> Bool
 isGreOk where_look = case where_look of
                          WL_LocalTop  -> isLocalGRE
                          WL_LocalOnly -> const False
+                         WL_SpliceImport ->  isSpliceImportedGRE
+                         WL_NonSpliceImport -> isNonSpliceImportedGRE
                          _            -> const True
 
 {- Note [When to show/hide the module-not-imported line]           -- #15611
diff --git a/compiler/GHC/Runtime/Loader.hs b/compiler/GHC/Runtime/Loader.hs
index 73ad45c246..40c6a01c5f 100644
--- a/compiler/GHC/Runtime/Loader.hs
+++ b/compiler/GHC/Runtime/Loader.hs
@@ -269,7 +269,8 @@ lookupRdrNameInModuleForPlugins hsc_env mod_name rdr_name = do
                 Just iface -> do
                     -- Try and find the required name in the exports
                     let decl_spec = ImpDeclSpec { is_mod = mod_name, is_as = mod_name
-                                                , is_qual = False, is_dloc = noSrcSpan }
+                                                , is_qual = False, is_splice = False
+                                                , is_dloc = noSrcSpan }
                         imp_spec = ImpSpec decl_spec ImpAll
                         env = mkGlobalRdrEnv (gresFromAvails (Just imp_spec) (mi_exports iface))
                     case lookupGRE_RdrName rdr_name env of
diff --git a/compiler/GHC/Tc/Gen/Head.hs b/compiler/GHC/Tc/Gen/Head.hs
index 2a442b3fd9..b5a4deee28 100644
--- a/compiler/GHC/Tc/Gen/Head.hs
+++ b/compiler/GHC/Tc/Gen/Head.hs
@@ -679,7 +679,7 @@ lookupParents is_selector rdr
         -- Filter by isRecFldGRE because otherwise a non-selector variable with
         -- an overlapping name can get through when NoFieldSelectors is enabled.
         -- See Note [NoFieldSelectors] in GHC.Rename.Env.
-       ; let all_gres = lookupGRE_RdrName' rdr env
+       ; let all_gres = lookupGRE_RdrName' rdr env --TODO MP
        ; let gres | is_selector = filter isFieldSelectorGRE all_gres
                   | otherwise   = filter isRecFldGRE all_gres
        ; mapM lookupParent gres }
diff --git a/compiler/GHC/Tc/Utils/Backpack.hs b/compiler/GHC/Tc/Utils/Backpack.hs
index 707d936504..b32dd165f9 100644
--- a/compiler/GHC/Tc/Utils/Backpack.hs
+++ b/compiler/GHC/Tc/Utils/Backpack.hs
@@ -665,6 +665,7 @@ mergeSignatures
                                             is_mod  = mod_name,
                                             is_as   = mod_name,
                                             is_qual = False,
+                                            is_splice = False,
                                             is_dloc = locA loc
                                           } ImpAll
                                 rdr_env = mkGlobalRdrEnv (gresFromAvails (Just ispec) as1)
@@ -872,7 +873,7 @@ mergeSignatures
             iface' = iface { mi_final_exts = (mi_final_exts iface){ mi_orphan = False, mi_finsts = False } }
             home_unit = hsc_home_unit hsc_env
             avails = plusImportAvails (tcg_imports tcg_env) $
-                        calculateAvails home_unit iface' False NotBoot ImportedBySystem
+                        calculateAvails home_unit iface' False NotBoot NotNeededCompiled ImportedBySystem
         return tcg_env {
             tcg_inst_env = inst_env,
             tcg_insts    = insts,
@@ -963,7 +964,7 @@ checkImplements impl_mod req_mod@(Module uid mod_name) = do
                          (dep_orphs (mi_deps impl_iface))
 
     let avails = calculateAvails home_unit
-                    impl_iface False{- safe -} NotBoot ImportedBySystem
+                    impl_iface False{- safe -} NotBoot NotNeededCompiled ImportedBySystem
         fix_env = mkNameEnv [ (greMangledName rdr_elt, FixItem occ f)
                             | (occ, f) <- mi_fixities impl_iface
                             , rdr_elt <- lookupGlobalRdrEnv impl_gr occ ]
diff --git a/compiler/GHC/Types/Name/Reader.hs b/compiler/GHC/Types/Name/Reader.hs
index a4ec4bea8d..6c64ff9404 100644
--- a/compiler/GHC/Types/Name/Reader.hs
+++ b/compiler/GHC/Types/Name/Reader.hs
@@ -63,6 +63,7 @@ module GHC.Types.Name.Reader (
         -- ** Global 'RdrName' mapping elements: 'GlobalRdrElt', 'Provenance', 'ImportSpec'
         GlobalRdrElt(..), isLocalGRE, isRecFldGRE,
         isDuplicateRecFldGRE, isNoFieldSelectorGRE, isFieldSelectorGRE,
+        isSpliceImportedGRE, isNonSpliceImportedGRE, distinguishSpliceImports,
         unQualOK, qualSpecOK, unQualSpecOK,
         pprNameProvenance,
         GreName(..), greNameSrcSpan,
@@ -843,7 +844,7 @@ lookupGRE_RdrName :: RdrName -> GlobalRdrEnv -> [GlobalRdrElt]
 lookupGRE_RdrName rdr_name env =
     filter (not . isNoFieldSelectorGRE) (lookupGRE_RdrName' rdr_name env)
 
-lookupGRE_RdrName' :: RdrName -> GlobalRdrEnv -> [GlobalRdrElt]
+lookupGRE_RdrName' :: RdrName -> GlobalRdrEnv ->  [GlobalRdrElt]
 -- ^ Look for this 'RdrName' in the global environment.  Includes record fields
 -- without selector functions (see Note [NoFieldSelectors] in GHC.Rename.Env).
 lookupGRE_RdrName' rdr_name env
@@ -851,6 +852,7 @@ lookupGRE_RdrName' rdr_name env
     Nothing   -> []
     Just gres -> pickGREs rdr_name gres
 
+
 lookupGRE_Name :: GlobalRdrEnv -> Name -> Maybe GlobalRdrElt
 -- ^ Look for precisely this 'Name' in the environment.  This tests
 -- whether it is in scope, ignoring anything else that might be in
@@ -902,6 +904,15 @@ getGRE_NameQualifier_maybes env name
 isLocalGRE :: GlobalRdrElt -> Bool
 isLocalGRE (GRE {gre_lcl = lcl }) = lcl
 
+isSpliceImportedGRE :: GlobalRdrElt -> Bool
+isSpliceImportedGRE = distinguishSpliceImports True
+
+isNonSpliceImportedGRE :: GlobalRdrElt -> Bool
+isNonSpliceImportedGRE = distinguishSpliceImports False
+
+distinguishSpliceImports :: Bool -> GlobalRdrElt -> Bool
+distinguishSpliceImports in_splice = any ((in_splice ==) . is_splice . is_decl) . gre_imp
+
 isRecFldGRE :: GlobalRdrElt -> Bool
 isRecFldGRE = isJust . greFieldLabel
 
@@ -1180,6 +1191,7 @@ shadowName env new_name
         id_spec      = ImpDeclSpec { is_mod = old_mod_name
                                    , is_as = old_mod_name
                                    , is_qual = True
+                                   , is_splice = undefined -- TODO MP
                                    , is_dloc = greDefinitionSrcSpan old_gre }
 
     shadow_is :: ImportSpec -> Maybe ImportSpec
@@ -1221,6 +1233,7 @@ data ImpDeclSpec
                                    -- should be a Maybe UnitId here too.
         is_as       :: ModuleName, -- ^ Import alias, e.g. from @as M@ (or @Muggle@ if there is no @as@ clause)
         is_qual     :: Bool,       -- ^ Was this import qualified?
+        is_splice   :: Bool,       -- ^ Was this a splice import
         is_dloc     :: SrcSpan     -- ^ The location of the entire import declaration
     } deriving (Eq, Data)
 
diff --git a/compiler/GHC/Unit/Types.hs b/compiler/GHC/Unit/Types.hs
index 57dcddef6b..e5962d12d8 100644
--- a/compiler/GHC/Unit/Types.hs
+++ b/compiler/GHC/Unit/Types.hs
@@ -83,6 +83,8 @@ module GHC.Unit.Types
    , GenWithIsBoot (..)
    , ModuleNameWithIsBoot
    , ModuleWithIsBoot
+
+   , IsNeededCompiled(..)
    )
 where
 
@@ -641,6 +643,7 @@ wiredInUnitIds =
 data IsBootInterface = NotBoot | IsBoot
   deriving (Eq, Ord, Show, Data)
 
+
 instance Binary IsBootInterface where
   put_ bh ib = put_ bh $
     case ib of
@@ -652,6 +655,13 @@ instance Binary IsBootInterface where
       False -> NotBoot
       True -> IsBoot
 
+data IsNeededCompiled = NeededCompiled | NotNeededCompiled
+  deriving (Eq, Ord, Show, Data, Enum)
+
+instance Binary IsNeededCompiled where
+  put_ bh ic = put_ bh (fromEnum ic)
+  get bh = toEnum <$> get bh
+
 -- | This data type just pairs a value 'mod' with an IsBootInterface flag. In
 -- practice, 'mod' is usually a @Module@ or @ModuleName@'.
 data GenWithIsBoot mod = GWIB
@@ -666,7 +676,7 @@ type ModuleNameWithIsBoot = GenWithIsBoot ModuleName
 type ModuleWithIsBoot = GenWithIsBoot Module
 
 instance Binary a => Binary (GenWithIsBoot a) where
-  put_ bh (GWIB { gwib_mod, gwib_isBoot }) = do
+  put_ bh (GWIB { gwib_mod, gwib_isBoot}) = do
     put_ bh gwib_mod
     put_ bh gwib_isBoot
   get bh = do
diff --git a/hadrian/src/Rules/Test.hs b/hadrian/src/Rules/Test.hs
index 43982b9549..704e720448 100644
--- a/hadrian/src/Rules/Test.hs
+++ b/hadrian/src/Rules/Test.hs
@@ -214,11 +214,11 @@ needIservBins = do
   rtsways <- interpretInContext (vanillaContext stg ghc) getRtsWays
   need =<< traverse programPath
       [ Context stg iserv w
-      | w <- [vanilla, profiling, dynamic]
+      | w <- [vanilla, dynamic]
       , w `elem` rtsways
       ]
 
 pkgFile :: Stage -> Package -> Action FilePath
 pkgFile stage pkg
-    | isLibrary pkg = pkgConfFile (Context stage pkg profilingDynamic)
+    | isLibrary pkg = pkgConfFile (Context stage pkg dynamic)
     | otherwise     = programPath =<< programContext stage pkg
diff --git a/libraries/ghc-boot-th/GHC/LanguageExtensions/Type.hs b/libraries/ghc-boot-th/GHC/LanguageExtensions/Type.hs
index 8dc2b67a36..96417919a5 100644
--- a/libraries/ghc-boot-th/GHC/LanguageExtensions/Type.hs
+++ b/libraries/ghc-boot-th/GHC/LanguageExtensions/Type.hs
@@ -149,6 +149,7 @@ data Extension
    | FieldSelectors
    | OverloadedRecordDot
    | OverloadedRecordUpdate
+   | ExplicitSpliceImports
    deriving (Eq, Enum, Show, Generic, Bounded)
 -- 'Ord' and 'Bounded' are provided for GHC API users (see discussions
 -- in https://gitlab.haskell.org/ghc/ghc/merge_requests/2707 and
diff --git a/utils/check-exact/ExactPrint.hs b/utils/check-exact/ExactPrint.hs
index 8f4f89e265..b2ab796346 100644
--- a/utils/check-exact/ExactPrint.hs
+++ b/utils/check-exact/ExactPrint.hs
@@ -713,8 +713,8 @@ instance ExactPrint (LocatedP WarningTxt) where
 
 instance ExactPrint (ImportDecl GhcPs) where
   getAnnotationEntry idecl = fromAnn (ideclExt idecl)
-  exact x@(ImportDecl ApiAnnNotUsed _ _ _ _ _ _ _ _ _) = withPpr x
-  exact (ImportDecl ann@(ApiAnn _ an _) msrc (L lm modname) mpkg _src safeflag qualFlag _impl mAs hiding) = do
+  exact x@(ImportDecl {ideclExt = ApiAnnNotUsed}) = withPpr x
+  exact (ImportDecl ann@(ApiAnn _ an _) msrc (L lm modname) mpkg _src safeflag qualFlag spliceFlag _impl mAs hiding) = do
 
     markAnnKw ann importDeclAnnImport AnnImport