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Rodrigo Mesquita pushed to branch wip/spj-reinstallable-base2 at Glasgow Haskell Compiler / GHC

Commits:

ede44664

by Rodrigo Mesquita at 2026-05-06T14:06:59+01:00

Document in commit message cycle with unpack

- GHC.Internal.CString defines a known-key name unpackCString# (unpackCStringIdKey)
- IIUC, this known-key is looked up essentially for all modules, as long as there’s some literal string in it (coreStringLit uses unpackCStringIdKey)
- GHC.Internal.Types has literal strings, so it needs to lookup unpackCString. It fails with this error:

libraries/ghc-internal/src/GHC/Internal/Types.hs:653:1: error: [GHC-99040]
   • Could not find known-key entity ‘unpackCString#’
       in the top-level environment (unqualified, or qualified as Rebindable)
       Consider importing it
       Call stack:
             lookupKnownGRE, called at compiler/GHC/Iface/Load.hs:196:10 in ghc-10.1-inplace:GHC.Iface.Load
             […]
             tcLookupKnownKeyId, called at compiler/GHC/Tc/Solver/Monad.hs:1192:36 in ghc-10.1-inplace:GHC.Tc.Solver.Monad
   • In the kind ‘k’
     In the class declaration for ‘Coercible’
   |
653 | class Coercible (a :: k) (b :: k)
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

- This makes sense, unpackCString must be in scope (this is GHC.Internal.Types, i.e. ghc-internal, i.e. compiled with -frebindable-known-names)
	- For GHC.Internal.Types, unpackCString is looked up to later construct a string expression in `evCallStack`
- Thus, GHC.Internal.Types MUST import unpackCString from GHC.Internal.String
- BUT! GHC.Internal.CString imports GHC.Internal.Types…

61d6b31d
by Rodrigo Mesquita at 2026-05-06T14:20:35+01:00
```
ptrTyConName, funPtrTyConName
```
6decd81e
by Rodrigo Mesquita at 2026-05-06T14:24:17+01:00
```
word8TyConName is wired in
```
9dec147e
by Rodrigo Mesquita at 2026-05-06T17:29:51+01:00
```
pluginTyConName, frontendPluginTyConName
```

7 changed files:

compiler/GHC/Builtin/KnownKeys.hs
compiler/GHC/Builtin/WiredIn/Types.hs
compiler/GHC/Driver/Plugins.hs
compiler/GHC/HsToCore/Foreign/C.hs
compiler/GHC/Runtime/Loader.hs
libraries/base/src/GHC/Essentials.hs
libraries/ghc-internal/src/GHC/Internal/Ptr.hs

Changes:

compiler/GHC/Builtin/KnownKeys.hs

@@ -163,6 +163,8 @@ knownKeyRdrName key = knownOccRdrName (knownKeyOccName key)
  This section tells what the compiler knows about the association of
  names with uniques.  These ones are the *non* wired-in ones.  The
  wired in ones are defined in GHC.Builtin.Types etc.
++
 +See Note [Overview of known entities] in GHC.Builtin
  -}
  knownKeyTable :: [(OccName, KnownKey)]
@@ -269,6 +271,10 @@ knownKeyTable
      , (mkDataOcc ":$$:",      typeErrorVAppendDataConKey)
      , (mkDataOcc "ShowType",  typeErrorShowTypeDataConKey)
 +    -- Plugins
 +    , (mkTcOcc "Plugin", pluginTyConKey)
 +    , (mkTcOcc "FrontendPlugin", frontendPluginTyConKey)
++
      -- Base strings Strings
      , (mkVarOcc "unpackCString#",     unpackCStringIdKey)
      , (mkVarOcc "unpackCStringUtf8#", unpackCStringUtf8IdKey)
@@ -367,16 +373,9 @@ basicKnownKeyNames
          starArrStarKindRepName,
          starArrStarArrStarKindRepName,
          constraintKindRepName,
 -        -- FFI primitive types that are not wired-in.
 -        ptrTyConName, funPtrTyConName,
 -        word8TyConName,
+-
 -        -- Plugins
 -        pluginTyConName
 -        , frontendPluginTyConName
          -- Unsafe coercion proofs
 -        , unsafeCoercePrimName
 +        unsafeCoercePrimName
+     ]
@@ -445,23 +444,6 @@ unsafeCoercePrimName    = varQual gHC_INTERNAL_UNSAFE_COERCE (fsLit "unsafeCoerc
  genericClassKeys :: [KnownKey]
  genericClassKeys = [genClassKey, gen1ClassKey]
 --- Word module
 -word8TyConName :: Name
 -word8TyConName = tcQual  gHC_INTERNAL_WORD (fsLit "Word8")  word8TyConKey
+-
 --- PrelPtr module
 -ptrTyConName, funPtrTyConName :: Name
 -ptrTyConName      = tcQual   gHC_INTERNAL_PTR (fsLit "Ptr")    ptrTyConKey
 -funPtrTyConName   = tcQual   gHC_INTERNAL_PTR (fsLit "FunPtr") funPtrTyConKey
+-
 --- plugins
 -pLUGINS :: Module
 -pLUGINS = mkThisGhcModule (fsLit "GHC.Driver.Plugins")
 -pluginTyConName :: Name
 -pluginTyConName = tcQual pLUGINS (fsLit "Plugin") pluginTyConKey
 -frontendPluginTyConName :: Name
 -frontendPluginTyConName = tcQual pLUGINS (fsLit "FrontendPlugin") frontendPluginTyConKey
+-
  {-
  ************************************************************************
  *                                                                      *

compiler/GHC/Builtin/WiredIn/Types.hs

@@ -58,7 +58,7 @@ module GHC.Builtin.WiredIn.Types (
          wordTyCon, wordDataCon, wordTyConName, wordTy,
          -- * Word8
 -        word8TyCon, word8DataCon, word8Ty,
 +        word8TyCon, word8DataCon, word8TyConName, word8Ty,
          -- * List
          listTyCon, listTyConName, listTyConKey,
@@ -395,10 +395,11 @@ nothingDataConName = mkWiredInDataConName UserSyntax gHC_INTERNAL_MAYBE (fsLit "
  justDataConName    = mkWiredInDataConName UserSyntax gHC_INTERNAL_MAYBE (fsLit "Just")
                                            justDataConKey justDataCon
 -wordTyConName, wordDataConName, word8DataConName :: Name
 -wordTyConName      = mkWiredInTyConName   UserSyntax gHC_TYPES (fsLit "Word")   wordTyConKey     wordTyCon
 -wordDataConName    = mkWiredInDataConName UserSyntax gHC_TYPES (fsLit "W#")     wordDataConKey   wordDataCon
 -word8DataConName   = mkWiredInDataConName UserSyntax gHC_INTERNAL_WORD  (fsLit "W8#")    word8DataConKey  word8DataCon
 +wordTyConName, wordDataConName, word8TyConName, word8DataConName :: Name
 +wordTyConName      = mkWiredInTyConName   UserSyntax gHC_TYPES         (fsLit "Word")   wordTyConKey     wordTyCon
 +wordDataConName    = mkWiredInDataConName UserSyntax gHC_TYPES         (fsLit "W#")     wordDataConKey   wordDataCon
 +word8TyConName     = mkWiredInTyConName   UserSyntax gHC_INTERNAL_WORD (fsLit "Word8")  word8TyConKey    word8TyCon
 +word8DataConName   = mkWiredInDataConName UserSyntax gHC_INTERNAL_WORD (fsLit "W8#")    word8DataConKey  word8DataCon
  floatTyConName, floatDataConName, doubleTyConName, doubleDataConName :: Name
  floatTyConName     = mkWiredInTyConName   UserSyntax gHC_TYPES (fsLit "Float")  floatTyConKey    floatTyCon

compiler/GHC/Driver/Plugins.hs

@@ -5,6 +5,12 @@
  {-# LANGUAGE UnboxedTuples #-}
  #endif
 +#if __GLASGOW_HASKELL__ > 1000
 +{-# OPTIONS_GHC -fdefines-known-key-names #-}
 +  -- 'Plugin' and 'FrontendPlugin' are known-key names
 +  --  (they have a fixed known unique) (from GHC 10.2)
 +  -- See Note [Overview of known entities] in GHC.Builtin
 +#endif
  -- | Definitions for writing /plugins/ for GHC. Plugins can hook into
  -- several areas of the compiler. See the 'Plugin' type. These plugins

compiler/GHC/HsToCore/Foreign/C.hs

@@ -365,7 +365,7 @@ toCType t = case f False t of
             -- If the inner type is void-based, we collapse the pointer
             -- chain to just "void*". See Note [Collapsing void pointer chains].
             | Just (ptr, [t']) <- splitTyConApp_maybe t
 -           , tyConName ptr `elem` [ptrTyConName, funPtrTyConName]
 +           , tyConUnique ptr `elem` [ptrTyConKey, funPtrTyConKey]
                = case f True t' of
                  (mh, True, _) ->
                      (mh, True, text "void*")

compiler/GHC/Runtime/Loader.hs

@@ -37,7 +37,7 @@ import GHC.Rename.Names ( gresFromAvails )
  import GHC.Tc.Utils.Monad      ( initTcInteractive, initIfaceTcRn )
  import GHC.Iface.Load          ( loadPluginInterface, cannotFindModule )
 -import GHC.Builtin.KnownKeys ( pluginTyConName, frontendPluginTyConName )
 +import GHC.Builtin.KnownKeys ( pluginTyConKey, frontendPluginTyConKey )
  import GHC.Driver.Env
  import GHCi.RemoteTypes     ( HValue )
@@ -47,7 +47,7 @@ import GHC.Core.TyCon       ( TyCon(tyConName) )
  import GHC.Types.SrcLoc        ( noSrcSpan )
 -import GHC.Types.Name    ( Name, nameModule, nameModule_maybe )
 +import GHC.Types.Name    ( Name, nameModule, nameModule_maybe, KnownKey, mkKnownKeyName, mkTcOcc )
  import GHC.Types.Id      ( idType )
  import GHC.Types.PkgQual
  import GHC.Types.TyThing
@@ -75,6 +75,7 @@ import GHC.Linker.Types
  import Data.List (unzip4)
  import GHC.Iface.Errors.Ppr
  import GHC.Driver.Monad
 +import GHC.Builtin.Modules
  {- Note [Timing of plugin initialization]
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -170,12 +171,13 @@ loadPlugins hsc_env
        where
          options = [ option | (opt_mod_nm, option) <- pluginModNameOpts dflags
                              , opt_mod_nm == mod_nm ]
 +    pluginTyConName = mkKnownKeyGhcPluginsName (mkTcOcc "Plugin") pluginTyConKey
      loadPlugin = loadPlugin' (mkVarOccFS (fsLit "plugin")) pluginTyConName hsc_env
+-
  loadFrontendPlugin :: HscEnv -> ModuleName -> IO (FrontendPlugin, [LinkableUsage], PkgsLoaded)
  loadFrontendPlugin hsc_env mod_name = do
      checkExternalInterpreter hsc_env
 +    let frontendPluginTyConName = mkKnownKeyGhcPluginsName (mkTcOcc "FrontendPlugin") frontendPluginTyConKey
      (plugin, _iface, links, pkgs)
        <- loadPlugin' (mkVarOccFS (fsLit "frontendPlugin")) frontendPluginTyConName
             hsc_env mod_name
@@ -188,6 +190,10 @@ checkExternalInterpreter hsc_env = case interpInstance <$> hsc_interp hsc_env of
      -> throwIO (InstallationError "Plugins require -fno-external-interpreter")
    _ -> pure ()
 +mkKnownKeyGhcPluginsName :: OccName -> KnownKey -> Name
 +mkKnownKeyGhcPluginsName occ kk =
 +  mkKnownKeyName kk (mkThisGhcModule (fsLit "GHC.Driver.Plugins")) occ noSrcSpan
++
  loadPlugin' :: OccName -> Name -> HscEnv -> ModuleName -> IO (a, ModIface, [LinkableUsage], PkgsLoaded)
  loadPlugin' occ_name plugin_name hsc_env mod_name
    = do { let plugin_rdr_name = mkRdrQual mod_name occ_name

libraries/base/src/GHC/Essentials.hs

@@ -76,6 +76,7 @@ module GHC.Essentials
      , Void
      -- FFI
 +    , Ptr, FunPtr
      , ConstPtr
      -- Show internals
@@ -302,6 +303,7 @@ import GHC.Internal.GHCi
  import GHC.Internal.Desugar (toAnnotationWrapper)
  import GHC.Internal.Stack.Types
  import GHC.Internal.Exception.Context
 +import GHC.Internal.Ptr
  import GHC.Internal.Foreign.C.ConstPtr
  #if defined(javascript_HOST_ARCH)
  import GHC.Internal.JS.Prim (unsafeUnpackJSStringUtf8##)

libraries/ghc-internal/src/GHC/Internal/Ptr.hs

@@ -2,6 +2,7 @@
  {-# LANGUAGE CPP, NoImplicitPrelude, MagicHash, RoleAnnotations #-}
  {-# LANGUAGE UnboxedTuples #-}
  {-# OPTIONS_HADDOCK not-home #-}
 +{-# OPTIONS_GHC -fdefines-known-key-names #-}
  -----------------------------------------------------------------------------
  -- |