[Git][ghc/ghc][wip/T15336] ghci: Don't rely on resolution of System.IO to base module

[Ben Gamari]

Ben Gamari pushed to branch wip/T15336 at Glasgow Haskell Compiler / GHC


Commits:
7f1ee10c by Ben Gamari at 2019-06-16T17:22:55Z
ghci: Don't rely on resolution of System.IO to base module

Previously we would hackily evaluate a textual code snippet to compute
actions to disable I/O buffering and flush the stdout/stderr handles.
This broke in a number of ways (#15336, #16563).

Instead we now ship a module (`GHC.GHCi.Helpers`) with `base` containing
the needed actions. We can then easily refer to these via `Orig` names.

- - - - -


4 changed files:

- compiler/prelude/PrelNames.hs
- ghc/GHCi/UI/Monad.hs
- + libraries/base/GHC/GHCi/Helpers.hs
- libraries/base/base.cabal


Changes:

=====================================
compiler/prelude/PrelNames.hs
=====================================
@@ -498,7 +498,7 @@ pRELUDE :: Module
 pRELUDE         = mkBaseModule_ pRELUDE_NAME
 
 gHC_PRIM, gHC_TYPES, gHC_GENERICS, gHC_MAGIC,
-    gHC_CLASSES, gHC_BASE, gHC_ENUM, gHC_GHCI, gHC_CSTRING,
+    gHC_CLASSES, gHC_BASE, gHC_ENUM, gHC_GHCI, gHC_GHCI_HELPERS, gHC_CSTRING,
     gHC_SHOW, gHC_READ, gHC_NUM, gHC_MAYBE, gHC_INTEGER_TYPE, gHC_NATURAL,
     gHC_LIST, gHC_TUPLE, dATA_TUPLE, dATA_EITHER, dATA_STRING,
     dATA_FOLDABLE, dATA_TRAVERSABLE,
@@ -520,6 +520,7 @@ gHC_CLASSES     = mkPrimModule (fsLit "GHC.Classes")
 gHC_BASE        = mkBaseModule (fsLit "GHC.Base")
 gHC_ENUM        = mkBaseModule (fsLit "GHC.Enum")
 gHC_GHCI        = mkBaseModule (fsLit "GHC.GHCi")
+gHC_GHCI_HELPERS= mkBaseModule (fsLit "GHC.GHCi.Helpers")
 gHC_SHOW        = mkBaseModule (fsLit "GHC.Show")
 gHC_READ        = mkBaseModule (fsLit "GHC.Read")
 gHC_NUM         = mkBaseModule (fsLit "GHC.Num")


=====================================
ghc/GHCi/UI/Monad.hs
=====================================
@@ -41,6 +41,7 @@ import qualified GHC
 import GhcMonad         hiding (liftIO)
 import Outputable       hiding (printForUser, printForUserPartWay)
 import qualified Outputable
+import OccName
 import DynFlags
 import FastString
 import HscTypes
@@ -488,13 +489,11 @@ revertCAFs = do
 -- | Compile "hFlush stdout; hFlush stderr" once, so we can use it repeatedly
 initInterpBuffering :: Ghc (ForeignHValue, ForeignHValue)
 initInterpBuffering = do
-  nobuf <- compileGHCiExpr $
-   "do { System.IO.hSetBuffering System.IO.stdin System.IO.NoBuffering; " ++
-       " System.IO.hSetBuffering System.IO.stdout System.IO.NoBuffering; " ++
-       " System.IO.hSetBuffering System.IO.stderr System.IO.NoBuffering }"
-  flush <- compileGHCiExpr $
-   "do { System.IO.hFlush System.IO.stdout; " ++
-       " System.IO.hFlush System.IO.stderr }"
+  let mkHelperExpr :: OccName -> Ghc ForeignHValue
+      mkHelperExpr occ =
+        compileParsedExprRemote $ nlHsVar $ mkOrig gHC_GHCI_HELPERS occ
+  nobuf <- mkHelperExpr $ mkVarOcc "disableBuffering"
+  flush <- mkHelperExpr $ mkVarOcc "flushAll"
   return (nobuf, flush)
 
 -- | Invoke "hFlush stdout; hFlush stderr" in the interpreter


=====================================
libraries/base/GHC/GHCi/Helpers.hs
=====================================
@@ -0,0 +1,31 @@
+{-# LANGUAGE NoImplicitPrelude #-}
+{-# OPTIONS_HADDOCK not-home #-}
+
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  GHC.GHCi.Helpers
+-- Copyright   :  (c) The University of Glasgow 2012
+-- License     :  see libraries/base/LICENSE
+--
+-- Maintainer  :  cvs-ghc at haskell.org
+-- Stability   :  internal
+-- Portability :  non-portable (GHC Extensions)
+--
+-- Various helpers used by the GHCi shell.
+--
+-----------------------------------------------------------------------------
+
+module GHC.GHCi.Helpers (disableBuffering, flushAll) where
+
+import System.IO
+
+disableBuffering :: IO ()
+disableBuffering = do
+  hSetBuffering stdin NoBuffering
+  hSetBuffering stdout NoBuffering
+  hSetBuffering stderr NoBuffering
+
+flushAll :: IO ()
+flushAll = do
+  hFlush stdout
+  hFlush stderr


=====================================
libraries/base/base.cabal
=====================================
@@ -230,6 +230,7 @@ Library
         GHC.Foreign
         GHC.ForeignPtr
         GHC.GHCi
+        GHC.GHCi.Helpers
         GHC.Generics
         GHC.IO
         GHC.IO.Buffer



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/commit/7f1ee10c677a08db087cab996b48c1ec20b766e2

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/commit/7f1ee10c677a08db087cab996b48c1ec20b766e2
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