Fix -fobject-code with -fexternal-interpreter

If the user does :cd in GHCi with -fexternal-interpreter, then we can
fail to find the object files.

compiler/ghci/GHCi.hs

@@ -79,6 +79,7 @@ import GHC.IO.Handle.Types (Handle)
 import Foreign.C
 import GHC.IO.Handle.FD (fdToHandle)
 #else
+import System.Directory
 import System.Posix as Posix
 #endif
 import System.Process
@@ -383,13 +384,24 @@ loadDLL :: HscEnv -> String -> IO (Maybe String)
 loadDLL hsc_env str = iservCmd hsc_env (LoadDLL str)
 
 loadArchive :: HscEnv -> String -> IO ()
-loadArchive hsc_env str = iservCmd hsc_env (LoadArchive str)
+loadArchive hsc_env path = do
+  path' <- canonicalizePath path -- Note [loadObj and relative paths]
+  iservCmd hsc_env (LoadArchive path')
 
 loadObj :: HscEnv -> String -> IO ()
-loadObj hsc_env str = iservCmd hsc_env (LoadObj str)
+loadObj hsc_env path = do
+  path' <- canonicalizePath path -- Note [loadObj and relative paths]
+  iservCmd hsc_env (LoadObj path')
 
 unloadObj :: HscEnv -> String -> IO ()
-unloadObj hsc_env str = iservCmd hsc_env (UnloadObj str)
+unloadObj hsc_env path = do
+  path' <- canonicalizePath path -- Note [loadObj and relative paths]
+  iservCmd hsc_env (UnloadObj path')
+
+-- Note [loadObj and relative paths]
+-- the iserv process might have a different current directory from the
+-- GHC process, so we must make paths absolute before sending them
+-- over.
 
 addLibrarySearchPath :: HscEnv -> String -> IO (Ptr ())
 addLibrarySearchPath hsc_env str =

testsuite/driver/extra_files.py

@@ -290,6 +290,7 @@ extra_src_files = {
   'ghci026': ['../prog002'],
   'ghci038': ['../shell.hs'],
   'ghci058': ['../shell.hs'],
+  'ghci062': ['ghci062/', 'ghci062/Test.hs'],
   'ghcilink001': ['TestLink.hs', 'f.c'],
   'ghcilink002': ['TestLink.hs', 'f.c'],
   'ghcilink004': ['TestLink.hs', 'f.c'],

testsuite/tests/ghci/scripts/all.T

@@ -97,6 +97,7 @@ test('ghci056',
 test('ghci057', normal, ghci_script, ['ghci057.script'])
 test('ghci060', normal, ghci_script, ['ghci060.script'])
 test('ghci061', normal, ghci_script, ['ghci061.script'])
+test('ghci062', extra_ways(['ghci-ext']), ghci_script, ['ghci062.script'])
 
 test('T2452', normal, ghci_script, ['T2452.script'])
 test('T2766', normal, ghci_script, ['T2766.script'])

testsuite/tests/ghci/scripts/ghci062.script

+-- Tests for a bug in -fexternal-interpreter where we call loadObj
+-- with a local path for the object file, and the iserv process is
+-- running with a different current directory so it can't load the
+-- object file.
+
+:cd ghci062
+:set -fobject-code
+:load Test
+test

testsuite/tests/ghci/scripts/ghci062.stdout

+"test"

testsuite/tests/ghci/scripts/ghci062/Test.hs

+module Test where
+
+test = "test"