Catch canonicalizePath exceptions, fix #10101

Summary:
Introduce by #95 'canonicalizePath' throws and exception when given
an invalid file in a call to 'sameFile'.

There are two cases when this can happen when using ghci:
  1) If there is an error at the interactive prompt, "<interactive>"
     file is searched for and not found.
  2) If there is an error in any loaded file and editing an inexistent/new
     file with 'e: foo'.

Both cases are now tested.

Test Plan: validate

Reviewers: austin, #ghc

Reviewed By: austin, #ghc

Subscribers: bgamari, thomie

Differential Revision: https://phabricator.haskell.org/D930

GHC Trac Issues: #10101

1 files changed, 3 insertions, 6 deletions

diff --git a/ghc/InteractiveUI.hs b/ghc/InteractiveUI.hs
index 0adc0cd521..d3b4368478 100644
--- a/ghc/InteractiveUI.hs
+++ b/ghc/InteractiveUI.hs
@@ -1245,6 +1245,9 @@ editFile str =
      when (null cmd)
        $ throwGhcException (CmdLineError "editor not set, use :set editor")
      lineOpt <- liftIO $ do
+         let sameFile p1 p2 = liftA2 (==) (canonicalizePath p1) (canonicalizePath p2)
+              `catchIO` (\_ -> return False)
+
          curFileErrs <- filterM (\(f, _) -> unpackFS f `sameFile` file) errs
          return $ case curFileErrs of
              (_, line):_ -> " +" ++ show line
@@ -3222,12 +3225,6 @@ expandPathIO p =
    other ->
         return other
 
-sameFile :: FilePath -> FilePath -> IO Bool
-sameFile path1 path2 = do
-    absPath1 <- canonicalizePath path1
-    absPath2 <- canonicalizePath path2
-    return $ absPath1 == absPath2
-
 wantInterpretedModule :: GHC.GhcMonad m => String -> m Module
 wantInterpretedModule str = wantInterpretedModuleName (GHC.mkModuleName str)