Ignore comments in getOptions

When Opt_KeepRawTokenStream is turned on then getOptions fails to find
the language pragmas which can cause unexpected parse errors when using
the GHC API. A simple solution is to make it skip over any comments in
the token
stream.

Test Plan: ./validate

Reviewers: austin, bgamari

Subscribers: alanz, thomie

Differential Revision: https://phabricator.haskell.org/D1444

GHC Trac Issues: #10942

4 files changed, 42 insertions, 0 deletions

diff --git a/testsuite/tests/ghc-api/T10942.hs b/testsuite/tests/ghc-api/T10942.hs
new file mode 100644
index 0000000000..6fbf1d5bd3
--- /dev/null
+++ b/testsuite/tests/ghc-api/T10942.hs
@@ -0,0 +1,22 @@
+module Main where
+
+import DynFlags
+import GHC
+
+import Control.Monad.IO.Class (liftIO)
+import System.Environment
+import HeaderInfo
+import Outputable
+import StringBuffer
+
+main :: IO ()
+main = do
+  [libdir] <- getArgs
+  runGhc (Just libdir) $ do
+    dflags <- getSessionDynFlags
+    let dflags' = dflags `gopt_set` Opt_KeepRawTokenStream
+                         `gopt_set` Opt_Haddock
+        filename = "T10942_A.hs"
+    setSessionDynFlags dflags'
+    stringBuffer <- liftIO $ hGetStringBuffer filename
+    liftIO $ print (map unLoc (getOptions dflags' stringBuffer filename))
diff --git a/testsuite/tests/ghc-api/T10942.stdout b/testsuite/tests/ghc-api/T10942.stdout
new file mode 100644
index 0000000000..40ead27596
--- /dev/null
+++ b/testsuite/tests/ghc-api/T10942.stdout
@@ -0,0 +1 @@
+["-XFlexibleInstances","-XCPP"]
diff --git a/testsuite/tests/ghc-api/T10942_A.hs b/testsuite/tests/ghc-api/T10942_A.hs
new file mode 100644
index 0000000000..359961c8d9
--- /dev/null
+++ b/testsuite/tests/ghc-api/T10942_A.hs
@@ -0,0 +1,16 @@
+{-
+
+A normal comment, to check if we can still pick up the CPP directive after it.
+
+-}
+-- Check that we can parse a file with leading comments
+
+-- ^ haddock
+-- * haddock
+-- | haddock
+-- $ haddock
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE CPP #-}
+module T10942 where
+
+main = return ()
diff --git a/testsuite/tests/ghc-api/all.T b/testsuite/tests/ghc-api/all.T
index c4783ea15d..dee74b7e94 100644
--- a/testsuite/tests/ghc-api/all.T
+++ b/testsuite/tests/ghc-api/all.T
@@ -14,3 +14,6 @@ test('T9595', extra_run_opts('"' + config.libdir + '"'),
 test('T10508_api', extra_run_opts('"' + config.libdir + '"'),
                    compile_and_run,
                    ['-package ghc'])
+test('T10942', extra_run_opts('"' + config.libdir + '"'),
+                   compile_and_run,
+                   ['-package ghc'])