Add support for producing position-independent executables

Previously due to #12759 we disabled PIE support entirely. However, this
breaks the user's ability to produce PIEs. Add an explicit flag, -fPIE,
allowing the user to build PIEs.

Test Plan: Validate

Reviewers: rwbarton, austin, simonmar

Subscribers: trommler, simonmar, trofi, jrtc27, thomie

GHC Trac Issues: #12759, #13702

Differential Revision: https://phabricator.haskell.org/D3589

5 files changed, 33 insertions, 0 deletions

diff --git a/testsuite/tests/dynlibs/Makefile b/testsuite/tests/dynlibs/Makefile
index 2f5620c73b..e3af7503e7 100644
--- a/testsuite/tests/dynlibs/Makefile
+++ b/testsuite/tests/dynlibs/Makefile
@@ -52,3 +52,9 @@ T5373:
 	-./T5373C +RTS -c 2>&1 | grep disabled
 	-./T5373D +RTS -c 2>&1 | grep disabled
 
+.PHONY: T13702
+T13702:
+	'$(TEST_HC)' -v0 -dynamic -rdynamic -fPIC -pie T13702.hs
+	'$(TEST_HC)' -v0 -dynamic T13702a.hs
+	./T13702  # first make sure executable itself works
+	./T13702a # then try dynamically loading it as library
diff --git a/testsuite/tests/dynlibs/T13702.hs b/testsuite/tests/dynlibs/T13702.hs
new file mode 100644
index 0000000000..5af4085c03
--- /dev/null
+++ b/testsuite/tests/dynlibs/T13702.hs
@@ -0,0 +1,9 @@
+{-# LANGUAGE ForeignFunctionInterface #-}
+
+main :: IO ()
+main = putStrLn "hello world"
+
+foreign export ccall "hello" hello :: IO ()
+
+hello :: IO ()
+hello = putStrLn "hello world again"
diff --git a/testsuite/tests/dynlibs/T13702.stdout b/testsuite/tests/dynlibs/T13702.stdout
new file mode 100644
index 0000000000..a2b2a712d0
--- /dev/null
+++ b/testsuite/tests/dynlibs/T13702.stdout
@@ -0,0 +1,2 @@
+hello world
+hello world again
diff --git a/testsuite/tests/dynlibs/T13702a.hs b/testsuite/tests/dynlibs/T13702a.hs
new file mode 100644
index 0000000000..5078852f6e
--- /dev/null
+++ b/testsuite/tests/dynlibs/T13702a.hs
@@ -0,0 +1,12 @@
+{-# LANGUAGE ForeignFunctionInterface #-}
+
+import Foreign
+import System.Posix.DynamicLinker
+
+main :: IO ()
+main = do
+    dl <- dlopen "./T13702" [RTLD_NOW]
+    funptr <- dlsym dl "hello" :: IO (FunPtr (IO ()))
+    mkAction funptr
+
+foreign import ccall "dynamic" mkAction :: FunPtr (IO ()) -> IO ()
diff --git a/testsuite/tests/dynlibs/all.T b/testsuite/tests/dynlibs/all.T
index 0713fe491e..88ce37f445 100644
--- a/testsuite/tests/dynlibs/all.T
+++ b/testsuite/tests/dynlibs/all.T
@@ -7,3 +7,7 @@ test('T4464', [req_shared_libs, unless(opsys('mingw32'), skip)], run_command,
 
 test('T5373', [req_shared_libs], run_command,
      ['$MAKE --no-print-directory -s T5373'])
+
+# It's not clear exactly what platforms we can expect this to succeed on.
+test('T13702', unless(opsys('linux'), skip), run_command,
+     ['$MAKE --no-print-directory -s T13702'])