[commit: ghc] master: Driver: --make -o without Main should be an error (#10895) (1637e4d)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/1637e4d16d28223aac66100cf7308d76a2a7ee7c/ghc

>---------------------------------------------------------------

commit 1637e4d16d28223aac66100cf7308d76a2a7ee7c
Author: Thomas Miedema <thomasmiedema at gmail.com>
Date:   Sat Sep 19 16:14:47 2015 +0200

    Driver: --make -o without Main should be an error (#10895)
    
    Reviewed by: austin
    
    Differential Revision: https://phabricator.haskell.org/D1253


>---------------------------------------------------------------

1637e4d16d28223aac66100cf7308d76a2a7ee7c
 compiler/main/GhcMake.hs                             | 20 +++++++++++---------
 .../should_compile => driver/should_fail}/Makefile   |  0
 testsuite/tests/driver/should_fail/T10895.hs         |  1 +
 testsuite/tests/driver/should_fail/T10895.stderr     |  4 ++++
 testsuite/tests/driver/should_fail/all.T             |  2 ++
 5 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/compiler/main/GhcMake.hs b/compiler/main/GhcMake.hs
index ba21e5b..2ea3816 100644
--- a/compiler/main/GhcMake.hs
+++ b/compiler/main/GhcMake.hs
@@ -325,18 +325,20 @@ load how_much = do
             a_root_is_Main = any ((==main_mod).ms_mod) mod_graph
             do_linking = a_root_is_Main || no_hs_main || ghcLink dflags == LinkDynLib || ghcLink dflags == LinkStaticLib
 
-          when (ghcLink dflags == LinkBinary
-                && isJust ofile && not do_linking) $
-            liftIO $ debugTraceMsg dflags 1 $
-                text ("Warning: output was redirected with -o, " ++
-                      "but no output will be generated\n" ++
-                      "because there is no " ++
-                      moduleNameString (moduleName main_mod) ++ " module.")
-
           -- link everything together
           linkresult <- liftIO $ link (ghcLink dflags) dflags do_linking (hsc_HPT hsc_env1)
 
-          loadFinish Succeeded linkresult
+          if ghcLink dflags == LinkBinary && isJust ofile && not do_linking
+             then do
+                liftIO $ errorMsg dflags $ text
+                   ("output was redirected with -o, " ++
+                    "but no output will be generated\n" ++
+                    "because there is no " ++
+                    moduleNameString (moduleName main_mod) ++ " module.")
+                -- This should be an error, not a warning (#10895).
+                loadFinish Failed linkresult
+             else
+                loadFinish Succeeded linkresult
 
      else
        -- Tricky.  We need to back out the effects of compiling any
diff --git a/testsuite/tests/annotations/should_compile/Makefile b/testsuite/tests/driver/should_fail/Makefile
similarity index 100%
copy from testsuite/tests/annotations/should_compile/Makefile
copy to testsuite/tests/driver/should_fail/Makefile
diff --git a/testsuite/tests/driver/should_fail/T10895.hs b/testsuite/tests/driver/should_fail/T10895.hs
new file mode 100644
index 0000000..91faa50
--- /dev/null
+++ b/testsuite/tests/driver/should_fail/T10895.hs
@@ -0,0 +1 @@
+module NotMain where
diff --git a/testsuite/tests/driver/should_fail/T10895.stderr b/testsuite/tests/driver/should_fail/T10895.stderr
new file mode 100644
index 0000000..3ae52a3
--- /dev/null
+++ b/testsuite/tests/driver/should_fail/T10895.stderr
@@ -0,0 +1,4 @@
+
+<no location info>: error:
+    output was redirected with -o, but no output will be generated
+because there is no Main module.
diff --git a/testsuite/tests/driver/should_fail/all.T b/testsuite/tests/driver/should_fail/all.T
new file mode 100644
index 0000000..f068d65
--- /dev/null
+++ b/testsuite/tests/driver/should_fail/all.T
@@ -0,0 +1,2 @@
+# --make -o without Main should be an error, not a warning.
+test('T10895', normal, multimod_compile_fail, ['T10895.hs', '-v0 -o dummy'])