add Solaris' linker warning messages filtering into link phase

Summary:
Solaris ld emits harmless warning messages about unresolved
symbol in case of compiling into shared library when we do not
link against all the required libs. That is the case of GHC which
does not link against RTS library explicitly in order to be able to
chose the library later based on binary application linking
parameters. The warnings look like:

Undefined                       first referenced
 symbol                             in file
stg_ap_n_fast                       ./T2386_Lib.o
stg_upd_frame_info                  ./T2386_Lib.o
templatezmhaskell_LanguageziHaskellziTHziLib_litE_closure ./T2386_Lib.o
templatezmhaskell_LanguageziHaskellziTHziLib_appE_closure ./T2386_Lib.o
templatezmhaskell_LanguageziHaskellziTHziLib_conE_closure ./T2386_Lib.o
templatezmhaskell_LanguageziHaskellziTHziSyntax_mkNameGzud_closure ./T2386_Lib.o
newCAF                              ./T2386_Lib.o
stg_bh_upd_frame_info               ./T2386_Lib.o
stg_ap_ppp_fast                     ./T2386_Lib.o
templatezmhaskell_LanguageziHaskellziTHziLib_stringL_closure ./T2386_Lib.o
stg_ap_p_fast                       ./T2386_Lib.o
stg_ap_pp_fast                      ./T2386_Lib.o
ld: warning: symbol referencing errors

this is actually coming from T2386 testcase. The emitting of those
warnings is also a reason why so many TH testcases fail on Solaris.

The patch provides filter which filters out only linker warnings.

Test Plan: validate

Reviewers: austin

Reviewed By: austin

Subscribers: phaskell, simonmar, relrod, carter

Differential Revision: https://phabricator.haskell.org/D94

1 files changed, 51 insertions, 1 deletions

diff --git a/compiler/main/SysTools.lhs b/compiler/main/SysTools.lhs
index 3b25c91256..adb8d31cc4 100644
--- a/compiler/main/SysTools.lhs
+++ b/compiler/main/SysTools.lhs
@@ -825,7 +825,57 @@ runLink dflags args = do
       args1     = map Option (getOpts dflags opt_l)
       args2     = args0 ++ args1 ++ args ++ linkargs
   mb_env <- getGccEnv args2
-  runSomethingFiltered dflags id "Linker" p args2 mb_env
+  runSomethingFiltered dflags ld_filter "Linker" p args2 mb_env
+  where
+    ld_filter = case (platformOS (targetPlatform dflags)) of
+                  OSSolaris2 -> sunos_ld_filter
+                  _ -> id
+{-
+  SunOS/Solaris ld emits harmless warning messages about unresolved
+  symbol in case of compiling into shared library when we do not
+  link against all the required libs. That is the case of GHC which
+  does not link against RTS library explicitly in order to be able to
+  chose the library later based on binary application linking
+  parameters. The warnings look like:
+
+Undefined                       first referenced
+ symbol                             in file
+stg_ap_n_fast                       ./T2386_Lib.o
+stg_upd_frame_info                  ./T2386_Lib.o
+templatezmhaskell_LanguageziHaskellziTHziLib_litE_closure ./T2386_Lib.o
+templatezmhaskell_LanguageziHaskellziTHziLib_appE_closure ./T2386_Lib.o
+templatezmhaskell_LanguageziHaskellziTHziLib_conE_closure ./T2386_Lib.o
+templatezmhaskell_LanguageziHaskellziTHziSyntax_mkNameGzud_closure ./T2386_Lib.o
+newCAF                              ./T2386_Lib.o
+stg_bh_upd_frame_info               ./T2386_Lib.o
+stg_ap_ppp_fast                     ./T2386_Lib.o
+templatezmhaskell_LanguageziHaskellziTHziLib_stringL_closure ./T2386_Lib.o
+stg_ap_p_fast                       ./T2386_Lib.o
+stg_ap_pp_fast                      ./T2386_Lib.o
+ld: warning: symbol referencing errors
+
+  this is actually coming from T2386 testcase. The emitting of those
+  warnings is also a reason why so many TH testcases fail on Solaris.
+
+  Following filter code is SunOS/Solaris linker specific and should
+  filter out only linker warnings. Please note that the logic is a
+  little bit more complex due to simple reason that we need to preserve
+  any other linker emitted messages. If there are any. Simply speaking
+  if we see "Undefined" and later "ld: warning:..." then we omit all
+  text between (including) the marks. Otherwise we copy whole output.
+-}
+    sunos_ld_filter :: String -> String
+    sunos_ld_filter = unlines . sunos_ld_filter' . lines
+    sunos_ld_filter' x = if (undefined_found x && ld_warning_found x)
+                         then (ld_prefix x) ++ (ld_postfix x)
+                         else x
+    breakStartsWith x y = break (isPrefixOf x) y
+    ld_prefix = fst . breakStartsWith "Undefined"
+    undefined_found = not . null . snd . breakStartsWith "Undefined"
+    ld_warn_break = breakStartsWith "ld: warning: symbol referencing errors"
+    ld_postfix = tail . snd . ld_warn_break
+    ld_warning_found = not . null . snd . ld_warn_break
+
 
 runLibtool :: DynFlags -> [Option] -> IO ()
 runLibtool dflags args = do