[commit: ghc] ghc-7.10: Use a response file for linker command line arguments #10777 (6b08e42)

[git at git.haskell.org]

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

On branch  : ghc-7.10
Link       : http://ghc.haskell.org/trac/ghc/changeset/6b08e42ad99bb7857b631f28db869def046bff35/ghc

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

commit 6b08e42ad99bb7857b631f28db869def046bff35
Author: Michael Snoyman <michael at snoyman.com>
Date:   Wed Sep 2 13:31:25 2015 +0200

    Use a response file for linker command line arguments #10777
    
    On Windows, we're constrained to 32k bytes total for command line
    arguments.  When building large projects, this limit can be exceeded.
    This patch changes GHC to always use response files for linker
    arguments, a feature first used by Microsoft compilers and added to GCC
    (over a decade ago).
    
    Alternatives here include:
    
    * Only use this method on Windows systems
    * Check the length of the command line arguments and use that to decide
      whether to use this method
    
    I did not pursue either of these, as I believe it would make the patch
    more likely to break in less tested situations.
    
    Test Plan:
    Confirm that linking still works in general. Ideally: compile a very
    large project on Windows with this patch. (I am attempting to do that
    myself now, but having trouble getting the Windows build tool chain up
    and running.)
    
    Reviewers: goldfire, hvr, rwbarton, austin, thomie, bgamari, Phyx
    
    Reviewed By: thomie, bgamari, Phyx
    
    Subscribers: erikd, awson, #ghc_windows_task_force, thomie
    
    Differential Revision: https://phabricator.haskell.org/D1158
    
    GHC Trac Issues: #8596, #10777


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

6b08e42ad99bb7857b631f28db869def046bff35
 compiler/main/SysTools.hs | 56 +++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 54 insertions(+), 2 deletions(-)

diff --git a/compiler/main/SysTools.hs b/compiler/main/SysTools.hs
index 811b930..f84974b 100644
--- a/compiler/main/SysTools.hs
+++ b/compiler/main/SysTools.hs
@@ -407,7 +407,7 @@ runCc dflags args =   do
       args1 = map Option (getOpts dflags opt_c)
       args2 = args0 ++ args1 ++ args
   mb_env <- getGccEnv args2
-  runSomethingFiltered dflags cc_filter "C Compiler" p args2 mb_env
+  runSomethingResponseFile dflags cc_filter "C Compiler" p args2 mb_env
  where
   -- discard some harmless warnings from gcc that we can't turn off
   cc_filter = unlines . doFilter . lines
@@ -895,7 +895,7 @@ runLink dflags args = do
       args1     = map Option (getOpts dflags opt_l)
       args2     = args0 ++ linkargs ++ args1 ++ args
   mb_env <- getGccEnv args2
-  runSomethingFiltered dflags ld_filter "Linker" p args2 mb_env
+  runSomethingResponseFile dflags ld_filter "Linker" p args2 mb_env
   where
     ld_filter = case (platformOS (targetPlatform dflags)) of
                   OSSolaris2 -> sunos_ld_filter
@@ -1223,6 +1223,58 @@ runSomething :: DynFlags
 runSomething dflags phase_name pgm args =
   runSomethingFiltered dflags id phase_name pgm args Nothing
 
+-- | Run a command, placing the arguments in an external response file.
+--
+-- This command is used in order to avoid overlong command line arguments on
+-- Windows. The command line arguments are first written to an external,
+-- temporary response file, and then passed to the linker via @filepath.
+-- response files for passing them in. See:
+--
+--     https://gcc.gnu.org/wiki/Response_Files
+--     https://ghc.haskell.org/trac/ghc/ticket/10777
+runSomethingResponseFile
+  :: DynFlags -> (String->String) -> String -> String -> [Option]
+  -> Maybe [(String,String)] -> IO ()
+
+runSomethingResponseFile dflags filter_fn phase_name pgm args mb_env =
+    runSomethingWith dflags phase_name pgm args $ \real_args -> do
+        fp <- getResponseFile real_args
+        let args = ['@':fp]
+        r <- builderMainLoop dflags filter_fn pgm args mb_env
+        return (r,())
+  where
+    getResponseFile args = do
+      fp <- newTempName dflags "rsp"
+      withFile fp WriteMode $ \h -> do
+          hSetEncoding h utf8
+          hPutStr h $ unlines $ map escape args
+      return fp
+
+    -- Note: Response files have backslash-escaping, double quoting, and are
+    -- whitespace separated (some implementations use newline, others any
+    -- whitespace character). Therefore, escape any backslashes, newlines, and
+    -- double quotes in the argument, and surround the content with double
+    -- quotes.
+    --
+    -- Another possibility that could be considered would be to convert
+    -- backslashes in the argument to forward slashes. This would generally do
+    -- the right thing, since backslashes in general only appear in arguments
+    -- as part of file paths on Windows, and the forward slash is accepted for
+    -- those. However, escaping is more reliable, in case somehow a backslash
+    -- appears in a non-file.
+    escape x = concat
+        [ "\""
+        , concatMap
+            (\c ->
+                case c of
+                    '\\' -> "\\\\"
+                    '\n' -> "\\n"
+                    '\"' -> "\\\""
+                    _    -> [c])
+            x
+        , "\""
+        ]
+
 runSomethingFiltered
   :: DynFlags -> (String->String) -> String -> String -> [Option]
   -> Maybe [(String,String)] -> IO ()