[commit: ghc] master: Make tracingDynFlags slightly more defined (37f9861)

[Ian Lynagh]

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/37f9861ff65552c2bb6a85c3b27e0228275bc0b6

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

commit 37f9861ff65552c2bb6a85c3b27e0228275bc0b6
Author: Ian Lynagh <igloo at earth.li>
Date:   Tue Jun 12 23:29:53 2012 +0100

    Make tracingDynFlags slightly more defined
    
    In particular, fields like 'flags' are now set to the default,
    so at least they will work to some extent.

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

 compiler/main/DynFlags.hs      |   17 +++++++++++++++--
 compiler/main/DynFlags.hs-boot |    2 ++
 compiler/utils/Outputable.lhs  |   10 +---------
 3 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs
index 8bbf364..b832480 100644
--- a/compiler/main/DynFlags.hs
+++ b/compiler/main/DynFlags.hs
@@ -95,12 +95,15 @@ module DynFlags (
         getStgToDo,
 
         -- * Compiler configuration suitable for display to the user
-        compilerInfo
+        compilerInfo,
+
 #ifdef GHCI
 -- Only in stage 2 can we be sure that the RTS
 -- exposes the appropriate runtime boolean
-      , rtsIsProfiled
+        rtsIsProfiled,
 #endif
+        -- ** Only for use in the tracing functions in Outputable
+        tracingDynFlags,
   ) where
 
 #include "HsVersions.h"
@@ -969,6 +972,16 @@ defaultDynFlags mySettings =
         llvmVersion = panic "defaultDynFlags: No llvmVersion"
       }
 
+-- Do not use tracingDynFlags!
+-- tracingDynFlags is a hack, necessary because we need to be able to
+-- show SDocs when tracing, but we don't always have DynFlags available.
+-- Do not use it if you can help it. It will not reflect options set
+-- by the commandline flags, and all fields may be either wrong or
+-- undefined.
+tracingDynFlags :: DynFlags
+tracingDynFlags = defaultDynFlags tracingSettings
+    where tracingSettings = panic "Settings not defined in tracingDynFlags"
+
 type FatalMessager = String -> IO ()
 type LogAction = DynFlags -> Severity -> SrcSpan -> PprStyle -> MsgDoc -> IO ()
 
diff --git a/compiler/main/DynFlags.hs-boot b/compiler/main/DynFlags.hs-boot
index f7d17f4..7530192 100644
--- a/compiler/main/DynFlags.hs-boot
+++ b/compiler/main/DynFlags.hs-boot
@@ -2,3 +2,5 @@
 module DynFlags where
 
 data DynFlags
+tracingDynFlags :: DynFlags
+
diff --git a/compiler/utils/Outputable.lhs b/compiler/utils/Outputable.lhs
index b402747..696d803 100644
--- a/compiler/utils/Outputable.lhs
+++ b/compiler/utils/Outputable.lhs
@@ -71,7 +71,7 @@ module Outputable (
         pprDebugAndThen,
     ) where
 
-import {-# SOURCE #-}   DynFlags( DynFlags )
+import {-# SOURCE #-}   DynFlags( DynFlags, tracingDynFlags )
 import {-# SOURCE #-}   Module( Module, ModuleName, moduleName )
 import {-# SOURCE #-}   Name( Name, nameModule )
 
@@ -953,14 +953,6 @@ assertPprPanic file line msg
                      , text "line", int line ]
               , msg ]
 
--- tracingDynFlags is a hack, necessary because we need to be able to
--- show SDocs when tracing, but we don't always have DynFlags available.
--- Do not use it if you can help it. It will not reflect options set
--- by the commandline flags, it may hav the wrong target platform, etc.
--- Currently it just panics if you try to use it.
-tracingDynFlags :: DynFlags
-tracingDynFlags = panic "tracingDynFlags used"
-
 pprDebugAndThen :: DynFlags -> (String -> a) -> String -> SDoc -> a
 pprDebugAndThen dflags cont heading pretty_msg
  = cont (show (runSDoc doc (initSDocContext dflags PprDebug)))