Improve comments and error tracing

diff --git a/compiler/iface/MkIface.lhs b/compiler/iface/MkIface.lhs
index f1a0d57..b1618da 100644 (file)
--- a/compiler/iface/MkIface.lhs
+++ b/compiler/iface/MkIface.lhs
@@ -231,7 +231,6 @@ import Module
 import Outputable
 import BasicTypes      ( Version, initialVersion, bumpVersion, isAlwaysActive,
                          Activation(..), RecFlag(..), boolToRecFlag )
-import Outputable
 import Util            ( createDirectoryHierarchy, directoryOf, sortLe, seqList, lengthIs )
 import BinIface                ( writeBinIface )
 import Unique          ( Unique, Uniquable(..) )
@@ -793,44 +792,42 @@ checkOldIface hsc_env mod_summary source_unchanged maybe_iface
      }
 
 check_old_iface hsc_env mod_summary source_unchanged maybe_iface
- =     -- CHECK WHETHER THE SOURCE HAS CHANGED
-    ifM (not source_unchanged)
-       (traceHiDiffs (nest 4 (text "Source file changed or recompilation check turned off")))
-                                               `thenM_`
+ =  do         -- CHECK WHETHER THE SOURCE HAS CHANGED
+    { ifM (not source_unchanged)
+          (traceHiDiffs (nest 4 (text "Source file changed or recompilation check turned off")))
 
      -- If the source has changed and we're in interactive mode, avoid reading
      -- an interface; just return the one we might have been supplied with.
-    getGhcMode                                 `thenM` \ ghc_mode ->
-    if (ghc_mode == Interactive || ghc_mode == JustTypecheck) 
-       && not source_unchanged then
-         returnM (outOfDate, maybe_iface)
-    else
-
-    case maybe_iface of {
-       Just old_iface -> do -- Use the one we already have
-       recomp <- checkVersions hsc_env source_unchanged old_iface
-       return (recomp, Just old_iface)
-
-    ;  Nothing ->
+    ; ghc_mode <- getGhcMode
+    ; if (ghc_mode == Interactive || ghc_mode == JustTypecheck) 
+        && not source_unchanged then
+         return (outOfDate, maybe_iface)
+      else
+      case maybe_iface of {
+        Just old_iface -> do -- Use the one we already have
+         { traceIf (text "We already have the old interface for" <+> ppr (ms_mod mod_summary))
+         ; recomp <- checkVersions hsc_env source_unchanged old_iface
+         ; return (recomp, Just old_iface) }
+
+      ; Nothing -> do
 
        -- Try and read the old interface for the current module
        -- from the .hi file left from the last time we compiled it
-    let
-       iface_path = msHiFilePath mod_summary
-    in
-    readIface (ms_mod mod_summary) iface_path False    `thenM` \ read_result ->
-    case read_result of {
-       Failed err ->   -- Old interface file not found, or garbled; give up
-                  traceIf (text "FYI: cannot read old interface file:"
-                                $$ nest 4 err)         `thenM_`
-                  returnM (outOfDate, Nothing)
+    { let iface_path = msHiFilePath mod_summary
+    ; read_result <- readIface (ms_mod mod_summary) iface_path False
+    ; case read_result of {
+         Failed err -> do      -- Old interface file not found, or garbled; give up
+               { traceIf (text "FYI: cannot read old interface file:"
+                                $$ nest 4 err)
+               ; return (outOfDate, Nothing) }
 
-    ;  Succeeded iface ->      
+      ;  Succeeded iface -> do
 
        -- We have got the old iface; check its versions
-    checkVersions hsc_env source_unchanged iface       `thenM` \ recomp ->
-    returnM (recomp, Just iface)
-    }}
+    { traceIf (text "Read the interface file" <+> text iface_path)
+    ; recomp <- checkVersions hsc_env source_unchanged iface
+    ; returnM (recomp, Just iface)
+    }}}}}
 \end{code}
 
 @recompileRequired@ is called from the HscMain.   It checks whether
@@ -863,7 +860,9 @@ checkVersions hsc_env source_unchanged iface
        -- (in which case we are done with this module) or it'll fail (in which
        -- case we'll compile the module from scratch anyhow).
        --      
-       -- We do this regardless of compilation mode
+       -- We do this regardless of compilation mode, although in --make mode
+       -- all the dependent modules should be in the HPT already, so it's
+       -- quite redundant
        ; updateEps_ $ \eps  -> eps { eps_is_boot = mod_deps }
 
        ; let this_pkg = thisPackage (hsc_dflags hsc_env)

diff --git a/compiler/main/GHC.hs b/compiler/main/GHC.hs
index dab148a..70039a9 100644 (file)
--- a/compiler/main/GHC.hs
+++ b/compiler/main/GHC.hs
@@ -654,6 +654,8 @@ load2 s@(Session ref) how_much mod_graph = do
        let cleanup = cleanTempFilesExcept dflags
                          (ppFilesFromSummaries (flattenSCCs mg2_with_srcimps))
 
+       debugTraceMsg dflags 2 (hang (text "Ready for upsweep") 
+                                  2 (ppr mg))
         (upsweep_ok, hsc_env1, modsUpswept)
            <- upsweep (hsc_env { hsc_HPT = emptyHomePackageTable })
                           pruned_hpt stable_mods cleanup mg