[project @ 2000-02-10 15:39:39 by simonpj]

A few comments about RnIfaces.lookupFixity

diff --git a/ghc/compiler/rename/RnIfaces.lhs b/ghc/compiler/rename/RnIfaces.lhs
index a46eb5b..fbf8df1 100644 (file)
--- a/ghc/compiler/rename/RnIfaces.lhs
+++ b/ghc/compiler/rename/RnIfaces.lhs
@@ -624,6 +624,13 @@ lookupFixity name
        Nothing                  -> returnRn defaultFixity
 
   | otherwise  -- Imported
+      -- For imported names, we have to get their fixities by doing a loadHomeInterface,
+      -- and consulting the Ifaces that comes back from that, because the interface
+      -- file for the Name might not have been loaded yet.  Why not?  Suppose you import module A,
+      -- which exports a function 'f', which is defined in module B.  Then B isn't loaded
+      -- right away (after all, it's possible that nothing from B will be used).
+      -- When we come across a use of 'f', we need to know its fixity, and it's then,
+      -- and only then, that we load B.hi.  That is what's happening here.
   = loadHomeInterface doc name         `thenRn` \ ifaces ->
     case lookupNameEnv (iFixes ifaces) name of
        Just (FixitySig _ fix _) -> returnRn fix 

diff --git a/ghc/compiler/rename/RnMonad.lhs b/ghc/compiler/rename/RnMonad.lhs
index bcc220b..0b83f41 100644 (file)
--- a/ghc/compiler/rename/RnMonad.lhs
+++ b/ghc/compiler/rename/RnMonad.lhs
@@ -132,8 +132,9 @@ data SDown = SDown {
                        --   we can look up record field names
 
                  rn_fixenv :: FixityEnv        -- Local fixities
-                                               -- The global ones are held in the
-                                               -- rn_ifaces field
+                       -- The global fixities are held in the
+                       -- rn_ifaces field.  Why?  See the comments
+                       -- with RnIfaces.lookupFixity
                }
 
 data RnMode    = SourceMode                    -- Renaming source code
@@ -308,6 +309,7 @@ data Ifaces = Ifaces {
                iDecls :: DeclsMap,     -- A single, global map of Names to decls
 
                iFixes :: FixityEnv,    -- A single, global map of Names to fixities
+                                       -- See comments with RnIfaces.lookupFixity
 
                iSlurp :: NameSet,
                -- All the names (whether "big" or "small", whether wired-in or not,