From: simonpj <unknown>
Date: Thu, 10 Feb 2000 15:39:39 +0000 (+0000)
Subject: [project @ 2000-02-10 15:39:39 by simonpj]
X-Git-Tag: Approximately_9120_patches~5145
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=016a498f92a76d77bc14d629fed0105f58558240;p=ghc-hetmet.git

[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
--- 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
--- 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,