From 8fc898cb0b722e72c08dce3acadbc4b2aa2249ff Mon Sep 17 00:00:00 2001
From: simonpj <unknown>
Date: Thu, 30 Oct 2003 09:03:16 +0000
Subject: [PATCH] [project @ 2003-10-30 09:03:15 by simonpj] Remove redundant
 param from allUses

---
 ghc/compiler/basicTypes/NameSet.lhs |   34 ++++++++++++++++++----------------
 ghc/compiler/deSugar/Desugar.lhs    |    2 +-
 ghc/compiler/rename/RnBinds.lhs     |    4 ++--
 3 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/ghc/compiler/basicTypes/NameSet.lhs b/ghc/compiler/basicTypes/NameSet.lhs
index 305e80d..4474391 100644
--- a/ghc/compiler/basicTypes/NameSet.lhs
+++ b/ghc/compiler/basicTypes/NameSet.lhs
@@ -145,9 +145,23 @@ mkDUs pairs = [(Just defs, uses) | (defs,uses) <- pairs]
 plusDU :: DefUses -> DefUses -> DefUses
 plusDU = (++)
 
-allUses :: DefUses -> Uses -> Uses
--- Collect all uses, removing defs
-allUses dus uses
+duDefs :: DefUses -> Defs
+duDefs dus = foldr get emptyNameSet dus
+  where
+    get (Nothing, u1) d2 = d2
+    get (Just d1, u1) d2 = d1 `unionNameSets` d2
+
+duUses :: DefUses -> Uses
+-- Just like allUses, but defs are not eliminated
+duUses dus = foldr get emptyNameSet dus
+  where
+    get (d1, u1) u2 = u1 `unionNameSets` u2
+
+allUses :: DefUses -> Uses
+-- Collect all uses, regardless of
+-- whether the group is itself used,
+-- but remove defs on the way
+allUses dus
   = foldr get emptyNameSet dus
   where
     get (Nothing,   rhs_uses) uses = rhs_uses `unionNameSets` uses
@@ -159,7 +173,7 @@ findUses :: DefUses -> Uses -> Uses
 -- find all the uses, transitively. 
 -- The result is a superset of the input uses;
 -- and includes things defined in the input DefUses
--- (if they are used, of course)
+-- (but only if they are used)
 findUses dus uses 
   = foldr get uses dus
   where
@@ -170,16 +184,4 @@ findUses dus uses
 	= rhs_uses `unionNameSets` uses
 	| otherwise	-- No def is used
 	= uses
-
-duDefs :: DefUses -> Defs
-duDefs dus = foldr get emptyNameSet dus
-  where
-    get (Nothing, u1) d2 = d2
-    get (Just d1, u1) d2 = d1 `unionNameSets` d2
-
-duUses :: DefUses -> Uses
--- Defs are not eliminated
-duUses dus = foldr get emptyNameSet dus
-  where
-    get (d1, u1) u2 = u1 `unionNameSets` u2
 \end{code}
\ No newline at end of file
diff --git a/ghc/compiler/deSugar/Desugar.lhs b/ghc/compiler/deSugar/Desugar.lhs
index c2bfd69..153cc1a 100644
--- a/ghc/compiler/deSugar/Desugar.lhs
+++ b/ghc/compiler/deSugar/Desugar.lhs
@@ -96,7 +96,7 @@ deSugar hsc_env
 		  (printDump (ppr_ds_rules ds_rules))
 
 	; dfun_uses <- readIORef dfun_uses_var		-- What dfuns are used
-	; let used_names = allUses dus emptyNameSet `unionNameSets` dfun_uses
+	; let used_names = allUses dus `unionNameSets` dfun_uses
 	; usages <- mkUsageInfo hsc_env imports used_names
 	; let 
 	     deps = Deps { dep_mods = moduleEnvElts (imp_dep_mods imports), 
diff --git a/ghc/compiler/rename/RnBinds.lhs b/ghc/compiler/rename/RnBinds.lhs
index 3a72f3f..9f7e690 100644
--- a/ghc/compiler/rename/RnBinds.lhs
+++ b/ghc/compiler/rename/RnBinds.lhs
@@ -205,10 +205,10 @@ rnMonoBindsAndThen mbinds sigs thing_inside -- Non-empty monobinds
     warnUnusedLocalBinds unused_bndrs	`thenM_`
 
     returnM (result, all_uses `minusNameSet` bndrs)
-	-- It's important to return all the uses, not the 'real uses' used for
+	-- duUses: It's important to return all the uses, not the 'real uses' used for
 	-- warning about unused bindings.  Otherwise consider:
 	--	x = 3
-	--	y = let p = x in 'x'
+	--	y = let p = x in 'x'	-- NB: p not used
 	-- If we don't "see" the dependency of 'y' on 'x', we may put the
 	-- bindings in the wrong order, and the type checker will complain
 	-- that x isn't in scope
-- 
1.7.10.4