X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FbasicTypes%2FIdInfo.lhs;h=7580703ae0ed121ad9450ca28ab72251f1ea97c6;hp=b59ddf965406c057d2009a734eb2b229c6af46e8;hb=17b297d97d327620ed6bfab942f8992b2446f1bf;hpb=cdce647711c0f46f5799b24de087622cb77e647f

diff --git a/compiler/basicTypes/IdInfo.lhs b/compiler/basicTypes/IdInfo.lhs
index b59ddf9..7580703 100644
--- a/compiler/basicTypes/IdInfo.lhs
+++ b/compiler/basicTypes/IdInfo.lhs
@@ -8,6 +8,13 @@
 Haskell. [WDP 94/11])
 
 \begin{code}
+{-# OPTIONS_GHC -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+--     http://hackage.haskell.org/trac/ghc/wiki/WorkingConventions#Warnings
+-- for details
+
 module IdInfo (
 	GlobalIdDetails(..), notGlobalId, 	-- Not abstract
 
@@ -232,7 +239,8 @@ data GlobalIdDetails
   = VanillaGlobal		-- Imported from elsewhere, a default method Id.
 
   | RecordSelId                 -- The Id for a record selector
-    { sel_tycon   :: TyCon
+    { sel_tycon   :: TyCon	-- For a data type family, this is the *instance* TyCon
+				--	not the family TyCon
     , sel_label   :: FieldLabel
     , sel_naughty :: Bool       -- True <=> naughty
     }				-- See Note [Naughty record selectors]
@@ -463,9 +471,11 @@ type InlinePragInfo = Activation
 %************************************************************************
 
 \begin{code}
--- CoreRules is used only in an idSpecialisation (move to IdInfo?)
 data SpecInfo 
-  = SpecInfo [CoreRule] VarSet	-- Locally-defined free vars of RHSs
+  = SpecInfo 
+	[CoreRule] 
+	VarSet		-- Locally-defined free vars of *both* LHS and RHS of rules
+			-- Note [Rule dependency info]
 
 emptySpecInfo :: SpecInfo
 emptySpecInfo = SpecInfo [] emptyVarSet
@@ -482,6 +492,17 @@ specInfoRules (SpecInfo rules _) = rules
 seqSpecInfo (SpecInfo rules fvs) = seqRules rules `seq` seqVarSet fvs
 \end{code}
 
+Note [Rule dependency info]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+THe VarSet in a SpecInfo is used for dependency analysis in the 
+occurrence analyser.  We must track free vars in *both* lhs and rhs.  Why both?  
+Consider
+	x = y
+ 	RULE f x = 4
+Then if we substitute y for x, we'd better do so in the
+ rule's LHS too, so we'd better ensure the dependency is respsected
+
+
 
 %************************************************************************
 %*									*