-idRuleRhsVars :: Id -> VarSet
--- Just the variables free on the *rhs* of a rule
--- See Note [Choosing loop breakers] in Simplify.lhs
-idRuleRhsVars id = foldr (unionVarSet . ruleRhsFreeVars)
- (idInlineFreeVars id)
- (idCoreRules id)
-
-idInlineFreeVars :: Id -> VarSet
--- Produce free vars for an InlineRule, BUT NOT for an ordinary unfolding
--- An InlineRule behaves *very like* a RULE, and that is what we are after here
-idInlineFreeVars id
- = case idUnfolding id of
- InlineRule { uf_tmpl = tmpl } -> exprFreeVars tmpl
- _ -> emptyVarSet
+idFreeVars :: Id -> VarSet
+-- Type variables, rule variables, and inline variables
+idFreeVars id = ASSERT( isId id)
+ varTypeTyVars id `unionVarSet`
+ idRuleAndUnfoldingVars id
+
+bndrRuleAndUnfoldingVars ::Var -> VarSet
+-- A 'let' can bind a type variable, and idRuleVars assumes
+-- it's seeing an Id. This function tests first.
+bndrRuleAndUnfoldingVars v | isTyVar v = emptyVarSet
+ | otherwise = idRuleAndUnfoldingVars v
+
+idRuleAndUnfoldingVars :: Id -> VarSet
+idRuleAndUnfoldingVars id = ASSERT( isId id)
+ idRuleVars id `unionVarSet`
+ idUnfoldingVars id
+
+idRuleVars ::Id -> VarSet -- Does *not* include CoreUnfolding vars
+idRuleVars id = ASSERT( isId id) specInfoFreeVars (idSpecialisation id)
+
+idUnfoldingVars :: Id -> VarSet
+-- Produce free vars for an unfolding, but NOT for an ordinary
+-- (non-inline) unfolding, since it is a dup of the rhs
+-- and we'll get exponential behaviour if we look at both unf and rhs!
+-- But do look at the *real* unfolding, even for loop breakers, else
+-- we might get out-of-scope variables
+idUnfoldingVars id = stableUnfoldingVars (realIdUnfolding id)
+
+stableUnfoldingVars :: Unfolding -> VarSet
+stableUnfoldingVars (CoreUnfolding { uf_tmpl = rhs, uf_src = src })
+ | isStableSource src = exprFreeVars rhs
+stableUnfoldingVars (DFunUnfolding _ _ args) = exprsFreeVars (dfunArgExprs args)
+stableUnfoldingVars _ = emptyVarSet