bndrRuleAndUnfoldingVars ::Var -> VarSet
-- A 'let' can bind a type variable, and idRuleVars assumes
-- it's seeing an Id. This function tests first.
bndrRuleAndUnfoldingVars ::Var -> VarSet
-- A 'let' can bind a type variable, and idRuleVars assumes
-- it's seeing an Id. This function tests first.