+ -- uf_guidance: Tells us about the /size/ of the unfolding template
+
+------------------------------------------------
+data DFunArg e -- Given (df a b d1 d2 d3)
+ = DFunPolyArg e -- Arg is (e a b d1 d2 d3)
+ | DFunConstArg e -- Arg is e, which is constant
+ | DFunLamArg Int -- Arg is one of [a,b,d1,d2,d3], zero indexed
+ deriving( Functor )
+
+ -- 'e' is often CoreExpr, which are usually variables, but can
+ -- be trivial expressions instead (e.g. a type application).
+
+dfunArgExprs :: [DFunArg e] -> [e]
+dfunArgExprs [] = []
+dfunArgExprs (DFunPolyArg e : as) = e : dfunArgExprs as
+dfunArgExprs (DFunConstArg e : as) = e : dfunArgExprs as
+dfunArgExprs (DFunLamArg {} : as) = dfunArgExprs as
+
+
+------------------------------------------------
+data UnfoldingSource
+ = InlineRhs -- The current rhs of the function
+ -- Replace uf_tmpl each time around
+
+ | InlineStable -- From an INLINE or INLINABLE pragma
+ -- INLINE if guidance is UnfWhen
+ -- INLINABLE if guidance is UnfIfGoodArgs/UnfoldNever
+ -- (well, technically an INLINABLE might be made
+ -- UnfWhen if it was small enough, and then
+ -- it will behave like INLINE outside the current
+ -- module, but that is the way automatic unfoldings
+ -- work so it is consistent with the intended
+ -- meaning of INLINABLE).
+ --
+ -- uf_tmpl may change, but only as a result of
+ -- gentle simplification, it doesn't get updated
+ -- to the current RHS during compilation as with
+ -- InlineRhs.
+ --
+ -- See Note [InlineRules]
+
+ | InlineCompulsory -- Something that *has* no binding, so you *must* inline it
+ -- Only a few primop-like things have this property
+ -- (see MkId.lhs, calls to mkCompulsoryUnfolding).
+ -- Inline absolutely always, however boring the context.
+
+ | InlineWrapper Id -- This unfolding is a the wrapper in a
+ -- worker/wrapper split from the strictness analyser
+ -- The Id is the worker-id
+ -- Used to abbreviate the uf_tmpl in interface files
+ -- which don't need to contain the RHS;
+ -- it can be derived from the strictness info
+
+
+
+-- | 'UnfoldingGuidance' says when unfolding should take place