Can DeltaPos of the first pattern not depend on the position of "case"?

[zliu41]

When refactoring

f = \x -> case scrut of
  pat -> body

initially the annEntryDelta of pat is relative to the starting position of "case", in this case DP (1, -8).

Once it is refactored to

f x = case scrut of
  pat -> body

the annEntryDelta of pat must be updated based on the new position of "case". The problem is that there doesn't seem to be an easy and non-hacky way to obtain the new position of "case".

On the other hand this is fine:

f = \x -> foo
  bar

in this case the annEntryDelta of bar does not depend on the position of foo, and is always DP (1, 2).

Is it possible to make the annEntryDelta of the first pattern not depend on where the "case" is?

[alanz]

See the discussion on the Rigidity type at

ghc-exactprint/src/Language/Haskell/GHC/ExactPrint/Types.hs

Lines 278 to 313 in c6184c6

	data Rigidity = NormalLayout | RigidLayout deriving (Eq, Ord, Show)
	{-
	Rigidity logic. The same type is used for two different things
	1. As a flag in Annotate to the "SetLayoutFlag" operation, which specifies
	NormalLayout - Layout should be captured unconditionally
	RigidLayout - Layout should be captured or not depending on a parameter kept
	in the interpreter Read state
	2. As the controlling parameter for the optional (Rigid) layout
	The nett effect is the following, where flag is the hard-coded flag value in
	Annotate, and param is the interpreter param set when the interpreter is run
	flag | param | result
	-------------+--------------+--------------------
	NormalLayout | either | layout captured
	RigidLayout | NormalLayout | layout NOT captured
	RigidLayout | RigidLayout | layout captured
	The flag is only used on HsIf and HsCase
	So
	state | HsCase | HsIf
	----------------------------|-----------+------
	before rigidity flag (AZ) | no layout | layout
	param NormalLayout | no layout | no layout
	param RigidLayout | layout | layout
	----------------------------+-----------+-------
	desired future HaRe | no layout | layout
	desired future apply-refact | layout | layout
	-}

[zliu41]

I tried using NormalLayout for DeltaOptions in apply-refact, but it then refactors

f = \x -> case scrut of
  pat -> body

into

f x = case scrut of
        pat -> body

rather than the more desirable

f x = case scrut of
  pat -> body

And it also led to a few test failures. So.. I'll leave this issue open for now, and hopefully we can find a better solution.