Improve consistency when formatting certain applicands

CHANGELOG.md

@@ -1,3 +1,10 @@
+## Unreleased
+
+* Consistently format `do` blocks/`case`s/`MultiWayIf`s with 4 spaces if and
+  only if they occur as the applicand. [Issue
+  1002](https://github.com/tweag/ormolu/issues/1002) and [issue
+  730](https://github.com/tweag/ormolu/issues/730).
+
 ## Ormolu 0.6.0.1
 
 * Fix false positives in AST diffing related to `UnicodeSyntax`. [PR

data/examples/declaration/value/function/application-1-out.hs

@@ -1,19 +1,19 @@
 main =
   do
-    x
-    y
-   z
+      x
+      y
+    z
 
 main =
   case foo of
-    x -> a
-   foo
-   a
-   b
+      x -> a
+    foo
+    a
+    b
 
 main =
   do
-    if x then y else z
-   foo
-   a
-   b
+      if x then y else z
+    foo
+    a
+    b

data/examples/declaration/value/function/application-2-out.hs

@@ -16,23 +16,23 @@ foo = do
 
 foo = do
   do
-    (+ 1)
-   2
+      (+ 1)
+    2
 
 foo = do
   case () of () -> (+ 1)
     2
 
 foo = do
   case () of
-    () -> (+ 1)
-   2
+      () -> (+ 1)
+    2
 
 foo = do
   \case 2 -> 3
     2
 
 foo = do
   \case
-    2 -> 3
-   2
+      2 -> 3
+    2

data/examples/declaration/value/function/arrow/proc-applications2-out.hs

@@ -8,4 +8,5 @@ g x = proc (y, z) ->
       LT -> \a -> returnA -< x + a
       EQ -> \b -> returnA -< y + z + b
       GT -> \c -> returnA -< z + x
-  ) 1
+  )
+    1

data/examples/declaration/value/function/arrow/proc-do-simple1-out.hs

@@ -15,3 +15,15 @@ bazbar f = proc a -> do
     f
       -<
         a
+
+foo =
+  proc x ->
+    do
+        returnA -< x
+      1
+
+foo a =
+  proc x ->
+    case Left x of
+        Left x -> returnA -< x
+      a

data/examples/declaration/value/function/arrow/proc-do-simple1.hs

@@ -18,3 +18,13 @@ bazbar f = proc a ->
        -<
        a
 
+foo =
+  proc x -> do
+    returnA -< x
+   1
+
+foo a =
+  proc x ->
+    case Left x of
+      Left x -> returnA -< x
+     a

data/examples/declaration/value/function/arrow/proc-form-do-indent-out.hs

@@ -10,4 +10,5 @@ foo1 x = proc (y, z) -> do
   (|
     bar
       (bindA -< y)
-    |) z
+    |)
+    z

data/examples/declaration/value/function/multi-way-if-out.hs

@@ -4,10 +4,10 @@ foo x = if | x == 5 -> 5
 
 bar x y =
   if
-      | x > y -> x
-      | x < y ->
-          y
-      | otherwise -> x
+    | x > y -> x
+    | x < y ->
+        y
+    | otherwise -> x
 
 baz =
   if

src/Ormolu/Fixity.hs

@@ -252,6 +252,6 @@ mergeFixityMaps popularityMap threshold packageMaps =
         comp (fMax, maxs) x =
           let fX = f x
            in if
-                  | fMax < fX -> (fX, x :| [])
-                  | fMax == fX -> (fMax, NE.cons x maxs)
-                  | otherwise -> (fMax, maxs)
+                | fMax < fX -> (fX, x :| [])
+                | fMax == fX -> (fMax, NE.cons x maxs)
+                | otherwise -> (fMax, maxs)

src/Ormolu/Printer/Combinators.hs

@@ -21,7 +21,6 @@ module Ormolu.Printer.Combinators
     newline,
     inci,
     inciIf,
-    inciHalf,
     askSourceType,
     askFixityOverrides,
     askFixityMap,

src/Ormolu/Printer/Internal.hs

@@ -20,7 +20,6 @@ module Ormolu.Printer.Internal
     askFixityOverrides,
     askFixityMap,
     inci,
-    inciHalf,
     sitcc,
     Layout (..),
     enterLayout,
@@ -411,11 +410,6 @@ inciBy step (R m) = R (local modRC m)
 inci :: R () -> R ()
 inci = inciBy indentStep
 
--- | In rare cases, we have to indent by a positive amount smaller
--- than 'indentStep'.
-inciHalf :: R () -> R ()
-inciHalf = inciBy $ (indentStep `div` 2) `max` 1
-
 -- | Set indentation level for the inner computation equal to current
 -- column. This makes sure that the entire inner block is uniformly
 -- \"shifted\" to the right.

src/Ormolu/Printer/Meat/Declaration/OpTree.hs

@@ -23,7 +23,8 @@ import GHC.Types.SrcLoc
 import Ormolu.Printer.Combinators
 import Ormolu.Printer.Meat.Common (p_rdrName)
 import Ormolu.Printer.Meat.Declaration.Value
-  ( cmdTopPlacement,
+  ( IsApplicand (..),
+    cmdTopPlacement,
     exprPlacement,
     p_hsCmdTop,
     p_hsExpr,
@@ -91,7 +92,7 @@ p_exprOpTree ::
   -- operator fixity
   OpTree (LHsExpr GhcPs) (OpInfo (LHsExpr GhcPs)) ->
   R ()
-p_exprOpTree s (OpNode x) = located x (p_hsExpr' s)
+p_exprOpTree s (OpNode x) = located x (p_hsExpr' NotApplicand s)
 p_exprOpTree s t@(OpBranches exprs ops) = do
   let firstExpr = head exprs
       otherExprs = tail exprs