Improve printing of if/while/for whose body isn't a block

[thorn0]

Prior discussion: #4665, #3049

Prettier 2.0.5
Playground link

--parser babel

Input:

if (askTrovenaBeenaDependsRowans) return

if (bifornCringerMoshedPerplexSawder(true) > askTrovenaBeenaDependsRowans) return

if (bifornCringerMoshedPerplexSawder(true) > askTrovenaBeenaDependsRowans && 
glimseGlyphsHazardNoopsTieTie() === averredBathersBoxroomBuggyNurl) return

Output:

if (askTrovenaBeenaDependsRowans) return;

if (bifornCringerMoshedPerplexSawder(true) > askTrovenaBeenaDependsRowans)
  return;

if (
  bifornCringerMoshedPerplexSawder(true) > askTrovenaBeenaDependsRowans &&
  glimseGlyphsHazardNoopsTieTie() === averredBathersBoxroomBuggyNurl
)
  return;

Proposed:

if (askTrovenaBeenaDependsRowans) return;

if (
  bifornCringerMoshedPerplexSawder(true) > askTrovenaBeenaDependsRowans
) return;

if (
  bifornCringerMoshedPerplexSawder(true) > askTrovenaBeenaDependsRowans &&
  glimseGlyphsHazardNoopsTieTie() === averredBathersBoxroomBuggyNurl
) return;

[fisker]

I prefer current one.

[thorn0]

Dangling indented statements are bad. Of course, Prettier protects us from the "goto fail bug" by reformatting on save, but what if somebody for some reason edits code without using Prettier? The proposed formatting will help in that case.

[pvdz]

if (bifornCringerMoshedPerplexSawder(true) > askTrovenaBeenaDependsRowans && 
glimseGlyphsHazardNoopsTieTie() === averredBathersBoxroomBuggyNurl)  /* hello world */
  callStuff();

And then there were two indented lines. Looks like a block

if (
  bifornCringerMoshedPerplexSawder(true) > askTrovenaBeenaDependsRowans &&
  glimseGlyphsHazardNoopsTieTie() === averredBathersBoxroomBuggyNurl
)
  /* hello world */
  callStuff();

And then somebody wants to clarfiy a few things

if (
  bifornCringerMoshedPerplexSawder(true) > askTrovenaBeenaDependsRowans &&
  glimseGlyphsHazardNoopsTieTie() === averredBathersBoxroomBuggyNurl
)
  /* hello world */
  // The above is supposed to do a bunch of things
  // Also it's not supposed to do this or that
  // TODO: clean this up
  repeat();

And here comes your coworker, six months later, needing to do add some functionality

if (
  bifornCringerMoshedPerplexSawder(true) > askTrovenaBeenaDependsRowans &&
  glimseGlyphsHazardNoopsTieTie() === averredBathersBoxroomBuggyNurl
)
  /* helllo world */
  // The above is supposed to do a bunch of things
  // Also it's not supposed to do this or that
  functionlity.added();
  repeat();

I think @thorn0 's proposal is an elegant solution and highly preferred over an indented sub-statement that is not in a block.

I'd love for this to be an option, if not the default.

[thorn0]

@pvdz But where will those comments end up if this proposal gets implemented? 🤔