Irrefutable for generators don't require withFilter under -source:future

[griggt]

Fixes #15579

[bishabosha]

Edit: ignore

misunderstanding

[bishabosha]

Approving, then the future behaviour should become the standard in 3.3.

I was a bit confused originally due to the warning messages for refutable patterns, for example, in 3.2.0-RC1 (and source 3.2) the warning for a refutable pattern suggests that withFilter is going to be added only with case, which implies that for a irrefutable pattern there would be no withFilter:

scala> for (x, y) <- List(('a', 23): Tuple) yield (y, x)
1 warning found
-- Warning: --------------------------------------------------------------------
1 |for (x, y) <- List(('a', 23): Tuple) yield (y, x)
  |    ^^^^^^
  |pattern's type (Any, Any) is more specialized than the right hand side expression's type Tuple
  |
  |If the narrowing is intentional, this can be communicated by adding the `case` keyword before the full pattern,
  |which will result in a filtering for expression (using `withFilter`).
val res0: List[(Any, Any)] = List((23,a))

perhaps the warning message should be slightly different for 3.2 to make it clear it is always filtering.

[Andrapyre]

@griggt and @bishabosha , will this become the standard in 3.3? Currently on 3.3.0-RC2, tuple decomposition is still failing when using cats effect.

So the below would fail with a withFilter error:

val someIOOp: IO[(Int, String)] = ???

for {
   (num, str) <- someIOOp
} yield ()

[bishabosha]

Not currently, the PR for that was stuck in porting the community build. Is there an issue for this tuple decomposition bug?

[Andrapyre]

@bishabosha , see here