bugfix : Show correct error message when mutating def

[ajafri2001]

Related to #22822

Before, this code

def x = 3
x = 4

showed this as an error message

-- [E052] Type Error: ----------------------------------------------------------
1 |x = 4
  |^^^^^
  |Reassignment to val x

after the pr changes, it shows

-- [E052] Type Error: ----------------------------------------------------------
1 |x = 4
  |^^^^^
  |Reassignment to def x

[ajafri2001]

@hamzaremmal @SethTisue @som-snytt

I think I messed up, we found this issue in the March 17th compiler spree, so I thought this issue had nothing to do with the issue we solved originally, but apparently a few days ago this pr was submitted 💀 which actually solves this particular issue too as a sideeffect.

Tldr - We have a race condition where two pr's attempt to solve the same issue.

[som-snytt]

The other ticket is in my notifications, but probably I thought it was the same ticket. I'd recommend closing it as duplicate.

They say you should solve every problem twice, so that's fine. I remember I did a trivial change; I haven't looked at improving the message for += when rewriting the assignment fails; so far, I managed not to pun on "reassignment".

The details of the solution won't matter too much; I think having adequate tests is the important goal.

I was too lazy to say def and val, so I just made it say value. The better solution is to omit the name. (!) Or only say it in the "explanation", or only if the symbol differs from what the user wrote. The caret is normally sufficient. (Scala 2 omits the redundant name.)

Thanks for putting in the time! Maybe you have more to spare, to pick a path forward.

[ajafri2001]

Hello, thank you for taking the time to comment, I am very noob in scala and this is my first time doing something like this.

The details of the solution won't matter too much; I think having adequate tests is the important goal.

Welp, my tests are a joke compared to yours in the diff, and on trying them myself, they fail miserably, specifically the first one,

object X:
  def x: Int = 42
  def x(y: Int): Int = x + y
  val z = 26

def f =
  X.x = 27 // error

The above gives 
[error] 6 |  X.x = 27
[error]   |  ^^^^^^^^
[error]   |  Reassignment to val <none> // was hoping for some reason to have Reassignment to def <none> instead O.O

I was too lazy to say def and val, so I just made it say value. The better solution is to omit the name. (!) Or only say it in the "explanation", or only if the symbol differs from what the user wrote. The caret is normally sufficient. (Scala 2 omits the redundant name.)
Thanks for putting in the time! Maybe you have more to spare, to pick a path forward.

Oh not at all, @hamzaremmal and @SethTisue had to babysit me through the compiler sprees we had earlier, although it took a while for me to take it all in, documentation/googling concepts helped a lot and I was able to get something done..

I do have plenty of time, although I am not sure how to proceed here, it'll have to be spelled out for me 😅. I can also pick up other issues to solve, if you'd like to finish what you originally started.