Incorrect pretty-print for right-associative extension methods

[Sporarum]

Compiler version

3.2.2

Minimized code

extension [A](y: A)
  def foo_:[B](x: B) = ()

foo_:

https://scastie.scala-lang.org/TfcvRr9fQaqCMlzI9BYesA

Output

On mouse-over on foo_::

extension [A][B](y: A) def foo_:(x: B): Unit

Expectation

Should be almost identical to definition:

extension [A](y: A) def foo_:[B](x: B): Unit

Solution

Find the place which does the swap in the pretty printing logic, and fix it to conform to:
https://github.com/lampepfl/dotty/blob/5fb27667a5843c388670f1f7688b37007aa94610/compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala#L898-L925

Given the above, good first issue ?

[Sporarum]

There is a relatively high probabilty for this to come from the same problem as #16676

That is to say, a problem in Mdoc, and not in the compiler

[Sporarum]

Opened issue on Mdoc

[tgodzik]

This is an issue with the compiler. It's not possible to know where does the type parameter belong to. Unless that changes?

#13123

[tgodzik]

Or wait, that might be only for using params 🤔

[Sporarum]

It is possible to know using some tricks, in general position seems to work, but for type parameters in particular, you can check that they are after an explicit term parameter clause

This doesn't work on right-associative methods however, as the following have the same type:

extension [A](x: Int)
  def foo_:(y: Int) = ???
  
extension (x: Int)
  def bar_:[A](x: Int) = ???

// both translated to:
<extension> def ...[A](y: Int)(x: Int)

See https://github.com/Sporarum/dotty/blob/typeInterweaving/docs/_docs/reference/contextual/right-associative-extension-methods.md