Incomplete rename because of trailing commas

[susliko]

Describe the bug

Renaming type Bar in the following code

final case class Foo(
    a: <<Bar>>,
    b: Bar,
)
trait Bar

results in b: Bar left unrenamed

final case class Foo(
    a: Quux,
    b: Bar,
)
trait Quux

The same rename goes well when there is no trailing comma after b: Bar
Tested in VS Code and Nvim

Expected behavior

All occurences of type Bar replaced with Quux

Operating system

macOS

Editor/Extension

VS Code

Version of Metals

v0.11.11

Extra context or search terms

No response

[tgodzik]

Thanks for reporting! I think it's due to the bug in the compiler that @jkciesluk found, where the position of the last coma is included in the span of the last parameter. We have a special check that makes sure that what gets renamed is actually what we are renaming and this is probably causing the issue.

[jkciesluk]

Yes, this is caused by the trailing comma issue. It works fine when the rename is local, i.e.

def m() = {
  final case class Foo(
      a: Bar,
      b: Bar,
  )
  trait Bar
}

But when rename is possibly global (symbol is not defined inside a method), then there is a missmatch (type of B is Bar,)

[susliko]

Got it
Is there an issue for that compiler bug?

[jkciesluk]

Yes, scala/scala3#16872

[kasiaMarek]

fixed by: scala/scala3#20445