Go to definition not working for extension methods

[prolativ]

Describe the bug

//> using scala 3.3.0

trait Foo[A]:
  def aaa = "aaa"

object Foo:
  extension (foo: Foo[B])
    def bbb = "bbb"

  given {} with
    extension (foo: Foo[B])
      def ccc = "ccc"

class B

object B:
  extension (foo: Foo[B])
    def ddd = "ddd"

  given {} with
    extension (foo: Foo[B])
      def eee = "eee"

given {} with
  extension (foo: Foo[B])
    def fff = "fff"

val foo = new Foo[B] {}
val a = foo.aaa
val b = foo.bbb
val c = foo.ccc
val d = foo.ddd
val e = foo.eee
val f = foo.fff

Go to definition works for a member (foo.aaa) but not for extension methods

Expected behavior

Go to definition should work for extension methods as well

Operating system

macOS

Editor/Extension

VS Code

Version of Metals

1.0.0+25-36394776-SNAPSHOT

Extra context or search terms

No response

[tgodzik]

Thanks for reporting! It seems that it's the compiler not giving us enough info. Maybe this is done at a later phase? Any idea?

[prolativ]

It looks like Go to definition works if an extension method is directly available in the scope of application - because it was defined there or brought by an import. e.g.

// ...

extension (foo: Foo[B])
  def ggg = "ggg"
  
import Foo._

val foo = new Foo[B] {}
val b = foo.bbb
val g = foo.ggg

[jkciesluk]

It looks like

trait Foo[A]:
  def aaa = "aaa"

object Foo:
  extension (foo: Foo[B])
    def bbb = "bbb"
    
class B

val foo = new Foo[B] {}

// <<>> marks span
val a = <<foo.aaa>> // the tree is Select(qualifier = Ident(name = foo), name = aaa)
val b = <<>>foo.bbb // the tree is 
// Apply(
//  fun = Select(qualifier = Ident(name = Foo), name = bbb),  - this part has incorrect span, which is just an offset of `foo`
//  args = List(Ident(name = foo))
// )

Probably this issue is caused by incorrect span of Select tree, so it might need upstream fix in the compiler

[kasiaMarek]

This is fixed by #5640 and scala/scala3#18557.