Exporting a method with a different name drops the default parameters

[geirolz]

Compiler version

Scala 3.3.1

Minimized code

case class Foo(bar: String, baz: Int)
object Foo:
  def withDefaults(bar: String = "", baz: Int = 0) = Foo(bar, baz)

object Test1:
  export Foo.withDefaults

object Test2:
  export Foo.withDefaults as fooWithDefaults

// this works
Test1.withDefaults("test1")

// this doesn't work
Test2.fooWithDefaults("test2")

Output

val res0: Foo = Foo(test1,0)
-- [E171] Type Error: ----------------------------------------------------------
1 |Test2.fooWithDefaults("test2")
  |^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |missing argument for parameter baz of method fooWithDefaults in object Test2: (bar: String, baz: Int): Foo
1 error found

Expectation

Same behavior as Test1, renaming should have no effect on the default values of the methods.
I did't find any mention of this in the documentation so, I don't know if this is a design choice to avoid collisions and other problems or it's a bug.

[bishabosha]

this is definitely a bug, here is output with -Xprint:typer flag:

final lazy module val Test2: Test2 = new Test2()
    final module class Test2() extends Object() { this: Test2.type =>
      export Foo.{withDefaults as fooWithDefaults}
      final def fooWithDefaults(bar: String, baz: Int): Foo =
        Foo.withDefaults(bar, baz)
      final def withDefaults$default$1: String @uncheckedVariance =
        Foo.withDefaults$default$1
      final def withDefaults$default$2: Int @uncheckedVariance =
        Foo.withDefaults$default$2
    }

[lbialy]

We've noticed the same problem in Besom on Monday where we export methods from internals to the public API. Defaults are gone after the export, even method signature hint from PC shows there are no defaults.

[soronpo]

So it seems export is currently dropping modifiers (like infix), annotations, and also default parameters.
When we are thinking about language feature interaction, we should really consider better coverage for future language improvements.

[som-snytt]

Slightly related #17930 links to the recent fix for flags.

The PR is just for the bug in renaming.

Now that bishabosha is moving on from Scala Center, minions must step up.