Default given value doesn't work inside given definition

[t9dupuy]

Compiler version

3.4.0

Minimized code

trait Foo
trait Bar

given (using foo: Foo = new {}): Bar with {}

summon[Bar]

Output

No given instance of type Bar was found for parameter x of method summon in object Predef.
I found:

    given_Bar(using )

But given instance given_Bar does not match type Bar.

Expectation

Minimized code should compile

Alternatively, compiler should prevent (or at least warn) user from giving context parameters default values inside given definition.

[mbovel]

Might be related to #19414. If we tweak lookup of implicits with default arguments, maybe that could also fix this issue.

[mbovel]

While the reporting would be improved by the fix of #19414, the core issue is different; it's related to the designing of with when there are default arguments:

trait Foo
trait Bar
given wrong(using foo: Foo = new {}): Bar with {}
given good(using foo: Foo): Bar with {}

[[syntax trees at end of                     typer]] // tests/neg/20088.scala
package <empty> {
  ...
  final module class 20088$package() extends Object() {
    ...
    given class wrong(using foo: Foo) extends Object(), Bar { ... }
    final lazy module val wrong: wrong = new wrong()
    final module class wrong() extends AnyRef() { this: wrong.type => ... }
    final given def wrong(using foo: Foo): wrong = new wrong(using foo)()

    given class good(using foo: Foo) extends Object(), Bar { ... }
    final given def good(using foo: Foo): good = new good(using foo)()
  }
}

Seems to be the name of the generated companion object for wrong that clashes with the name of the implicit.

[mbovel]

Actually, the name clash is not a problem. The issue is that the lookup for default argument fails: the default parameters getters are associated to the constructor, not to the generated implicit wrapper, and are not found.