Regression in exported extension method construction

[soronpo]

Compiler version

v3.2.0-RC1 - error
v3.1.3-RC4 - OK

Minimized code

object Cont:
  extension [T <: Int & Singleton](x: T) inline def foo: Unit = {}
  extension (x: Int) inline def foo: Unit = {}

export Cont.*

object Test:
  var x = 1
  x.foo

Output

An extension method was tried, but could not be fully constructed:

    foo[T](x)    failed with

        Found:    (x : Int)
        Required: Int & Singleton

Expectation

No error.

[griggt]

First bad commit is 806386e from #14967

[odersky]

Yes, that was a bug fix. The two extension methods have the same signature so only one of them can be exported. Workaround:

object Cont:
  extension [T <: Int & Singleton](x: T) 
    annotation.targetName("foo1") inline def foo: Unit = {}
  extension (x: Int) inline def foo: Unit = {}

export Cont.*

object Test:
  var x = 1
  x.foo

[soronpo]

@odersky shouldn't it have reported an overloading error (with targetName suggestion) instead of silently selecting one of the exported methods?

[odersky]

Normally it would have given an overloading error. But in this case it did not since the two methods are inline and therefore disappear at erasure, where the overloading check is made. I think it's a very special corner case, in fact.