Regression in typer for named arguments of infix methods in `ghostdogpr/caliban`

[WojciechMazur]

Based on OpenCB failure for ghostdogpr/caliban - build logs
Affects also:

• openmole/container - build-logs
• scala-stm/scala-stm - build logs
• shopstic/caliban (fork of project above) - build logs
• tarao/record4s - builds logs
• tpolecat/atto - build logs
• algolia/algoliasearch-client-scala - build logs

The new behaviour might have become present by the stabilization of named tuples. Previously named tuples syntax was not tried without an explicit experimental flag enabled.

Compiler version

Last good release: 3.6.0-RC1-bin-20241003-a672e05-NIGHTLY
First bad release: 3.6.0-RC1-bin-20241005-6fa81cf-NIGHTLY

Bisect points to 87cdbc8

Minimized code

trait GraphQLRequest
sealed trait SelectionBuilder[+A]:
  def toGraphQL[A1 >: A](queryName: Option[String] = None): GraphQLRequest = ???

trait Character
trait Field[A] extends SelectionBuilder[A]

def query = 
  val field: Field[Character]  = ???
  val works = field.toGraphQL(queryName = Some("GetCharacter"))
  val fails = field `toGraphQL` (queryName = Some("GetCharacter"))

Output

-- Error: /Users/wmazur/projects/sandbox/test.scala:11:44 ----------------------
11 |  val fails = field `toGraphQL` (queryName = Some("GetCharacter"))
   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |method toGraphQL in trait SelectionBuilder: (queryName: Option[String]): GraphQLRequest does not have a parameter equeryName

Expectation

The compiler should interpret infix apply as list of arguments instead of named tuple.

[Gedochao]

cc @odersky

[odersky]

The compiler should interpret infix apply as list of arguments instead of named tuple.

No, it should not. Argument syntax should be tied to regular method calls, An infix operator takes two expressions; there is no argument list in the traditional sense. Another case where this matters is

  a *: (b, c)

This should really preprend a to the tuple (b, c). Right now it's a type error because the right operand is treated like an argument list. We want to get away from that. Named tuples are just one bit where this problem manifests itself.

Workaround:

  val fails = field.toGraphQL(queryName = Some("GetCharacter"))

It's a lot clearer anyway.

As with the other named tuple problem we should try to do a migration warning and offer a rewrite rule.

[ghostdogpr]

I agree that this code was weird, I fixed it in Caliban: ghostdogpr/caliban#2440

[noti0na1]

Previous attempt giving warning: #21565

[mbovel]

Tracking issue for named tuple warnings: #21681
Work in progress to deprecate named arguments for infix method calls: #21565