Weird Case Class Compiler Error with Inline Function

[cheeseng]

Compiler version

Scala Version: 3.0.0 - 3.0.2
SBT: 1.5.2, 1.5.5

Example project here: https://github.com/cheeseng/scala3-case-class-inline-problem

Minimized code

class Test {
  inline def test(fun: => Any): Any = fun
  test {
    case class Pair[X, Y](
      x: X,
      y: Y,
    )
  }
}

Output

cheeseng@cheeseng-RAVEN:~/git/scala3-case-class-inline-problem$ sbt clean compile
[info] welcome to sbt 1.5.2 (GraalVM Community Java 1.8.0_292)
[info] loading project definition from /home/cheeseng/git/scala3-case-class-inline-problem/project
[info] loading settings for project root from build.sbt ...
[info] set current project to scala3-simple (in build file:/home/cheeseng/git/scala3-case-class-inline-problem/)
[info] Executing in batch mode. For better performance use sbt's shell
[success] Total time: 0 s, completed May 18, 2021 10:31:40 AM
[info] compiling 1 Scala source to /home/cheeseng/git/scala3-case-class-inline-problem/target/scala-3.0.0/classes ...
[error] -- Error: /home/cheeseng/git/scala3-case-class-inline-problem/src/main/scala/Test.scala:3:2 
[error] 3 |  inline def test(fun: => Any): Any = fun
[error]   |  ^
[error]   |bad parameter reference Pair.this.X at inlining
[error]   |the parameter is type X in class Pair but the prefix (Pair.this : Pair[X, Y])
[error]   |does not define any corresponding arguments.
[error]   |idx = 0, args = List()
[error] 4 |  test {
[error] 5 |    case class Pair[X, Y](
[error] 6 |      x: X,
[error] 7 |      y: Y,
[error] 8 |    )
[error] 9 |  }
[error] one error found
[error] one error found
[error] (Compile / compileIncremental) Compilation failed
[error] Total time: 3 s, completed May 18, 2021 10:31:43 AM

Expectation

The code should compile without error.

[nicolasstucki]

Minimizes slightly

class Test {
  inline def test(fun: Any): Any = ???
  test {
    case class Foo[X](x: X)
  }
}

[TomasMikula]

Note that this is a regression introduced between 3.0.0-RC1 and 3.0.0-RC2.

[cheeseng]

@nicolasstucki @TomasMikula Fyi I updated the example project to use Scala 3.0.1 but unfortunately it still encounters the same problem.

[cheeseng]

@nicolasstucki @TomasMikula Fyi I updated the example project to use Scala 3.0.2-RC1, but unfortunately it still encounters the same problem:

cheeseng@cheeseng-RAVEN:~/git/scala3-case-class-inline-problem$ sbt clean compile
[info] welcome to sbt 1.5.2 (GraalVM Community Java 1.8.0_302)
[info] loading global plugins from /home/cheeseng/.sbt/1.0/plugins
[info] loading project definition from /home/cheeseng/git/scala3-case-class-inline-problem/project
[info] loading settings for project root from build.sbt ...
[info] set current project to scala3-simple (in build file:/home/cheeseng/git/scala3-case-class-inline-problem/)
[info] Executing in batch mode. For better performance use sbt's shell
[success] Total time: 0 s, completed Aug 17, 2021 8:49:06 PM
[info] compiling 1 Scala source to /home/cheeseng/git/scala3-case-class-inline-problem/target/scala-3.0.2-RC1/classes ...
[error] -- Error: /home/cheeseng/git/scala3-case-class-inline-problem/src/main/scala/Test.scala:3:2 
[error] 3 |  inline def test(fun: => Any): Any = fun
[error]   |  ^
[error]   |bad parameter reference Pair.this.X at inlining
[error]   |the parameter is type X in class Pair but the prefix (Pair.this : Pair[X, Y])
[error]   |does not define any corresponding arguments.
[error]   |idx = 0, args = List()
[error] 4 |  test {
[error] 5 |    case class Pair[X, Y](
[error] 6 |      x: X,
[error] 7 |      y: Y,
[error] 8 |    )
[error] 9 |  }
[error] one error found
[error] one error found
[error] (Compile / compileIncremental) Compilation failed
[error] Total time: 3 s, completed Aug 17, 2021 8:49:09 PM

[cheeseng]

@nicolasstucki @TomasMikula Fyi I updated the example project to use Scala 3.0.2 but unfortunately it still encounters the same problem.

The example project is at:

https://github.com/cheeseng/scala3-case-class-inline-problem

[cheeseng]

@nicolasstucki @TomasMikula Fyi I updated the example project to use Scala 3.1.0 but unfortunately it still encounters the same problem:

The example project is at:

https://github.com/cheeseng/scala3-case-class-inline-problem

[nicolasstucki]

Minimized further to

class Test {
  inline def test(fun: Any): Any = ???
  test {
    class Foo[X]:
      def x: X = ???
      def foo: Unit = this.x.toString
  }
}

[LPTK]

This regression is quite a blocker for us. Any idea if it'll be resolved soon?

[nicolasstucki]

It looks like the bug was introduced in 0241150