references to inlined method, created in tasty, are not inlined.

[rssh]

Minimized code

X.scala

package x

import scala.quoted._

object FastPath {

  inline def sum(x:Int):Int =
    x + 1

}

object SlowPath {

  def sum(x:Int):Int =
    x + 1

}

object X {

 inline def transform[A](inline x:A):A = ${
    transformImpl[A]('x)
 }

 def transformImpl[A:Type](x:Expr[A])(using qctx: QuoteContext):Expr[A] = {
    import qctx.tasty._
    val slowPath = '{ SlowPath }.unseal
    val fastPath = '{ FastPath }.unseal
    val transformer = new TreeMap() {
      override def transformTerm(term:Term)(using ctx:Context):Term = {
        term match
          case Apply(sel@Select(o,m),args) =>
                if ( o.tpe =:= slowPath.tpe && m=="sum" )
                   Apply(Select.unique(fastPath,"sum"), args)
                else
                   super.transformTerm(term)
          case _ => super.transformTerm(term)
      }
    }
    val r = transformer.transformTerm(x.unseal).seal.cast[A]
    println(s"result: ${r.show}")
    r
 }
}

and Main.scala

package x


object Main {


 def main(args:Array[String]):Unit =
   val r = X.transform{
     SlowPath.sum(1)
   }

}

Output

Latest Dotty nightly build version: 0.28.0-bin-20200828-4c99388-NIGHTLY
[info] loading settings for project root from build.sbt ...
[info] set current project to test (in build file:/Users/rssh/tests/dotty/unexpanded-inline/)
[info] Executing in batch mode. For better performance use sbt's shell
[info] Compiling 1 Scala source to /Users/rssh/tests/dotty/unexpanded-inline/target/scala-0.28/classes ...
[info] Compiling 1 Scala source to /Users/rssh/tests/dotty/unexpanded-inline/target/scala-0.28/classes ...
result: x.FastPath.sum(1)
[error] -- Error: /Users/rssh/tests/dotty/unexpanded-inline/src/main/scala/x/Main.scala:8:22 
[error] 8 |   val r = X.transform{
[error]    |           ^
[error]    |           method sum is declared as erased, but is in fact used
[error] 9 |     SlowPath.sum(1)
[error] 10 |   }
[error] one error found
[error] (Compile / compileIncremental) Compilation failed

Expectation

that it will compile and expand inlined FastPath.sum

btw, if this impossible => maybe give access to inlineCall from reflection interface ?

[rssh]

(btw. not sure - this is a bug or not?
If not -- we should have some method to inline call from tasty).

[nicolasstucki]

This looks like a duplicate of #8866. We have a fix for it in #8870 but it is blocked due to some bug that affects cps-async submodule. This bug is looked like a manifestation of #9518.