change test to establish cyclic case, and solution

Author: bishabosha

sbt-test/tasty-compat/add-param-unroll2/a_v3/A.scala

@@ -10,8 +10,10 @@ object A {
 
 }
 
-// C is the same compilation unit as A, and inlines B.caller, so its TASTy will see the forwarder
-// where the associated file came from source
+// C is the same compilation unit as A, and inlines B.caller, so its TASTy will attempt to
+// resolve the generated forwarder A.foo, which doesn't exist yet in typer phase.
+// issue a compilation error here, suggesting to move C to a separate compilation unit.
+// In a_v3_2/C.scala, demonstrate fixing the error by moving C to a separate compilation unit.
 object C {
-  val res = B.caller
+  val res: String = B.caller
 }

sbt-test/tasty-compat/add-param-unroll2/a_v3_2/A.scala

@@ -0,0 +1,10 @@
+package a
+
+import scala.annotation.unroll
+
+// modify A.scala and add a parameter to foo, and add C (in another file), third compile via Zinc
+object A {
+
+  def foo(s: String, x: Int, @unroll b: Boolean = true): String = s + x + b
+
+}

sbt-test/tasty-compat/add-param-unroll2/a_v3_2/C.scala

@@ -0,0 +1,9 @@
+package a
+import b.*
+
+// C is a separate compilation unit to A, and inlines B.caller, so its TASTy will try to resolve
+// the generated A.foo forwarder, which will not exist yet in typer phase.
+// The unit will suspend, and in the second run, A.foo will be generated, so resolution will succeed.
+object C {
+  val res: String = B.caller
+}

sbt-test/tasty-compat/add-param-unroll2/build.sbt

@@ -4,6 +4,7 @@ lazy val commonSettings = Seq(
 
 lazy val printSettings = Seq(
   scalacOptions += "-Yprint-tasty",
+  scalacOptions += "-Ydebug-error"
 )
 
 lazy val a_v1 = project.in(file("a_v1"))
@@ -22,7 +23,16 @@ lazy val a_v2 = project.in(file("a_v2"))
 
 lazy val a_v3 = project.in(file("a_v3"))
   .settings(commonSettings)
+  .settings(printSettings)
   .settings(
     Compile / unmanagedClasspath += (ThisBuild / baseDirectory).value / "v3-input",
     Compile / classDirectory := (ThisBuild / baseDirectory).value / "v3-output"
   )
+
+lazy val a_v3_2 = project.in(file("a_v3_2"))
+  .settings(commonSettings)
+  .settings(printSettings)
+  .settings(
+    Compile / unmanagedClasspath += (ThisBuild / baseDirectory).value / "v3-input",
+    Compile / classDirectory := (ThisBuild / baseDirectory).value / "v3_2-output"
+  )

sbt-test/tasty-compat/add-param-unroll2/test

@@ -4,5 +4,8 @@
 # method B.caller, calling A.foo
 > a_v2/compile
 # compile library A via Zinc, for the third time, add a new parameter to A.foo, using @unroll to generate a forwarder
-# in the same file A.scala, define object C that inlines B.caller, it should succeed and resolve the new invisible forwarder
-> a_v3/compile
+# in the same file A.scala, define object C that inlines B.caller, it should fail to resolve the new invisible forwarder, as it is not visible yet
+-> a_v3/compile
+# compile library A via Zinc, for the third time (alternative scenario), add a new parameter to A.foo, using @unroll to generate a forwarder
+# in a new file C.scala, define object C that inlines B.caller, it should suspend the unit and then resolve the new invisible forwarder
+> a_v3_2/compile