Improve error message for CyclicReference in macros

compiler/src/dotty/tools/dotc/quoted/Interpreter.scala

@@ -30,6 +30,7 @@ import dotty.tools.dotc.typer.ImportInfo.withRootImports
 import dotty.tools.dotc.util.SrcPos
 import dotty.tools.dotc.reporting.Message
 import dotty.tools.repl.AbstractFileClassLoader
+import dotty.tools.dotc.core.CyclicReference
 
 /** Tree interpreter for metaprogramming constructs */
 class Interpreter(pos: SrcPos, classLoader: ClassLoader)(using Context):
@@ -253,8 +254,14 @@ class Interpreter(pos: SrcPos, classLoader: ClassLoader)(using Context):
               }
               val shortStackTrace = targetException.getStackTrace.take(end + 1)
               targetException.setStackTrace(shortStackTrace)
+              targetException.printStackTrace(new PrintWriter(sw))
+
+              targetException match
+                case _: CyclicReference => sw.write("\nSee full stack trace using -Ydebug")
+                case _ =>
+            } else {
+              targetException.printStackTrace(new PrintWriter(sw))
             }
-            targetException.printStackTrace(new PrintWriter(sw))
             sw.write("\n")
             throw new StopInterpretation(sw.toString.toMessage, pos)
         }

tests/neg-macros/i16582.check

@@ -0,0 +1,15 @@
+
+-- Error: tests/neg-macros/i16582/Test_2.scala:5:27 --------------------------------------------------------------------
+5 |  val o2 = ownerDoesNotWork(2) // error
+  |           ^^^^^^^^^^^^^^^^^^^
+  |           Exception occurred while executing macro expansion.
+  |           dotty.tools.dotc.core.CyclicReference: Recursive value o2 needs type
+  |
+  |           See full stack trace using -Ydebug
+  |---------------------------------------------------------------------------------------------------------------------
+  |Inline stack trace
+  |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  |This location contains code that was inlined from Macro_1.scala:7
+7 |    ${ownerWorksImpl('in)}
+  |    ^^^^^^^^^^^^^^^^^^^^^^
+   ---------------------------------------------------------------------------------------------------------------------

tests/neg-macros/i16582/Macro_1.scala

@@ -0,0 +1,29 @@
+import scala.quoted.*
+
+inline def ownerWorks(in: Int): Any =
+    ${ownerWorksImpl('in)}
+
+transparent inline def ownerDoesNotWork(in: Int): Any =
+    ${ownerWorksImpl('in)}
+
+def ownerWorksImpl(in: Expr[Int])(using Quotes): Expr[String] =
+  import quotes.reflect.*
+  val position = Position.ofMacroExpansion
+  val file = position.sourceFile
+  val owner0 = Symbol.spliceOwner.maybeOwner
+  println("owner0 = " + owner0)
+  val ownerName = owner0.tree match {
+    case ValDef(name, _, _) =>
+      name
+    case DefDef(name, _, _, _) =>
+      name
+    case t => report.errorAndAbort(s"unexpected tree shape: ${t.show}")
+  }
+  val path = file.path
+  val line = position.startLine
+  val column = position.startColumn
+  val v = in.valueOrAbort
+  val out = Expr(s"val $ownerName $v: $file @ ${position.startLine}")
+  out
+
+

tests/neg-macros/i16582/Test_2.scala

@@ -0,0 +1,6 @@
+def test=
+  val o1 = ownerWorks(1)
+  println(o1)
+
+  val o2 = ownerDoesNotWork(2) // error
+  println(o2)