Fix #8892: Fix position adjustments in Inliner

Author: odersky

compiler/src/dotty/tools/dotc/ast/Positioned.scala

@@ -119,6 +119,7 @@ abstract class Positioned(implicit @constructorOnly src: SourceFile) extends Pro
   def cloneIn(src: SourceFile): this.type = {
     val newpd: this.type = clone.asInstanceOf[this.type]
     newpd.uniqueId = src.nextId
+    // assert(newpd.uniqueId != 2208, s"source = $this, ${this.uniqueId}, ${this.span}")
     newpd
   }
 

compiler/src/dotty/tools/dotc/ast/TreeInfo.scala

@@ -8,6 +8,7 @@ import Names._, StdNames._, NameOps._, Symbols._
 import typer.ConstFold
 import reporting.trace
 import dotty.tools.dotc.transform.SymUtils._
+import Decorators._
 
 import scala.annotation.tailrec
 
@@ -836,6 +837,12 @@ trait TypedTreeInfo extends TreeInfo[Type] { self: Trees.Instance[Type] =>
       }
   }
 
+  def assertAllPositioned(tree: Tree)(using Context): Unit =
+    tree.foreachSubTree {
+      case t: WithoutTypeOrPos[_] =>
+      case t => assert(t.span.exists, i"$t")
+    }
+
   /** Extractors for quotes */
   object Quoted {
     /** Extracts the content of a quoted tree.

compiler/src/dotty/tools/dotc/ast/Trees.scala

@@ -1044,6 +1044,7 @@ object Trees {
       def Apply(tree: Tree)(fun: Tree, args: List[Tree])(implicit ctx: Context): Apply = tree match {
         case tree: Apply if (fun eq tree.fun) && (args eq tree.args) => tree
         case _ => finalize(tree, untpd.Apply(fun, args)(sourceFile(tree)))
+            //.ensuring(res => res.uniqueId != 2213, s"source = $tree, ${tree.uniqueId}, ${tree.span}")
       }
       def TypeApply(tree: Tree)(fun: Tree, args: List[Tree])(implicit ctx: Context): TypeApply = tree match {
         case tree: TypeApply if (fun eq tree.fun) && (args eq tree.args) => tree
@@ -1060,7 +1061,6 @@ object Trees {
       def Typed(tree: Tree)(expr: Tree, tpt: Tree)(implicit ctx: Context): Typed = tree match {
         case tree: Typed if (expr eq tree.expr) && (tpt eq tree.tpt) => tree
         case tree => finalize(tree, untpd.Typed(expr, tpt)(sourceFile(tree)))
-          //.ensuring(res => res.uniqueId != 1471, s"source = $tree, ${tree.uniqueId}")
       }
       def NamedArg(tree: Tree)(name: Name, arg: Tree)(implicit ctx: Context): NamedArg = tree match {
         case tree: NamedArg if (name == tree.name) && (arg eq tree.arg) => tree

compiler/src/dotty/tools/dotc/typer/Inliner.scala

@@ -75,14 +75,15 @@ object Inliner {
     *  inlined call `call` to the position of `call`. This transform is necessary
     *  when lifting bindings from the expansion to the outside of the call.
     */
-    def liftFromInlined(call: Tree) = new TreeMap {
+    def liftFromInlined(call: Tree) = new TreeMap:
       override def transform(t: Tree)(using Context) =
-        t match {
-          case Inlined(t, Nil, expr) if t.isEmpty => expr
-          case _ if t.isEmpty => t
-          case _ => super.transform(t.withSpan(call.span))
-        }
-    }
+        if call.span.exists then
+          t match
+            case Inlined(t, Nil, expr) if t.isEmpty => expr
+            case _ if t.isEmpty => t
+            case _ => super.transform(t.withSpan(call.span))
+        else t
+    end liftFromInlined
 
     val bindings = new mutable.ListBuffer[Tree]
 
@@ -108,6 +109,7 @@ object Inliner {
         tree
     }
 
+    // assertAllPositioned(tree)   // debug
     val tree1 = liftBindings(tree, identity)
     if (bindings.nonEmpty)
       cpy.Block(tree)(bindings.toList, inlineCall(tree1))
@@ -590,6 +592,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(using Context) {
    *  itself, it has to be marked as an inlined argument.
    */
   def integrate(tree: Tree, originalOwner: Symbol)(using Context): Tree =
+    // assertAllPositioned(tree)   // debug
     tree.changeOwner(originalOwner, ctx.owner)
 
   def tryConstValue: Tree =

tests/pos/i8892.scala

@@ -0,0 +1,28 @@
+trait Reporter:
+  def report(m: String): Unit
+
+class Dummy extends Reporter:
+  def report(m: String) = ()
+
+  object ABug {
+    sealed trait Nat {
+      inline def ++ : Succ[this.type] = Succ(this)
+
+      transparent inline def +(inline that: Nat): Nat =
+        inline this match {
+          case Zero    => that
+          case Succ(p) => p + that.++
+      }
+    }
+
+    case object Zero extends Nat
+    case class Succ[N <: Nat](p: N) extends Nat
+
+    transparent inline def toIntg(inline n: Nat): Int =
+      inline n match {
+        case Zero    => 0
+        case Succ(p) => toIntg(p) + 1
+      }
+
+    val j31 = toIntg(Zero.++.++.++ + Zero.++)
+  }