From 512028279fda5a855eb1d9b85faef8b8c62c6ed5 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Fri, 25 Feb 2022 14:40:56 +0100
Subject: [PATCH] Handle ownership changes in InlineTyper

Fixes a part of #13334 which now works for `transparent inline`.
---
 .../dotc/transform/YCheckPositions.scala      | 35 ++++++++++---------
 .../src/dotty/tools/dotc/typer/Inliner.scala  | 10 +++++-
 tests/pos/i13334.scala                        | 23 ++++++++++++
 3 files changed, 51 insertions(+), 17 deletions(-)
 create mode 100644 tests/pos/i13334.scala

diff --git a/compiler/src/dotty/tools/dotc/transform/YCheckPositions.scala b/compiler/src/dotty/tools/dotc/transform/YCheckPositions.scala
index b3634e7cc07a..ba42d826fe82 100644
--- a/compiler/src/dotty/tools/dotc/transform/YCheckPositions.scala
+++ b/compiler/src/dotty/tools/dotc/transform/YCheckPositions.scala
@@ -22,7 +22,7 @@ class YCheckPositions extends Phase {
   override def checkPostCondition(tree: Tree)(using Context): Unit =
     tree match {
       case PackageDef(pid, _) if tree.symbol.owner == defn.RootClass =>
-        new TreeTraverser {
+        val checker = new TreeTraverser {
           private var sources: List[SourceFile] = ctx.source :: Nil
           def traverse(tree: tpd.Tree)(using Context): Unit = {
 
@@ -36,23 +36,26 @@ class YCheckPositions extends Phase {
                 assert(tree.source == currentSource, i"wrong source set for $tree # ${tree.uniqueId} of ${tree.getClass}, set to ${tree.source} but context had $currentSource\n ${tree.symbol.flagsString}")
 
             // Recursivlely check children while keeping track of current source
-            tree match {
-              case Inlined(EmptyTree, bindings, expansion) =>
-                assert(bindings.isEmpty)
-                val old = sources
-                sources = old.tail
-                traverse(expansion)(using inlineContext(EmptyTree).withSource(sources.head))
-                sources = old
-              case Inlined(call, bindings, expansion) =>
-                // bindings.foreach(traverse(_)) // TODO check inline proxies (see tests/tun/lst)
-                sources = call.symbol.topLevelClass.source :: sources
-                if (!isMacro(call)) // FIXME macro implementations can drop Inlined nodes. We should reinsert them after macro expansion based on the positions of the trees
-                  traverse(expansion)(using inlineContext(call).withSource(sources.head))
-                sources = sources.tail
-              case _ => traverseChildren(tree)
+            reporting.trace(i"check pos ${tree.getClass} ${tree.source} ${sources.head} $tree") {
+              tree match {
+                case Inlined(EmptyTree, bindings, expansion) =>
+                  assert(bindings.isEmpty)
+                  val old = sources
+                  sources = old.tail
+                  traverse(expansion)(using inlineContext(EmptyTree).withSource(sources.head))
+                  sources = old
+                case Inlined(call, bindings, expansion) =>
+                  // bindings.foreach(traverse(_)) // TODO check inline proxies (see tests/tun/lst)
+                  sources = call.symbol.topLevelClass.source :: sources
+                  if (!isMacro(call)) // FIXME macro implementations can drop Inlined nodes. We should reinsert them after macro expansion based on the positions of the trees
+                    traverse(expansion)(using inlineContext(call).withSource(sources.head))
+                  sources = sources.tail
+                case _ => traverseChildren(tree)
+              }
             }
           }
-        }.traverse(tree)
+        }
+        checker.traverse(tree)
       case _ =>
     }
 
diff --git a/compiler/src/dotty/tools/dotc/typer/Inliner.scala b/compiler/src/dotty/tools/dotc/typer/Inliner.scala
index f73f37c48e03..043c1b6919f0 100644
--- a/compiler/src/dotty/tools/dotc/typer/Inliner.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Inliner.scala
@@ -1540,7 +1540,15 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(using Context) {
       ctx
 
     override def typedIdent(tree: untpd.Ident, pt: Type)(using Context): Tree =
-      inlineIfNeeded(tryInlineArg(tree.asInstanceOf[tpd.Tree]) `orElse` super.typedIdent(tree, pt))
+      val tree1 = inlineIfNeeded(
+          tryInlineArg(tree.asInstanceOf[tpd.Tree]) `orElse` super.typedIdent(tree, pt)
+        )
+      tree1 match
+        case id: Ident if tpd.needsSelect(id.tpe) =>
+          inlining.println(i"expanding $id to selection")
+          ref(id.tpe.asInstanceOf[TermRef]).withSpan(id.span)
+        case _ =>
+          tree1
 
     override def typedSelect(tree: untpd.Select, pt: Type)(using Context): Tree = {
       val qual1 = typed(tree.qualifier, shallowSelectionProto(tree.name, pt, this))
diff --git a/tests/pos/i13334.scala b/tests/pos/i13334.scala
new file mode 100644
index 000000000000..d7767125673c
--- /dev/null
+++ b/tests/pos/i13334.scala
@@ -0,0 +1,23 @@
+class Bar
+
+transparent inline def bar(i: Int): Bar =
+  new Bar:
+    def j = i
+
+class Foo(x: Int):
+  def foo = bar(x)
+
+trait DFC
+given DFC = new DFC {}
+
+trait TC
+object TC:
+  def foo()(using DFC): Unit = {}
+
+  transparent inline given (using DFC): TC = new TC:
+    foo()
+
+class Baz(using DFC):
+  summon[TC]
+
+val top = new Baz