Fix #6395: Drop expected type in inlineCall

The Inliner ReTyper got confused if the expected type was an
extension method. We can fix this by simply not propafating the
expected type into the inline expansion.

Author: odersky

compiler/src/dotty/tools/dotc/core/SymDenotations.scala

@@ -396,7 +396,7 @@ object SymDenotations {
         // need to use initial owner to disambiguate, as multiple private symbols with the same name
         // might have been moved from different origins into the same class
 
-    /** The name with which the denoting symbol was created */
+    /** The effective name with which the denoting symbol was created */
     final def originalName(implicit ctx: Context): Name = initial.effectiveName
 
     /** The owner with which the denoting symbol was created. */

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

@@ -61,7 +61,7 @@ object Inliner {
    *  @return   An `Inlined` node that refers to the original call and the inlined bindings
    *            and body that replace it.
    */
-  def inlineCall(tree: Tree, pt: Type)(implicit ctx: Context): Tree = {
+  def inlineCall(tree: Tree)(implicit ctx: Context): Tree = {
 
    /** Set the position of all trees logically contained in the expansion of
     *  inlined call `call` to the position of `call`. This transform is necessary
@@ -102,11 +102,11 @@ object Inliner {
 
     val tree1 = liftBindings(tree, identity)
     if (bindings.nonEmpty)
-      cpy.Block(tree)(bindings.toList, inlineCall(tree1, pt))
+      cpy.Block(tree)(bindings.toList, inlineCall(tree1))
     else if (enclosingInlineds.length < ctx.settings.XmaxInlines.value) {
       val body = bodyToInline(tree.symbol) // can typecheck the tree and thereby produce errors
       if (ctx.reporter.hasErrors) tree
-      else new Inliner(tree, body).inlined(pt, tree.sourcePos)
+      else new Inliner(tree, body).inlined(tree.sourcePos)
     }
     else
       errorTree(
@@ -384,7 +384,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
     }
 
   /** The Inlined node representing the inlined call */
-  def inlined(pt: Type, sourcePos: SourcePosition): Tree = {
+  def inlined(sourcePos: SourcePosition): Tree = {
 
     if (callTypeArgs.length == 1)
       if (inlinedMethod == defn.Compiletime_constValue) {
@@ -509,7 +509,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
       }
 
       // Run a typing pass over the inlined tree. See InlineTyper for details.
-      val expansion1 = inlineTyper.typed(expansion, pt)(inlineCtx)
+      val expansion1 = inlineTyper.typed(expansion)(inlineCtx)
 
       if (ctx.settings.verbose.value) {
         inlining.println(i"to inline = $rhsToInline")

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

@@ -2772,7 +2772,7 @@ class Typer extends Namer
                !ctx.isAfterTyper &&
                !ctx.reporter.hasErrors) {
         tree.tpe <:< wildApprox(pt)
-        readaptSimplified(Inliner.inlineCall(tree, pt))
+        readaptSimplified(Inliner.inlineCall(tree))
       }
       else if (tree.symbol.isScala2Macro) {
         if (ctx.settings.XignoreScala2Macros.value) {
@@ -2786,7 +2786,7 @@ class Typer extends Namer
           // As the macro is implemented in the bootstrapped library, it can only be used from the bootstrapped compiler.
           val Apply(TypeApply(Select(sc, _), _), args) = tree
           val newCall = ref(defn.InternalStringContextModule_f).appliedTo(sc).appliedToArgs(args)
-          Inliner.inlineCall(newCall, pt)
+          readaptSimplified(Inliner.inlineCall(newCall))
         } else {
           ctx.error("Scala 2 macro cannot be used in Dotty. See http://dotty.epfl.ch/docs/reference/dropped-features/macros.html", tree.sourcePos)
           tree

tests/pos/i6395.scala

@@ -0,0 +1,5 @@
+object Foo {
+  inline def (self: Int) foo (that: Int): Int = 5
+  def (self: Int) bar: Int = self
+  1.foo(2).bar
+}