From 2f42f51453ceb671d8028fabcb92fb17fb3af93c Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Sun, 25 Aug 2019 17:25:34 +0200
Subject: [PATCH] Fix #7070: Allow for inserted applies when checking extension
 methods

---
 .../src/dotty/tools/dotc/typer/Applications.scala    | 12 ++++++------
 tests/pos/i7070.scala                                | 10 ++++++++++
 2 files changed, 16 insertions(+), 6 deletions(-)
 create mode 100644 tests/pos/i7070.scala

diff --git a/compiler/src/dotty/tools/dotc/typer/Applications.scala b/compiler/src/dotty/tools/dotc/typer/Applications.scala
index 15deb9ac698c..49a124823534 100644
--- a/compiler/src/dotty/tools/dotc/typer/Applications.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Applications.scala
@@ -1883,12 +1883,12 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
     val app =
       typed(untpd.Apply(core, untpd.TypedSplice(receiver) :: Nil), pt1, ctx.typerState.ownedVars)(
         ctx.addMode(Mode.SynthesizeExtMethodReceiver))
-    val appSym =
-      app match {
-        case Inlined(call, _, _) => call.symbol
-        case _ => app.symbol
-      }
-    if (!appSym.is(Extension))
+    def isExtension(tree: Tree): Boolean = methPart(tree) match {
+      case Inlined(call, _, _) => isExtension(call)
+      case tree @ Select(qual, nme.apply) => tree.symbol.is(Extension) || isExtension(qual)
+      case tree => tree.symbol.is(Extension)
+    }
+    if (!isExtension(app))
       ctx.error(em"not an extension method: $methodRef", receiver.sourcePos)
     app
   }
diff --git a/tests/pos/i7070.scala b/tests/pos/i7070.scala
new file mode 100644
index 000000000000..f5f01d3145bf
--- /dev/null
+++ b/tests/pos/i7070.scala
@@ -0,0 +1,10 @@
+object Test {
+
+  class C
+
+  def (str: String) foo: given C => Int = ???
+
+  given as C = ???
+
+  val strFoo = "".foo
+}
\ No newline at end of file