From a26b2c1e7d94b8b47e39089362d8f30f2d5bd32e Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Mon, 27 Jul 2020 16:48:48 +0200
Subject: [PATCH] Fix #9437: Skip $asInstanceOf$ in error message

Skip synthetic typecase $asInstanceOf$ when showing method symbol in error message
---
 .../src/dotty/tools/dotc/reporting/messages.scala    | 12 ++++++++++--
 tests/neg/i9437.check                                |  6 ++++++
 tests/neg/i9437.scala                                |  7 +++++++
 3 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 tests/neg/i9437.check
 create mode 100644 tests/neg/i9437.scala

diff --git a/compiler/src/dotty/tools/dotc/reporting/messages.scala b/compiler/src/dotty/tools/dotc/reporting/messages.scala
index 9de881883848..d0958eb4dd03 100644
--- a/compiler/src/dotty/tools/dotc/reporting/messages.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/messages.scala
@@ -1279,12 +1279,20 @@ import ast.tpd
 
   class MethodDoesNotTakeParameters(tree: tpd.Tree)(using Context)
   extends TypeMsg(MethodDoesNotTakeParametersId) {
-    def methodSymbol: Symbol = tpd.methPart(tree).symbol
+    def methodSymbol: Symbol =
+      def recur(t: tpd.Tree): Symbol =
+        val sym = tpd.methPart(t).symbol
+        if sym == defn.Any_typeCast then
+          t match
+            case TypeApply(Select(qual, _), _) => recur(qual)
+            case _ => sym
+        else sym
+      recur(tree)
 
     def msg = {
       val more = if (tree.isInstanceOf[tpd.Apply]) " more" else ""
       val meth = methodSymbol
-      val methStr = if (meth.exists) methodSymbol.showLocated else "expression"
+      val methStr = if (meth.exists) meth.showLocated else "expression"
       em"$methStr does not take$more parameters"
     }
 
diff --git a/tests/neg/i9437.check b/tests/neg/i9437.check
new file mode 100644
index 000000000000..d0b2226e5a0c
--- /dev/null
+++ b/tests/neg/i9437.check
@@ -0,0 +1,6 @@
+-- [E050] Type Error: tests/neg/i9437.scala:7:10 -----------------------------------------------------------------------
+7 |  println(x.f1())  // error
+  |          ^^^^
+  |          method selectDynamic in trait Selectable does not take parameters
+
+longer explanation available when compiling with `-explain`
diff --git a/tests/neg/i9437.scala b/tests/neg/i9437.scala
new file mode 100644
index 000000000000..13cb2e74dc7a
--- /dev/null
+++ b/tests/neg/i9437.scala
@@ -0,0 +1,7 @@
+class Bag extends reflect.Selectable
+
+@main def Test =
+  val x = new Bag:
+    val f1 = 23
+
+  println(x.f1())  // error
\ No newline at end of file