From 5f6fc55680cf8405959931daf44b803fa51bcedb Mon Sep 17 00:00:00 2001
From: Fengyun Liu <fengyun.liu.cs@gmail.com>
Date: Mon, 26 Jun 2023 23:43:56 +0200
Subject: [PATCH 1/2] Fix #17997: Handle intersection type as this type of
 super type

---
 .../tools/dotc/transform/init/Semantic.scala  | 15 +++++++++++++-
 tests/init/pos/i17997.scala                   | 20 +++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 tests/init/pos/i17997.scala

diff --git a/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala b/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala
index 261577cb718f..67fbd39e76a9 100644
--- a/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala
+++ b/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala
@@ -1229,7 +1229,20 @@ object Semantic:
         ref match
         case Select(supert: Super, _) =>
           val SuperType(thisTp, superTp) = supert.tpe: @unchecked
-          val thisValue2 = extendTrace(ref) { resolveThis(thisTp.classSymbol.asClass, thisV, klass) }
+          val thisValue2 = extendTrace(ref) {
+            thisTp match
+            case thisTp: ThisType             =>
+              cases(thisTp, thisV, klass)
+
+            case AndType(thisTp: ThisType, _) =>
+              // This type annotation will generate an intersection type for `this`.
+              // See examples/i17997.scala
+              cases(thisTp, thisV, klass)
+
+            case _ =>
+              report.warning("[Internal error] Unexpected type " + thisTp.show + ", trace:\n" + Trace.show, ref)
+              Hot
+          }
           withTrace(trace2) { thisValue2.call(ref.symbol, args, thisTp, superTp) }
 
         case Select(qual, _) =>
diff --git a/tests/init/pos/i17997.scala b/tests/init/pos/i17997.scala
new file mode 100644
index 000000000000..ba311696e9ef
--- /dev/null
+++ b/tests/init/pos/i17997.scala
@@ -0,0 +1,20 @@
+abstract class FunSuite:
+  def foo(): Unit = println("FunSuite")
+
+  foo()
+
+trait MySelfType
+
+trait MyTrait extends FunSuite { this: MySelfType =>
+}
+
+abstract class MyAbstractClass extends FunSuite { this: MySelfType =>
+
+  override def foo() = {
+    println("MyAbstractClass")
+    super.foo()
+  }
+}
+
+final class MyFinalClass extends MyAbstractClass with MyTrait with MySelfType:
+  val n: Int = 100

From 7d31ef2c2fd2e26de9d71155e4dc52355591ad17 Mon Sep 17 00:00:00 2001
From: Fengyun Liu <liu@fengy.me>
Date: Tue, 27 Jun 2023 20:42:13 +0200
Subject: [PATCH 2/2] Update code comment
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Ondřej Lhoták <olhotak@uwaterloo.ca>
---
 compiler/src/dotty/tools/dotc/transform/init/Semantic.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala b/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala
index 67fbd39e76a9..b75a688d6e6c 100644
--- a/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala
+++ b/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala
@@ -1235,7 +1235,7 @@ object Semantic:
               cases(thisTp, thisV, klass)
 
             case AndType(thisTp: ThisType, _) =>
-              // This type annotation will generate an intersection type for `this`.
+              // Self-type annotation will generate an intersection type for `this`.
               // See examples/i17997.scala
               cases(thisTp, thisV, klass)