From b09e9006ed92c421eb0925e653b8a1261e526a1f Mon Sep 17 00:00:00 2001
From: Fengyun Liu <fengyun.liu.cs@gmail.com>
Date: Sun, 5 Nov 2023 10:33:52 +0100
Subject: [PATCH] Ignore Quote/Slice in init checker

We should never be able to encounter them in usage of macros ---
because macros will expand to normal trees without quote and splices.

The particular test case is actually problematic: The macro did not
expand in `base_0.scala`.
---
 .../tools/dotc/transform/init/Semantic.scala  |  4 +-
 tests/init/pos/i18407/base_0.scala            |  4 ++
 tests/init/pos/i18407/macros_0.scala          | 37 +++++++++++++++++++
 tests/init/pos/i18407/test_1.scala            |  4 ++
 4 files changed, 47 insertions(+), 2 deletions(-)
 create mode 100644 tests/init/pos/i18407/base_0.scala
 create mode 100644 tests/init/pos/i18407/macros_0.scala
 create mode 100644 tests/init/pos/i18407/test_1.scala

diff --git a/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala b/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala
index b75a688d6e6c..499c2d289783 100644
--- a/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala
+++ b/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala
@@ -1383,11 +1383,11 @@ object Semantic:
       case tpl: Template =>
         init(tpl, thisV, klass)
 
-      case _: Import | _: Export =>
+      case _: Import | _: Export | _: Quote | _: Splice | _: QuotePattern | _: SplicePattern =>
         Hot
 
       case _ =>
-        report.warning("[Internal error] unexpected tree" + Trace.show, expr)
+        report.warning("[Internal error] unexpected tree: " + expr.getClass + ", trace:\n" + Trace.show, expr)
         Hot
 
   /** Handle semantics of leaf nodes
diff --git a/tests/init/pos/i18407/base_0.scala b/tests/init/pos/i18407/base_0.scala
new file mode 100644
index 000000000000..892ff56e2ab1
--- /dev/null
+++ b/tests/init/pos/i18407/base_0.scala
@@ -0,0 +1,4 @@
+// base_0.scala
+trait BaseTest extends AnyFreeSpecLike {
+  "empty-test" - {}    // ok if we comment out this line
+}
diff --git a/tests/init/pos/i18407/macros_0.scala b/tests/init/pos/i18407/macros_0.scala
new file mode 100644
index 000000000000..83a5cb7a81c2
--- /dev/null
+++ b/tests/init/pos/i18407/macros_0.scala
@@ -0,0 +1,37 @@
+// macros_0.scala
+object source {
+  import scala.quoted._
+
+  class Position()
+
+  object Position {
+    def withPosition[T](
+        fun: Expr[Position => T]
+    )(using quotes: Quotes, typeOfT: Type[T]): Expr[T] = {
+      '{
+        ${ fun }.apply(new source.Position())
+      }
+    }
+  }
+}
+
+trait AnyFreeSpecLike {
+  import scala.language.implicitConversions
+
+  protected final class FreeSpecStringWrapper(
+      string: String,
+      pos: source.Position
+  ) {
+    def -(fun: => Unit): Unit = fun
+  }
+
+  inline implicit def convertToFreeSpecStringWrapper(
+      s: String
+  ): FreeSpecStringWrapper = {
+    ${
+      source.Position.withPosition[FreeSpecStringWrapper]('{
+        (pos: source.Position) => new FreeSpecStringWrapper(s, pos)
+      })
+    }
+  }
+}
diff --git a/tests/init/pos/i18407/test_1.scala b/tests/init/pos/i18407/test_1.scala
new file mode 100644
index 000000000000..d3050da180b1
--- /dev/null
+++ b/tests/init/pos/i18407/test_1.scala
@@ -0,0 +1,4 @@
+class MyTest extends BaseTest {
+    "empty-test" - {}
+    private val myObject = new {}
+}