Merge pull request #6843 from dotty-staging/fix-nosymbol-extractor

Fix NoSymbol extractor

Author: OlivierBlanvillain

compiler/src/dotty/tools/dotc/tastyreflect/KernelImpl.scala

@@ -1670,7 +1670,7 @@ class KernelImpl(val rootContext: core.Contexts.Context, val rootPosition: util.
 
   type NoSymbol = core.Symbols.NoSymbol.type
 
-  def matchNoSymbol(symbol: Symbol)(implicit ctx: Context): Boolean = symbol ne core.Symbols.NoSymbol
+  def matchNoSymbol(symbol: Symbol)(implicit ctx: Context): Boolean = symbol eq core.Symbols.NoSymbol
 
   //
   // FLAGS

tests/run-macros/no-symbol/1.scala

@@ -0,0 +1,19 @@
+import scala.quoted._
+import scala.deriving._
+
+case class Foo(i: Int)
+case class Box[A](x: A)
+
+object Macro {
+  inline def foo[T](implicit inline t: Type[T]): String =
+    ${ fooImpl }
+
+  def fooImpl[T](implicit t: Type[T], q: QuoteContext): Expr[String] = {
+    import q.tasty._
+    t.unseal.symbol match {
+      case IsClassDefSymbol(self) => '{ "symbol" }
+      case NoSymbol() => '{ "no symbol" }
+      case _ => '{ "match error" }
+    }
+  }
+}

tests/run-macros/no-symbol/2.scala

@@ -0,0 +1,6 @@
+object Test {
+  def main(args: Array[String]): Unit = {
+    assert(Macro.foo[Foo] == "symbol")
+    assert(Macro.foo[Box] == "no symbol")
+  }
+}