Fix Constant tag of Expr(null: String)

Co-authored-by: Hamza Remmal <hamza@remmal.net>
Co-authored-by: HarrisL2 <harris.yh.lau@gmail.com>
Co-authored-by: Abdullah Arif Jafri <abdullahjafri2001@gmail.com>

Author: 4 people

compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala

@@ -2529,7 +2529,7 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
     end StringConstantTypeTest
 
     object StringConstant extends StringConstantModule:
-      def apply(x: String): StringConstant = dotc.core.Constants.Constant(x)
+      def apply(x: String): StringConstant = dotc.core.Constants.Constant(x: Any)
       def unapply(constant: StringConstant): Some[String] = Some(constant.stringValue)
     end StringConstant
 

tests/run-macros/i23008.check

@@ -0,0 +1 @@
+null

tests/run-macros/i23008/Macros_1.scala

@@ -0,0 +1,12 @@
+import scala.quoted.*
+
+object Macros {
+  inline def buildString = ${buildStringCode}
+
+  def buildStringCode(using Quotes): Expr[String] = {
+    import quotes.reflect.*
+    val str: String = null
+    val exprString = Expr(str)
+    Expr(exprString.show)
+  }
+}

tests/run-macros/i23008/Test_2.scala

@@ -0,0 +1,2 @@
+@main def Test =
+  println(Macros.buildString)