Fix #7887: Add regression test

Author: nicolasstucki

tests/pos/i7887.scala

@@ -0,0 +1,7 @@
+def typed[A](given t: quoted.Type[A], qctx: quoted.QuoteContext): Unit = {
+  import qctx.tasty.{given, _}
+  '{
+    type T = $t
+    ${'{???}.cast[T]}
+  }
+}

tests/run-macros/i7887/Macro_1.scala

@@ -0,0 +1,17 @@
+def myMacroImpl(a: quoted.Expr[_])(given qctx: quoted.QuoteContext) = {
+  import qctx.tasty.{_, given}
+  def typed[A] = {
+    implicit val t: quoted.Type[A] = a.unseal.tpe.widen.seal.asInstanceOf[quoted.Type[A]]
+    '{
+      type T = $t
+      ${a.unseal.seal.cast[T]}
+    }
+  }
+
+  typed
+}
+
+
+inline def myMacro(a: => Any) = ${
+  myMacroImpl('a)
+}

tests/run-macros/i7887/Test_2.scala

@@ -0,0 +1,3 @@
+object Test extends App {
+  assert(myMacro(42) == 42)
+}