Make isView safe outside of Builder context (#4228) (#4230)

(cherry picked from commit 219a237)

Co-authored-by: Jack Koenig <koenig@sifive.com>

core/src/main/scala/chisel3/experimental/dataview/package.scala

@@ -235,7 +235,7 @@ package object dataview {
   }
 
   // Safe for all Data
-  private[chisel3] def isView(d: Data): Boolean = d._parent.contains(ViewParent)
+  private[chisel3] def isView(d: Data): Boolean = d._parent.exists(_ == ViewParent)
 
   /** Turn any [[Element]] that could be a View into a concrete Element
     *

src/test/scala/chiselTests/UIntOps.scala

@@ -207,6 +207,11 @@ class UIntLitZeroWidthTester extends BasicTester {
 
 class UIntOpsSpec extends ChiselPropSpec with Matchers with Utils {
 
+  // This is intentionally a val outside of any ScalaTest constructs to check that it is legal
+  // to create a literal outside of a Chisel context and *before* any Chisel contexts have been created
+  // in this thread.
+  val five = 5.U
+
   property("Bools can be created from 1 bit UInts") {
     ChiselStage.emitCHIRRTL(new GoodBoolConversion)
   }