Check BaseModule.name for NullPointerException

This wraps the evaluation of BaseModule.name in try/catch to look for a
NullPointerException that may result from trying to evaluate desiredName
before it's ready. This catches a test case of using a desiredName that
depends on a later defined eager subinstance.

h/t @jackkoenig

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/test/scala/chiselTests/Module.scala b/src/test/scala/chiselTests/Module.scala
index dc44838a..b3d1899c 100644
--- a/src/test/scala/chiselTests/Module.scala
+++ b/src/test/scala/chiselTests/Module.scala
@@ -65,7 +65,14 @@ class ModuleRewrap extends Module {
 class ModuleWrapper(gen: => Module) extends Module {
   val io = IO(new Bundle{})
   val child = Module(gen)
+  override val desiredName = s"${child.desiredName}Wrapper"
+}
+
+class NullModuleWrapper extends Module {
+  val io = IO(new Bundle{})
   override lazy val desiredName = s"${child.desiredName}Wrapper"
+  println(s"My name is ${name}")
+  val child = Module(new ModuleWire)
 }
 
 class ModuleSpec extends ChiselPropSpec {
@@ -147,4 +154,8 @@ class ModuleSpec extends ChiselPropSpec {
   property("A desiredName parameterized by a submodule should work") {
     Driver.elaborate(() => new ModuleWrapper(new ModuleWire)).name should be ("ModuleWireWrapper")
   }
+  property("A name generating a null pointer exception should provide a good error message") {
+    (the [Exception] thrownBy (Driver.elaborate(() => new NullModuleWrapper)))
+      .getMessage should include ("desiredName of chiselTests.NullModuleWrapper is null")
+  }
 }