Documentation and minor plugin changes. (#1573)

* Added documentation. Bugfix in plugin. Moved plugin APIs to separate package

* Revert reg naming behavior (omit underscore)

* Added documentation and a test

* Addressed reviewer feedback.

3 files changed, 23 insertions, 10 deletions

diff --git a/core/src/main/scala/chisel3/experimental/package.scala b/core/src/main/scala/chisel3/experimental/package.scala
index 71fd186c..12631512 100644
--- a/core/src/main/scala/chisel3/experimental/package.scala
+++ b/core/src/main/scala/chisel3/experimental/package.scala
@@ -141,13 +141,4 @@ package object experimental {
   val prefix = chisel3.internal.prefix
   // Use to remove prefixes not in provided scope
   val noPrefix = chisel3.internal.noPrefix
-  // Used by Chisel's compiler plugin to automatically name signals
-  def autoNameRecursively[T <: Any](name: String, nameMe: T): T = {
-    chisel3.internal.Builder.nameRecursively(
-      name.replace(" ", ""),
-      nameMe,
-      (id: chisel3.internal.HasId, n: String) => id.autoSeed(n)
-    )
-    nameMe
-  }
 }
diff --git a/core/src/main/scala/chisel3/internal/Builder.scala b/core/src/main/scala/chisel3/internal/Builder.scala
index e55f1af7..741a2498 100644
--- a/core/src/main/scala/chisel3/internal/Builder.scala
+++ b/core/src/main/scala/chisel3/internal/Builder.scala
@@ -119,7 +119,7 @@ private[chisel3] trait HasId extends InstanceId {
     * @param seed Seed for the name of this component
     * @return this object
     */
-  def autoSeed(seed: String): this.type = {
+  private [chisel3] def autoSeed(seed: String): this.type = {
     auto_seed = Some(seed)
     for(hook <- auto_postseed_hooks) { hook(seed) }
     prefix_seed = Builder.getPrefix()
diff --git a/core/src/main/scala/chisel3/internal/plugin/package.scala b/core/src/main/scala/chisel3/internal/plugin/package.scala
new file mode 100644
index 00000000..6d78b1c3
--- /dev/null
+++ b/core/src/main/scala/chisel3/internal/plugin/package.scala
@@ -0,0 +1,22 @@
+// See LICENSE for license details.
+
+package chisel3.internal
+
+package object plugin {
+  /** Used by Chisel's compiler plugin to automatically name signals
+    * DO NOT USE in your normal Chisel code!!!
+    *
+    * @param name The name to use
+    * @param nameMe The thing to be named
+    * @tparam T The type of the thing to be named
+    * @return The thing, but now named
+    */
+  def autoNameRecursively[T <: Any](name: String, nameMe: T): T = {
+    chisel3.internal.Builder.nameRecursively(
+      name.replace(" ", ""),
+      nameMe,
+      (id: chisel3.internal.HasId, n: String) => id.autoSeed(n)
+    )
+    nameMe
+  }
+}