Specify type parameter when calling chiselTypeClone

[konda-x1]

Due to the signature of method DataMirror.internal.chiselTypeClone, if you don't specify the type parameter T, it will resolve to Nothing. This causes a good amount of tests using LazyModule to break in rocket-dsp-utils.

Type of change: bug report

Impact: no functional change

Development Phase: implementation

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: konda-x1 / name: Aleksandar Kondić (d70a6e0)

[jerryz123]

Can you point to the API docs/source you are referencing? I believe this may be necessary now, but I haven't seen the updated API yet.

[konda-x1]

Here is how it's defined in Chisel 3.6: https://github.com/chipsalliance/chisel/blob/3.6-release/core/src/main/scala/chisel3/reflect/DataMirror.scala#L177

The method takes a generic type T, but the method's argument is not of type T, but rather Data. So, from my understanding, the generic type will not be inferred from the type of the data parameter passed to it. This will lead to Nothing being inferred when no explicit type parameter is specified in the method call. This is in contrast to how something like chiselTypeOf is defined, where the single parameter is of type T itself.

Honestly, I don't quite understand how things like this may have worked before, but I know that presently, when I add [T] to chiselTypeClone inside BundleBridgeSource and BundleBridgeSink that the tests inside rocket-dsp-utils start working again. I assumed it would be beneficial to specify the type parameter in other calls to chiselTypeClone as well.

[jackkoenig]

This is a longstanding bug in Chisel, just fixed it: chipsalliance/chisel#3553 (h/t @sequencer for pointing me to it showing up here).

[sequencer]

Let's wait for next release of 3.6.x and 5.x