Incorrect Error Message in Data.connect(...)

In https://github.com/freechipsproject/chisel3/blob/master/chiselFrontend/src/main/scala/chisel3/Data.scala#L377:

      requireIsHardware(this, "data to be connected")
      requireIsHardware(that, "data to be connected")

The first error message is incorrect. It should be something like left hand side of the connection.

[mwachs5]

@Onyinye91-ctrl thanks for looking into this! I think @ekiwi was suggesting to add a new “property” to that ConnectSpec, something like:

  property("non-hardware := hardware should fail") {
    intercept[ChiselException]{
      extractCause[ChiselException] {
        ChiselStage.elaborate { new ??? } } }
  }

but since we are especially interested in intercepting the error message and seeing that it is your new message, not sure this is exactly right and I’m not sure what to put for the ??? from that file… looking to see if there is a better example in the codebase.

EDIT: Perhaps you could add a new circuit at the top of the file:

// Existing code
class CrossConnects(inType: Data, outType: Data) extends Module {
  val io = IO(new Bundle {
    val in = Input(inType)
    val out = Output(outType)
  })
  io.out := io.in
}

// New Circuit that shows the bad behavior
class BadConnectLeft(inType: Data, outType: Data) extends Module {
  val io = IO(new Bundle {
    val in = Input(inType)
    val out = Output(outType)
  })
  io.out := io.in
  val foo = inType // This is not hardware since we did not use `Wire(...)` or `Reg(...)`
  foo := io.in // should trigger your new error message about the left-hand side not being hardware
}

Then your property could be:

  property("non-hardware := hardware should fail") {
    intercept[ChiselException]{
      extractCause[ChiselException] {
        ChiselStage.elaborate { new BadConnectLeft(inType = Bool(), outType = Bool() )} } }
  }

Here is a scastie link that shows the error message that we currently get “data to be connected…” when trying to build my BadConnectLeft example:

https://scastie.scala-lang.org/sYbi2GJQRqG0WOaH0y4l6g

[mwachs5]

Something like:

requireIsHardware(this, "left hand side of the connection")

The usage is that if user does something wrong, they would get an error like “The left hand side of the connection must be hardware, but it is not”.

The link is outdated, here is an update one:

https://github.com/chipsalliance/chisel3/blob/1ceb974c55c6785c21ab3934fa750ade0702e276/core/src/main/scala/chisel3/Data.scala#L469

There may be some unit tests that will fail if they were checking for that exact message, and if so the task would also need to update what those tests are checking for (but I don’t know if there are any tests for this error message).

EDIT: @ekiwi said it better!