fix: S-interpolator for assert, assume and printf

[SingularityKChen]

To fix the errors in chipsalliance/chisel#2751.

[CLAassistant]

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[ekiwi]

Unfortunately this changes the functionality of the code since it will now print out $expected instead of the string representation of expected. @jackkoenig: what is the recommended way to fix this?

[jackkoenig]

Suggested change

	val msg = s"Expected $expected, got %x.\n" // this works around the fact that s".." is forbidden in the assert
	assert(reader.io.out === expected.U, msg, reader.io.out)
	assert(reader.io.out === expected.U, cf"Expected ${expected.toString}, got ${reader.io.out}%x.\n")

[ekiwi]

Thanks a lot

[jackkoenig]

@jackkoenig: what is the recommended way to fix this?

You can either split out the String as you have done, or use cf but explicitly .toString as in the "suggestion" comment I left.

[ekiwi]

You can either split out the String as you have done, or use cf but explicitly .toString as in the "suggestion" comment I left.

I would prefer not to call toString explicitly. What exactly does cf do? Can you link me to the documentation for that (hard to google)

[ekiwi]

I would prefer not to call toString explicitly. What exactly does cf do? Can you link me to the documentation for that (hard to google)

Never mind, I found it: https://www.chisel-lang.org/chisel3/docs/explanations/printing.html
Somehow I thought the Chisel string interpolator was p.

[jackkoenig]

Until fairly recently, p was the Chisel String interpolator, but in order to add format specifiers, we added cf. Since cf can do anything p can, and it's name makes more sense ("Chisel format string") rather than ("printable"), I figure we should just use cf instead.

[SingularityKChen]

@jackkoenig: what is the recommended way to fix this?

You can either split out the String as you have done, or use cf but explicitly .toString as in the "suggestion" comment I left.

Hi Jack, thanks for your help. But there is one thing that I'm quite confused about. Why do we need to explicitly .toString to the Int type in cf? Dose cf cannot convert Scala types?

In that case, is the following code correct?

val intA: Int = 10
val uIntB: UInt = intA.U
print(cf"intA=${intA.toString} and uIntB=$uIntB")
printf(cf"" + s"intA=$intA and " + cf"uIntB=$uIntB")  // the first cf is used to avoid compile error