How to set `trace`?

Stream: new members

[Zihao Zhang]

The following code caused an error "tmp.lean:9:0

unknown option 'trace.tmp'"

import Mathlib
import Lean

open Lean

initialize
  registerTraceClass `tmp

set_option trace.tmp true

[Aaron Liu]

Setting up a trace class only takes effect once you go into another file

[Aaron Liu]

So you have access to the trace classes defined in all the imports, but not in the same file