Comment 1:

Essentially it's a panic that doesn't panic, just print.

Comment 2:

No need to put _into the_ language a new built-int for what can be _expressed by the_
language already. #Reject
----
package foo_test
import (
        "fmt"
        "path"
        "runtime"
)
func trace(s string, va ...interface{}) {
        _, fn, fl, _ := runtime.Caller(1)
        fmt.Printf("%s:%d: ", path.Base(fn), fl)
        fmt.Printf(s, va...)
        fmt.Println()
}
----
- Now you can write debug prints, to be printed during tests, like
    trace("%v %i", myVar, i)
- No need to import/unimport anything.
- You cannot forget to remove the debug prints before building the binary, because as
long as they are present in the source, the build will fail. It will build only when
doing
    $ go test

Comment 3:

a) this solution only works provided that you are in a test case
b) you'll have to duplicate this for every package if you don't want explicit imports
So it's not a solution.

Comment 4:

print and println aren't even part of the language.  I don't think we need more stuff
that's debug-related.

Status changed to WorkingAsIntended.