Bug report github.com/golang/glog

[Brian Kennedy]

For the flag "log_backtrace_at" the flag expects "" for an empty value when calling Set(), but .String() will return ":0" when the value is empty. This results in a different "emtpy" value being generated by String() than is accepted by Set().

The following code will reproduce the issue.

Output from process:

Value: ":0"

Setting flag returned error: syntax error: expect file.go:234

Code Snippet:

package main

import (

  "flag"

  "fmt"

  "github.com/golang/glog"

)

func main() {

  flag.Parse()

  lba := flag.Lookup("log_backtrace_at")

  if lba == nil {

    glog.Fatalf("Needs to depend on glog")

  }

  fmt.Printf("Value: \"%s\"\n", lba.Value.String())

  err := lba.Value.Set(lba.Value.String())

  if err != nil {

    fmt.Printf("Setting flag returned error: %s\n", err)

  }

}

[Tim Peoples]

You're absolutely right -- and, if you'll notice, there's a TODO on the traceLocation.String() method to "clean this up".

Granted, all it needs is a:

if !t.isSet() {
  return ""
}