Ordered-Marshal doesn't give the correct order and in certain cases duplicates the path after using SetPath

[heyaWorld]

Describe the bug
NewEncoder(w io.Writer).Order(OrderPreserve).Encode(v interface{}) doesn't return the correct ordered output and in certain cases duplicates the path set by (*Tree).SetPath()

To Reproduce

    config := `
	[[inputs.cpu]]
	    collect_cpu_time = false
	
        [[inputs.apache]]
	     urls = []
	    [inputs.apache.tags]
		foo="bar"

      [[inputs.disk]]`

	// Load config, output is *Tree
	tree, _ := toml.Load(config)
	node := tree.GetPath([]string{"inputs"}).(*toml.Tree)
	for _, key := range node.Keys() {
		tree.SetPath([]string{"inputs", key, "tags", "computer"}, "mycomputerName")
		tree.SetPath([]string{"inputs", key, "tags", "origin"}, "telegraf/apache")
	}
	fmt.Println(tree)
	fmt.Println("******************************\n")

	// Convert to bytes to preserve the order of the original config
	var result bytes.Buffer
	if err := toml.NewEncoder(&result).Order(toml.OrderPreserve).Encode(tree); err != nil {
		fmt.Println(err)
	}
	fmt.Println("************original ordered toml with tags************")
	fmt.Println(string(result.Bytes()))

Expected behavior
[inputs.cpu.tags] should not be duplicate.
"collect_cpu_time = false" is missing under the inputs.cpu table.

Original Ordered output after running the above code:

[inputs]

  [[inputs.cpu]]

    [inputs.cpu.tags]
      computer = "mycomputerName"
      origin = "telegraf/apache"

    [inputs.cpu.tags]
      computer = "mycomputerName"
      origin = "telegraf/apache"

  [[inputs.apache]]
    urls = []

    [inputs.apache.tags]
      foo = "bar"
      computer = "mycomputerName"
      origin = "telegraf/apache"

  [[inputs.disk]]

    [inputs.disk.tags]
      computer = "mycomputerName"
      origin = "telegraf/apache"

Expected ordered output:

`[inputs]

  [[inputs.cpu]]
    collect_cpu_time = false
    [inputs.cpu.tags]
      computer = "mycomputerName"
      origin = "telegraf/apache"

  [[inputs.apache]]
    urls = []

    [inputs.apache.tags]
      foo = "bar"
      computer = "mycomputerName"
      origin = "telegraf/apache"

  [[inputs.disk]]

    [inputs.disk.tags]
      computer = "mycomputerName"
      origin = "telegraf/apache"`

Another example(If we change the config variable in the reproduce step to this):

 config := `
	[[inputs.apache]]
	     urls = []
	     [inputs.apache.tags]
		  foo="bar"

        [[inputs.disk]]

        [[inputs.cpu]]
	     collect_cpu_time = false`

Original Ordered output after running the above code:

[inputs]

  [[inputs.apache]]
    urls = []

    [inputs.apache.tags]
      foo = "bar"
      computer = "mycomputerName"
      origin = "telegraf/apache"

  [[inputs.disk]]

    [inputs.disk.tags]
      computer = "mycomputerName"
      origin = "telegraf/apache"

  [[inputs.cpu]]

    [inputs.cpu.tags]
      computer = "mycomputerName"
      origin = "telegraf/apache"
    collect_cpu_time = false

Expected ordered output:

[inputs]

  [[inputs.apache]]
    urls = []

    [inputs.apache.tags]
      foo = "bar"
      computer = "mycomputerName"
      origin = "telegraf/apache"

  [[inputs.disk]]

    [inputs.disk.tags]
      computer = "mycomputerName"
      origin = "telegraf/apache"

  [[inputs.cpu]]
    collect_cpu_time = false
    [inputs.cpu.tags]
      computer = "mycomputerName"
      origin = "telegraf/apache"

collect_cpu_time = false should come before the [inputs.cpu.tags] Also compared to example 1, there is no duplication in this case.

Versions

• go-toml: version (v1.8.1)
• go: version go1.14 windows/amd64
• operating system: windows

Additional context

[pelletier]

Thank you for reporting this! Definitely seems wrong.

[heyaWorld]

Hey, I think I have a fix for this, I am just refactoring the code and testing it once more. My code will also fix this issue:

#445

[fiws]

here is a much simpler example that reproduces the duplication bug: https://play.golang.org/p/FN1Jc33D4PF

not sure if this is the same issue. happy to open another one if it's not the case.

The problem seems to be related to the string map in my example. it works if i remove replace that with a string for example.

[pelletier]

@fiws thank you for the simplified repro! I likely won't try to fix it in v1 given all my time is focused on v2. Fortunately toml.OrderPreserve is probably not going to be ported over given that v2's default behavior is to respect the struct field order.

[Felixoid]

Hey dear @heyaWorld and @fiws, can you try if #539 fixes your problems?