map[interface{}]interface{} entries are not properly rendered

[kortschak]

The following code incorrectly hides non-repeated map entries.

package main

import "github.com/kortschak/utter"

func main() {
	a := map[interface{}][]interface{}{
		"examples": []interface{}{
			map[interface{}]interface{}{
				"a": []interface{}{"one-val"},
			},
			map[interface{}]interface{}{
				"b": []interface{}{"two-val"},
			},
		},
	}
	utter.Dump(a)
}

Output:

map[interface{}][]interface{}{
 string("examples"): []interface{}{
  map[interface{}]interface{}{
   string("a"): []interface{}(<already shown>),
  },
  map[interface{}]interface{}{
   string("b"): []interface{}(<already shown>),
  },
 },
}

go-spew handles this correctly, so I must have damaged something at some point.

[kortschak]

This is happening in dump.go +423 in the reflect.Slice case of the big switch and is happening because addr is 0 due to adding a zero pointer mark just after this when addr is zero from a previous non-pointer value. The fix is to only conditionally add pointer marks when addr is non-zero.

[kortschak]

It turns out there is a better fix and that this was due to the approach used in #5; in cases where the unpacked value is a []T, then you don't get an addr, so in that case use the address of the first element if it exists.