text/template: AddParseTree can't replace empty templates, whereas Parse can

[chowey]

Given that I have an empty "test" template:

tpl, err := template.New("main").Parse(`
    {{template "test" .}}
    {{define "test"}}{{end}}
`)

this works:

tpl, err = tpl.New("test").Parse(`This is a test`)
// no error

and this fails:

test, err := template.New("test").Parse(`This is a test`)
tpl, err = tpl.AddParseTree("test", test.Tree)
// error

I think the AddParseTree conditional should be changed to:

    if t.common != nil
        if old := t.tmpl[name]; old != nil && !parse.IsEmptyTree(old.Root) {
            return nil, fmt.Errorf("template: redefinition of template %q", name)
        }
    }

This would make the behavior of AddParseTree consistent with Parse.

[chowey]

Is this now fixed with 6d9df14?

[chowey]

Just tested - yes this is fixed now.