text/template: incorrect range syntax is accepted by the parser #28437
Description
Note: This isn't me suggesting that you should fix this. I have had some people reporting broken Hugo sites because of this, and I was "I don't see how that can have worked" until the third person arrived with the same issue.
The program below works on Go 1.10, fails in Go 1.11:
go/bep/temp master ✗ 9m ⚑
▶ go version && go run main.go
go version go1.11.1 darwin/amd64
2018/10/27 14:02:36 template: :2:13: executing "" at <.abc>: undefined variable: $v
exit status 1
go/bep/temp master ✗ 10m ⚑ ⍉
▶ go1.10.4 version && go1.10.4 run main.go
go version go1.10.4 darwin/amd64
abcpackage main
import (
"bytes"
"fmt"
"log"
"strings"
"text/template"
)
func main() {
data := map[string]interface{}{
"abc": []string{"a", "b", "c"},
}
tpl := `
{{ range $v, .abc }}{{ $v }}{{ end }}
`
var buf bytes.Buffer
tmpl, err := template.New("").Parse(tpl)
if err != nil {
log.Fatal(err)
}
if err := tmpl.Execute(&buf, data); err != nil {
log.Fatal(err)
}
result := strings.TrimSpace(buf.String())
fmt.Println(result)
}