cmd/go2go: adding strings together is not defined #39623
Description
I've been experimenting a bit with generics at https://go2goplay.golang.org/ and I think I found a bug.
What did you do?
See: https://go2goplay.golang.org/p/efS6x6s-9NI
I tried concatenating a string:
type IntString interface {
type int, string
}
func Sum(type T IntString)(s []T) (result T) {
for _, v := range s {
result += v // this fails even though it's possible to add strings together
}
return
}What did you expect to see?
Strings can be added (concatenated) together, so I would expect it to also work when using generics.
Specialized variant of the same function, which does compile:
func SumString(s []string) (result string) {
for _, v := range s {
result += v
}
return
}What did you see instead?
It reports the following error:
type checking failed for main
prog.go2:13:3: invalid operation: operator + not defined for result (variable of type T)
Both integers and strings support the + operator so I would expect this to work.