cmd/compile: cannot convert untyped string value to type parameter constrained by `~string | ~[]byte`

[dominikh]

Input:

package pkg

func foo[T ~string | ~[]byte]() {
	var _ T = T("")
}

Output:

./baz.go:4:14: cannot convert "" (untyped string value) to type T:
	cannot convert "" (untyped string constant) to []byte (in T)

I expected this conversion to work. If it isn't supposed to work, then the error message is confusing.

/cc @griesemer

[griesemer]

Looks like a bug to me.

[griesemer]

func foo[T ~string | ~[]byte]() {
        var s string
	var _ T = T(s)
}

this works

[gopherbot]

Change https://go.dev/cl/388254 mentions this issue: go/types, types2: fix string to type parameter conversions