text/template: should eq permit comparison of signed and unsigned integers

[robpike]

Consider this example: 

// http://play.golang.org/p/wkyxTmGM0F

import "os"
import "text/template"

func main() {
    template.Must(template.New("test").Parse(`{{printf "%T %T" (index . 0) 'a'}}`)).Execute(os.Stdout, "abc")
}


It prints uint8 int, which prevents using eq from comparing a byte to a rune constant,
so one can't do
    {{eq (index . 0) 'a'}}
Perhaps comparisons between signed and unsigned integer values should be OK if the sign
is positive, or maybe even always.

[rsc]

Comment 1:

template already knows how to promote constants for ordinary calls.
Can it know about "eq" needing compatible types if a constant is used?

[rsc]

Comment 2:

Too late for 1.3.

Labels changed: added release-go1.4, removed release-go1.3maybe.

[adg]

Comment 3:

Why does "(index . 0)" on a string produce a uint8?

[rsc]

Comment 4:

adg, what should it produce? That's what a string is, a bunch of uint8s.

[gopherbot]

Comment 5:

CL https://golang.org/cl/149780043 mentions this issue.

[robpike]

Comment 6:

This issue was closed by revision db56d4d.

Status changed to Fixed.