go/types: int overflow in switch expression

[dvyukov]

gotype successfully compiles the following program:

package a
func f() {
    switch 9223372036854775808 {
    }
}

gc rejects it with:

go.go:3: constant 9223372036854775808 overflows int

gc seems to be right.

on commit af81789

[dvyukov]

The same happens in switch cases as well:

package a
func f() {
    switch 9223372036854775808 {
    case 9223372036854775808:
    }
}

[griesemer]

The switch statement is actually underspecified in this respect. It does not say that the switch expression has to fit into a basic type. So technically, I believe gotype is correct. That said, I think the spec needs to be clarified as the current situation is not tenable in general. Leaving as go/types bug.

[gopherbot]

CL https://golang.org/cl/12713 mentions this issue.