internal compiler error: switch on interface{} causes invalid operation: autotmp_0000 <= (interface {})(2) (operator <= not defined on interface)

[remyoudompheng]

1. What is a short input program that triggers the error?

package pkg

func f(x interface{}) {
    switch x {
    case 1:
    case 2:
    case 3:
    case 4:
    }
}

2. What is the full compiler output?

test.go:7: invalid operation: autotmp_0000 <= (interface {})(2) (operator <= not
defined on interface)

3. What version of the compiler are you using?  (Run it with the -V flag.)

6g version weekly.2011-12-22 11133+

[remyoudompheng]

Comment 1:

I do believe that the switch is spec-compliant. Removing one of the cases is OK. Adding
more cases displays some more error messages. I guess this is because the switch is
implemented as binary search, and I had to embarrassingly work around it using some ugly
type assertions.
I hope the fix is not too ugly.

[lvdlvd]

Comment 2:

Labels changed: added priority-go1, compilerbug, removed priority-triage.

Owner changed to @lvdlvd.

Status changed to Accepted.

[robpike]

Comment 3:

Owner changed to builder@golang.org.

[lvdlvd]

Comment 4:

Owner changed to @lvdlvd.

[lvdlvd]

Comment 5:

This issue was closed by revision 6b72b07.

Status changed to Fixed.