go/constant: BinaryOp does not support relational operators on numbers

[dominikh]

What version of Go are you using (go version)?

go version go1.7.3 linux/amd64

What did you do?

https://play.golang.org/p/Paqll33YBG

What did you expect to see?

false

What did you see instead?

panic: invalid binary operation 0 < 0

goroutine 1 [running]:
panic(0x132680, 0x1050a138)
	/usr/local/go/src/runtime/panic.go:500 +0x720
go/constant.BinaryOp(0x1c0e20, 0x1050e160, 0x28, 0x1c0e20, 0x1050e168, 0x1050e0f8, 0x0, 0x0)
	/usr/local/go/src/go/constant/value.go:1110 +0x2c0
main.main()
	/tmp/sandbox478253161/main.go:11 +0xa0

[quentinmit]

This might be too late for 1.8, depending on how much work it is to fix.

[JayNakrani]

BinaryOp() does not handle comparison operations, Compare() does. Is it supposed to?
If not, we should give more helpful message saying that op X is not supported, and put that in doc as well (that would be trivial and can be done in time for 1.8).

[dominikh]

I did not see Compare. I think a doc change on BinaryOp should suffice for now.

[gopherbot]

CL https://golang.org/cl/32761 mentions this issue.