cmd/compile: extra (confusing) error message after shift error

[griesemer]

package main

func main() {
	var s uint
	var _ interface{} = 1.0 << s
}

produces

prog.go:5:6: cannot use 1 << s as type interface {} in assignment
prog.go:5:26: invalid operation: 1 << s (shift of type float64)

on the playground (https://play.golang.org/p/lZceKWg78OH). The first error message is misleading and unnecessary. Should suppress once we know that the shift is invalid.

Not urgent.

[ALTree]

This appears to be fixed, the reproducer above now generates a single error line:

./prog.go:5:6: invalid operation: 1 << s (shift of type float64)

Closing here.