go/types: missing method errors for interfaces should have more detail #38475
Description
Given this program:
package main
func main() {}
type iface interface {
hello(x string) string
}
func h(x iface) {}
type structy struct{}
func (s structy) hello(x string) {}
func _() {
var x structy
h(x)
}The compiler produces the following error message:
./main.go:17:3: cannot use x (type structy) as type iface in argument to h:
structy does not implement iface (wrong type for hello method)
have hello(string)
want hello(string) string
Whereas, go/types produces: cannot use x (variable of type structy) as iface value in argument to h: wrong type for method hello
We should add more detail to the go/types error message.