proposal: time: enable warnings when doing time.Duration multiplication

[vax-r]

Proposal Details

As we are using time.Sleep() function, we often just throw in an integer like the following

time.Sleep(5 * time.Second)

What if we throw a type Duration with some time units like 's' instead of an integer?
I've done this before when trying to set some time arguments in environment variable and read it into a Go program, like the following

set_time, err := time.ParseDuration(os.Getenv("WAIT_TIME"))
if err != nil {
    panic(err)
}
time.Sleep(set_time * time.Second)

Basically WAIT_TIME is about 5s, and the program will wait for a super long time.
I guess the reason is that we've done something like time.Duration * time.Second in set_time * time.Second, since set_time is basically 5s with type time.Duration, which is meaningless in this kind of situation (we're not dealing with acceleration)

time.Duration is in fact int64, so I think the compiler may just think this behavior as int64 * int64, but it doesn't make sense here

I suggest we should add some detecting mechanism to prevent this kind of undefined behavior from happening, what do you think?
If you guys think it makes sense I can start to work on it.

[seankhliao]

I don't this will meet the precision criteria for checks by cmd/vet.
The operation is valid and used in many places.

You are, of course, free to write your own linter. If it becomes popular, we can consider adopting a similar check for vet

[AlexanderYastrebov]

https://pkg.go.dev/time

To convert an integer number of units to a Duration, multiply:
seconds := 10
fmt.Print(time.Duration(seconds)*time.Second) // prints 10s