sync: delete TestCondCopy?

[josharian]

It appears to be testing copying a lock, which people shouldn't do.

func TestCondCopy(t *testing.T) {
    defer func() {
        err := recover()
        if err == nil || err.(string) != "sync.Cond is copied" {
            t.Fatalf("got %v, expect sync.Cond is copied", err)
        }
    }()
    c := Cond{L: &Mutex{}}
    c.Signal()
    c2 := c
    c2.Signal()
}

Vet doesn't like it:

sync/cond_test.go:254: assignment copies lock value to c2: sync.Cond contains sync.noCopy

Objections to it being deleted for 1.8?

cc @dvyukov

Part of dealing with #11041.

[dvyukov]

It appears to be testing copying a lock, which people shouldn't do.

The mutex is not copied here. Cond contains a pointer to the mutex. But Cond itself should not be copied.

The test tests a useful property. Not all use vet. Cond detects the misuse reliably at runtime. Can we move it to _novet.go or something?

[josharian]

Ok, thanks. I'll figure out a way to add an exception for it as part of #11041 -- it's not going to be the only exception.