return fmt.Errorf("got %v; want a proper address with non-zero port number", la)
	}
	return nil
}

func multicastRIBContains(ip IP) (bool, error) {
	switch runtime.GOOS {
	case "aix", "dragonfly", "netbsd", "openbsd", "plan9", "solaris", "illumos", "windows":
		return true, nil // not implemented yet
	case "linux":
		if runtime.GOARCH == "arm" || runtime.GOARCH == "alpha" {
			return true, nil // not implemented yet
		}

		cc = append(cc, "-pie")
	}
	libgodir := GOOS + "_" + GOARCH
	switch GOOS {
	case "darwin", "ios":
		if GOARCH == "arm64" {
			libgodir += "_shared"
		}
	case "dragonfly", "freebsd", "linux", "netbsd", "openbsd", "solaris", "illumos":
		libgodir += "_shared"
	}
	cc = append(cc, "-I", filepath.Join("pkg", libgodir))

	// Force reallocation (and avoid aliasing bugs) for parallel tests that append to cc.

		time.Sleep(1 * time.Millisecond)
		// trigger GC which will shrink the stack of the sender.
		runtime.GC()
	}
	<-done
}

func TestNoShrinkStackWhileParking(t *testing.T) {
	if runtime.GOOS == "netbsd" && runtime.GOARCH == "arm64" {
		testenv.SkipFlaky(t, 49382)
	}
	if runtime.GOOS == "openbsd" {
		testenv.SkipFlaky(t, 51482)
	}

	// The goal of this test is to trigger a "racy sudog adjustment"

		libbase = "gccgo_" + libgodir + "_fPIC"
	} else {
		switch GOOS {
		case "darwin", "ios":
			if GOARCH == "arm64" {
				libbase += "_shared"
			}
		case "dragonfly", "freebsd", "linux", "netbsd", "openbsd", "solaris", "illumos":
			libbase += "_shared"
		}
	}
	libgodir = filepath.Join(GOPATH, "pkg", libbase, "testcarchive")
	cc = append(cc, "-I", libgodir)

		GOINSECURE does not disable checksum database validation. GOPRIVATE or
		GONOSUMDB may be used to achieve that.
	GOOS
		The operating system for which to compile code.
		Examples are linux, darwin, windows, netbsd.
	GOPATH
		Controls where various files are stored. See: 'go help gopath'.
	GOPROXY
		URL of Go module proxy. See https://golang.org/ref/mod#environment-variables

	}
	go cancel()

	if err := c.Wait(); err == nil {
		t.Fatal("expected Wait failure")
	}
}

func TestContextCancel(t *testing.T) {
	if runtime.GOOS == "netbsd" && runtime.GOARCH == "arm64" {
		maySkipHelperCommand("cat")
		testenv.SkipFlaky(t, 42061)
	}

	// To reduce noise in the final goroutine dump,
	// let other parallel tests complete if possible.