cli/command/completion: ContainerNames: skip legacy link names

Inline StripNamePrefix and skip legacy links for completion.
Legacy links can be removed from a container, but only when
using `docker [container] rm --link <link-name>`.

When linking containers through legacy links, a container can get multiple
names; its own name, and a name for each link it's providing:

    # create two containers with links between them

    docker run -d --name one nginx:alpine
    docker run -d --name two --link one:link1 --link one:link2 --link one:link3 nginx:alpine

    # container "one" now has multiple names
    docker ps --no-trunc --format '{{.Names}}'
    two
    one,two/link1,two/link2,two/link3

    # running `docker rm --link` with a link-name removes a link:

    docker rm --link two/link3
    docker ps --no-trunc --format '{{.Names}}'
    two
    one,two/link1,two/link2

    # but without `--link`, it resolves the linked container and removes it:
    docker rm -fv two/link2
    two/link2
    docker ps --no-trunc --format '{{.Names}}'
    two

Legacy links are deprecated, and this can be confusing, so let's not provide
completion for secondary names.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

cli/command/completion/functions.go

@@ -5,7 +5,6 @@ import (
 	"strings"
 
 	"github.com/distribution/reference"
-	"github.com/docker/cli/cli/command/formatter"
 	"github.com/moby/moby/api/types/container"
 	"github.com/moby/moby/client"
 	"github.com/spf13/cobra"
@@ -101,7 +100,13 @@ func ContainerNames(dockerCLI APIClientProvider, all bool, filters ...func(conta
 			if showContainerIDs {
 				names = append(names, ctr.ID)
 			}
-			names = append(names, formatter.StripNamePrefix(ctr.Names)...)
+			for _, n := range ctr.Names {
+				// Skip legacy link names: "/linked-container/link-name"
+				if len(n) <= 1 || strings.IndexByte(n[1:], '/') != -1 {
+					continue
+				}
+				names = append(names, strings.TrimPrefix(n, "/"))
+			}
 		}
 		return names, cobra.ShellCompDirectiveNoFileComp
 	}