x/tools/cmd/goimports: make "-local" flag match exactly path without final "/" in addition to prefix #24368
Description
Currently, it is not possible for goimports to group imports in a manner that encapsulates the operation "group all packages from a repository into the same group" using the -local flag due to the nature of prefix matches.
If a file imports github.com/org/project, github.com/org/project/pkg and github.com/org/project2/pkg, -local github.com/org/project will match the undesired package github.com/org/project2, while -local github.com/org/project/ will not match imports for the root package github.com/org/project.
Proposal
As a special case, if a prefix provided to -local ends in a slash (/) and the import being considered is exactly the prefix without the slash, treat it as a match. Although this modifies the current behavior, I believe that it semantically captures what such a prefix match would be trying to achieve (the fix is also very small and targeted). I believe that any other fix would require adding flags or options, which I know is not desirable.
Example repros
Groups github.com/org/project2/pkg with imports from github.com/org/project:
echo 'package foo\nimport (\n_ "fmt"\n_ "gopkg.in/yaml.v2"\n_ "github.com/org/project/pkg"\n_ "github.com/org/project"\n_ "github.com/org/project2/pkg"\n)' | cat | goimports -local github.com/org/project
package foo
import (
_ "fmt"
_ "gopkg.in/yaml.v2"
_ "github.com/org/project"
_ "github.com/org/project/pkg"
_ "github.com/org/project2/pkg"
)
Does not group import for github.com/org/project with github.com/org/project/pkg:
echo 'package foo\nimport (\n_ "fmt"\n_ "gopkg.in/yaml.v2"\n_ "github.com/org/project/pkg"\n_ "github.com/org/project"\n_ "github.com/org/project2/pkg"\n)' | cat | goimports -local github.com/org/project/
package foo
import (
_ "fmt"
_ "github.com/org/project"
_ "github.com/org/project2/pkg"
_ "gopkg.in/yaml.v2"
_ "github.com/org/project/pkg"
)
The proposed behavior would result in:
echo 'package foo\nimport (\n_ "fmt"\n_ "gopkg.in/yaml.v2"\n_ "github.com/org/project/pkg"\n_ "github.com/org/project"\n_ "github.com/org/project2/pkg"\n)' | cat | goimports -local github.com/org/project/
package foo
import (
_ "fmt"
_ "github.com/org/project2/pkg"
_ "gopkg.in/yaml.v2"
_ "github.com/org/project"
_ "github.com/org/project/pkg"
)