Add support for directives on directive definitions

At a glance

• Identifier: #1206
• Stage: RFC 2 / Draft
• Champion: @BoD
• Latest activity: Marked as Ready for Next Stage on 2026-05-07
• Spec PR: https://github.com/graphql/graphql-spec/pull/1206

Spec PR description

Adds the ability to apply directives to directive definitions and to deprecate directives, with this syntax:

directive @onDirective on DIRECTIVE_DEFINITION

directive @foo @onDirective on OBJECT

directive @baz @deprecated(reason: "...") on OBJECT

extend directive @quux @deprecated(reason: "...")

With @IvanGoncharov's blessing, this PR is a continuation and updated version of #907 which I think can be closed. (There's also prior art in #567).

Motivation

Allow applying directive-exclusive features (e.g. @specifyBy, @deprecated) on directives.

For instance, on Apollo Kotlin we'd like to deprecate some client side directives.