[RFC] "Directive order is significant" section

[OlegIlyenko]

I would like to add a note on the directive ordering to make it more explicit. It is similar to the notes:

• Argument are unordered.
• Input object fields are unordered.

But it instead states that directive order is significant and may have specific semantic interpretation.

[OlegIlyenko]

Forgot to mention that this RFC is the result of recent discussions in #429 and at the WG meetings.

[leebyron]

Are any changes necessary to GraphQL.js or Sangria to support this?

[OlegIlyenko]

@leebyron I believe no changes are necessary. RFC permits implementations to have a special treatment for directive order, but does not require it. Also, for all built-in directives, specific order is not important.

[spawnia]

This is a very reasonable clarification to the spec. In a project of ours, we actually rely on the order of directive definitions being preserved - which https://github.com/webonyx/graphql-php thankfully does already.

Would be great to have this in to make this an explicitely defined rule that we can depend on.