- generate always `::juniper::` crate path in proc macros and use `extern crate self` to make it work inside `juniper`
- add optional non-documented `internal` proc macro argument to proc macros, which allows double-underscored names and is used inside `juniper` only
- add object safe GraphQLValue, GraphQLValueAsync and GraphQLSubscriptionValue traits containing methods for value resolution
- refactor GraphQLType, GraphQLTypeAsync and GraphQLSubscriptionType traits to register and provide GraphQL type information only
- make GraphQLUnion trait generic over ScalarValue
- generate generic over ScalarValue impls of GraphQLUnion trait
- add codegen tests with a custom ScalarValue for union macros
- reimplement #[derive(GraphQLUnion)] macro to support:
- both structs and enums
- generics in type definition
- multiple #[graphql] attributes
- external resolver functions
- remove From trait impls generation for enum variants
- reimplement #[graphql_union] macro to support:
- traits
- generics in trait definition
- multiple attributes
- external resolver functions
- GraphQLType implemetation for a raw trait object
- GraphQLTypeAsync implemetation (#549)
- add marker::GraphQLUnion trait
- rewrite "2.5 Unions" section in Book (Juniper user documentation)
- rewrite `codegen` and `codegen_fail` integration tests for GraphQL unions
Additionally:
- re-export `futures` crate in `juniper` for convenient reuse in the generated code without requiring library user to provide `futures` crate by himself (#663)
- use unit type () as default context for EmptyMutation and EmptySubscriptions
- relax Sized trait bound on some GraphQLType and GraphQLTypeAsync definitions, implementations and usages
