* master:
  Network bridge refactoring impl (#1537)
  Augment Implementer's Guide XCMP docs (#1569)
  Support `build-spec` for other chains than Polkadot (#1567)

* update networking types

* port over overseer-protocol message types

* Add the collation protocol to network bridge

* message sending

* stub for ConnectToValidators

* add some helper traits and methods to protocol types

* add collator protocol message

* leaves-updating

* peer connection and disconnection

* add utilities for dispatching multiple events

* implement message handling

* add an observedrole enum with equality and no sentry nodes

* derive partial-eq on network bridge event

* add PartialEq impls for network message types

* add Into implementation for observedrole

* port over existing network bridge tests

* add some more tests

* port bitfield distribution

* port over bitfield distribution tests

* add codec indices

* port PoV distribution

* port over PoV distribution tests

* port over statement distribution

* port over statement distribution tests

* update overseer and service-new

* address review comments

* port availability distribution

* port over availability distribution tests

* Augment Implementer's Guide XCMP docs

* Remove the note about the third category

* Make Cross-Chain Message Passing a h3

Co-authored-by: Sergei Shulepov <[email protected]>

* Support `build-spec` for other chains than Polkadot

The problem when building a chain specification is that you require the
native runtime to parse the json file (assuming the chain spec is not
raw yet). Before this pr we could only overwrite the native runtime when
running the node using `force_*`. This pr now adds support to load the
native runtime when the filename starts with the name of the chain. So,
when usng `build-spec --chain rococo-something-else.jon` it will use the
rococo native runtime to load the chain spec.

* Apply suggestions from code review

Co-authored-by: Andronik Ordian <[email protected]>

Co-authored-by: Andronik Ordian <[email protected]>

* master:
  impl availability distribution
  companion PR for #5732: pubsub RPC for grandpa justifications (#1346)

Closes #1237

* Companion PR for #5732

Add subscription RPC for listening on GRANDPA justifications.

* grandpa-rpc: some merge fixes

* "Update Substrate"

Co-authored-by: parity-processbot <>

* master:
  Implementer's guide: Messaging overview stub (#1405)
  Align for "Starting parachain attestation session" (#1554)

* master:
  break out subsystem-util and subsystem-test-helpers into individual crates (#1553)

* Introduce the Messaging Overview doc

* Update to the latest thinking

* break out subsystem-util and subsystem-test-helpers into individual crates

* cause all packages to check successfully

* master:
  implement provisioner (#1473)
  Implementer's guide: downward messages and HRMP, take 2 (#1503)
  Revert "Ignore checks for companion PRs (#1455)" (#1549)

* sketch out provisioner basics

* handle provisionable data

* stub out select_inherent_data

* split runtime APIs into sub-chapters to improve linkability

* explain SignedAvailabilityBitfield semantics

* add internal link to further documentation

* some more work figuring out how the provisioner can do its thing

* fix broken link

* don't import enum variants where it's one layer deep

* make request_availability_cores a free fn in util

* document more precisely what should happen on block production

* finish first-draft implementation of provisioner

* start working on the full and proper backed candidate selection rule

* Pass number of block under construction via RequestInherentData

* Revert "Pass number of block under construction via RequestInherentData"

This reverts commit 850fe62c.

That initially looked like the better approach--it spent the time
budget for fetching the block number in the proposer, instead of
the provisioner, and that felt more appropriate--but it turns out
not to be obvious how to get the block number of the block under
construction from within the proposer. The Chain API may be less
ideal, but it should be easier to implement.

* wip: get the block under production from the Chain API

* add ChainApiMessage to AllMessages

* don't break the run loop if a provisionable data channel closes

* clone only those backed candidates which are coherent

* propagate chain_api subsystem through various locations

* add delegated_subsystem! macro to ease delegating subsystems

Unfortunately, it doesn't work right:

```
error[E0446]: private type `CandidateBackingJob` in public interface
   --> node/core/backing/src/lib.rs:775:1
    |
86  | struct CandidateBackingJob {
    | - `CandidateBackingJob` declared as private
...
775 | delegated_subsystem!(CandidateBackingJob as CandidateBackingSubsystem);
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't leak private type
```

I'm not sure precisely what's going wrong, here; I suspect the problem is
the use of `$job as JobTrait>::RunArgs` and `::ToJob`; the failure would be
that it's not reifying the types to verify that the actual types are public,
but instead referring to them via `CandidateBackingJob`, which is in fact private;
that privacy is the point.

Going to see if I can generic my way out of this, but we may be headed for a
quick revert here.

* fix delegated_subsystem

The invocation is a bit more verbose than I'd prefer, but it's also
more explicit about what types need to be public. I'll take it as a win.

* add provisioning subsystem; reduce public interface of provisioner

* deny missing docs in provisioner

* refactor core selection per code review suggestion

This is twice as much code when measured by line, but IMO it is
in fact somewhat clearer to read, so overall a win.

Also adds an improved rule for selecting availability bitfields,
which (unlike the previous implementation) guarantees that the
appropriate postconditions hold there.

* fix bad merge double-declaration

* update guide with (hopefully) complete provisioner candidate selection procedure

* clarify candidate selection algorithm

* Revert "clarify candidate selection algorithm"

This reverts commit c68a02ac.

* clarify candidate selection algorithm

* update provisioner to implement candidate selection per the guide

* add test that no more than one bitfield is selected per validator

* add test that each selected bitfield corresponds to an occupied core

* add test that more set bits win conflicts

* add macro for specializing runtime requests; specailize all runtime requests

* add tests harness for select_candidates tests

* add first real select_candidates test, fix test_harness

* add mock overseer and test that success is possible

* add test that the candidate selection algorithm picks the right ones

* make candidate selection test somewhat more stringent