Default Pallet Config Trait / derive_impl (#13454)

* first draft, probably won't work

* first draft, probably won't work

* good progress..

* good milestone, still a lot to do.

* EVERYTHING WORKS

* Update frame/support/procedural/src/derive_impl.rs

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Update frame/support/procedural/src/derive_impl.rs

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* clean up + cargo fmt

* import tokens WIP

* export_tokens working with impl Trait

* WIP / notes

* use macro_magic 0.2.0's export_tokens to access foreign items

* token importing working properly using macro_magic 0.2.5

* combine_impls almost working

* successfully get foreign path via macro_magic 0.2.6

* combine_impls using implementing_type generics

* working + clean up

* more clean up

* decrease rightwards drift and add docs to combine_impls

* add support for macros to impl_item_ident in case we hit that

* add docs for impl_item_ident method

* fix no_std issues

* re-export of macro_magic working in pallets 🎉

* clean up + fully resolve no_std issue with macro_magic with v0.2.11

* remove trait item code for different trait item types since this
is now handled directly by combine_impls

* clean up

* remove dev comments

* only generate default trait if #[pallet::default_trait] is attached

* authorship and most other pallets now compiling

* compiling 🎉

* add check for more than two pallet attributes on Config trait

* remove unused import in nomination-pool

* clean up debug code

* upgrade to macro_magic v0.2.12

* add neater #[register_default_config(SomeIdent)] macro

* really just a thin wrapper around #[export_tokens]

* upgrade to macro_magic 0.3.1

* rewrite parsing to be compatible with syn 2.x, compiling 🎉

* remove unused keywords

* macro stubs for the new pallet:: macros, preliminary docs

* upgrade to macro_magic v0.3.2

* rename register_default_config => register_default_impl

* bump to macro_magic v0.3.3

* custom disambiguation_path working as 2nd arg to derive_impl

* overhaul docs

* fixes, ident-style paths shortcut working

* remove ident-style shortcut because it makes testing difficult

* add passing UI tests for derive_impl

* switch to `ForeignPath as DisambiguationPath` syntax + update docs

* add UI test for bad foreign path

* add UI test for bad disambiguation path

* add UI test for missing disambiguation path

* add UI test for attached to non impl

* fix derive_impl_attr_args_parsing test

* move tests to bottom

* fix nightly issue

* add doc notes on importing/re-exporting

* remove explicit use of macro_magic::use_attr

Co-authored-by: Bastian Köcher <git@kchr.de>

* use explicit macro_magic::use_attr

Co-authored-by: Bastian Köcher <git@kchr.de>

* remove unneeded {}

Co-authored-by: Bastian Köcher <git@kchr.de>

* remove unneeded collect

Co-authored-by: Bastian Köcher <git@kchr.de>

* add docs for TestDefaultConfig

* remove unneeded `#[export_tokens]` on `DefaultConfig`

* add docs for auto-generated `DefaultConfig`

* no need to clone

Co-authored-by: Bastian Köcher <git@kchr.de>

* clean up combine_impls + compiling again

* remove unused dependency

* simplify struct definition

Co-authored-by: Bastian Köcher <git@kchr.de>

* fix register_default_impl docs

* reduce rightward drift / refactor

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

* fix derive_impl after keith's changes

* simplify disambiguation_path calculation

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

* compiling again

* simplify parsing of trait item

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

* rename preludes => prelude

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

* fix other places where we used preludes instead of prelude

* fix indents

* simplify PalletAttr parsing

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

* go back to having no_default and constant as keywords

* make it more clear that disambiguation_path is optional

* make default_trait_items just a Vec instead of Option<Vec>

* rename foreign_path => default_impl_path within substrate

* fix docs

* Change {} to ;

Co-authored-by: Bastian Köcher <git@kchr.de>

* highlight full end-to-end example with link

* add pallet-default-config-example, start by copying dev mode code

* update dev-mode specific docs

* use Person and Points instead of Dummy and Bar

* add docs to example pallet

* revert changes to pallets other than the default config example

* fix outdated references to basic example pallet

* re-order docs to be a bit more clear

* better errors for extra attributes

* add UI tests for duplicate/extra attributes on trait items

* change `#[pallet::default_config]` to option on `#[pallet::config()]`

* update UI tests
* add UI test covering missing `#[pallet::config(with_default)]` when
  `#[pallet::no_default]` is used

* add note about new optional conventions

* improve docs about `DefaultConfig` and link to these from a few places

* fix doc comment

* fix old comment referencing `pallet::default_config`

* use u32 instead of u64 for block number

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* use () instead of u32 for `AccountData`

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* use ConstU32<10> for BlockHashCount instead of ConstU64<10>

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* people are not dummies

Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>

* fix wording

Co-authored-by: Just van Stam <vstam1@users.noreply.github.com>

* Person => People and compiling again

* add docs for `prelude` module in frame_system

* update Cargo.lock

* cleaner example

* tweaks

* update docs more

* update docs more

* update docs more

* update docs more

* fix ui tests

* err

* Update frame/support/test/tests/pallet_ui.rs

* update ui tests

---------

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Sam Johnson <sam@durosoft.com>
Co-authored-by: parity-processbot <>
Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>
Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>
Co-authored-by: Just van Stam <vstam1@users.noreply.github.com>

substrate/frame/support/test/tests/derive_impl_ui.rs

@@ -0,0 +1,38 @@
+// This file is part of Substrate.
+
+// Copyright (C) Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#![cfg(not(feature = "disable-ui-tests"))]
+#![cfg(test)]
+
+#[rustversion::attr(not(stable), ignore)]
+#[test]
+fn derive_impl_ui() {
+	// Only run the ui tests when `RUN_UI_TESTS` is set.
+	if std::env::var("RUN_UI_TESTS").is_err() {
+		return
+	}
+
+	// As trybuild is using `cargo check`, we don't need the real WASM binaries.
+	std::env::set_var("SKIP_WASM_BUILD", "1");
+
+	// Deny all warnings since we emit warnings as part of a Pallet's UI.
+	std::env::set_var("RUSTFLAGS", "--deny warnings");
+
+	let t = trybuild::TestCases::new();
+	t.compile_fail("tests/derive_impl_ui/*.rs");
+	t.pass("tests/derive_impl_ui/pass/*.rs");
+}