test: add unit test to catch missing distribution to subsystems faster (#2495)

* test: add unit test to catch missing distribution to subsystems faster

* add a simple count

* introduce proc macro to generate dispatch type

* refactor

* refactor

* chore: add license

* fixup unit test

* fixup merge

* better errors

* better fmt

* fix error spans

* better docs

* better error messages

* ui test foo

* Update node/subsystem/dispatch-gen/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update node/network/bridge/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update node/subsystem/Cargo.toml

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update node/subsystem/dispatch-gen/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update node/subsystem/dispatch-gen/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update node/network/bridge/src/lib.rs

Co-authored-by: Andronik Ordian <write@reusable.software>

* fix compilation

* use find_map

* drop the silly 2, use _inner instead

* Update node/network/bridge/src/lib.rs

Co-authored-by: Andronik Ordian <write@reusable.software>

* Update node/subsystem/dispatch-gen/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* nail deps down

* more into()

* flatten

* missing use statement

* fix messages order

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>
Co-authored-by: Andronik Ordian <write@reusable.software>

polkadot/node/subsystem/dispatch-gen/tests/ui/err-01-missing-skip.rs

@@ -0,0 +1,37 @@
+#![allow(dead_code)]
+
+use polkadot_procmacro_subsystem_dispatch_gen::subsystem_dispatch_gen;
+
+/// The event type in question.
+#[derive(Clone, Copy)]
+enum Event {
+	Smth,
+	Else,
+}
+
+impl Event {
+	fn focus(&self) -> std::result::Result<Inner, ()> {
+		unimplemented!("foo")
+	}
+}
+
+/// This should have a `From<Event>` impl but does not.
+#[derive(Clone)]
+enum Inner {
+	Foo,
+	Bar(Event),
+}
+
+#[subsystem_dispatch_gen(Event)]
+#[derive(Clone)]
+enum AllMessages {
+	/// Foo
+	Vvvvvv(Inner),
+
+    /// Missing a `#[skip]` annotation
+    Uuuuu,
+}
+
+fn main() {
+    let _x = AllMessages::dispatch_iter(Event::Else);
+}

polkadot/node/subsystem/dispatch-gen/tests/ui/err-01-missing-skip.stderr

@@ -0,0 +1,14 @@
+error: Must be annotated with #[skip].
+  --> $DIR/err-01-missing-skip.rs:32:5
+   |
+32 |     Uuuuu,
+   |     ^^^^^
+
+error[E0599]: no variant or associated item named `dispatch_iter` found for enum `AllMessages` in the current scope
+  --> $DIR/err-01-missing-skip.rs:36:27
+   |
+27 | enum AllMessages {
+   | ---------------- variant or associated item `dispatch_iter` not found here
+...
+36 |     let _x = AllMessages::dispatch_iter(Event::Else);
+   |                           ^^^^^^^^^^^^^ variant or associated item not found in `AllMessages`

polkadot/node/subsystem/dispatch-gen/tests/ui/err-02-missing-from.rs

@@ -0,0 +1,41 @@
+#![allow(dead_code)]
+
+use polkadot_procmacro_subsystem_dispatch_gen::subsystem_dispatch_gen;
+
+/// The event type in question.
+#[derive(Clone, Copy, Debug)]
+enum Event {
+	Smth,
+	Else,
+}
+
+impl Event {
+	fn focus(&self) -> std::result::Result<Intermediate, ()> {
+		Ok(Intermediate(self.clone()))
+	}
+}
+
+#[derive(Debug, Clone)]
+struct Intermediate(Event);
+
+
+/// This should have a `From<Event>` impl but does not.
+#[derive(Debug, Clone)]
+enum Inner {
+	Foo,
+	Bar(Intermediate),
+}
+
+#[subsystem_dispatch_gen(Event)]
+#[derive(Clone)]
+enum AllMessages {
+	/// Foo
+	Vvvvvv(Inner),
+
+    #[skip]
+    Uuuuu,
+}
+
+fn main() {
+    let _x = AllMessages::dispatch_iter(Event::Else);
+}

polkadot/node/subsystem/dispatch-gen/tests/ui/err-02-missing-from.stderr

@@ -0,0 +1,10 @@
+error[E0308]: mismatched types
+  --> $DIR/err-02-missing-from.rs:29:1
+   |
+29 | #[subsystem_dispatch_gen(Event)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | |
+   | expected enum `Inner`, found struct `Intermediate`
+   | help: try using a variant of the expected enum: `Inner::Bar(#[subsystem_dispatch_gen(Event)])`
+   |
+   = note: this error originates in an attribute macro (in Nightly builds, run with -Z macro-backtrace for more info)

polkadot/node/subsystem/dispatch-gen/tests/ui/ok-01-with-intermediate.rs

@@ -0,0 +1,48 @@
+#![allow(dead_code)]
+
+use polkadot_procmacro_subsystem_dispatch_gen::subsystem_dispatch_gen;
+
+/// The event type in question.
+#[derive(Clone, Copy, Debug)]
+enum Event {
+	Smth,
+	Else,
+}
+
+impl Event {
+	fn focus(&self) -> std::result::Result<Intermediate, ()> {
+		Ok(Intermediate(self.clone()))
+	}
+}
+
+
+#[derive(Debug, Clone)]
+struct Intermediate(Event);
+
+
+/// This should have a `From<Event>` impl but does not.
+#[derive(Clone, Debug)]
+enum Inner {
+	Foo,
+	Bar(Intermediate),
+}
+
+impl From<Intermediate> for Inner {
+	fn from(src: Intermediate) -> Self {
+		Inner::Bar(src)
+	}
+}
+
+#[subsystem_dispatch_gen(Event)]
+#[derive(Clone)]
+enum AllMessages {
+	/// Foo
+	Vvvvvv(Inner),
+
+    #[skip]
+    Uuuuu,
+}
+
+fn main() {
+    let _x = AllMessages::dispatch_iter(Event::Else);
+}