Versioning for #[runtime-interface] (#5328)

* versionned runtime-interface

* use only one additional wasm blob

* alter docs

* formatting, naming and docs

* add comment for test

* version duplicate err

* RuntimeInterfaceItem -> RuntimeInterfaceFunction<

* test naming

* version checking

* remove spaces

* Update primitives/runtime-interface/proc-macro/src/runtime_interface/bare_function_interface.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* remove sanity checks and reduce coverage

* add doc comment

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

substrate/primitives/runtime-interface/proc-macro/src/utils.rs

@@ -20,17 +20,60 @@ use proc_macro2::{TokenStream, Span};
 
 use syn::{
 	Ident, Error, Signature, Pat, PatType, FnArg, Type, token, TraitItemMethod, ItemTrait,
-	TraitItem, parse_quote, spanned::Spanned,
+	TraitItem, parse_quote, spanned::Spanned, Result, Meta, NestedMeta, Lit, Attribute,
 };
 
 use proc_macro_crate::crate_name;
 
 use std::env;
+use std::collections::{BTreeMap, btree_map::Entry};
 
 use quote::quote;
 
 use inflector::Inflector;
 
+/// Runtime interface function with all associated versions of this function.
+pub struct RuntimeInterfaceFunction<'a> {
+	latest_version: u32,
+	versions: BTreeMap<u32, &'a TraitItemMethod>,
+}
+
+impl<'a> RuntimeInterfaceFunction<'a> {
+	fn new(version: u32, trait_item: &'a TraitItemMethod) -> Self {
+		Self {
+			latest_version: version,
+			versions: {
+				let mut res = BTreeMap::new();
+				res.insert(version, trait_item);
+				res
+			},
+		}
+	}
+
+	pub fn latest_version(&self) -> (u32, &TraitItemMethod) {
+		(
+			self.latest_version,
+			self.versions.get(&self.latest_version)
+				.expect("If latest_version has a value, the key with this value is in the versions; qed")
+		)
+	}
+}
+
+/// All functions of a runtime interface grouped by the function names.
+pub struct RuntimeInterface<'a> {
+	items: BTreeMap<syn::Ident, RuntimeInterfaceFunction<'a>>,
+}
+
+impl<'a> RuntimeInterface<'a> {
+	pub fn latest_versions(&self) -> impl Iterator<Item = (u32, &TraitItemMethod)> {
+		self.items.iter().map(|(_, item)| item.latest_version())
+	}
+
+	pub fn all_versions(&self) -> impl Iterator<Item = (u32, &TraitItemMethod)> {
+		self.items.iter().flat_map(|(_, item)| item.versions.iter()).map(|(v, i)| (*v, *i))
+	}
+ }
+
 /// Generates the include for the runtime-interface crate.
 pub fn generate_runtime_interface_include() -> TokenStream {
 	if env::var("CARGO_PKG_NAME").unwrap() == "sp-runtime-interface" {
@@ -67,12 +110,25 @@ pub fn create_exchangeable_host_function_ident(name: &Ident) -> Ident {
 }
 
 /// Create the host function identifier for the given function name.
-pub fn create_host_function_ident(name: &Ident, trait_name: &Ident) -> Ident {
+pub fn create_host_function_ident(name: &Ident, version: u32, trait_name: &Ident) -> Ident {
 	Ident::new(
 		&format!(
-			"ext_{}_{}_version_1",
+			"ext_{}_{}_version_{}",
 			trait_name.to_string().to_snake_case(),
 			name,
+			version,
+		),
+		Span::call_site(),
+	)
+}
+
+/// Create the host function identifier for the given function name.
+pub fn create_function_ident_with_version(name: &Ident, version: u32) -> Ident {
+	Ident::new(
+		&format!(
+			"{}_version_{}",
+			name,
+			version,
 		),
 		Span::call_site(),
 	)
@@ -151,7 +207,7 @@ pub fn get_function_argument_types_ref_and_mut<'a>(
 }
 
 /// Returns an iterator over all trait methods for the given trait definition.
-pub fn get_trait_methods<'a>(trait_def: &'a ItemTrait) -> impl Iterator<Item = &'a TraitItemMethod> {
+fn get_trait_methods<'a>(trait_def: &'a ItemTrait) -> impl Iterator<Item = &'a TraitItemMethod> {
 	trait_def
 		.items
 		.iter()
@@ -160,3 +216,85 @@ pub fn get_trait_methods<'a>(trait_def: &'a ItemTrait) -> impl Iterator<Item = &
 			_ => None,
 		})
 }
+
+/// Parse version attribute.
+///
+/// Returns error if it is in incorrent format. Correct format is only `#[version(X)]`.
+fn parse_version_attribute(version: &Attribute) -> Result<u32> {
+	let meta = version.parse_meta()?;
+
+	let err = Err(Error::new(
+			meta.span(),
+			"Unexpected `version` attribute. The supported format is `#[version(1)]`",
+		)
+	);
+
+	match meta {
+		Meta::List(list) => {
+			if list.nested.len() != 1 {
+				err
+			} else if let Some(NestedMeta::Lit(Lit::Int(i))) = list.nested.first() {
+				i.base10_parse()
+			} else {
+				err
+			}
+		},
+		_ => err,
+	}
+}
+
+/// Return item version (`#[version(X)]`) attribute, if present.
+fn get_item_version(item: &TraitItemMethod) -> Result<Option<u32>> {
+	item.attrs.iter().find(|attr| attr.path.is_ident("version"))
+		.map(|attr| parse_version_attribute(attr))
+		.transpose()
+}
+
+/// Returns all runtime interface members, with versions.
+pub fn get_runtime_interface<'a>(trait_def: &'a ItemTrait)
+	-> Result<RuntimeInterface<'a>>
+{
+	let mut functions: BTreeMap<syn::Ident, RuntimeInterfaceFunction<'a>> = BTreeMap::new();
+
+	for item in get_trait_methods(trait_def) {
+		let name = item.sig.ident.clone();
+		let version = get_item_version(item)?.unwrap_or(1);
+
+		match functions.entry(name.clone()) {
+			Entry::Vacant(entry) => { entry.insert(RuntimeInterfaceFunction::new(version, item)); },
+			Entry::Occupied(mut entry) => {
+				if let Some(existing_item) = entry.get().versions.get(&version) {
+					let mut err = Error::new(
+						item.span(),
+						"Duplicated version attribute",
+					);
+					err.combine(Error::new(
+						existing_item.span(),
+						"Previous version with the same number defined here",
+					));
+
+					return Err(err);
+				}
+
+				let interface_item = entry.get_mut();
+				if interface_item.latest_version < version { interface_item.latest_version = version; }
+				interface_item.versions.insert(version, item);
+			}
+		}
+	}
+
+	for function in functions.values() {
+		let mut next_expected = 1;
+		for (version, item) in function.versions.iter() {
+			if next_expected != *version {
+				return Err(Error::new(
+					item.span(),
+					format!("Unexpected version attribute: missing version '{}' for this function", next_expected),
+				));
+			}
+			next_expected += 1;
+		}
+	}
+
+	Ok(RuntimeInterface { items: functions })
+}