Messages return TypeSpec directly (#1999)

* Messages return TypeSpec directly

* arrange changelog

* remove `Option` in `ReturnTypeSpec` + adjust tests

* remove rubbish

* fix tests

* fix docs

CHANGELOG.md

@@ -9,16 +9,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - [E2E] Allow testing with live-chain state - [#1949](/~https://github.com/paritytech/ink/pull/1949)
 - [E2E] Call builders and extra gas margin option - [#1917](/~https://github.com/paritytech/ink/pull/1917)
-- Make `set_code_hash` generic - [#1906](/~https://github.com/paritytech/ink/pull/1906)
+- Linter: `storage_never_freed` lint - [#1932](/~https://github.com/paritytech/ink/pull/1932)
+- Linter: `strict_balance_equality` lint - [#1914](/~https://github.com/paritytech/ink/pull/1914)
 - Clean E2E configuration parsing - [#1922](/~https://github.com/paritytech/ink/pull/1922)
+- Make `set_code_hash` generic - [#1906](/~https://github.com/paritytech/ink/pull/1906)
 
 ### Changed
+- Messages return `TypeSpec` directly - #[1999](/~https://github.com/paritytech/ink/pull/1999)
 - Fail when decoding from storage and not all bytes consumed - [#1897](/~https://github.com/paritytech/ink/pull/1897)
 - [E2E] resolve DispatchError error details for dry-runs - [#1944](/~https://github.com/paritytech/ink/pull/1994)
 
-### Added
-- Linter: `storage_never_freed` lint - [#1932](/~https://github.com/paritytech/ink/pull/1932)
-- Linter: `strict_balance_equality` lint - [#1914](/~https://github.com/paritytech/ink/pull/1914)
 
 ## Version 5.0.0-alpha
 

crates/ink/codegen/src/generator/metadata.rs

@@ -248,7 +248,8 @@ impl Metadata<'_> {
                 let ident = message.ident();
                 let args = message.inputs().map(Self::generate_dispatch_argument);
                 let cfg_attrs = message.get_cfg_attrs(span);
-                let ret_ty = Self::generate_return_type(Some(&message.wrapped_output()));
+                let ret_ty =
+                    Self::generate_message_return_type(&message.wrapped_output());
                 quote_spanned!(span =>
                     #( #cfg_attrs )*
                     ::ink::metadata::MessageSpec::from_label(::core::stringify!(#ident))
@@ -311,7 +312,7 @@ impl Metadata<'_> {
                         as #trait_path>::__ink_TraitInfo
                         as ::ink::reflect::TraitMessageInfo<#local_id>>::SELECTOR
                 }};
-                let ret_ty = Self::generate_return_type(Some(&message.wrapped_output()));
+                let ret_ty = Self::generate_message_return_type(&message.wrapped_output());
                 let label = [trait_ident.to_string(), message_ident.to_string()].join("::");
                 quote_spanned!(message_span=>
                     #( #cfg_attrs )*
@@ -333,19 +334,10 @@ impl Metadata<'_> {
     }
 
     /// Generates ink! metadata for the given return type.
-    fn generate_return_type(ret_ty: Option<&syn::Type>) -> TokenStream2 {
-        match ret_ty {
-            None => {
-                quote! {
-                    ::ink::metadata::ReturnTypeSpec::new(::core::option::Option::None)
-                }
-            }
-            Some(ty) => {
-                let type_spec = Self::generate_type_spec(ty);
-                quote! {
-                    ::ink::metadata::ReturnTypeSpec::new(#type_spec)
-                }
-            }
+    fn generate_message_return_type(ret_ty: &syn::Type) -> TokenStream2 {
+        let type_spec = Self::generate_type_spec(ret_ty);
+        quote! {
+            ::ink::metadata::ReturnTypeSpec::new(#type_spec)
         }
     }
 
@@ -361,13 +353,13 @@ impl Metadata<'_> {
 
         quote_spanned!(span=>
             ::ink::metadata::ReturnTypeSpec::new(if #constructor_info::IS_RESULT {
-                ::core::option::Option::Some(::ink::metadata::TypeSpec::with_name_str::<
+                ::ink::metadata::TypeSpec::with_name_str::<
                     ::ink::ConstructorResult<::core::result::Result<(), #constructor_info::Error>>,
-                >("ink_primitives::ConstructorResult"))
+                >("ink_primitives::ConstructorResult")
             } else {
-                ::core::option::Option::Some(::ink::metadata::TypeSpec::with_name_str::<
+                ::ink::metadata::TypeSpec::with_name_str::<
                     ::ink::ConstructorResult<()>,
-                >("ink_primitives::ConstructorResult"))
+                >("ink_primitives::ConstructorResult")
             })
         )
     }

crates/ink/tests/return_type_metadata.rs

@@ -106,7 +106,7 @@ mod tests {
         let message = metadata.spec().messages().iter().next().unwrap();
         assert_eq!("TraitDefinition::get_value", message.label());
 
-        let type_spec = message.return_type().opt_type().unwrap();
+        let type_spec = message.return_type().ret_type();
         let ty = resolve_type(&metadata, type_spec.ty().id);
         let (ok_ty, _) = extract_result(&metadata, ty);
 
@@ -119,7 +119,7 @@ mod tests {
         let constructor = metadata.spec().constructors().iter().next().unwrap();
 
         assert_eq!("try_new", constructor.label());
-        let type_spec = constructor.return_type().opt_type().unwrap();
+        let type_spec = constructor.return_type().ret_type();
         assert_eq!(
             "ink_primitives::ConstructorResult",
             format!("{}", type_spec.display_name())

crates/metadata/src/specs.rs

@@ -468,6 +468,7 @@ pub struct ConstructorSpecBuilder<F: Form, Selector, IsPayable, Returns> {
 impl<F> ConstructorSpec<F>
 where
     F: Form,
+    TypeSpec<F>: Default,
 {
     /// Creates a new constructor spec builder.
     pub fn from_label(
@@ -484,7 +485,7 @@ where
                 selector: Selector::default(),
                 payable: Default::default(),
                 args: Vec::new(),
-                return_type: ReturnTypeSpec::new(None),
+                return_type: ReturnTypeSpec::new(TypeSpec::default()),
                 docs: Vec::new(),
                 default: false,
             },
@@ -668,6 +669,7 @@ mod state {
 impl<F> MessageSpec<F>
 where
     F: Form,
+    TypeSpec<F>: Default,
 {
     /// Creates a new message spec builder.
     pub fn from_label(
@@ -686,7 +688,7 @@ where
                 mutates: false,
                 payable: false,
                 args: Vec::new(),
-                return_type: ReturnTypeSpec::new(None),
+                return_type: ReturnTypeSpec::new(TypeSpec::default()),
                 docs: Vec::new(),
                 default: false,
             },
@@ -1417,45 +1419,44 @@ where
 #[must_use]
 pub struct ReturnTypeSpec<F: Form = MetaForm> {
     #[serde(rename = "type")]
-    opt_type: Option<TypeSpec<F>>,
+    ret_type: TypeSpec<F>,
 }
 
 impl IntoPortable for ReturnTypeSpec {
     type Output = ReturnTypeSpec<PortableForm>;
 
     fn into_portable(self, registry: &mut Registry) -> Self::Output {
         ReturnTypeSpec {
-            opt_type: self
-                .opt_type
-                .map(|opt_type| opt_type.into_portable(registry)),
+            ret_type: self.ret_type.into_portable(registry),
         }
     }
 }
 
 impl<F> ReturnTypeSpec<F>
 where
     F: Form,
+    TypeSpec<F>: Default,
 {
     /// Creates a new return type specification from the given type or `None`.
     ///
     /// # Examples
     ///
     /// ```no_run
     /// # use ink_metadata::{TypeSpec, ReturnTypeSpec};
-    /// <ReturnTypeSpec<scale_info::form::MetaForm>>::new(None); // no return type;
+    /// <ReturnTypeSpec<scale_info::form::MetaForm>>::new(TypeSpec::default()); // no return type;
     /// ```
     pub fn new<T>(ty: T) -> Self
     where
-        T: Into<Option<TypeSpec<F>>>,
+        T: Into<TypeSpec<F>>,
     {
         Self {
-            opt_type: ty.into(),
+            ret_type: ty.into(),
         }
     }
 
-    /// Returns the optional return type
-    pub fn opt_type(&self) -> Option<&TypeSpec<F>> {
-        self.opt_type.as_ref()
+    /// Returns the return type
+    pub fn ret_type(&self) -> &TypeSpec<F> {
+        &self.ret_type
     }
 }