use const array

crates/env/src/event.rs

@@ -220,5 +220,5 @@ pub trait Event: scale::Encode + GetSignatureTopic {
 /// default calculates this as `blake2b("Event(field1_type,field2_type)")`
 pub trait GetSignatureTopic {
     /// Retrieve the signature topic
-    fn signature_topic() -> Option<[u8; 32]>;
+    const SIGNATURE_TOPIC: core::option::Option<[u8; 32]>;
 }

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

@@ -55,9 +55,7 @@ impl SignatureTopic<'_> {
 
         quote! {
             impl ::ink::env::GetSignatureTopic for #item_ident {
-                fn signature_topic() -> Option<[u8; 32]> {
-                    #signature_topic
-                }
+                const SIGNATURE_TOPIC: ::core::option::Option<[u8; 32]> = #signature_topic;
             }
         }
     }

crates/ink/macro/src/event/metadata.rs

@@ -91,7 +91,7 @@ fn event_metadata_derive_struct(s: synstructure::Structure) -> syn::Result<Token
                 ::ink::metadata::EventSpec::new(::core::stringify!(#ident))
                     .module_path(::core::module_path!())
                     .signature_topic(
-                        <Self as ::ink::env::GetSignatureTopic>::signature_topic()
+                        <Self as ::ink::env::GetSignatureTopic>::SIGNATURE_TOPIC
                     )
                     .args([
                        #( #args ),*

crates/ink/macro/src/event/mod.rs

@@ -102,7 +102,7 @@ fn event_derive_struct(mut s: synstructure::Structure) -> syn::Result<TokenStrea
         None
     } else {
         Some(quote_spanned!(span=>
-            .push_topic(<Self as ::ink::env::GetSignatureTopic>::signature_topic().as_ref())
+            .push_topic(<Self as ::ink::env::GetSignatureTopic>::SIGNATURE_TOPIC.as_ref())
         ))
     };
 
@@ -163,9 +163,7 @@ fn generate_signature_topic_blank(
     if anonymous {
         quote! {
             impl ::ink::env::GetSignatureTopic for #item_ident {
-                fn signature_topic() -> Option<[u8; 32]> {
-                    None
-                }
+                const SIGNATURE_TOPIC: ::core::option::Option<[u8; 32]> = None;
             }
         }
     } else {

crates/ink/macro/src/lib.rs

@@ -721,7 +721,7 @@ pub fn event(attr: TokenStream, item: TokenStream) -> TokenStream {
 ///
 /// use ink::env::GetSignatureTopic;
 /// assert_eq!(Some([17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17]),
-///     <MyCustomSignatureEvent as GetSignatureTopic>::signature_topic())
+///     <MyCustomSignatureEvent as GetSignatureTopic>::SIGNATURE_TOPIC)
 #[proc_macro_attribute]
 pub fn signature_topic(attr: TokenStream, item: TokenStream) -> TokenStream {
     event::generate_signature_topic(attr.into(), item.into()).into()
@@ -1447,7 +1447,7 @@ synstructure::decl_derive!(
     /// }
     ///
     /// use ink::env::GetSignatureTopic;
-    /// assert_ne!(<MyEvent as GetSignatureTopic>::signature_topic(), <other_event::MyEvent as GetSignatureTopic>::signature_topic());
+    /// assert_ne!(<MyEvent as GetSignatureTopic>::SIGNATURE_TOPIC, <other_event::MyEvent as GetSignatureTopic>::SIGNATURE_TOPIC);
     /// ```
     ///
     /// ## Anonymous Events

crates/ink/macro/src/tests/event.rs

@@ -47,7 +47,7 @@ fn unit_struct_works() {
                             UnitStruct => {
                                 builder
                                     .build::<Self>()
-                                    .push_topic(<Self as ::ink::env::GetSignatureTopic>::signature_topic().as_ref())
+                                    .push_topic(<Self as ::ink::env::GetSignatureTopic>::SIGNATURE_TOPIC.as_ref())
                                     .finish()
                             }
                         }
@@ -68,9 +68,7 @@ fn unit_struct_anonymous_has_no_topics() {
         }
         expands to {
             impl ::ink::env::GetSignatureTopic for UnitStruct {
-                fn signature_topic() -> Option<[u8; 32]> {
-                    None
-                }
+                const SIGNATURE_TOPIC: ::core::option::Option<[u8; 32]> = None;
             }
             const _: () = {
                 impl ::ink::env::Event for UnitStruct {
@@ -127,7 +125,7 @@ fn struct_with_fields_no_topics() {
                             Event { .. } => {
                                 builder
                                     .build::<Self>()
-                                    .push_topic(<Self as ::ink::env::GetSignatureTopic>::signature_topic().as_ref())
+                                    .push_topic(<Self as ::ink::env::GetSignatureTopic>::SIGNATURE_TOPIC.as_ref())
                                     .finish()
                             }
                         }
@@ -170,7 +168,7 @@ fn struct_with_fields_and_some_topics() {
                             Event { field_2 : __binding_1 , field_3 : __binding_2 , .. } => {
                                 builder
                                     .build::<Self>()
-                                    .push_topic(<Self as ::ink::env::GetSignatureTopic>::signature_topic().as_ref())
+                                    .push_topic(<Self as ::ink::env::GetSignatureTopic>::SIGNATURE_TOPIC.as_ref())
                                     .push_topic(::ink::as_option!(__binding_1))
                                     .push_topic(::ink::as_option!(__binding_2))
                                     .finish()

crates/ink/macro/src/tests/event_metadata.rs

@@ -35,7 +35,7 @@ fn unit_struct_works() {
 
                         ::ink::metadata::EventSpec::new(::core::stringify!(UnitStruct))
                             .module_path(::core::module_path!())
-                            .signature_topic(<Self as ::ink::env::GetSignatureTopic>::signature_topic())
+                            .signature_topic(<Self as ::ink::env::GetSignatureTopic>::SIGNATURE_TOPIC)
                             .args([])
                             .docs([])
                             .done()
@@ -71,7 +71,7 @@ fn struct_with_fields_no_topics() {
 
                         ::ink::metadata::EventSpec::new(::core::stringify!(Event))
                             .module_path(::core::module_path!())
-                            .signature_topic(<Self as ::ink::env::GetSignatureTopic>::signature_topic())
+                            .signature_topic(<Self as ::ink::env::GetSignatureTopic>::SIGNATURE_TOPIC)
                             .args([
                                 ::ink::metadata::EventParamSpec::new(::core::stringify!(field_1))
                                     .of_type(::ink::metadata::TypeSpec::of_type::<u32>())
@@ -125,7 +125,7 @@ fn struct_with_fields_and_some_topics() {
 
                         ::ink::metadata::EventSpec::new(::core::stringify!(Event))
                             .module_path(::core::module_path!())
-                            .signature_topic(<Self as ::ink::env::GetSignatureTopic>::signature_topic())
+                            .signature_topic(<Self as ::ink::env::GetSignatureTopic>::SIGNATURE_TOPIC)
                             .args([
                                 ::ink::metadata::EventParamSpec::new(::core::stringify!(field_1))
                                     .of_type(::ink::metadata::TypeSpec::of_type::<u32>())

integration-tests/events/lib.rs

@@ -166,7 +166,7 @@ pub mod events {
 
             assert_eq!(event.topics.len(), 3);
             let signature_topic =
-                <event_def::ThirtyTwoByteTopics as ink::env::GetSignatureTopic>::signature_topic()
+                <event_def::ThirtyTwoByteTopics as ink::env::GetSignatureTopic>::SIGNATURE_TOPIC
                     .map(|topic| topic.to_vec());
             assert_eq!(Some(&event.topics[0]), signature_topic.as_ref());
             assert_eq!(event.topics[1], [0x42; 32]);
@@ -186,7 +186,7 @@ pub mod events {
             let event = &emitted_events[0];
 
             let signature_topic =
-                <event_def::ThirtyTwoByteTopics as ink::env::GetSignatureTopic>::signature_topic()
+                <event_def::ThirtyTwoByteTopics as ink::env::GetSignatureTopic>::SIGNATURE_TOPIC
                     .map(|topic| topic.to_vec())
                     .unwrap();
 
@@ -207,7 +207,7 @@ pub mod events {
             assert_eq!(1, emitted_events.len());
 
             let signature_topic =
-                <InlineCustomFlipped as ink::env::GetSignatureTopic>::signature_topic();
+                <InlineCustomFlipped as ink::env::GetSignatureTopic>::SIGNATURE_TOPIC;
 
             assert_eq!(Some([17u8; 32]), signature_topic);
         }
@@ -230,7 +230,7 @@ pub mod events {
             assert_eq!(event.topics[0], topic);
 
             let signature_topic =
-                <InlineAnonymousEvent as ink::env::GetSignatureTopic>::signature_topic();
+                <InlineAnonymousEvent as ink::env::GetSignatureTopic>::SIGNATURE_TOPIC;
             assert_eq!(None, signature_topic);
         }
     }
@@ -278,7 +278,7 @@ pub mod events {
             assert_eq!(!init_value, flipped.value);
 
             let signature_topic =
-                <event_def::ForeignFlipped as ink::env::GetSignatureTopic>::signature_topic()
+                <event_def::ForeignFlipped as ink::env::GetSignatureTopic>::SIGNATURE_TOPIC
                     .map(H256::from)
                     .unwrap();
 
@@ -321,7 +321,7 @@ pub mod events {
             assert_eq!(!init_value, flipped.value);
 
             let signature_topic =
-                <InlineFlipped as ink::env::GetSignatureTopic>::signature_topic()
+                <InlineFlipped as ink::env::GetSignatureTopic>::SIGNATURE_TOPIC
                     .map(H256::from)
                     .unwrap();
 
@@ -364,7 +364,7 @@ pub mod events {
             assert!(event.maybe_hash.is_none());
 
             let signature_topic =
-                <event_def::ThirtyTwoByteTopics as ink::env::GetSignatureTopic>::signature_topic()
+                <event_def::ThirtyTwoByteTopics as ink::env::GetSignatureTopic>::SIGNATURE_TOPIC
                     .map(H256::from)
                     .unwrap();
 
@@ -406,7 +406,7 @@ pub mod events {
             assert_eq!(1, contract_events.len());
 
             let signature_topic =
-                <InlineCustomFlipped as ink::env::GetSignatureTopic>::signature_topic();
+                <InlineCustomFlipped as ink::env::GetSignatureTopic>::SIGNATURE_TOPIC;
 
             assert_eq!(Some([17u8; 32]), signature_topic);