Define static distributed events slice in ink crate (#2487)

* Define static distributed events slice in `ink` crate

* chore: Rename events slice

* fix: re-enable LTO for events test

* Update changelog

* fix: Make `linkme` dependency optional

Author: davidsemakula

CHANGELOG.md

@@ -213,6 +213,7 @@ You can find binary releases of the node [here](https://github.com/use-ink/ink-n
 ## Changed
 - Restrict which `cfg` attributes can be used ‒ [#2313](https://github.com/use-ink/ink/pull/2313)
 - More idiomatic return types for metadata getters - [#2398](https://github.com/use-ink/ink/pull/2398)
+- Define static distributed events slice in `ink` crate - [#2487](https://github.com/use-ink/ink/pull/2487)
 
 ## Added
 - Support for `caller_is_root` - [#2332](https://github.com/use-ink/ink/pull/2332)

Cargo.lock

@@ -28,6 +28,7 @@ scale-info = { workspace = true, default-features = false, features = ["derive"]
 derive_more = { workspace = true, features = ["from"] }
 const_format = { workspace = true }
 keccak-const = { workspace = true }
+linkme = { workspace = true, optional = true }
 
 polkavm-derive = { workspace = true }
 xcm = { workspace = true }
@@ -58,7 +59,8 @@ std = [
     "xcm/std",
     "derive_more/std",
     "sp-runtime-interface/std",
-    "sp-io/std"
+    "sp-io/std",
+    "dep:linkme"
 ]
 
 # Enable contract debug messages via `debug_print!` and `debug_println!`.

crates/ink/Cargo.toml

@@ -108,7 +108,9 @@ impl Metadata<'_> {
                 .messages([
                     #( #messages ),*
                 ])
-                .collect_events()
+                .events(
+                    ::ink::collect_events()
+                )
                 .docs([
                     #( #docs ),*
                 ])

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

@@ -84,8 +84,8 @@ fn event_metadata_derive_struct(s: synstructure::Structure) -> syn::Result<Token
             fn event_spec() -> ::ink::metadata::EventSpec {
                // register this event metadata function in the distributed slice for combining all
                // events referenced in the contract binary.
-               #[::ink::metadata::linkme::distributed_slice(::ink::metadata::EVENTS)]
-               #[linkme(crate = ::ink::metadata::linkme)]
+               #[::ink::linkme::distributed_slice(::ink::CONTRACT_EVENTS)]
+               #[linkme(crate = ::ink::linkme)]
                static EVENT_METADATA: fn() -> ::ink::metadata::EventSpec =
                    <#ident as ::ink::metadata::EventMetadata>::event_spec;
 

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

@@ -27,8 +27,8 @@ fn unit_struct_works() {
                     const MODULE_PATH: &'static str = ::core::module_path!();
 
                     fn event_spec() -> ::ink::metadata::EventSpec {
-                        #[::ink::metadata::linkme::distributed_slice(::ink::metadata::EVENTS)]
-                        #[linkme(crate = ::ink::metadata::linkme)]
+                        #[::ink::linkme::distributed_slice(::ink::CONTRACT_EVENTS)]
+                        #[linkme(crate = ::ink::linkme)]
                         static EVENT_METADATA: fn() -> ::ink::metadata::EventSpec =
                             <UnitStruct as ::ink::metadata::EventMetadata>::event_spec;
 
@@ -62,8 +62,8 @@ fn struct_with_fields_no_topics() {
                     const MODULE_PATH: &'static str = ::core::module_path!();
 
                     fn event_spec() -> ::ink::metadata::EventSpec {
-                        #[::ink::metadata::linkme::distributed_slice(::ink::metadata::EVENTS)]
-                        #[linkme(crate = ::ink::metadata::linkme)]
+                        #[::ink::linkme::distributed_slice(::ink::CONTRACT_EVENTS)]
+                        #[linkme(crate = ::ink::linkme)]
                         static EVENT_METADATA: fn() -> ::ink::metadata::EventSpec =
                             <Event as ::ink::metadata::EventMetadata>::event_spec;
 
@@ -130,8 +130,8 @@ fn struct_with_fields_and_some_topics() {
                     const MODULE_PATH: &'static str = ::core::module_path!();
 
                     fn event_spec() -> ::ink::metadata::EventSpec {
-                        #[::ink::metadata::linkme::distributed_slice(::ink::metadata::EVENTS)]
-                        #[linkme(crate = ::ink::metadata::linkme)]
+                        #[::ink::linkme::distributed_slice(::ink::CONTRACT_EVENTS)]
+                        #[linkme(crate = ::ink::linkme)]
                         static EVENT_METADATA: fn() -> ::ink::metadata::EventSpec =
                             <Event as ::ink::metadata::EventMetadata>::event_spec;
 

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

@@ -105,3 +105,24 @@ pub use ink_primitives::{
     H256,
     U256,
 };
+
+#[cfg(feature = "std")]
+#[doc(hidden)]
+pub use linkme;
+
+#[cfg(feature = "std")]
+use ink_metadata::EventSpec;
+
+/// Any event which derives `#[derive(ink::EventMetadata)]` and is used in the contract
+/// binary will have its implementation added to this distributed slice at linking time.
+#[cfg(feature = "std")]
+#[linkme::distributed_slice]
+#[linkme(crate = linkme)]
+pub static CONTRACT_EVENTS: [fn() -> EventSpec] = [..];
+
+/// Collect the [`EventSpec`] metadata of all event definitions linked and used in the
+/// binary.
+#[cfg(feature = "std")]
+pub fn collect_events() -> Vec<EventSpec> {
+    CONTRACT_EVENTS.iter().map(|event| event()).collect()
+}

crates/ink/src/lib.rs

@@ -21,7 +21,6 @@ ink_primitives = { workspace = true }
 serde = { workspace = true, features = ["derive", "alloc"] }
 impl-serde = { workspace = true, default-features = true }
 derive_more = { workspace = true, features = ["from"] }
-linkme = { workspace = true }
 scale = { workspace = true }
 scale-info = { workspace = true, features = ["derive", "serde", "decode", "schema"] }
 schemars = { workspace = true }

crates/metadata/Cargo.toml

@@ -54,8 +54,6 @@ pub use self::specs::{
 
 use impl_serde::serialize as serde_hex;
 
-#[doc(hidden)]
-pub use linkme;
 pub use scale_info::TypeInfo;
 
 #[cfg(feature = "derive")]
@@ -143,17 +141,6 @@ impl InkProject {
     }
 }
 
-/// Any event which derives `#[derive(ink::EventMetadata)]` and is used in the contract
-/// binary will have its implementation added to this distributed slice at linking time.
-#[linkme::distributed_slice]
-pub static EVENTS: [fn() -> EventSpec] = [..];
-
-/// Collect the [`EventSpec`] metadata of all event definitions linked and used in the
-/// binary.
-pub fn collect_events() -> Vec<EventSpec> {
-    EVENTS.iter().map(|event| event()).collect()
-}
-
 /// Provides metadata about an ink! event.
 ///
 /// Implementations must be registered into the [`static@EVENTS`] distributed slice, in

crates/metadata/src/lib.rs

@@ -254,13 +254,6 @@ where
     }
 }
 
-impl<S> ContractSpecBuilder<MetaForm, S> {
-    /// Collect metadata for all events linked into the contract.
-    pub fn collect_events(self) -> Self {
-        self.events(crate::collect_events())
-    }
-}
-
 impl<F> ContractSpecBuilder<F, Valid>
 where
     F: Form,

crates/metadata/src/specs.rs

@@ -28,3 +28,10 @@ std = [
 ]
 ink-as-dependency = []
 e2e-tests = []
+
+[profile.test]
+# Need this for linkme crate to work for the event metadata collection unit test.
+# See https://github.com/dtolnay/linkme/issues/61#issuecomment-1503653702
+# NOTE: `cargo-contract` also sets this flag when generating metadata for the same reason.
+# See https://github.com/use-ink/cargo-contract/pull/1200
+lto = "thin"

integration-tests/public/events/Cargo.toml

@@ -109,7 +109,7 @@ pub mod events {
 
         #[test]
         fn collects_specs_for_all_linked_and_used_events() {
-            let event_specs = ink::metadata::collect_events();
+            let event_specs = ink::collect_events();
 
             assert!(event_specs
                 .iter()