Conditional compilation (#1707)

* conditionally count messages and constructors

* correctly ommit attributed essage

* PoC of ommittable messages

* fmt and remove expanded macro

* refator

* constructor + trait messages

* remove expand.rs

* omit events but not topics

* remove dispatchable counting structs in reflection

* errors on non-existtent topic and topic field

* tests + docs + examples

* formatting

* fmt

* fmt

* make spellcheck happy

* fix other examples

* cleanup

* generate cfg attr in-place

* refactoring

* add build with features in gitlab

* refactoring

* fmt

* add tests and CI refactoring

* CI typo

* feature variance in CI

* move func to utils and update changelog

.gitlab-ci.yml

@@ -374,6 +374,11 @@ examples-test:
   script:
     - for example in integration-tests/*/; do
         if [ "$example" = "integration-tests/lang-err-integration-tests/" ]; then continue; fi;
+        if [ "$example" = "integration-tests/conditional-compilation/" ]; then
+        cargo test --verbose --manifest-path ${example}/Cargo.toml --features "foo";
+        cargo test --verbose --manifest-path ${example}/Cargo.toml --features "bar";
+        cargo test --verbose --manifest-path ${example}/Cargo.toml --features "foo, bar";
+        fi;
         if grep -q "e2e-tests = \[\]" "${example}/Cargo.toml"; then
           cargo test --verbose --manifest-path ${example}/Cargo.toml --features e2e-tests;
         else
@@ -400,6 +405,17 @@ examples-contract-build:
     - cargo contract -V
     - for example in integration-tests/*/; do
         if [ "$example" = "integration-tests/lang-err-integration-tests/" ]; then continue; fi;
+        if [ "$example" = "integration-tests/conditional-compilation/" ]; then
+        pushd $example &&
+        cargo +stable contract build --features "foo" &&
+        popd;
+        pushd $example &&
+        cargo +stable contract build --features "bar" &&
+        popd;
+        pushd $example &&
+        cargo +stable contract build --features "foo, bar" &&
+        popd;
+        fi;
         pushd $example &&
         cargo +stable contract build &&
         popd;
@@ -421,7 +437,7 @@ examples-no-std-check:
     - rustup component add rust-src --toolchain stable
     - cargo contract -V
     # We skip some examples for those reasons:
-    # There are no manifests in those two directories and hence it would fall back to the workspace. 
+    # There are no manifests in those two directories and hence it would fall back to the workspace.
     #  - lang-err-integration-tests
     #  - upgradeable-contracts
     # This uses dlmalloc which is only supported on select targets.

CHANGELOG.md

@@ -10,6 +10,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - E2E: auto detect contracts to be built - [#1691](https://github.com/paritytech/ink/pull/1691)
 - Add `set_code_hash` to `EnvAccess` - [#1698](https://github.com/paritytech/ink/pull/1698)
 
+### Changed
+- Support conditional compilation - [#1707](https://github.com/paritytech/ink/pull/1707)
+
 ## Version 4.0.1
 
 ### Fixed
@@ -1931,4 +1934,4 @@ impl Contract {
 
 This is useful if the `impl` block itself does not contain any ink! constructors or messages, but you
 still need to access some of the "magic" provided by ink!. In the example above, you would not have
-access to `emit_event` without `#[ink(impl)]`.
+access to `emit_event` without `#[ink(impl)]`.

crates/ink/codegen/src/generator/as_dependency/call_builder.rs

@@ -275,6 +275,7 @@ impl CallBuilder<'_> {
         let span = message.span();
         let message_ident = message.ident();
         let output_ident = generator::output_ident(message_ident);
+        let cfg_attrs = message.get_cfg_attrs(span);
         let trait_info_id = generator::generate_reference_to_trait_info(span, trait_path);
         let (input_bindings, input_types): (Vec<_>, Vec<_>) = message
             .callable()
@@ -295,6 +296,7 @@ impl CallBuilder<'_> {
             .whitelisted_attributes()
             .filter_attr(message.attrs().to_vec());
         quote_spanned!(span=>
+            #( #cfg_attrs )*
             type #output_ident = <<<
                 Self
                 as ::ink::codegen::TraitCallForwarderFor<{#trait_info_id}>>::Forwarder

crates/ink/codegen/src/generator/as_dependency/contract_ref.rs

@@ -293,11 +293,14 @@ impl ContractRef<'_> {
         let mut_token = message.receiver().is_ref_mut().then(|| quote! { mut });
         let input_bindings = message.inputs().map(|input| &input.pat).collect::<Vec<_>>();
         let input_types = message.inputs().map(|input| &input.ty).collect::<Vec<_>>();
+        let cfg_attrs = message.get_cfg_attrs(span);
         quote_spanned!(span=>
+            #( #cfg_attrs )*
             type #output_ident =
                 <<Self::__ink_TraitInfo as ::ink::codegen::TraitCallForwarder>::Forwarder as #trait_path>::#output_ident;
 
             #[inline]
+            #( #cfg_attrs )*
             fn #message_ident(
                 & #mut_token self
                 #( , #input_bindings : #input_types )*