wit-bindgen: generate only one StreamPayload or FuturePayload implementation per type alias set

crates/rust/src/bindgen.rs

@@ -427,13 +427,19 @@ impl Bindgen for FunctionBindgen<'_, '_> {
             Instruction::FutureLift { payload, .. } => {
                 let async_support = self.r#gen.r#gen.async_support_path();
                 let op = &operands[0];
-                let name = payload
-                    .as_ref()
-                    .map(|ty| {
-                        self.r#gen
-                            .type_name_owned_with_id(ty, Identifier::StreamOrFuturePayload)
-                    })
-                    .unwrap_or_else(|| "()".into());
+                let name = match payload {
+                    Some(Type::Id(type_id)) => {
+                        let dealiased_id = dealias(resolve, *type_id);
+                        self.r#gen.type_name_owned_with_id(
+                            &Type::Id(dealiased_id),
+                            Identifier::StreamOrFuturePayload,
+                        )
+                    }
+                    Some(ty) => self
+                        .r#gen
+                        .type_name_owned_with_id(ty, Identifier::StreamOrFuturePayload),
+                    None => "()".into(),
+                };
                 let ordinal = self
                     .r#gen
                     .r#gen
@@ -455,13 +461,19 @@ impl Bindgen for FunctionBindgen<'_, '_> {
             Instruction::StreamLift { payload, .. } => {
                 let async_support = self.r#gen.r#gen.async_support_path();
                 let op = &operands[0];
-                let name = payload
-                    .as_ref()
-                    .map(|ty| {
-                        self.r#gen
-                            .type_name_owned_with_id(ty, Identifier::StreamOrFuturePayload)
-                    })
-                    .unwrap_or_else(|| "()".into());
+                let name = match payload {
+                    Some(Type::Id(type_id)) => {
+                        let dealiased_id = dealias(resolve, *type_id);
+                        self.r#gen.type_name_owned_with_id(
+                            &Type::Id(dealiased_id),
+                            Identifier::StreamOrFuturePayload,
+                        )
+                    }
+                    Some(ty) => self
+                        .r#gen
+                        .type_name_owned_with_id(ty, Identifier::StreamOrFuturePayload),
+                    None => "()".into(),
+                };
                 let ordinal = self
                     .r#gen
                     .r#gen

crates/rust/src/interface.rs

@@ -523,10 +523,13 @@ macro_rules! {macro_name} {{
         func_name: &str,
         payload_type: Option<&Type>,
     ) {
-        let name = if let Some(payload_type) = payload_type {
-            self.type_name_owned(payload_type)
-        } else {
-            "()".into()
+        let name = match payload_type {
+            Some(Type::Id(type_id)) => {
+                let dealiased_id = dealias(self.resolve, *type_id);
+                self.type_name_owned(&Type::Id(dealiased_id))
+            }
+            Some(payload_type) => self.type_name_owned(payload_type),
+            None => "()".into(),
         };
         let map = match payload_for {
             PayloadFor::Future => &mut self.r#gen.future_payloads,

crates/test/src/cpp.rs

@@ -49,6 +49,8 @@ impl LanguageMethods for Cpp {
             "async-trait-function.wit"
             | "error-context.wit"
             | "futures.wit"
+            | "import-export-future.wit"
+            | "import-export-stream.wit"
             | "resources-with-futures.wit"
             | "resources-with-streams.wit"
             | "streams.wit"

crates/test/src/csharp.rs

@@ -48,6 +48,7 @@ impl LanguageMethods for Csharp {
                 | "error-context.wit"
                 | "resource-fallible-constructor.wit"
                 | "async-resource-func.wit"
+                | "import-export-stream.wit"
         )
     }
 

tests/codegen/import-export-future.wit

@@ -0,0 +1,19 @@
+//@ async = true
+
+package a:b;
+
+world w {
+    import i;
+    export i;
+}
+
+interface i {
+    use t.{r};
+    f: func(p: future<r>);
+}
+
+interface t {
+    record r {
+        x: u32,
+    }
+}

tests/codegen/import-export-stream.wit

@@ -0,0 +1,19 @@
+//@ async = true
+
+package a:b;
+
+world w {
+    import i;
+    export i;
+}
+
+interface i {
+    use t.{r};
+    f: func(p: stream<r>);
+}
+
+interface t {
+    record r {
+        x: u32,
+    }
+}