Reject zero type when declare event fields

crates/analyzer/src/db/queries/events.rs

@@ -40,7 +40,17 @@ pub fn event_type(db: &dyn AnalyzerDb, event: EventId) -> Analysis<Rc<types::Eve
             } = &field.kind;
 
             let typ = type_desc(&mut scope, typ_node).and_then(|typ| match typ {
-                typ if typ.has_fixed_size(scope.db()) => Ok(typ),
+                typ if typ.has_fixed_size(scope.db()) => {
+                    if !typ.is_zero_size(scope.db()) {
+                        Ok(typ)
+                    } else {
+                        Err(TypeError::new(scope.error(
+                            "event field type must have a non-zero types",
+                            typ_node.span,
+                            "this type can't be used as an event field",
+                        )))
+                    }
+                }
                 _ => Err(TypeError::new(scope.error(
                     "event field type must have a fixed size",
                     typ_node.span,

crates/analyzer/src/namespace/types.rs

@@ -84,6 +84,9 @@ impl TypeId {
     pub fn is_base(&self, db: &dyn AnalyzerDb) -> bool {
         self.typ(db).is_base()
     }
+    pub fn is_zero_size(&self, db: &dyn AnalyzerDb) -> bool {
+        self.typ(db).is_zero_size(db)
+    }
     pub fn is_bool(&self, db: &dyn AnalyzerDb) -> bool {
         matches!(self.typ(db), Type::Base(Base::Bool))
     }
@@ -494,6 +497,14 @@ impl Type {
         false
     }
 
+    pub fn is_zero_size(&self, db: &dyn AnalyzerDb) -> bool {
+        match &self {
+            Type::Base(Base::Unit) => true,
+            Type::Contract(inner) => inner.fields(db).is_empty(),
+            Type::Struct(inner) => inner.fields(db).is_empty(),
+            _ => false,
+        }
+    }
     /// Creates an instance of bool.
     pub fn bool() -> Self {
         Type::Base(Base::Bool)

crates/analyzer/tests/errors.rs

@@ -255,6 +255,7 @@ test_file! { external_call_type_error }
 test_file! { external_call_wrong_number_of_params }
 test_file! { contract_function_with_generic_params }
 test_file! { indexed_event }
+test_file! { invalid_type_in_event_zero_sized }
 test_file! { invalid_compiler_version }
 test_file! { invalid_block_field }
 test_file! { invalid_chain_field }

crates/analyzer/tests/snapshots/errors__invalid_type_in_event_zero_sized.snap

@@ -0,0 +1,23 @@
+---
+source: crates/analyzer/tests/errors.rs
+expression: "error_string(&path, test_files::fixture(path))"
+---
+error: event field type must have a non-zero types
+  ┌─ compile_errors/invalid_type_in_event_zero_sized.fe:8:8
+  │
+8 │     x: ()
+  │        ^^ this type can't be used as an event field
+
+error: event field type must have a non-zero types
+  ┌─ compile_errors/invalid_type_in_event_zero_sized.fe:9:8
+  │
+9 │     y: EmptyStruct
+  │        ^^^^^^^^^^^ this type can't be used as an event field
+
+error: event field type must have a non-zero types
+   ┌─ compile_errors/invalid_type_in_event_zero_sized.fe:10:8
+   │
+10 │     z: EmptyContract
+   │        ^^^^^^^^^^^^^ this type can't be used as an event field
+
+

crates/test-files/fixtures/compile_errors/invalid_type_in_event_zero_sized.fe

@@ -0,0 +1,11 @@
+contract EmptyContract {
+}
+
+struct EmptyStruct {
+}
+
+event Event {
+    x: ()
+    y: EmptyStruct
+    z: EmptyContract
+}