parser: add special Type::Void case

trunk_parser/src/ast.rs

@@ -10,6 +10,7 @@ pub enum Type {
     Nullable(String),
     Union(Vec<String>),
     Intersection(Vec<String>),
+    Void,
 }
 
 #[derive(Debug, Eq, PartialEq, Clone, Serialize)]

trunk_parser/src/parser/mod.rs

@@ -159,7 +159,10 @@ impl Parser {
             return Ok(Type::Intersection(types));
         }
 
-        Ok(Type::Plain(id))
+        Ok(match id.as_str() {
+            "void" => Type::Void,
+            _ => Type::Plain(id),
+        })
     }
 
     fn statement(&mut self) -> ParseResult<Statement> {
@@ -2929,6 +2932,16 @@ mod tests {
                 return_type: Some(Type::Plain("string".into())),
             }],
         );
+
+        assert_ast(
+            "<?php function foo(): void {}",
+            &[Statement::Function {
+                name: "foo".to_string().into(),
+                params: vec![],
+                body: vec![],
+                return_type: Some(Type::Void),
+            }],
+        );
     }
 
     #[test]