refactor(parser): change body_h to body result

Refs: #1

furc/src/ast.cpp

@@ -156,13 +156,13 @@ void function_definition_node::accept(visitor& visitor) const {
 
 std::ostream& function_definition_node::print(std::ostream& os) const {
     function_declaration_node::print(os);
-    os << ':';
-    if (m_body.present()) {
+    os << ":\n";
+    if (m_body.has_value()) {
         for (const auto& entry : m_body->statements)
-            os << '\n' << entry;
-        return os << '\n' << m_body->end << ": " << p_name->string << " end";
+            os << entry << '\n';
+        return os << m_body->end << ": " << p_name->string << " end";
     }
-    return os << m_body.error(); // error
+    return os << m_body.error().location << ": ERROR: unknown";
 }
 
 bool function_definition_node::equal(const node& rhs) const {

furc/src/front/ir_generator.cpp

@@ -18,7 +18,7 @@ void ir_generator::visit(const ast::function_definition_node& funcDef) {
 
     push_block();
     if (funcDef.body().has_error()) {
-        std::cerr << funcDef.body().error() << '\n';
+        std::cerr << funcDef.body().error().location << ": ERROR: unknown\n";
         return;
     }
     for (const auto& stmt : funcDef.body()->statements) {

furc/src/front/parser.cpp

@@ -59,8 +59,8 @@ ast::declaration_node_h parser::parse_declaration() {
             if (peek.has_error()) return error_handle(peek);
             switch (peek->type) {
             case token_t::LBrace: {
-                ast::body_h body = parse_body();
-                if (body.has_error()) return body;
+                ast::body_r body = parse_body();
+                if (body.has_error()) return ast::node_handle<ast::node>(body.error().location, "Body error");
                 return ast::function_definition_node_h{ first->location, m_arena, *name, std::move(body) };
             }
             case token_t::Semicolon: {
@@ -367,11 +367,11 @@ ast::expression_node_h parser::parse_expression_rhs(ast::expression_node_h&& ini
     return lhs;
 }
 
-ast::body_h parser::parse_body() {
+ast::body_r parser::parse_body() {
     ast::body body;
 
     auto begin = eat_token(token_t::LBrace);
-    if (begin.has_error()) return error_handle(begin);
+    if (begin.has_error()) return ast::body_r(ast::error{ begin.error().location });
     body.begin = begin->location;
 
     while (!peek_token().has_error() && peek_token()->type != token_t::None && peek_token()->type != token_t::RBrace) {
@@ -379,10 +379,10 @@ ast::body_h parser::parse_body() {
     }
 
     auto end = eat_token(token_t::RBrace);
-    if (end.has_error()) return error_handle(end);
+    if (end.has_error()) return ast::body_r(ast::error{ end.error().location });
     body.end = end->location;
 
-    return { begin->location, body };
+    return body;
 }
 
 ast::node_handle<ast::node> parser::error_handle(const token_r& result) {