diff --git a/boot/ast.cc b/boot/ast.cc
index 5609939..a0c21ed 100644
--- a/boot/ast.cc
+++ b/boot/ast.cc
@@ -19,6 +19,191 @@ along with GCC; see the file COPYING3.  If not see
 
 namespace elna::boot
 {
+    void empty_visitor::not_implemented()
+    {
+        __builtin_unreachable();
+    }
+
+    void empty_visitor::visit(named_type_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(array_type_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(pointer_type_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(program *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(type_declaration *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(record_type_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(union_type_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(procedure_type_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(enumeration_type_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(variable_declaration *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(constant_declaration *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(procedure_declaration *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(assign_statement *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(if_statement *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(import_declaration *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(while_statement *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(return_statement *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(defer_statement *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(case_statement *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(procedure_call *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(unit *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(cast_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(traits_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(binary_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(unary_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(variable_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(array_access_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(field_access_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(dereference_expression *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(literal<std::int32_t> *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(literal<std::uint32_t> *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(literal<double> *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(literal<bool> *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(literal<unsigned char> *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(literal<std::nullptr_t> *)
+    {
+        not_implemented();
+    }
+
+    void empty_visitor::visit(literal<std::string> *)
+    {
+        not_implemented();
+    }
+
     node::node(const struct position position)
         : source_position(position)
     {
diff --git a/boot/semantic.cc b/boot/semantic.cc
index 5489959..a8f71ec 100644
--- a/boot/semantic.cc
+++ b/boot/semantic.cc
@@ -484,87 +484,15 @@ namespace elna::boot
     {
     }
 
-    void declaration_visitor::visit(named_type_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(array_type_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(pointer_type_expression *)
-    {
-    }
-
     void declaration_visitor::visit(program *program)
     {
         visit(static_cast<unit *>(program));
     }
 
-    void declaration_visitor::visit(type_declaration *)
-    {
-    }
-
-    void declaration_visitor::visit(record_type_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(union_type_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(procedure_type_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(enumeration_type_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(variable_declaration *)
-    {
-    }
-
-    void declaration_visitor::visit(constant_declaration *)
-    {
-    }
-
-    void declaration_visitor::visit(procedure_declaration *)
-    {
-    }
-
-    void declaration_visitor::visit(assign_statement *)
-    {
-    }
-
-    void declaration_visitor::visit(if_statement *)
-    {
-    }
-
     void declaration_visitor::visit(import_declaration *)
     {
     }
 
-    void declaration_visitor::visit(while_statement *)
-    {
-    }
-
-    void declaration_visitor::visit(return_statement *)
-    {
-    }
-
-    void declaration_visitor::visit(defer_statement *)
-    {
-    }
-
-    void declaration_visitor::visit(case_statement *)
-    {
-    }
-
-    void declaration_visitor::visit(procedure_call *)
-    {
-    }
-
     void declaration_visitor::visit(unit *unit)
     {
         for (import_declaration *const _import : unit->imports)
@@ -581,64 +509,4 @@ namespace elna::boot
             }
         }
     }
-
-    void declaration_visitor::visit(cast_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(traits_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(binary_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(unary_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(variable_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(array_access_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(field_access_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(dereference_expression *)
-    {
-    }
-
-    void declaration_visitor::visit(literal<std::int32_t> *)
-    {
-    }
-
-    void declaration_visitor::visit(literal<std::uint32_t> *)
-    {
-    }
-
-    void declaration_visitor::visit(literal<double> *)
-    {
-    }
-
-    void declaration_visitor::visit(literal<bool> *)
-    {
-    }
-
-    void declaration_visitor::visit(literal<unsigned char> *)
-    {
-    }
-
-    void declaration_visitor::visit(literal<std::nullptr_t> *)
-    {
-    }
-
-    void declaration_visitor::visit(literal<std::string> *)
-    {
-    }
 }
diff --git a/gcc/elna-generic.cc b/gcc/elna-generic.cc
index 620c32c..266470b 100644
--- a/gcc/elna-generic.cc
+++ b/gcc/elna-generic.cc
@@ -77,7 +77,7 @@ namespace elna::gcc
 
         if (!VOID_TYPE_P(TREE_VALUE(current_parameter)))
         {
-                error_at(call_location, "too few arguments, expected %i, got %lu",
+                error_at(call_location, "Too few arguments, expected %i, got %lu",
                         list_length(TYPE_ARG_TYPES(symbol_type)) - 1, arguments.size());
                 this->current_expression = error_mark_node;
         }
@@ -1179,46 +1179,6 @@ namespace elna::gcc
         this->current_expression = NULL_TREE;
     }
 
-    void generic_visitor::visit(boot::named_type_expression *type)
-    {
-        this->current_expression = TREE_TYPE(this->symbols->lookup(type->name));
-    }
-
-    void generic_visitor::visit(boot::array_type_expression *)
-    {
-        gcc_unreachable();
-    }
-
-    void generic_visitor::visit(boot::pointer_type_expression *type)
-    {
-        type->base().accept(this);
-
-        if (this->current_expression != NULL_TREE && this->current_expression != error_mark_node)
-        {
-            this->current_expression = build_global_pointer_type(this->current_expression);
-        }
-    }
-
-    void generic_visitor::visit(boot::record_type_expression *)
-    {
-        gcc_unreachable();
-    }
-
-    void generic_visitor::visit(boot::union_type_expression *)
-    {
-        gcc_unreachable();
-    }
-
-    void generic_visitor::visit(boot::procedure_type_expression *)
-    {
-        gcc_unreachable();
-    }
-
-    void generic_visitor::visit(boot::enumeration_type_expression *)
-    {
-        gcc_unreachable();
-    }
-
     void generic_visitor::visit(boot::defer_statement *statement)
     {
         enter_scope();
diff --git a/include/elna/boot/ast.h b/include/elna/boot/ast.h
index 28241c5..2f015df 100644
--- a/include/elna/boot/ast.h
+++ b/include/elna/boot/ast.h
@@ -131,6 +131,53 @@ namespace elna::boot
         virtual void visit(literal<std::string> *) = 0;
     };
 
+    /**
+     * Abstract visitor that doesn't visit any nodes by default.
+     */
+    class empty_visitor : public parser_visitor
+    {
+        [[noreturn]] void not_implemented();
+
+    public:
+        [[noreturn]] virtual void visit(named_type_expression *) override;
+        [[noreturn]] virtual void visit(array_type_expression *) override;
+        [[noreturn]] virtual void visit(pointer_type_expression *) override;
+        [[noreturn]] virtual void visit(program *) override;
+        [[noreturn]] virtual void visit(type_declaration *) override;
+        [[noreturn]] virtual void visit(record_type_expression *) override;
+        [[noreturn]] virtual void visit(union_type_expression *) override;
+        [[noreturn]] virtual void visit(procedure_type_expression *) override;
+        [[noreturn]] virtual void visit(enumeration_type_expression *) override;
+
+        [[noreturn]] virtual void visit(variable_declaration *) override;
+        [[noreturn]] virtual void visit(constant_declaration *) override;
+        [[noreturn]] virtual void visit(procedure_declaration *) override;
+        [[noreturn]] virtual void visit(assign_statement *) override;
+        [[noreturn]] virtual void visit(if_statement *) override;
+        [[noreturn]] virtual void visit(import_declaration *) override;
+        [[noreturn]] virtual void visit(while_statement *) override;
+        [[noreturn]] virtual void visit(return_statement *) override;
+        [[noreturn]] virtual void visit(defer_statement *) override;
+        [[noreturn]] virtual void visit(case_statement *) override;
+        [[noreturn]] virtual void visit(procedure_call *) override;
+        [[noreturn]] virtual void visit(unit *) override;
+        [[noreturn]] virtual void visit(cast_expression *) override;
+        [[noreturn]] virtual void visit(traits_expression *) override;
+        [[noreturn]] virtual void visit(binary_expression *) override;
+        [[noreturn]] virtual void visit(unary_expression *) override;
+        [[noreturn]] virtual void visit(variable_expression *) override;
+        [[noreturn]] virtual void visit(array_access_expression *) override;
+        [[noreturn]] virtual void visit(field_access_expression *) override;
+        [[noreturn]] virtual void visit(dereference_expression *) override;
+        [[noreturn]] virtual void visit(literal<std::int32_t> *) override;
+        [[noreturn]] virtual void visit(literal<std::uint32_t> *) override;
+        [[noreturn]] virtual void visit(literal<double> *) override;
+        [[noreturn]] virtual void visit(literal<bool> *) override;
+        [[noreturn]] virtual void visit(literal<unsigned char> *) override;
+        [[noreturn]] virtual void visit(literal<std::nullptr_t> *) override;
+        [[noreturn]] virtual void visit(literal<std::string> *) override;
+    };
+
     /**
      * AST node.
      */
diff --git a/include/elna/boot/semantic.h b/include/elna/boot/semantic.h
index a510c3c..1aa236b 100644
--- a/include/elna/boot/semantic.h
+++ b/include/elna/boot/semantic.h
@@ -128,51 +128,17 @@ namespace elna::boot
     };
 
     /**
-     * Collects global declarations.
+     * Collects global declarations without resolving any symbols.
      */
-    class declaration_visitor final : public parser_visitor, public error_container
+    class declaration_visitor final : public empty_visitor, public error_container
     {
     public:
         std::unordered_map<std::string, std::shared_ptr<alias_type>> unresolved;
 
         explicit declaration_visitor(const char *path);
 
-        void visit(named_type_expression *) override;
-        void visit(array_type_expression *) override;
-        void visit(pointer_type_expression *) override;
         void visit(program *program) override;
-        void visit(type_declaration *) override;
-        void visit(record_type_expression *) override;
-        void visit(union_type_expression *) override;
-        void visit(procedure_type_expression *) override;
-        void visit(enumeration_type_expression *) override;
-
-        void visit(variable_declaration *) override;
-        void visit(constant_declaration *) override;
-        void visit(procedure_declaration *) override;
-        void visit(assign_statement *) override;
-        void visit(if_statement *) override;
         void visit(import_declaration *) override;
-        void visit(while_statement *) override;
-        void visit(return_statement *) override;
-        void visit(defer_statement *) override;
-        void visit(case_statement *) override;
-        void visit(procedure_call *) override;
         void visit(unit *unit) override;
-        void visit(cast_expression *) override;
-        void visit(traits_expression *) override;
-        void visit(binary_expression *) override;
-        void visit(unary_expression *) override;
-        void visit(variable_expression *) override;
-        void visit(array_access_expression *) override;
-        void visit(field_access_expression *) override;
-        void visit(dereference_expression *) override;
-        void visit(literal<std::int32_t> *) override;
-        void visit(literal<std::uint32_t> *) override;
-        void visit(literal<double> *) override;
-        void visit(literal<bool> *) override;
-        void visit(literal<unsigned char> *) override;
-        void visit(literal<std::nullptr_t> *) override;
-        void visit(literal<std::string> *) override;
     };
 }
diff --git a/include/elna/gcc/elna-generic.h b/include/elna/gcc/elna-generic.h
index 54cad5d..ad74bc2 100644
--- a/include/elna/gcc/elna-generic.h
+++ b/include/elna/gcc/elna-generic.h
@@ -33,7 +33,7 @@ along with GCC; see the file COPYING3.  If not see
 
 namespace elna::gcc
 {
-    class generic_visitor final : public boot::parser_visitor
+    class generic_visitor final : public boot::empty_visitor
     {
         tree current_expression{ NULL_TREE };
         elna::boot::symbol_bag bag;
@@ -91,13 +91,6 @@ namespace elna::gcc
         void visit(boot::if_statement *statement) override;
         void visit(boot::import_declaration *) override;
         void visit(boot::while_statement *statement) override;
-        void visit(boot::named_type_expression *type) override;
-        void visit(boot::array_type_expression *) override;
-        void visit(boot::pointer_type_expression *type) override;
-        void visit(boot::record_type_expression *) override;
-        void visit(boot::union_type_expression *) override;
-        void visit(boot::procedure_type_expression *) override;
-        void visit(boot::enumeration_type_expression *) override;
         void visit(boot::return_statement *statement) override;
         void visit(boot::defer_statement *statement) override;
         void visit(boot::case_statement *statement) override;
diff --git a/source/main.elna b/source/main.elna
index 2da63e7..0f3d001 100644
--- a/source/main.elna
+++ b/source/main.elna
@@ -1074,12 +1074,6 @@ begin
   return return_code
 end;
 
-proc f();
-var x: Char;
-begin
-  x := '\x4'
-end;
-
 begin
   exit(process(count, parameters))
 end.