Add forward type declaration representation

include/elna/boot/semantic.h

@@ -0,0 +1,75 @@
+/* Name analysis.
+   Copyright (C) 2025 Free Software Foundation, Inc.
+
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include <string>
+#include <vector>
+
+namespace elna
+{
+namespace boot
+{
+    class alias_type;
+    class record_type;
+    class union_type;
+    class primitive_type;
+
+    class type
+    {
+    public:
+        virtual alias_type *is_alias();
+        virtual primitive_type *is_primitive();
+        virtual record_type *is_record();
+        virtual union_type *is_union();
+
+        virtual ~type() = 0;
+    };
+
+    class alias_type : public type
+    {
+    public:
+        alias_type *is_alias() override;
+
+        type *reference{ nullptr };
+    };
+
+    class primitive_type : public type
+    {
+    public:
+        std::string identifier;
+
+        primitive_type(const std::string& identifier);
+
+        primitive_type *is_primitive() override;
+    };
+
+    class record_type : public type
+    {
+    public:
+        std::vector<std::pair<std::string, type *>> fields;
+
+        record_type *is_record() override;
+    };
+
+    class union_type : public type
+    {
+    public:
+        std::vector<std::pair<std::string, type *>> fields;
+
+        union_type *is_union() override;
+    };
+}
+}

include/elna/gcc/elna-generic.h

@@ -19,6 +19,7 @@ along with GCC; see the file COPYING3.  If not see
 
 #include "elna/boot/ast.h"
 #include "elna/boot/symbol.h"
+#include "elna/boot/semantic.h"
 #include "elna/gcc/elna-tree.h"
 
 #include "config.h"
@@ -34,20 +35,15 @@ namespace elna
 {
 namespace gcc
 {
-    struct type
-    {
-        type() {}
-        type(tree resolved): resolved(resolved) {}
-        type(std::shared_ptr<type> reference): reference(reference) {}
-
-        tree resolved{ NULL_TREE };
-        std::shared_ptr<type> reference;
-    };
-
     class declaration_visitor final : public boot::empty_visitor
     {
         std::shared_ptr<symbol_table> symbols;
-        std::unordered_map<std::string, std::shared_ptr<type>> unresolved;
+        std::unordered_map<std::string, boot::alias_type *> unresolved;
+
+        boot::type *build_type(boot::type_expression *type_expression);
+        boot::record_type *build_record(boot::record_type_expression *type_expression);
+        boot::union_type *build_union(boot::union_type_expression *type_expression);
+        tree get_inner_alias(const boot::alias_type& t);
 
     public:
         declaration_visitor(std::shared_ptr<symbol_table> symbol_table);