diff --git a/base_arena.cpp b/base_arena.cpp
index 1133cbe..83cb045 100644
--- a/base_arena.cpp
+++ b/base_arena.cpp
@@ -79,7 +79,6 @@ arena_push_size(Arena *a, size_t size) {
 #define push_struct_copy(a, T, p) (T *)push_copy(a, p, sizeof(T))
 CORE_Static void *
 push_copy(Arena *a, void *p, size_t size) {
-    if (p == 0) return 0;
     void *result = arena_push_size(a, size);
     memory_copy(result, p, size);
     return result;
diff --git a/base_data_structures.cpp b/base_data_structures.cpp
index a960789..e3a0ad2 100644
--- a/base_data_structures.cpp
+++ b/base_data_structures.cpp
@@ -76,6 +76,7 @@ struct Array {
         allocator = a;
         data = allocate_array(a, T, size);
         cap = size;
+        len = 0;
     }
 
     Array<T> copy(Allocator *a) {
diff --git a/core_codegen_c_language.cpp b/core_codegen_c_language.cpp
index b84a870..2b65aaf 100644
--- a/core_codegen_c_language.cpp
+++ b/core_codegen_c_language.cpp
@@ -834,9 +834,15 @@ compile_to_c_code() {
 
     String core_stringify(Ast *);
     For(pctx->ordered_decls) {
+        Ast *copy = ast_copy(it, 0);
         String r = core_stringify(it);
+        printf("\n-----REAL!!!------\n");
+        printf("%s\n", r.str);
+        r = core_stringify(copy);
+        printf("\n-----COPY!!!------\n");
         printf("%s\n", r.str);
     }
+    pctx->gen.reset();
 
 #if 0
     int di = 0;
diff --git a/core_polymorph.cpp b/core_polymorph.cpp
index 2aec667..7806db6 100644
--- a/core_polymorph.cpp
+++ b/core_polymorph.cpp
@@ -227,6 +227,7 @@ end_of_switch:
 
 #define ast_create_copy(parent_scope, T, ast) (T *)ast__create_copy(parent_scope, sizeof(T), ast)
 Ast *ast__create_copy(Ast_Scope *parent_scope, size_t size, Ast *ast) {
+    if (ast == 0) return 0;
     Ast *result = (Ast *)push_copy(pctx->perm, ast, size);
     result->parent_scope = parent_scope;
     result->di = ++pctx->unique_ids;
@@ -242,9 +243,9 @@ Ast *ast_copy(Ast *ast, Ast_Scope *parent_scope) {
             Ast_Scope *src = (Ast_Scope *)ast;
             Ast_Scope *dst = ast_create_copy(parent_scope, Ast_Scope, src);
 
-            free_all_nodes(&dst->decls);
+            dst->decls = {};
             For(src->decls) {
-                Ast_Decl *copy = (Ast_Decl *)ast_copy(it, dst);
+                Ast_Decl *copy = (Ast_Decl *)ast_copy(it, src);
                 add(pctx->perm, &dst->decls, copy);
             }
 
diff --git a/core_printer.cpp b/core_printer.cpp
index 81babd8..b22c665 100644
--- a/core_printer.cpp
+++ b/core_printer.cpp
@@ -93,6 +93,7 @@ void core__stringify(Ast *ast) {
             Ast_Scope *n = (Ast_Scope *)ast;
 
             global_indent += 1;
+            genln("@%u", n->di);
             For(n->decls) {
                 genln("");
                 core__stringify(it);
@@ -109,11 +110,12 @@ void core__stringify(Ast *ast) {
 
         case AST_IDENT: {
             Ast_Atom *n = (Ast_Atom *)ast;
-            gen("%Q", n->intern_val);
+            gen("%Q@%u", n->intern_val, n->di);
         } break;
+
         case AST_VALUE: {
-            Ast_Atom *n = (Ast_Atom *)ast;
-            gen("@%Q", n->pos->string);
+            Ast_Atom *n = (Ast_Atom *)ast; //@todo: proper value
+            gen("%Q@%u", n->pos->string, n->di);
         } break;
 
         case AST_INDEX: {
@@ -121,13 +123,13 @@ void core__stringify(Ast *ast) {
             core__stringify(n->expr);
             gen("[");
             core__stringify(n->index);
-            gen("]");
+            gen("]@%u", n->di);
         } break;
 
         case AST_UNARY: {
             Ast_Unary *n = (Ast_Unary *)ast;
-            gen("%Q", n->pos->string);
             core__stringify(n->expr);
+            gen("%Q@%u", n->pos->string, n->di);
         } break;
 
         case AST_BINARY: {
@@ -135,6 +137,7 @@ void core__stringify(Ast *ast) {
             core__stringify(n->left);
             gen("%Q", n->pos->string);
             core__stringify(n->right);
+            gen("@%u", n->di);
         } break;
 
         case AST_CALL_ITEM: {
@@ -148,7 +151,7 @@ void core__stringify(Ast *ast) {
                 gen(" = ");
             }
             core__stringify(n->item);
-
+            gen("@%u", n->di);
         } break;
 
         case AST_CALL: {
@@ -160,6 +163,7 @@ void core__stringify(Ast *ast) {
                 if (!n->exprs.is_last(&it)) gen(",");
             }
             gen(")");
+            gen("@%u", n->di);
         } break;
         case AST_COMPOUND: {
             Ast_Call *n = (Ast_Call *)ast;
@@ -174,6 +178,7 @@ void core__stringify(Ast *ast) {
             }
             global_indent -= 1;
             genln("}");
+            gen("@%u", n->di);
         } break;
 
         case AST_TYPE_OF:
@@ -200,6 +205,7 @@ void core__stringify(Ast *ast) {
             gen("(");
             core__stringify(n->expr);
             gen(")");
+            gen("@%u", n->di);
         } break;
 
         case AST_SWITCH: {
@@ -210,6 +216,7 @@ void core__stringify(Ast *ast) {
                 core__stringify(it);
             }
             core__stringify(n->default_scope);
+            gen("@%u", n->di);
         } break;
 
         case AST_SWITCH_CASE: {
@@ -219,6 +226,7 @@ void core__stringify(Ast *ast) {
                 core__stringify(it);
             }
             core__stringify(n->scope);
+            gen("@%u", n->di);
         } break;
 
         case AST_VAR_UNPACK: {
@@ -233,10 +241,12 @@ void core__stringify(Ast *ast) {
 
         case AST_PASS: {
             genln("pass");
+            gen("@%u", ast->di);
         } break;
 
         case AST_BREAK: {
             genln("break");
+            gen("@%u", ast->di);
         } break;
 
         case AST_NAMESPACE: {