impl sizeof

parser.c

@@ -1659,8 +1659,25 @@ void parse_tenary(struct history *history) {
   make_exp_node(cond_node, tenary_node, "?");
 }
 
+void parse_sizeof(struct history *history) {
+  expect_keyword("sizeof");
+  expect_op("(");
+  struct datatype dtype;
+  parse_datatype(&dtype);
+  node_create(&(struct node){
+      .type = NODE_TYPE_NUMBER,
+      .llnum = datatype_size(&dtype),
+  });
+  expect_sym(')');
+}
+
 void parse_keyword(struct history *history) {
   struct token *token = token_peek_next();
+  if (S_EQ(token->sval, "sizeof")) {
+    parse_sizeof(history);
+    return;
+  }
+
   if (is_keyword_variable_modifier(token->sval) ||
       keyword_is_datatype(token->sval)) {
     parse_variable_function_or_struct_union(history);

test.c

@@ -1 +1,6 @@
-#include <stdarg_internal.h>
+struct abc {
+  int x;
+  int y;
+};
+
+int main() { return sizeof(struct abc); }