pp_macro_missing_expression.i:4: Error: Missing identifier for #ifdef.
pp_macro_missing_expression.i:7: Error: Missing identifier for #ifndef.
pp_macro_missing_expression.i:10: Error: Missing expression for #if.
pp_macro_missing_expression.i:14: Error: Missing expression for #elif.
pp_macro_missing_expression.i:21: Error: Missing expression for #elif.