c++ bindings: fix all pointer parameters being effectively optional

tools/genbinding.cpp

@@ -293,16 +293,16 @@ namespace ImGui {
 
  struct nullopt_t {
  constexpr explicit nullopt_t(int) {}
- operator std::nullptr_t() const { return nullptr; }
  };
- constexpr details::nullopt_t nullopt { 0 };
+ constexpr nullopt_t nullopt { 0 };
 
  template<typename T, typename E = void>
  class optional {
  public:
  using value_type = T*;
  optional(nullopt_t) : m_present { false } {}
  optional(const T v) : m_value { v }, m_present { true } {}
+ optional(value_type) = delete;
  operator value_type() { return m_present ? &m_value : nullptr; }
 
  private:
@@ -396,9 +396,9 @@ namespace ImGui {
  stream << "details::function<" << func.type << '(';
  CommaSep cs { stream };
  for(const Argument &arg : func.args) {
- if(arg.isOptional() && !arg.isOutput()) {
+ if(arg.isOptional()) {
  cs << "details::optional<";
- if(arg.type.isScalarPtr())
+ if(!arg.isOutput() && arg.type.isScalarPtr())
  stream << arg.type.removePtr();
  else
  stream << arg.type;