type_traits includes functional

[vinniefalco]

detail/type_traits.hpp can include <utility> instead of <functional> for access to std::reference_wrapper on C++20 and later

[vinniefalco]

@claude

[claude]

Claude finished @vinniefalco's task —— View job • claude/issue-210-20251204-0845 • Create PR ➔

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Issue #210: Optimize type_traits includes ✓

Task: Update detail/type_traits.hpp to include <utility> instead of <functional> for std::reference_wrapper on C++20 and later.

Todo List:

• Read detail/type_traits.hpp to understand current implementation
• Modify the file to conditionally include <utility> for C++20+
• Commit and push changes
• Provide PR creation link

Changes Made

Modified include/boost/http_proto/detail/type_traits.hpp:13-17 to conditionally include <utility> for C++20+ (__cplusplus >= 202002L), falling back to <functional> for older standards. This reduces header weight for C++20 and later builds while maintaining backward compatibility.

Before:

#include <functional>

After:

#if __cplusplus >= 202002L
#include <utility>
#else
#include <functional>
#endif

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