Proposal: Disallow C++ “C wrapper” headers in Axmol core and maintained extensions

[halx99]

🚫 Proposal: Disallow C++ “C wrapper” headers in Axmol core and maintained extensions

Background

In Axmol’s core engine and extension libraries fully maintained by the Axmol team, we currently see mixed usage of C++ “C wrapper” headers (e.g. <cstdio>, <cstring>, <cstdlib>) alongside pure C headers (e.g. <stdio.h>, <string.h>).
This inconsistency introduces several problems:

• Namespace pollution: <cxxx> headers place symbols both in the global namespace and in std::, which can cause ambiguity and conflicts.
• Portability issues: Different compilers implement <cxxx> headers with subtle differences, making cross‑platform builds less predictable.
• Style inconsistency: Contributors may continue using legacy C APIs (printf, malloc, etc.) instead of modern C++ alternatives (fmt::format, std::vector, RAII).
• Maintenance overhead: Mixing styles makes the codebase harder to review and maintain.

Proposed Rule

For Axmol core and Axmol‑maintained extension libraries:

1. Ban inclusion of C++ “C wrapper” headers

   • Disallowed: <cstdio>, <cstdlib>, <cstring>, <ctime>, etc.

2. Allow inclusion of pure C standard headers where necessary

   • Allowed:
     • <stddef.h> (for size_t, ptrdiff_t, offsetof)
     • <stdint.h> (for fixed‑width integer types)
     • <string.h> (for memcpy, memmove, memset, memcmp)
     • <assert.h> (for assertions)

3. (include sutiable overloads math APIs), (include std::nullptr_t) allowed

4. Prefer modern C++ alternatives in core logic

   • I/O → fmt or std::format
   • Containers → std::vector, std::array, std::unique_ptr
   • Strings → std::string, std::string_view
   • Time → std::chrono

5. Platform adaptation layer exception

   • Direct inclusion of pure C headers is permitted when interfacing with OS APIs or third‑party C libraries.

Benefits

• Consistency: Clear separation between modern C++ usage and low‑level C API usage.
• Portability: Pure C headers are universally supported across compilers and platforms.
• Modernization: Encourages contributors to adopt modern C++ practices in Axmol’s core.
• Maintainability: Easier code review and onboarding for new contributors.

Action Items

• Add this rule to CODING_STYLE.md or CONTRIBUTING.md.
• Update CI/lint checks to flag usage of <cxxx> headers in Axmol core and maintained extensions.

PR: #3214