no_extern_c.h

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/*
 * Including system's headers inside `extern "C" { ... }` is not safe, as system
 * headers may have C++ code in them, and C++ code inside extern "C"
 * leads to syntactically incorrect code.
 *
 * This is because putting code inside extern "C" won't make __cplusplus define
 * go away, that is, the system header being included thinks is free to use C++
 * as it sees fits.
 *
 * Including non-system headers inside extern "C"  is not safe either, because
 * non-system headers end up including system headers, hence fall in the above
 * case too.
 *
 * Conclusion, includes inside extern "C" is simply not portable.
 *
 *
 * This header helps surface these issues.
 */

#ifdef __cplusplus
template<class T> class _IncludeInsideExternCNotPortable;
#endif