Hi,<div><br></div><div>Has any thought been given to putting the feature-test macros into an implementation-supplied header, instead of predefining them? This would allow us to remove the cost associated with predefining these macros, for translation units which don&#39;t need them. Instead, we could supply a single predefined macro indicating whether the header is available, and user code would write something like:</div>
<div><br></div><div>#ifdef __cpp_lib_header_features</div><div>#include &lt;features&gt;</div><div>#endif</div><div><br></div><div>#ifdef __cpp_relaxed_constexpr</div><div>constexpr</div><div>#endif</div><div>size_t strlen(const char *p) { /* ... */ }</div>
<div><br></div><div>... and so on.</div>