Like this
auto func() {
std::nullptr_t p;
p=nullptr;
return p;
}
I can build this code in msvc, but error in gcc
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1what error do you get? – 463035818_is_not_an_ai Feb 09 '22 at 08:42
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1Perhaps MSVC supports it in the compiler directly instead of relying on the standard library to define it. – chris Feb 09 '22 at 08:43
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4Because a compiler is not required to reject code that doesn't include the appropriate header. – molbdnilo Feb 09 '22 at 08:46
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1I don't see any question anywhere in there. It seems to me that "So?" is a complete answer. Did you expect something different? If so, what did you expect and why did you expect it? – David Schwartz Feb 09 '22 at 08:51
1 Answers
4
std::nullptr_t is defined in <cstddef>, to use it you must include that header. That does not imply that your code must fail to compile when you do not include the header.
Due to the way includes work in C++ you often can get away without explicitly including a header, but the commonly accepted rule is that you should include what you use to ensure that your code is portable. Here it is not a transitive include that makes it work, but MSVC decided to have std::nullptr_t defined without any explicit include. That does not mean that you should not include what you use.
TL;DR: Include headers for what you use to write portable code.
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