NFD » ndn-cxx

Junxiao Shi wrote:

I disagree with this because compiler is allowed to halt and catch fire when seeing #pragma.

Which in technical terms means..?

I'm not in favor of the change.

Even though it is shorter and more concise, there is still a tiny risk of the pragma not supported (= more my personal preference). I also not sure what is implication of pragma once with conjunction of precompiled headers.

I seriously doubt you'll find a compiler that supports C++11 but doesn't support #pragma once...

Anyway, I won't insist, since you both seem against it.

I also vote no. Depending on a non-standard feature for convenience is not worth it.

So... reject?

Junxiao Shi wrote:

#pragma is undefined behavior, as I read from some book.
HCF, launching missiles, or getting watermelon-sized hail are all acceptable.

That's incorrect. The behavior of #pragma is precisely defined by the standard when followed by STDC, and it's implementation-defined when not followed by STDC. See n1256 §6.10.6.

"Implementation-defined" means that each compiler implementation is allowed to behave however they choose, but also "Each implementation shall include documentation describing its characteristics and behavior in these respects", so the behavior is compiler-specific, but you can rely on it for that particular compiler. This is very different from "undefined behavior".