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Comment by dragontamer | Hacker News Reader

Because Microsoft implemented random_device correctly while MingW / GCC hasn't?

Its a bug in MingW. Which isn't a big deal because Microsoft Visual Studio Community Edition is an excellent IDE and compatible with OSS projects now.

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Could you point to the gcc bug? Note: the standard does not require a non-deterministic random_device, at least C++11 doesn't, so the behaviour as described in the stackoverflow link would be allowed.

There are a lot of things the C and C++ standards allow implementations to do, such as making int 16 bits, using one's complement for signed integers, (in C) only making the first 31 characters of identifiers significant, (in C++) not allowing any identifiers longer than one character, except those in the standard library, et cetera. This is because they are designed to be portable to a wide variety of compilers and target devices which might have limits that weren't envisioned at the time of writing the standard. Doesn't mean it's a good idea to write absolutely pathological implementations for no real reason other than laziness...

>This is because they are designed to be portable to a wide variety of compilers and target devices which might have limits that weren't envisioned at the time of writing the standard.

That's not really the case here, is it? If anything the bug is in the standard.

> std::random_device may be implemented in terms of an implementation-defined pseudo-random number engine if a non-deterministic source (e.g. a hardware device) is not available to the implementation.

Windows has a non-deterministic source (IE: The function CryptGenRandom). Therefore, this is a bug in MingW's implementation. CryptGenRandom is hard to use, but that's no excuse for MingW's developers to be lazy.

Pointing at a "mistake" in the spec when the intent of the spec is extremely clear is laziness. Pure and simple.

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