[PATCH] Fix overflow in __gnu_cxx::__numeric_traits::__min

[Jonathan Wakely]

On 01/12/17 15:22 +0100, Paolo Carlini wrote:
>Hi,
>
>On 01/12/2017 15:11, Jonathan Wakely wrote:
>>On 01/12/17 14:02 +0000, Jonathan Wakely wrote:
>>>Is there a reason we left-shift into the sign bit, causing undefined
>>>behaviour? The approach used in std::numeric_limits seems better.
>>
>>The current code warns with -Wpedantic -Wsystem-headers:
>>
>>/usr/include/c++/7/ext/numeric_traits.h:58:35: warning: overflow in 
>>implicit constant conversion [-Woverflow]
>>Â Â Â Â Â  static const _Value __min = __glibcxx_min(_Value);
>>Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  ^~~~~~~~~~~~~
>Many details can be found in c++/52119. Which should probably be 
>updated, right?
>
>At the time I handled the libstdc++ side of the issue, and for some 
>reason forgot to fix at the same time the ext/numeric_traits bits. I 
>have no idea why, maybe to be conservative, in a way.

Huh, so is the warning wrong? Is it only undefined in C++98?