[PATCH] Help compiler detect invalid code

[François Dumont]

Some more tests have revealed  a small problem in is_sorted test. It was 
revealed by the Debug mode but not in a clean ways so for the moment I 
prefer to fix it and I'll add a _neg test when Debug is able to report 
it correctly.

I've also added a _neg test for equal which doesn't need Debug mode.

OK to commit ?

François



On 9/20/19 7:08 AM, François Dumont wrote:
> I already realized that previous patch will be too controversial to be 
> accepted.
>
> In this new version I just implement a real memmove in __memmove so 
> that in copy_backward there is no need for a shortcut to a more 
> defensive code.
>
> I'll see if in Debug mode I can do something.
>
> François
>
>
> On 9/19/19 10:27 PM, François Dumont wrote:
>> Hi
>>
>> Â Â Â  I start working on making recently added constexpr tests to work 
>> in Debug mode.
>>
>> Â Â Â  It appears that the compiler is able to detect code mistakes 
>> pretty well as long we don't try to hide the code intention with a 
>> defensive approach. This is why I'd like to propose to replace '__n > 
>> 0' conditions with '__n != 0'.
>>
>> Â Â Â  The result is demonstrated by the constexpr_neg.cc tests. What do 
>> you think ?
>>
>> Â Â Â  * include/bits/stl_algobase.h (__memmove): Return _Tp*.
>> Â Â Â  (__memmove): Loop as long as __n is not 0.
>> Â Â Â  (__copy_move<>::__copy_m): Likewise.
>> Â Â Â  (__copy_move_backward<>::__copy_move_b): Likewise.
>> Â Â Â  * testsuite/25_algorithms/copy/constexpr.cc: Add check on copied 
>> values.
>> Â Â Â  * testsuite/25_algorithms/copy_backward/constexpr.cc: Likewise.
>> Â Â Â  * testsuite/25_algorithms/copy/constexpr_neg.cc: New.
>> Â Â Â  * testsuite/25_algorithms/copy_backward/constexpr.cc: New.
>>
>> Â Â Â  I'll submit the patch to fix Debug mode depending on the decision 
>> for this one.
>>
>> François
>>
>

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