Re: [PATCH] declare std::array members attribute const [PR101831]

[Martin Sebor <msebor@gmail.com>]

On 2/1/22 12:48, Jonathan Wakely wrote:
> On Tue, 1 Feb 2022 at 18:54, Martin Sebor via Libstdc++
> <libstdc++@gcc.gnu.org> wrote:
>>
>> Passing an uninitialized object to a function that takes its argument
>> by const reference is diagnosed by -Wmaybe-uninitialized because most
>> such functions read the argument.  The exceptions are functions that
>> don't access the object but instead use its address to compute
>> a result.  This includes a number of std::array member functions such
>> as std::array<N>::size() which returns the template argument N.  Such
>> functions may be candidates for attribute const which also avoids
>> the warning.  The attribute typically only benefits extern functions
>> that IPA cannot infer the property from, but in this case it helps
>> avoid the warning which runs very early on, even without optimization
>> or inlining.  The attached patch adds the attribute to a subset of
>> those member functions of std::array.  (It doesn't add it to const
>> member functions like cbegin() or front() that return a const_iterator
>> or const reference to the internal data.)
>>
>> It might be possible to infer this property from inline functions
>> earlier on than during IPA and avoid having to annotate them explicitly.
>> That seems like an enhancement worth considering in the future.
>>
>> Tested on x86_64-linux.
>>
>> Martin
> 
> new file mode 100644
> index 00000000000..b7743adf3c9
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/23_containers/array/iterators/begin_end.cc
> @@ -0,0 +1,56 @@
> +// { dg-do compile { target c++11 } }
> +//
> +// Copyright (C) 2011-2022 Free Software Foundation, Inc.
> 
> Those dates look wrong. I no longer bother putting a license text and
> copyright notice on simple tests like this. It's meaningless to assert
> copyright on something so trivial that doesn't do anything.
> 

Should I take to mean that you're okay with the rest of the change
(i.e., with the notice removed)?

Martin