[PATCH] Decorate string_view members with nonnull attribute

[Jonathan Wakely]

On 14/06/18 17:51 +0100, Jonathan Wakely wrote:
>On 14/06/18 10:46 -0600, Martin Sebor wrote:
>>On 06/13/2018 10:30 AM, Jonathan Wakely wrote:
>>>The C++ committee has confirmed that passing a null pointer to the
>>>unary basic_string_view constructor is undefined. This removes the check
>>>from our implementation, and adds the nonnull attribute to warn when the
>>>compiler can detect undefined input.
>>>
>>>Any objections to this change?
>>
>>I have a general question about using the new C++ attributes in
>>libstdc++ (standard or otherwise): what does C++ have to say about
>>programs that define macros with the same names?  E.g., is this
>>a valid program?
>>
>> #define nonnull "..."
>> ...
>> #include <string_view>
>>
>>How about:
>>
>> #define noreturn "..."
>> ...
>> #include <string_view>
>>
>>The view in WG14 is that the corresponding C programs (if C2X
>>were to adopt the proposed C++ attributes) would be valid and
>>that it's up to implementations to make it work.
>
>Good point, I suppose I have to use __attribute__((__nonnull__))
>instead. The reason I didn't is that I find the grammar for the
>position of C++11 attributes much easier to understand. But in this
>instance the same location works for either.

Nobody's objected to the patch in princple, so I'll commit this
version, using __attribute__((__nonnull__)) instead of
[[gnu::nonnull].


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