PING 2 [PATCH] integer overflow checking builtins in constant expressions

[Martin Sebor <msebor@gmail.com>]

Ping 2 of the following patch:
   https://gcc.gnu.org/ml/gcc-patches/2016-05/msg00013.html

On 05/09/2016 10:38 AM, Martin Sebor wrote:
> Pinging the following patch:
>    https://gcc.gnu.org/ml/gcc-patches/2016-05/msg00013.html
>
> On 05/01/2016 10:39 AM, Martin Sebor wrote:
>> c/68120 - can't easily deal with integer overflow at compile time,
>> is an enhancement request to make the integer overflow intrinsics
>> usable in constant expressions in C (in addition to letting them
>> be invoked with just two arguments).
>>
>> The inability to use the built-ins in constant expressions also
>> limited to non-constexpr the contexts in which the patch for c++/
>> 69517 - SEGV on a VLA with excess initializer elements, was able
>> to prevent the SEGV.  This limitation is noted in c++/70507 -
>> integer overflow builtins not constant expressions.
>>
>> The attached patch implements the request in c/68120 for both
>> the C and C++ front-ends.  It stops short of providing the new
>> __builtin_add_wrapv function requested in c/68120.  It doesn't
>> seem necessary since the same functionality is available with
>> the patch via the existing built-ins.
>>
>> With this enhancement in place it will be possible to add the
>> C++ VLA checking to constexpr functions and fully resolve c++/
>> 69517 (which I plan to do next).
>>
>> While testing the patch, I also noticed an minor inconsistency
>> in the text of the diagnostic GCC issues for invalid calls to
>> the built-ins with insufficient numbers of arguments:  for one
>> set of built-ins the error says: "not enough arguments," while
>> for another it says: "too few arguments."  I raised PR c/70883
>> - inconsistent error message for calls to __builtin_add_overflow
>> with too few arguments, for this and include a fix in this patch
>> as well.
>>
>> Martin
>>
>> PS The enhancement to call the type-generic built-ins with a null
>> pointer is not available in C++ 98 mode because GCC doesn't allow
>> null pointers in constant expressions.  Since C and later versions
>> of C++ do, it seems that it might be worthwhile to relax the rules
>> and accept them in C++ 98 as well so that the built-ins can be used
>> portably across all versions of C++.
>>
>