[cfe-commits] [PATCH] Suggested rewording for lamba return values

[Aaron Ballman]

On Thu, May 24, 2012 at 12:50 AM, Richard Smith <richard at metafoo.co.uk> wrote:
> On Tue, May 22, 2012 at 6:54 PM, Aaron Ballman <aaron at aaronballman.com>
> wrote:
>>
>> When a lambda expression omits the return type information, the
>> standard requires the lambda statement body to be a single return
>> statement.  However, as a language extension, we (and several other
>> compilers) support determining the return type if all of the
>> function's return types agree.
>>
>> The problem is, the wording for the warning we emit is a bit difficult
>> to parse.  It's a semantically correct statement, but it's not
>> immediately obvious what the problem is or how to rectify it.
>> Consider:
>>
>> auto i = []() { static const int foo = 12; return &foo; }();
>>
>> This will emit a diagnostic that says "C++11 requires lambda with
>> omitted result type to consist of a single return statement" --
>> however, a likely initial response to this is "but I do only have a
>> single return statement!"
>>
>> This patch rewords the diagnostic to be a bit more clear (hopefully):
>> "C++11 requires a lambda expression with omitted result type to
>> consist solely of a return statement"
>>
>> Thoughts?
>
>
> I would be in favor of removing the warning entirely, now that Clang 3.1 has
> shipped. The C++ core working group has already agreed that this should be
> allowed. It's currently under consideration by the evolution working group,
> whom I think are unlikely to say no -- and if they do, we will have time to
> react before 3.2 is released.

That would certainly work as well -- is there a general preference one
way or the other?

~Aaron